CTG043
Industrial Energy Efficiency
Accelerator
Guide to the brick sector
1
Contents
Executive summary ........................................................................................ 3
1 Introduction ................................................................................................ 6
1.1 Carbon Trust & Industrial Energy Efficiency Accelerator (IEEA) ....................... 6
1.2 Clay brick IEEA ......................................................................................... 6
2 Background to the clay bricks sector ........................................................... 8
2.1 How clay bricks are made .......................................................................... 8
2.2 Energy consumption of the sector ............................................................. 11
2.3 Theoretical energy requirement for brick-making ........................................ 15
2.4 The manufacturers and the supply chain .................................................... 17
2.5 Impact of Carbon Legislation ................................................................... 18
2.6 Progress on improving energy performance ................................................ 19
2.7 Business drivers ..................................................................................... 20
3. Methodology ............................................................................................. 21
3.1 Monitoring the pilot sites.......................................................................... 21
3.2 Engagement with the sector ..................................................................... 30
3.3 Business drivers and barriers ................................................................... 32
4. Key findings .............................................................................................. 34
4.1 Raw data trends ..................................................................................... 34
4.2 Where is energy used in brick-making?...................................................... 38
4.3 Process heat balances ............................................................................. 40
4.4 A more detailed look at the kiln and dryer .................................................. 43
4.5 The dryer ............................................................................................... 46
4.6 Electricity consumption in clay preparation and forming ............................... 48
4.7 The impact of product weight on energy consumption ................................. 50
4.8 The impact firing temperature on energy consumption ................................ 52
4.9 Alternative energy sources ....................................................................... 52
4.10 Summary of key findings ....................................................................... 53
5. Opportunities ............................................................................................ 55
5.1 Introduction ........................................................................................... 55
5.2 Best practice opportunities ....................................................................... 55
5.3 Opportunities for innovation ..................................................................... 58
5.4 Recommendations................................................................................... 65
Next steps – business cases for challenges ...................................................... 67
Co-firing of kilns with syngas ......................................................................... 68
Process heat recovery and utilisation ............................................................. 71
Redesign of kiln cars and car seals ................................................................. 73
Low air movement kiln .................................................................................. 75
Low carbon products ..................................................................................... 77
Tools to improve overall equipment effectiveness ............................................. 79
Appendix A: Site details ................................................................................ 83
Appendix B: Sector wide opportunities workshop ......................................... 84
Appendix C: Calculations .............................................................................. 86
Appendix D: Flow meter specification ........................................................... 87
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Executive summary
The clay brick sector has completed a seven-month collaboration, working towards
Phase 1 of the Carbon Trust’s Industrial Energy Efficiency Accelerator (IEEA)
programme. This is the first part of a three phase programme which aims to identify,
develop and demonstrate energy efficiency innovations, and share the business cases in
their favour.
CO2 saving based on business as usual,
%
Energy efficiency has always been an important part of operational management in the
sector. Companies have previously made good use of innovations such as flat arch kilns,
ceramic fibre and variable speed drives. In recent years the brick sector has found it
increasingly difficult to further reduce energy consumption as current best practice has
been almost universally adopted already. If the current pattern of energy efficiency
improvement is maintained, it
50.0%
will take 23 years to reduce
CO2 emission by 20 per cent.
40.0%
The projects identified as a
30.0%
result of this study allow CO2
emissions to be reduced much
20.0%
more
quickly.
If
all
the
technologies are successful the
actual
10.0%
sector as a whole could save as
0.0%
much as 300,000 tonnes/year.
2000
2005
2010
2015
2020
2025
2030
A comparison of the two
scenarios is shown here.
year
The brick sector emits close to
one million tonnes of CO2 per
year through the use of fossil fuels – emissions equivalent to a city the size of Coventry.
Energy costs the sector over £100 million/year, a cost which is expected to continue to
rise above the rate of inflation for the foreseeable future. The cost of emitting carbon is
also expected to rise due to legislation such as the EU ETS, CCAs and CRC. Currently,
carbon emissions cost £12/tonne for EU ETS and, from 2012, £16/tonne for the CRC.
business as usual
accelerator technologies
The sector’s emissions therefore represent a potential additional cost of £12 to £16
million/year. However, if a carbon floor price of, for example, £30/tonne is agreed, as
the British Government is currently considering, the cost will increase to £30
million/year. This will increase the cost of fossil fuel derived energy by 25 per cent. It is
clear that by 2020 the cost of CO2 emissions will no longer be the minor part of the total
cost of fossil fuels it is now. Developing new technologies to cut CO2 emissions for the
sector will help mitigate those costs.
By measuring the energy consumption of three brickworks, we have been able to
attribute the sector’s CO2 emissions to specific processes. This is for a key stage in
determining a strategy for developing new techniques and technologies. The breakdown
of emissions is shown here and clearly shows that kilns and dryers are a crucial focus
for new energy efficient technologies. However, the power consumption of other
processes adds up to over 100,000 tonnes of CO2 – so potential reductions through best
practice and innovations are also an important consideration.
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Other compressors,
lighting, etc,
6.6%
Preparation
& Making,
4.6%
Setting, 1.0%
Dehacking,
0.3%
Drying &
Firing, 87.5%
Sector CO2 Emssions by Process
In total, the sector and its supply chain identified and assessed nearly 40 energy
efficiency ideas, all of which are described in the main report. A process of consultation
led by the British Ceramic Confederation and involving 20 manufacturers, equipment
suppliers and research organisations led to the selection of six technologies which have
been recommended for further development.
Together the six technologies tackle almost all of the emissions emitted by the process
of manufacturing bricks. They include projects with different levels of risk and market
readiness, and they represent a significant opportunity for the sector to work
collectively with the Carbon Trust to gain the following benefits:






an increase in the choice of energy efficiency options available;
an increase in the pace of CO2 reduction;
cost savings as a result of energy savings;
increased revenues or decreased costs from carbon trading;
lower dependency on fossil fuels and the supply risks expected in the future;
a rejuvenation of process development in the UK and an increase in skills within the
sector.
For technology suppliers and researchers, these projects offer an opportunity to gain
new skills, get a head start in the exploitation of the new technology and generate a
significant new income stream.
All the recommended technologies are forecast to have payback periods of between two
and five years once fully developed. They represent the options best able to deliver
significant CO2 reductions. The technologies are shown in the table below, with their
estimated costs and savings:
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Challenge
Project
Cost1, £
Potential
sector
wide CO2
saving
£500k to £1
million
200,000
25,000
1
Co-firing of kilns with
Syngas
2
Process heat recovery &
utilisation
£400k
3
Redesign of kiln cars
£300k
9,500
4
Low air movement kiln
£500k
40,000
5
Low carbon products
£300k
20,000
6
Tool to improve process &
equipment effectiveness
£300k
13,000
1
An estimate of the cost of a typical installation after development which is divided
between the participants and the Carbon Trust.
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1. Introduction
1.1 Carbon Trust & Industrial Energy Efficiency Accelerator
(IEEA)
The Carbon Trust is a not-for-profit company with the mission to accelerate the move to
a low carbon economy. It provides specialist support to help businesses and the public
sector cut carbon emissions, save energy and commercialise low carbon technologies.
By stimulating low carbon action the Carbon Trust contributes to the UK’s key goals of
lower carbon emissions, the development of low carbon businesses, increased energy
security and associated jobs.
The Industrial Energy Efficiency Accelerator (IEEA) is a major element of the current
programme of work being undertaken by the Carbon Trust. The IEEA aims to identify
and accelerate the take up of innovations by industry to reduce CO2 emissions.
The IEEA will enable the Carbon Trust to collaborate with industrial sectors to identify
low carbon innovations that go beyond “good practice”, which require support for their
implementation and roll out. To achieve this, the IEEA is split into three distinct stages:
The IEEA Programme began in 2008 and is currently working with 14 sectors to identify,
implement and replicate carbon saving innovations.
1.2 Clay brick IEEA
We identified the clay brick sector as an area which has made significant strides in
improving the energy efficiency of its operations and would benefit from the IEEA
programme to continue towards low carbon operations. The UK sector is represented by
the British Ceramic Confederation (BCC), and our engagement with the sector and its
supply chain was facilitated by Dave Beardsworth, the BCC’s technical director. The
project began on 1 March 2010.
The clay brick sector is part of the wider ceramic industry, which also includes the
manufacture of clay tiles, pipes, tableware, sanitaryware, refractories and industrial
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ceramics. The brick sector dominates UK production in tonnage terms and in energy
consumption. It is therefore the primary focus of this project, but many of the energy
efficiency opportunities identified here are also relevant to the other ceramic industries.
2
Committee on Climate Change Report, December 2008.
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2. Background to the clay bricks sector
2.1 How clay bricks are made
Most clay bricks made in the UK are used in the external walls of buildings. Some are
also used in retaining walls, bridges, pavements or decorative internal walls. Brick
shape tiles are also made, which can be stuck onto panels to give the appearance of
bricks.
Brick manufacture is part of an industry known as “heavy clay”, which distinguishes it
from the production of other ceramic items such as tableware, sanitaryware and
refractories. Roof tiles and clay pipes also come under the umbrella of heavy clay,
though their carbon footprint is much smaller than that of bricks. However, many of the
technologies described here will be relevant to these sectors.
Clay bricks are, as the name suggests, made from clay - a very fine sedimentary
material laid down in seas, lakes and slow moving rivers. Clay is extracted in quarries
either as the main mineral or in conjunction with another natural resource such as coal.
Most bricks in the UK are made from the following:

Carboniferous shale

Etruria marl

Keuper marl

Weald clay

Lower Oxford clay.
Others such as boulder and alluvial clays are also used, but those listed above are the
most common.
After it has been extracted, clay is stockpiled before being used to make bricks through
the following key steps:
1. Clay preparation
The clay is crushed and ground, before being blended with additives to achieve the
desired physical properties. Water may then be added to achieve the required
consistency.
2. Forming
The bricks are then shaped, most commonly through the extrusion of a continuous
column which is then cut to size. They can also be mechanically pressed into moulds, be
made by hand, by throwing clay into a wooden mould, or by machines designed to
mechanise the handmade process (known as the soft mud process).
Approximately 78 per cent of current production is extruded and 22 per cent is through
the soft mud process. Handmade production makes up a very small amount of the
output.
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Bricks can be made in many different sizes but the market is dominated by units that
are 65mm high, 215mm long and 103mm wide. Some plants also make bricks that are
73mm high, to be compatible with older properties and used for extensions and
refurbishment.
3. Drying
The moisture in the extruded or pressed green bricks is removed in a dryer (normally
down to levels of one per cent or below) to make sure that they can be safely handled
and fired. The bricks shrink during the drying process, so it needs to be carried out
carefully to make sure that they don’t crack. Drying is very heat intensive as a large
amount of water needs to be evaporated. Most dryers rely on recovered heat from the
kiln to provide the bulk of their heat requirements.
4. Firing
Dried bricks are fired in kilns at temperatures between 900 oC and 1100oC. The intense
heat changes the chemical make-up of the clays, and partly melts them to give the
desired strength and appearance.
There are three main types of kiln:



Tunnel kilns in which stacks of bricks are transported continuously through the
kiln. These are the most common kilns used, and are responsible for most brick
production in the UK.
Intermittent kilns in which bricks are placed in a single compartment, fired and
removed on a batch basis. These are used for small throughput operations.
Continuous chamber kilns in which a number of intermittent kilns are built into a
single structure which are heated in sequence to give continuous production and to
recover some of the waste heat. These were once relatively common but are no
longer widely used as they are expensive to build and difficult to load and unload.
5. Inspection and packing
After firing, the bricks are unloaded and inspected for appearance in a process known as
“dehacking”, before being packed and dispatched.
A typical factory layout is shown below in Figure 1 and the main brick making processes
are shown in Figure 2.
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
Figure 1: A typical modern factory layout

Figure 2: The main brick-making processes
Extrusion
Forming
Quarry
Stockpile
Clay Preparation
Setting
Softmud
Packing & Dispatch
Dehacking
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Firing
Drying
10
2.2 Energy consumption of the sector
This section summarises the energy use of the sector and some of the key drivers
influencing its consumption and energy performance.
Most of the energy consumed in a brickworks (and most of the carbon emitted) is the
result of the firing process (??%). Drying is also energy intensive, but requires less fuel
to be directly supplied as heat is recovered from the kilns for use within the driers. We
estimate that approximately 20 per cent of the fuel consumed is used for drying across
the sector. In some factories no additional fuel is used for drying but in most cases it is
is needed, especially where soft mud techniques are used. Although many fuels are
used in brickworks, natural gas is favoured because of its clean burn charateristics and
easier maintenance.
Electricity makes up around 8 per cent of the energy consumption of a typical factory
and 19 per cent of the CO2 emitted. Unlike fossil fuel however, there is no single process
that dominates electricity consumption. The main users of electricity are:

Clay preparation in which crushers and mixers use large motors;

Forming, where the extruder or, in the case of soft mud, the brick-making machine
will consume a large amount of motive power;

Kilns and dryers where large air movement fans are used;

Setting and dehacking2; and

Compressed air.
The table below summarises the annual energy consumption for the sector. The
information is collated from 74 brick factories, three of which make tiles as well as
bricks.

Figure 3: Annual energy consumption, brick sector 2007 (data source BCC)
Energy Type
Electricity
Natural Gas
LPG
Energy Use, MWh
Emissions, tonnes CO2
314,695
166,258
3,585,346
658,198
155,852
33,382
Gas Oil/Fuel Oil
13,924
7,164
Solid Fuel
93,889
28,167
4,176,631
893,169
Totals
The total brick production in the UK was 6 million tonnes in 2007 (representing
approximately 2.5 billion clay bricks). This gives an average specific energy
consumption of 706 kWh/tonne as shown in the figure below:
2
Setting is the placing of green or dried bricks on kiln cars for firing; dehacking is the
removal of fired bricks from kiln cars for inspection & packing.
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Figure 4: Specific energy consumption

Energy type
SEC, kWh/tonne
Electricity
53
Fuel
651
TOTAL
706
A graph of annual consumption (electricity and fuel) vs. production is plotted in Figure
5. It shows a relatively strong correlation between production and energy consumption.
There are some outlying points, particularly in relation to fuel. Some of these represent
sites making soft mud bricks, which use more energy for drying. Those falling below the
general group include sites using clays with a high natural carbon content, which helps
reduce the amount of fuel required for firing.
Figure 5: Energy consumption at 73 brick factories

250,000
fuel
annual consumption MWh
200,000
R² = 0.7419
150,000
electricity
gas
100,000
50,000
electricity
R² = 0.8236
0
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
annual production, tonnes
Power and heat are both essential for making bricks. The amount of electricity needed is
determined by the amount of crushing and grinding the materials require, the amount
of automation employed and by the efficiency of the technology used. The average
electricity requirement for the sector is 53 kWh/tonne. However this requirement varies,
as we can see from the histogram in figure 3, with most sites (80%) having an SEC for
electricity of between 30 and 70 kWh/tonne.
The plot of SEC vs. production (Figure 6) shows that across the sector production is not
the main factor in determining SEC for electricity (except at low production rates). This
indicates that either electricity consumption is process specific or that the level of
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energy efficiency between sites is highly variable. The former is likely to be the major
factor processing the clay consumes a high proportion of electricity and harder clays
require more energy intensive processing. The degree to which a factory uses
automated rather than manual handling will also affect electricity consumption.
Figure 6: SEC for electricity at 73 brick factories

30
25
20
15
10
5
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
More
0
Power SEC, kWh/tonne
Figure 7: SEC for electricity vs. production at 73 brick factories

350
300
SEC, kWh/tonne
250
200
electricity SEC
150
100
50
0
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
annual production, tonnes
Fuel is the dominant energy and carbon source in the sector and the distribution of SEC
for fuel is shown below. The variation in SEC is roughly the same for fuel as it is for
electricity - both have a standard deviation of around 35 per cent of the mean. There is
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a stronger, though still weak correlation between SEC and production as shown in
Figure 7.
Figure 8: SEC for fuel at 73 brick factories

12
10
8
6
4
2
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
More
0
Fuel SEC, kWh/tonne
Figure 9: SEC for fuel vs. production at 73 brick factories

3000
2500
SEC, kWh/tonne
2000
1500
fuel SEC
1000
500
0
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
annual production, tonnes
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2.3 Theoretical energy requirement for brick-making
The consumption of electrical energy in the process of brick making varies considerably
according to the technology used in a particular factory, the degree of automation and
the mechanical preparation required by the raw materials.
If we assume that the upper quartile performance (i.e. the SEC level above which only
25 per cent of sites fall) represents best practice, the benchmark would be 43
kWh/tonne against the current mean of 53 kWh/tonne (representing a reduction of 19
per cent). A simple (but unproven) assumption that 50 per cent of this gap could be
delivered by implementing all current best practice technology measures (i.e. without
building a new factory) suggests a potential saving of 9.5 per cent for electricity and a
resulting sector saving of 15,800 tonnes of CO2/year.
In practice, electrical SEC depends on production continuity as much as on the efficiency
of the technology. Improvements to electrical energy efficiency should therefore target
the efficiency of both the equipment and its use. Any innovations that increase
equipment use may be applicable to more than one process.
Key finding: improving electricity consumption across the sector
Electricity consumption is responsible for 166,000 tonnes of CO 2 each year, 19 per
cent of the CO2 emitted by the sector. We estimate that by widely deploying best
practice in energy efficiency this could be reduced by 9.5 per cent, or 15,800
tonnes/year. The main barrier is the dispersed nature of consumption, which
makes it difficult to achieve large CO2 reductions through the use of a single
technology. “Enabling technologies” that make it easier to adopt best practice may
help the sector achieve this saving.
In contrast to electricity consumption, it is possible to calculate the theoretical minimum
heat energy requirement for firing and drying as these are thermodynamic
processes. There are a number of different ways of doing this. The table below shows
our estimate of the minimum energy requirement for drying and firing a brick and
compares it with the current fuel consumptions in the sector. The entries in red are the
recoverable heat from the drying and firing processes. As there is currently no heat
recovery from dryers we have given this a value of zero. The value for firing is
significant as once the bricks reach their peak temperature their heat can be recovered.
These minimum energy requirements are estimates and, for firing in particular, do not
take into account higher peak temperature, which would increase the minimum fuel
requirement, or combustible carbon content of the clay, which would decrease it.
The table makes clear that the very best plants are already close to the minimum
energy requirement. However in general most kilns use much more heat than is
necessary in simple thermodynamic terms, which suggests that a significant amount of
heat is lost. The current gap between the average performance and the minimum
energy requirement is 250 kWh/tonne for extruded bricks and 73 kWh/tonne for soft
mud. Soft mud plants are much closer to their theoretical minimum energy
requirements because they tend to be modern plants. In addition, because they are
known to be higher energy consumers more effort may be put into managing energy
performance. If the gap between current performance and the minimum requirement
were closed by 50 per cent then the CO2 saving to the sector would be over 100,000
tonnes of CO2/year.
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
Figure 10: Theoretical minimum energy for drying and firing
Requirement
Estimated minimum energy use,
kWh/tonne (assuming 40% flue and
structural losses)
Drying extruded brick, 15% moisture content
194
Drying soft mud brick, 28% moisture
330
Recoverable heat from a dryer using current
technology
0
Heating requirement in firing
416
Recoverable heat from a kiln using current
technology
250
Minimum energy requirement for an extruded
brick
360
Minimum energy requirement for a soft mud
brick
496
Mean extruded plant
700
Mean soft mud plant
670
Best extruded plant
370
Best soft mud plant
500
Key finding: improving fuel consumption across the sector
Fuel consumption in the brick sector represents 82 per cent of the CO2 emitted.
We estimate that by improving kiln performance by eliminating sources of heat
loss, the sector could save up to 100,000 tonnes/year.
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2.4 The manufacturers and the supply chain
The brick sector is dominated by three large manufacturers, while several smaller
companies each have one or two brick plants. The table below includes most of the UK’s
manufacturers.

Figure 11: UK brick manufacturers
Manufacturer
Number of UK brick
sites
Number of UK brick
sites
Manufacturer
Hanson
15
Furness Brick
1
Ibstock
20
WH Colliers
1
Wienererger
14
Normanton Brick
1
Michelmersh
4
Nothcot Brick
1
Carlton Brick
1
Plasmor
1
York Handmade
1
William Reade
1
Bovingdon Brick
1
Swarland Brick
1
Broadmoor Brick
1
Raeburn Brick
1
Bulmer Brick & Tile
1
Hinton
Perry
Davenhill
Caradale Brick
2
Sussex Handmade
1
Coleford Brick
1
Webster Hammond
1
Freshfield Lane
1
&
1
The supply chain for brick manufacturing equipment is dominated by a small number of
key suppliers based in France and Germany, as shown in Figure 5. The UK has a small
machinery manufacturing capability, including both domestic companies and
subsidiaries of the major suppliers.

Figure 12: Key equipment suppliers to the sector
Company
Based in
UK
agent
factory
or
Ceric
Heidelberg
No
Complete plants
Lingl
CRC
UK factory
Complete plants
CDS
Stoke-on-Trent UK
UK based
Kilns & dryers
Craven Fawcett
Wakefield, UK
UK based
Clay preparation
Keller
Laggenbeck,
Germany
No
Complete plants
Burton Refractories
Germany
No
Kiln car refractories
Bricesco
Stoke-on-Trent
UK factory
Kilns
Technology
The relative shortage of suppliers creates a challenge, as there is no significant supply
chain community generating innovative products. The major equipment manufacturers
are based overseas. While they do have large and expert development departments,
they are seen by the sector as providers of factories rather than providers of the niche
process innovations that are likely to emerge from this project. It is also clear that
having UK-based technology providers who can innovate and adapt quickly is important.
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The accelerator pilot sectors (asphalt, animal feeds and blow moulded plastics) as a
whole have demonstrated that technology providers need to be motivated to assist with
the development. They are most likely to do that if they are involved from the start of
an innovation process and can see that they will benefit through participation.
The brick sector is not known for its fast pace of technological change; although over
the years a number of innovations have been developed or imported. Most R&D takes
place within the manufacturers and their supply chain, but this is supplemented by
CERAM in Stoke-on-Trent, the only UK-based research and technology organisation
(RTO) with significant ceramic expertise. Key recent innovations introduced by the
sector within the past 20 years have included:

Lightweight refractories (particularly ceramic fibre) for kilns and kiln cars.

Advanced control systems.

Automation e.g. robotics (not an energy efficiency measure).

New burner technology, (e.g. pulse burners).

Use of landfill gas for firing.

Use of additives to modify fired properties.

New kiln designs (e.g. flat arch, water seals).

Improved dryers design (e.g. rotating cones, recirculation and airless drying).
In the early 1990s, regulations were introduced to limit the concentration of hydrogen
fluoride which could be emitted during brick-making. Although technology was available
in Germany, where regulations had been in place for some time, there was a burst of
activity in the UK to develop and adopt a range of solutions. Many innovations therefore
date from this time.
2.5 Impact of Carbon Legislation
The Climate Change Levy (CCL) is charged on non-domestic energy bills for both
electricity and selected fossil fuels including natural gas. Brickworks receive a rebate on
this levy through a Climate Change Agreement (CCA). To retain the levy, rebate energy
reduction targets need to be achieved, or carbon purchased if they are exceeded. As
CCAs provide a significant financial benefit, they have been an important driver for
energy efficiency. The levy rebate (assuming the maximum rebate is achieved by all
sites) is worth approximately £5 million per year, although this will be lower if rebate
rates are reduced in future.
The Carbon Reduction Commitment (CRC), which was launched in April 2010, does not
affect brickworks with a CCA. However it does affect many of the parent companies. In
some cases, this may divert the management focus away from brick operations and
towards operations newly captured by the CRC.
Brickworks are also covered by the EU Emissions Trading Scheme (EUETS) with the
reporting and trading obligations that go along with participation. There is a fear within
the sector that the increasing costs (actual and hidden) of these schemes compared to
those experienced by substitute products such as cladding and cement-based
alternatives will artificially reduce the market for bricks. This would have a real impact
on the appearance and durability of our built environment.
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Other policy measures affecting the sector are the Renewable Obligation (RO), Feed in
Tariffs (FIT) and the widely anticipated renewable heat incentive (RHI). The market for
renewables within the brick sector is still immature, although landfill gas has been used
in kilns for many years. This is expected to change in the future as companies look to
reduce their dependence on fossil fuels and to respond to the government policy
initiatives on renewables.
2.6 Progress on improving energy performance
The sector’s consumption and CO2 emissions between 2000 and 2008 are shown in
Figure 13:

Figure 13: Brick sector CCA performance 2000 to 2008 (Source: BCC)
Total Energy, MWh
Output, tonnes
SEC, kWh/tonne
CO2, tonnes
2000
5,100,131
6,539,688
779.9
1,267,000
2002
4,872,263
6,456,265
754.7
1,240,000
2004
4,963,269
6,652,605
746.1
1,263,000
2006
4,357,362
5,877,820
741.3
1,109,000
2008
3,396,225
4,495,349
755.5
857,000
Sector interest in energy efficiency has always been high due to the energy intensive
nature of the process.
The Carbon Trust has completed over 30 energy efficiency surveys in the brick sector.
These have focused on providing site specific advice such as:

Automated switch off motors and drives.

Installation and optimised use of variable speed drives.

Efficient generation and use of compressed air.

Insulation of ductwork.

Improving dryer temperature, humidity and flow control.

Energy performance reporting.
Between 2000 and 2006 the brick sector reduced its CO 2 emissions and also improved
its specific energy consumption. This was in spite of a significant reduction in sales in
2006. In 2008, however, the impact of the recession was at its height and production
fell steeply, with a corresponding drop in CO2 emissions. In that year the SEC rose for
the first time, reflecting that many plants were operating sub-optimally due to low
production rates.
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2.7 Business drivers
Brick is increasingly a commodity product. Although it is still the first choice for external
walls in housing, this is less true for flats, commercial buildings and civil engineering
projects. Partial render and cladding are increasingly used on domestic properties,
which further reduces the size of the market. The recession has had a significant impact
on the sector, causing some plants to close, others to be mothballed, and many to run
at sub-optimal production.
The sector has responded to market trends by developing alternative brick-related
products to maintain sales. These include brick-shaped tiles that can be stuck onto
panels for rapid construction techniques; high insulation value products designed to be
rendered (competing with concrete blocks); and sustainable product which either
incorporate waste materials or have a very low carbon footprint. These developments
have been slow, partly because the construction sector as a whole in known to be risk
averse.
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3. Methodology
The first stage of the IEEA took an in-depth look at the sector-specific manufacturing
processes, aiming to understand their energy use and interaction with other systems
and identify possible energy efficiencies.
This section describes the pilot sites that we chose to assist the project and the
monitoring that was carried out on them. It also outlines how we engaged with the
sector and its supply chain to develop new opportunities to reduce CO 2 emissions, and
identify the barriers to putting these opportunities into practice.
3.1 Monitoring the pilot sites
To understand how a modern brickworks uses energy, and to explore how new
technology can be applied to reduce it, we chose three pilot plants. Their energy
consumption was monitored continuously and in detail, and we also looked at process
parameters such as production and moisture content. The sites were selected in
consultation with the BCC and sector representatives.
In selecting the three pilot sites, we considered the type of raw material and the
manufacturing method used, to make sure that the results were representative of the
sector.

Figure 14: The selected sites
Process
Age of main
process
equipment
Current output
Significant
process changes
during
monitoring
Site
1
Extruded.
Tunnel kiln.
Carbonaceous shale
Moisture content:
15 per cent
Fired to 1,060oC
Firing time: 52 hours
30 years
Kiln at 80 per cent
of design output 30
million bricks/year
Flashing on all
products. Some
73mm made
Site
2
Extruded
Tunnel kiln
Keuper marl
Moisture content:
15 per cent
Fired to 1,000oC
Firing time 75 hours
20 years
75 per cent of
design output
100 million
bricks/year
Flashing on all
products. All
products 65mm
Site
3
Soft mud
Tunnel kiln
Boulder clay
Moisture content
26 per cent
Fired to 1,030oC
Firing time 140 hours
30 year (kiln
refurbishment
five years ago)
Design output:
26 million
bricks/year
Flashing on all
products. All
products 65mm
CARBON TRUST INTERNAL USE ONLY
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The diagrams below indicate the main manufacturing steps at each site.

Figure 15: Process flow diagrams for the monitored sites
Site 1
Site 2
Site 3
We visited each site with the metering contractor to discuss the monitoring
requirements. The final specification was determined by considering the existing
metering, the need to understand the energy consumption of the processes and the
metering budget.
The metering was agreed during April 2010 and installed in June and July of the same
year. Data was gathered from kiln records and production data systems, potential CO2
savings to be assessed.
Site 1
This factory dates back to the 1960s, and received a major technology upgrade in the
1980s. It manufactures extruded wire cut facing bricks, using coal measure shale and
CARBON TRUST INTERNAL USE ONLY
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fireclay, fired in two Lingl tunnel kilns with the combined capacity to produce 65 million
bricks per year.
The raw material passes through a clay preparation area consisting of a kibbler (a
primary crusher), hammer mill, screens and mixer. The processed clay is stored in a
silo, before being worked further in the mixer extruder unit. The extruder produces
21,500 bricks per hour. Textures and stains are applied to the bricks, which are then
loaded onto dryer cars. The plant has six continuous tunnel dryers which, on their
current output, dry the bricks to around one per cent in 18 hours.
After leaving the dryer the bricks are set onto kiln cars, which transport them through
the kiln. Each kiln car holds 3,960 65mm bricks, which spend two days in the kiln. After
this the bricks are unloaded and sorted at the dehacker before being packaged and
transported to the stockyard. The plant is currently operating just one kiln, which
reduces the site output to around 34 million bricks per year. The kiln runs continuously
but production operates on a four-day weekly pattern.
Efforts have been made to improve the energy efficiency of the site. Variable speed
drives have been fitted to the large fans, and the kiln control software has been
upgraded to PLC control. In the clay preparation area heavy load motors used for
crushing and mixing have had torque controllers fitted, reducing power consumption by
six per cent.
The energy consumption for the site between October 2009 and September 2010 is
summarised below.

Figure 16
Site 1. Annual energy consumption October 2009 to September 2010
Gas
consumption
kWh
Power
consumption
kWh
Total kWh
Production
(bricks)
Production
(tonnes)
SEC
(kWh/tonne)
32,228,998
3,097,400
35,326,398
22,010,952
46,223
764
At Site 1, the metering was intended to:
a) measure an accurate breakdown of the energy consumption of each part of the
process; and
b) measure the key heat losses from the kiln and the dryer.
The following meters were installed and/or monitored to get an accurate breakdown of
consumption:
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We also monitored the mass flow of air carrying heat from the kiln and the dryer, and
have shown the measurements taken on the diagram below. The flow monitoring
equipment used in the kiln and dryer exhaust (pictured below) gave good results, but
unfortunately the oxygen analyser installed did not provide sufficiently accurate results
to be useful.
Flow meter probe and display unit
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Site 2
Tunnel kiln exit
Site 2 is an extruded wire cut facing brick plant, built in the late 1980s to produce 100
million facing bricks per year (2 million/week). The raw material is Keuper Marl, which is
combined with other clays to produce a wide range of facing bricks.
As it enters the plant, the raw material passes through a kibbler crusher before entering
the clay storage area. The clay passes through a wet pan mill and two sets of high
speed rollers before being fed to one of two Craven Fawcett Centaur 510 extruders.
Textures and stains are added to the clay column before the bricks are wire cut and
loaded onto dryer cars. The bricks are then dried in one of three continuous tunnel
driers, before being set on kiln cars by the setting machine. They are then fired through
the Walter Craven tunnel kiln in a three day cycle. After firing, the bricks are unloaded
from the kiln cars via the dehacker, and sorted and packaged for sale. The plant runs a
production shift five days and five nights each week, and currently the kiln is running at
a reduced output of 1.3 million bricks per week.
The site has main gas and electricity incoming meters and a series of gas submeters on
the kiln and three dryers. A range of electrical submeters also cover the site’s main
energy users. This data is gathered on a central server, with site access available.
The site’s energy consumption in 2009 is shown below, a year when total production
was one third of the design capacity.

Figure 17
Site 2. Annual energy consumption 2009
Gas
consumption,
kWh
46,175,896
Power
consumption,
kWh
9,786,750
Total,
kWh
Production
(bricks)
Production
(tonnes)
SEC
(kWh/tonne)
55,962,646
34,564,000
73,968
757
The site management team have access to detailed energy data, and have considered
various energy reduction opportunities including pre-heating combustion air; modifying
raw material to reduce firing temperature via various additives; biomass power
generation; using waste heat in the combustion process and reducing heat loss through
innovative kiln linings.
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The site staff are conscious they have recently increased their specific energy
consumption as the kiln throughput has been reduced to match production volume
requirements. They have commented that innovations which would allow them to
maintain a low specific energy consumption during reduced consumption would be of
great benefit to the sector.
By metering at Site 2, we hoped to measure an accurate breakdown of the energy
consumption of each part of the process. The site already had significant submetering in
place, which we were able to make use of, developing the following metering structure:
CARBON TRUST INTERNAL USE ONLY
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Site 3
Bricks entering the kiln and the kiln exhaust stack
Site 3 is a soft mud plant which produces facing bricks from the glacial boulder clay of
local deposits. The plant combines 1960s brick press technology with a modern kiln
design and robot brick handling. The site produces 26 million bricks per year, mainly of
boulder clay but with a proportion of marl and fireclay blends.
In the manufacturing process the clay raw material passes through a separator followed
by high speed rolls, clay silo and mixer. Sand, PET coke and other additives are
combined with clay and water to feed the Petterson DB12 brick presses. The pressed
bricks are then loaded onto dryer cars and transported to one of seven chamber dryers.
The bricks are dried in approximately 25 hours and then transferred to the robots which
set the bricks on kiln cars.
The kiln cars transport the bricks through the kiln in around five days. After firing they
pass to the unloader, which unloads the kiln car and builds finished packs of bricks,
ready for sale.
A series of major improvements have been introduced over the past 15 years, including
the commissioning of robot setting, the removal of carousel sorting in favour of direct
pack unloading and the installation of modern high velocity side burners in the centre
section of the kiln.
The site has a main gas meter with submeters on the kiln, side burners, specials and
the seven chamber dryers. Electricity is measured via the main incomer and
submetering on the tunnel kiln building. The site personnel use manual submeter
readings to produce a specific energy consumption figure each week, broken down into
kiln and individual chamber dryers. This information has helped to reduce the drying
time from 35 to 25 hours for most products.
The site has also reduced its energy use by:
adding varying proportions of PET coke or clay conditioners to reduce the water
content;
CARBON TRUST INTERNAL USE ONLY
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using recovered heat in the dryer or pre heater;
pre-heating burner combustion air;
introducing low thermal mass dryers;
coating the kiln wall.
Site 3’s soft mud production method creates a shaped brick with a much higher
moisture content than a comparable extruded brick process. Much more energy is
therefore needed to dry the units than at other sites. The consumption in 2009 is shown
below.

Figure 18
Site 3. Annual energy consumption January 2009 to December 2009
Gas
consumption,
kWh
26,200,801
Power
consumption,
kWh
2,101,648
Total,
kWh
Production
(bricks)
Production
(tonnes)
SEC
(kWh/tonne)
28,302,449
15,239,842
39,624
714
The site’s main gas users – kiln and chamber dryers – were fully submetered. The
electricity metering was limited to the main incomer and a submeter for the kiln
building. As part of the metering and monitoring plan, the existing gas meters were
connected to the data capture system and new power meters were fitted so that
consumption in each process area could be monitored to deliver the following system.
CARBON TRUST INTERNAL USE ONLY
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Summary
The data provided by metering has informed an investigation into the opportunities for
reducing the mass flow of air within a kiln; the results of the metering are discussed in
section 4. If the exercise were to be repeated, portable equipment would be used to
examine the flow of air and heat more thoroughly. It is too expensive to do this with
fixed equipment.
Key finding: Monitoring
If thermal processes make up the bulk of your process energy consumption,
consider monitoring heat flows using portable equipment. This would allow you to
build a comprehensive picture of the energy used by the process, in an affordable
way.
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3.2 Engagement with the sector
The BCC, and its Technical Director, Dave Beardsworth, has been involved at every
stage of the project. The BCC’s existing Energy and Emissions committee has formed
the steering team for the project, made up of the following members:
Figure 19: Accelerator Steering Committee

Name
Company
Dave Beardsworth
BCC
John Sandford
Wienerberger
Paul Attack
Wienerberger
Mathew Newton
Hanson
Neil Kilner
Hanson
Allan Austin
Ibstock
Dr David Hills
Ibstock
Paul Freeman
Michelmersh
Kevin Preston
Hinton Perry & Davenhill
Georgina Salt (occasional attendee)
Ideal Standard
Mike Gould (occasional attendee)
Marley-Eternit
This group has held four workshops to discuss the project and its findings:




9 March 2010: to launch the project in the sector
30 March 2010: initial brainstorm for ideas and to identify key equipment suppliers
and technology companies
11 May 2010: to review the supply chain consultation and assess the initial
opportunities
21 September 2010: a review of the monitoring data and final consultation on
technology concepts and sector barriers.
A larger workshop was also arranged to engage the whole sector and its supply chain,
at Wienerberger’s Waresley works on 6 July 2010. A list of attendees and their contact
emails is included in the Appendix.
Finally, a presentation at the New Ceramics Conference in Stoke-on-Trent on 14
October outlined the project to the wider ceramic community.
The sector was consulted for four reasons:
i.
To gain insights into the manufacturing process;
ii.
To identify and prioritise potential innovations that will deliver a step change in CO 2
emissions;
iii. To identify the barriers to innovations being adopted;
iv. To promote partnering between organisations - in particular technology suppliers or
researchers and brick manufacturers.
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Site visits formed an important part of the consultation process. We spent a total of 15
days at the three monitored sites, collecting data and consulting management and
operators on the emerging areas for savings, and potential solutions.
We then arranged a programme of meetings and visits with the supply chain, involving
the following companies. While each meeting was useful, not every company became an
active participant in developing technology concepts.

Figure 20: Supply chain consultation
Contact
Company
Type of business
Stage 2
participant?
Richard Bridgewater
Bricesco
Kiln builders &
combustion systems
Possible
Darren Bryant
Efficient Air Ltd
Electricity generation
from waste heat
Yes
Adrian Meacham
Lingl
Kiln builders
Unlikely
Andy Biggs
Akristos
Novel clay additives &
formulations
Yes
Andrew Smith
CERAM
Main R&D centre for
the sector
Possible
Steve Hudd
SPS Controls
Equipment operational
efficiency
Yes
Graham Bird
CDS Drying
Drying systems
Possible
Colin Townsend
Hotwork
Burners & combustion
systems
Yes
Vinod Bhatia
Paragon Simulation
Process modelling &
simulation
Yes
Glyn Dixon
Craven Fawcett
Clay preparation &
forming
Yes
Andrew Frost
Ceramic Gas Products
Lightweight kiln car
construction
Yes
Dave Clitheroe
Bio-Mass Engineering
Bio-mass gasification
Possible
Claudius Dittrich
Keller
Kiln & dryer builders,
combustion systems
and plant control
systems
Yes
Dr David Manning
Newcastle University
Utilisation of syn gas
in conventional
combustion systems
Possible
International perspective
The fact that the large equipment suppliers: Lingl, Keller (Germany) and Ceric (France)
have their technical centres outside the UK should make them a good, if distant, source
of innovation. As innovation is usually introduced in domestic and nearby markets to
begin with, it is reasonable to assume that some developments in continental Europe
may be ahead of best practice in the UK.
However, we have found that as the brick sector has gradual declined across Europe,
major innovation has slowed down. The 1980s was a high point, with the development
CARBON TRUST INTERNAL USE ONLY
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of highly automated plants, increased use of ceramic fibre, water seal kilns, pulse fired
burners, new grinding technologies and larger kilns.
There is a continuing trend to use robotics for handling, as well as for the use of wider,
lower kilns with improved instrumentation and control systems. Even these well-known
technologies will take several years to spread throughout the sector, as the average life
of a plant is 30 years. These technologies are available in the UK, and in fact the most
efficient plants in the UK are among the most efficient in Europe.
One European innovation which is not in use in the UK is the hollow clay block, used as
a masonry unit in internal walling or rendered external walls. In the UK this market is
dominated completely by cementitious products.
Two other practices which have been introduced in continental Europe but not in the UK
are:


the heating of clay feedstock to reduce the moisture content of brick, therefore
reducing the energy needed for drying; and
the increased use of heat recovery from the kiln exhaust to preheat combustion air
as an integral part of the kiln.
A new development being considered in Germany (although also well researched in the
UK) is the development of low air movement kilns. Low air movement is associated with
low heat loss, leading to a more efficient firing process.
Outside the UK, particularly in warmer climates, there is the beginning of a trend
towards clay building products similar to those used hundreds of years ago and which
are still used commonly in developing countries. Unfired clay products are strengthened
though the addition of a small amount of cementitious material or simply through the
forming and drying process.
In the UK, projects have been completed to reduce firing temperatures by introducing
flux type materials such as very fine glass cullet to the clay, or by incorporating waste
materials which mean the kiln doesn’t need to be so hot.
3.3 Business drivers and barriers
The engagement processed identified the following key drivers and barriers to
developing and adopting innovations.
a) Cost – new innovations must have a good return on investment if they are to be
implemented. In most cases the payback on investment was required to be less
than four years, and some companies reported non-essential investment was limited
to projects with a year’s payback or less.
b) Business case – this will need to be robust. Savings must be deliverable and all
financial savings and costs captured. The sector would like to see all potential
benefits captured. For example, could a carbon reduction measure also help to
deliver productivity improvements or reduce maintenance requirement?
CARBON TRUST INTERNAL USE ONLY
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c)
Product quality – an innovation would be unlikely to be adopted if it could affect
product quality. Innovations would need to have a proven track record to gain
credibility with the sector.
d) Proven technology – the sector has implemented some innovations in the past
which have failed. This has resulted in concerns about the potential of some of the
projects to deliver over the long term.
e) Maintenance – companies are keen not to increase maintenance responsibilities or
costs unnecessarily; if an installation needs too much maintenance is might fall into
disrepair. Staff would also need to be trained in the upkeep of new equipment, and
this needs to be addressed by solution providers.
f)
Scarcity of capital – In the current economic climate essential maintenance
consumes the bulk of funding. Projects that enable third party funding such as an
ESCO type model are likely to be adopted more quickly.
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4. Key findings
This section looks at the key findings from the monitoring carried out at the three sites,
and explores what the data tells us about the opportunity for reducing energy within the
sector. We start with some raw data trends and what they reveal, before moving on to
more detailed analysis of where the energy is consumed.
4.1 Raw data trends
16,000
140,000
14,000
120,000
12,000
100,000
10,000
80,000
8,000
60,000
6,000
40,000
4,000
20,000
2,000
0
power, kWh
fuel, kWh
Site 1. Daily Power & Fuel Consumption
160,000
0
total fuel, kWh
total electricity, kWh
20,000
180,000
18,000
160,000
16,000
140,000
14,000
120,000
12,000
100,000
10,000
80,000
8,000
60,000
6,000
40,000
4,000
20,000
2,000
0
power, kWh
fuel, kWh
Site 2. Daily Power & Fuel Consumption
200,000
0
total fuel, kWh
total electricity, kWh
CARBON TRUST INTERNAL USE ONLY
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Site 3. Daily Power & Fuel Consumption
140,000
8,000
120,000
7,000
fuel, kWh
5,000
80,000
4,000
60,000
3,000
40,000
power, kWh
6,000
100,000
2,000
20,000
1,000
0
0
total fuel, kWh
total electricity, kWh
These graphs show the daily trend of fuel and power consumption for the three
monitored sites. For sites 1 and 2 the power consumption shows a regular pattern of
high consumption during the week, with a lower and more consistent base load during
the weekend when only the kilns and dryers are operating. However, Site 3 was working
seven days a week, and therefore shows far more consistent consumption. All three
sites demonstrate significant variation in daily fuel consumption. This is surprising, as
the fuel is used primarily in the kilns and dryers which tend to be operated fairly
consistently from day to day.
Site 1. Daily Power Consumption
6,000
sub process power, kWh
5,000
4,000
3,000
2,000
1,000
0
preparation
making
setting
dryer
kiln
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dehacker
35
Site 2. Daily Power Consumption
5,000
4,500
sub process power, kWh
4,000
3,500
3,000
2,500
2,000
1,500
1,000
500
0
preparation
making
setting
dryer
kiln
dehacker
Site 3. Daily Power Consumption
1,800
1,600
sub process power, kWh
1,400
1,200
1,000
800
600
400
200
0
preparation
making
setting
dryer
kiln
dehacker
These graphs show the daily power consumption for the main processes on the three
sites. They make clear the relatively constant demand of the kiln and dryer. Clay
preparation and making are the other significant power consumers.
The range of power consumption indicates variation in product type, raw material
hardness, moisture content, equipment downtime etc. Measuring weekend or overnight
base load is a good energy management technique as it makes it obvious when
equipment that is running which could be switched off. This is usually relatively easy for
a skilled process operator or engineer to spot and correct.
It’s more difficult to make the manufacturing process consistent, as there are so many
variables affecting energy consumption. This can be so complex that it’s not practical for
sites to try to reduce process variation beyond critical measures such as kiln
temperature variation and product quality.
CARBON TRUST INTERNAL USE ONLY
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Site 3 Total Power (30 minute readings)
300
250
power, kWh
200
150
100
50
0
The power consumption at Site 3 is particularly interesting. As it operates seven days a
week its power consumption doesn’t dip at weekends. Consumption is, however,
reduced at night, when the production shift finishes. Although it cannot be proven
through monitoring, a project that reduced the process and control variability should
reduce energy consumption, as a change of state is always associated with a higher
level of energy waste. So a more consistent process and control response may deliver
significant energy savings.
Site 1. Kiln Fuel Consumption & Heat Transfer to
Dryer
140,000
120,000
fuel, kWh
100,000
80,000
60,000
40,000
20,000
0
kiln fuel
heat transfer to dryer
This graph shows the fuel consumption of the kiln, along with the heat flows from the
kilns - the heat that is lost through the stack and the heat that is recovered during
cooling to be sent to the dryers. It is clear that a large proportion of the heat is lost
through the stack, but also that a lot is recovered from the kiln and sent to the dryers
(whether this heat is used efficiently is dealt with later in the report). With such a large
amounts of heat tied up in air flow movement, it is perhaps surprising that these
airflows are not monitored as part of the kiln control system. The measurement of this
and its use in managing kiln operation is discussed later in section 4.
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4.2 Where is energy used in brick-making?
In this section we analyse the raw data to determine where energy is consumed in a
brickworks and where the most carbon intensive processes are.
Our first table shows a breakdown of where energy is used. The consumption of the kiln
and the dryer have been reported together to make it easier to compare the sites. Clay
preparation and forming, along with drying and firing dominate the electricity
consumption; however a significant amount of electricity is also used in ancillary
processes such as compressors, lighting, small power and offices. Compressor control,
leak surveys and energy efficient lighting are all well-known and worthwhile initiatives
to reduce ancillary consumption. The table also shows that little fuel is used outside the
kiln and drying processes.

Figure 21: Energy consumption summary of the three sites May to July 2010
Site 1
Site 2
Site 3
TK Extrusion TK Extrusion TK Soft Mud
Power
Making & Forming
Setting
Drying & Firing
Dehacking
Other - compressors, lighting etc
Fuel
Drying & Firing
Other
25.9%
7.4%
41.2%
1.3%
24.2%
26.1%
1.4%
40.6%
2.8%
29.2%
22.7%
6.8%
32.0%
0.3%
38.3%
100.0%
0%
100.0%
0%
96.7%
3%
We have used these figures to calculate the relative CO 2 emissions from the main brickmaking processes. These amounts and percentages are shown in the table and pie chart
below.

Figure 22: Breakdown of CO2 emissions by process
Site 1
Site 2
Site 3
TK Extrusion TK Extrusion TK Soft Mud
Making & Forming
Setting
Drying & Firing
Dehacking
Other - compressors, lighting etc.
TOTAL
5.4%
1.5%
87.7%
0.3%
5.1%
100.0%
CARBON TRUST INTERNAL USE ONLY
4.0%
0.2%
90.9%
0.4%
4.5%
100.0%
3.6%
1.1%
86.3%
0.0%
8.9%
100.0%
Weighted
Average
4.6%
1.0%
87.5%
0.3%
6.6%
100.0%
Overall CO2
emissions in
2007, tonnes
41,379
8,640
781,912
2,407
58,830
893,169
38

Figure 23: Sector CO2 emissions by process
Other compressors,
lighting, etc,
6.6%
Dehacking,
0.3%
Making and
Forming, 4.6%
Setting, 1.0%
Drying & Firing,
87.5%
The kiln and dryer process is responsible for over 85 per cent of the carbon emissions in
all cases. It is therefore the largest potential source of low carbon solutions. The next
largest single process in terms of CO2 emissions is making and forming which represents
five per cent of the total. The huge difference between these two figures confirms that
drying and firing is likely to be the most profitable area to focus on.
CARBON TRUST INTERNAL USE ONLY
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4.3 Process heat balances
Firing and drying are by far the most energy intensive processes in brick-making. As the
dryer uses waste heat from the kiln, it is the kiln that is responsible for most of the
sector’s CO2 emissions.
We have carried out heat balances on each of the three kilns to determine how the heat
is used within them. As the dryers receive a large percentage of the heat supplied to the
kiln, the table also shows the thermal input to the dryers at each site. Our survey team
took measurements over a six hour period, providing a snapshot of the process. The
results are given in the table below:

Figure 24: Process heat balance
Kiln 1
Kiln 2
Kiln 3
Kiln & Dryer Heat Balance
Fuel supplied to kiln, (net heat)
Fuel supplied to kiln & dryer, (net heat)
kW
5,484
5,484
%
kWh/tonne
719
719
kW
7,715
8,135
279
10
0
454
36
5
Exhaust
Undercar & roof cooling
Heat recovery to pre heater/combustion air
Heat recovery to dryer
Structural heat Loss
Bricks leaving kiln
2,129
80
0
3,461
278
39
36%
1%
0%
58%
5%
1%
Heat accounted for
5,987
100%
-503
-9%
-66
1,492
524
180
4,616
386
56
7,254
461
Net heat used for firing
2,023
37%
265
Gas supplied to dryer, (net)
Total heat supplied to dryer
Sensible heat in dryer exhaust
0
3,461
1,273
63%
37%
454
167
Energy required to heat bricks
Energy to dry bricks
Overall thermal effeciency
1,770
1,048
88%
30%
Difference from heat supplied
Production, kg/hr
21%
7%
2%
64%
5%
1%
kWh/tonne
462
487
kW
1,901
4,051
89
31
11
277
23
3
1,166
%
kWh/tonne
312
665
6%
28
-69
59%
9%
0%
22%
8%
2%
100%
-4%
3,099
38%
186
1,464
36%
240
420
5,036
62%
302
2,150
2,587
64%
425
3,654
2,294
118%
46%
1,374
1,347
94%
52%
51%
7,623
%
100%
173
0
437
150
44
1,970
73%
16,692
151
28
40
72
25
7
-11
67%
6,092
We have also used the data to produce the Sankey diagrams for the process below.
CARBON TRUST INTERNAL USE ONLY
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
Figure 25: Sankey drying and firing
heat recovery 48%
kiln 83%
TOTAL FUEL
dryer 15%
other 2%
dryer 48%
exhaust 38%
KILN
under car &
roof cooling 6%
structural
loss es 6%
preheater/combustion air 1%
bricks 1%
CARBON TRUST INTERNAL USE ONLY
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These results indicate that there are a number of opportunities to reduce energy
consumption through innovation:
i.
the heat balances have accounted for over 90 per cent of the heat supplied to the
kiln and are therefore likely to be accurate (being dependant on flow
measurements, heat balances tend to have an accuracy of around + or – 15%);
ii.
the largest heat losses from the kiln are the exhaust and the heat recovery system
supplying hot air to the dryers;
iii. the amount of heat recovered for the kiln and sent to the dryer varies between 454
kWh/tonne and 72 kWh/tonne. This represents differences in the way each kiln and
dryer are operated;
iv. the large amount of heat that is supplied to the dryer shows that when considering
energy efficiency it should be given equal attention to the kiln;
v.
the least efficient kiln and dryer use a process which extracts the highest
percentage of heat from the kiln. In this case it also extracts more heat from the
cooling heat recovery system than is available from the sensible heat within the
bricks. This could mean the heat recovery system is pulling heat from the firing
zones, reducing the site’s efficiency;
vi. although all three sites operate different heat recovery regimes and have different
efficiencies, the net proportion of heat used for drying and firing is the same at each
of them, at 34 per cent for firing and 66 per cent for drying. This suggests that
there is an efficiency link between the two processes that may be down to the air
flow regime. If this is the case, an efficient process will have low air flow in both kiln
and dryer whereas an inefficient process will have high airflows in both. The ratio is
therefore maintained.
Key finding: balancing airflow in kilns and dryers
The proportion of heat used for firing and drying appears to be constant and
independent of the technology employed. This suggests that it is a function of
operation and control. We conclude that it is caused by sites adopting a
common airflow strategy for both processes i.e. high or low air, with low airflow
being associated with higher efficiency.
CARBON TRUST INTERNAL USE ONLY
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4.4 A more detailed look at the kiln and dryer
This section looks at the data collected on the drying and firing process.
Figure 26: Site 1 kiln fuel consumption vs. throughput
Site 1: Kiln Gas vs Throughput
20/06/10 to 29/07/10
160,000
140,000
Kiln Gas (kWh)
120,000
100,000
80,000
60,000
40,000
20,000
0
160,000
170,000
180,000
190,000
200,000
210,000
220,000
Kiln Out, kg
The first graph shows the trend of increasing gas consumption with increasing
production. Energy consumption varies widely, particularly at the most common daily
production of 200 tonnes. The trend line crosses the y axis at around 110,000 kWh and
as the slope of the graph is low this means that higher production rates are the most
efficient, as this “energy overhead” is absorbed by a higher production.
A production rate of 180 tonnes/day, for example, would deliver an average kiln specific
energy consumption (SEC) of 667 kWh/tonne. By contrast, a production rate of 220
tonnes/day would deliver an SEC of 590 kWh/tonne, a difference in performance of 13
per cent for a change in production rate of 22 per cent. Production rate is therefore a
major driver in improving kiln performance. However, because production rate is
normally set by market demand, the scope to change it may be limited.
The graph is strikingly flat. The difference between the fuel consumption at 180,000kg
and 210,000kg is approximately 5,000 kWh, which is roughly equivalent to the 6,000
kWh in sensible heat required to heat the extra 30,000kg of bricks to 1000oC. This
demonstrates that the losses in the kiln are remaining constant, not as a percentage but
in absolute terms. As the majority of heat losses occur through the stack and in the
transfer of heat from the cooling zone to the dryers, it follows that these are remaining
constant and the mass flows are not being controlled in an optimum way. If the flows
were better controlled, the slope of the graph would increase and SEC would be
increased at a slower rate at sub-optimal production rates.
CARBON TRUST INTERNAL USE ONLY
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Key Finding: Keep kilns operating at high throughputs
Under normal operation, a 10 per cent change in throughput of the kiln and
dryer will change the specific energy performance by 6 per cent. Therefore,
preventing periods of avoidable slow kiln throughput is an important factor in
maintaining the good energy performance of a kiln.
Key Finding: Measure heat flows in the stack and to the dryers
The SEC of a kiln is primarily determined by the heat loss from the stack and
the heat recovered for drying purposes. It therefore makes sense to measure
these inputs in the same way as gas and electricity, so that process control
decisions can be made and their overall heat consequences assessed.
Figure 27: Site 1. Kiln power consumption vs. throughput

Site 1: Kiln Electricity vs Throughput
20/06/10 to 29/07/10
4,000
3,500
Kiln Electricity (kWh)
3,000
2,500
2,000
1,500
1,000
500
0
160,000
170,000
180,000
190,000
200,000
210,000
220,000
Kiln Out, kg
Figure 27 shows the impact of throughput on kiln electricity consumption. Changing
production seems to cause very little changes to the kiln’s electricity consumption. This
is surprising, as the previous graph has shown that higher throughputs mean higher gas
consumption. As higher gas consumption means more mass flow within the kiln, this
should lead to faster fan speeds and higher power consumption. Even more surprising is
the finding shown in figure 28 that the power consumption of the exhaust fan on its own
goes down as the throughput increases. At higher fuel consumption there is normally
more air to exhaust, which should lead to higher exhaust fan consumption.
CARBON TRUST INTERNAL USE ONLY
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Figure 3: Site 1. Kiln exhaust power consumption vs. throughput

Site 1: Kiln Exhaust Fan vs Throughput
20/06/10 to 29/07/10
2,000
1,900
Kiln Exhaust Electricity (kWh)
1,800
1,700
1,600
1,500
1,400
1,300
1,200
1,100
1,000
160,000
170,000
180,000
190,000
200,000
210,000
220,000
Kiln Out, kg
It is clear that something unexpected is happening, which is worthy of further
investigation. The increase in fuel consumption is affecting the control system for the
exhaust fans and causing the speed of the fan to reduce. The fans are controlled by a
variable speed drive that enables the motor speed to be precisely changed, and as it is
lowered there is a reduction in energy consumption. The exhaust fan of a tunnel kiln is
controlled to maintain a constant pressure close to the kiln entrance. Normally an
increase in fuel consumption will increase kiln pressure (as more hot air is being forced
into the kiln) and therefore a higher fan speed would be required.
However a higher kiln pressure has many advantages from an energy efficiency point of
view. Less cold air is drawn into the kiln, so less fuel is needed to maintain the set point
temperatures, and the natural draft from the kiln is increased due to the higher
temperature, increasing the stack effect and the higher pressure before the fan.
One possibility is that a higher kiln pressure mitigates the increase in hot air mass
within the kiln by reducing the harmful “in-leakage” of cold air by an amount that is
greater than the increase in supply through the burners. Therefore the fan consumes
less power, and the kiln is more thermally efficient.
In addition, the higher temperature and increase in pressure before the fan increases
the buoyancy of the hot air in the kiln, and decreases power consumption. These
processes explain the marked decrease in specific fuel consumption and in power
consumption with increasing throughputs. They suggest that better air flow control
within the kilns could improve energy efficiency as less heat will be lost and less
electricity consumed, through the exhaust fan.
We can estimate the impact of managing a kiln to have lower air flow by quantifying the
improvement shown at the monitored site.
The average flow rate in the exhaust is 52,000 kg/hr which at 140oC represents a heat
loss of 1,800 kW.
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At a production rate of 220 tonnes a day the exhaust power consumption is 1,550 kWh.
At a production rate of 180 tonnes a day the exhaust power consumption is 1,625 kWh.
We estimate that this reduction in power consumption corresponds to a mass flow
decrease of two per cent, representing an energy saving at this site alone of:
Electricity:
Gas
27,000 kWh/year
300,000 kWh/year
14,300 kg CO2/year
57,000 kg CO2/year
However, savings resulting from controlling the air mass flow rates are likely to be
higher than this. The current exhaust flow at this site is approximately five times the
mass flow of product flowing down the kiln. We believe that it may be possible to reduce
this ratio to three (the ratios of the other two kilns in the study). If this was achieved
the exhaust gas mass flow would decrease by 40 per cent, and the temperature of the
exhaust would increase, making it more useful for heat recovery. We have assumed an
increase to 180oC, reducing thermal loss through the stack by 1,430 kW. Electricity
consumption would also decrease as the volume of hot air being exhausted is reduced,
giving an electricity saving of at least 20 per cent. This equates to:
Electricity:
Gas
118,000 kWh/year 62,500 kg CO2/year
3,000,000 kWh/year 570,000 kg CO2/year
Although estimated in a hypothetical situation, these potential savings illustrate the high
energy and carbon savings that are available by operating a kiln with a low air mass
flow. The challenge is to run the kiln at a lower air flow while maintaining the heat
transfer characteristics of the kiln and the physical properties of the final product.
Key finding: Lower air flow in kilns means lower power and fuel
consumption.
By managing the air flows into and out of a tunnel kiln, it may be possible to
significantly reduce the mass of air that leaves the kiln. This retains more heat
within the kiln and will reduce energy consumption. The challenge will be to
achieve this while retaining the heat transfer characteristics of the kiln and the
physical properties of the fired products.
4.5 The dryer
The drying process removes the moisture needed for forming, so that the product is
strong enough to be handled and won’t crack during firing. Bricks are usually dried
down to below one per cent moisture content from an initial level of 15 per cent (dry
basis) for extruded products and 25-30 per cent (dry basis) for soft mud products. Most
of the thermal requirement comes from the evaporation of the water.
Dryers operate at much lower temperatures than kilns (typically 130 oC maximum as
compared to 1,000oC). Much of this heat is recovered from the kiln. The amount and
source of the heat used in the dryers for the three sites is shown below.
CARBON TRUST INTERNAL USE ONLY
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
Figure 29: Energy balance for the dryers at each site
Moisture
content
of green
brick,
dry basis
Site 1
TK
Extruded
15%
(dried
1%)
to
Site 2
TK
Extruded
15%
(dried
0%)
to
Site 3
TK
Softmud
26%
(dried
2%)
to
Drier
throughput,
kg/hr
Thermal
energy
Required
to heat
and dry
bricks, kW
Hot air
Supplied
from
Kiln, kW
Gas
consumed,
kW
Total
heat
supplied,
kW
Net fuel
SEC,
kWh/
tonne
8,000
1,048
30%
of
supplied
heat
3,461
0
3,461
432
17,500
2,294
46%
of
supplied
heat
4,616
420
5,036
287
6,400
1,347
52%
of
supplied
heat
437
2,150
2,587
404
This shows that the drying process uses between two and three times the amount of
heat required to heat the brick to 120oC and evaporate all the water within it.
The least efficient site (Site 1) supplies all the heat for the drying process from the kiln.
This is surprising, as it seems logical to assume that the kiln that recovers all the heat
needed for drying would be the most efficient. However it is possible to over-extract
heat from the kiln, so that heat is transferred from the burner zones as well as from the
residual heat in the bricks that are being cooled. This is inefficient - kilns aren’t
designed to transfer combustion heat from the firing zone into the cooling zone - and
the result is higher structural heat loss and higher consumption in the kiln. If the kiln’s
cooling process were controlled better, the plant would be more efficient.
Key finding: Better control of cooling in kilns
Over-extraction from the kiln cooling zone leads hot gases being transferred
from the burner zone to the cooling zone, with increased energy loss.
The table also shows that it takes a huge amount of energy to evaporate the water. It’s
therefore obvious that bricks with a lower moisture content would have a lower specific
energy consumption. Clay extracted from a quarry has a moisture content of between 8
and 15 per cent, and in general very little moisture is added to bricks that are made by
the stiff extrusion method. However, a lot of water is added to soft mud bricks to make
them the right consistency for forming (usually between 20 per cent and 30 per cent
moisture content). This is why the soft mud plant uses more energy for drying. For each
kg of water added, approximately 2600 kJ of additional heat is needed to evaporate it.
If a dryer is approximately 60 per cent efficient, the thermal requirement is 4,300 kJ.
This is the potential saving if the moisture content of a soft mud product was reduced.
The problem with reducing the moisture content of a clay mix is that is becomes stiffer
and may not form correctly. However, if the temperature is simultaneously increased,
the consistency can remain the same as moisture content is reduced.
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Assuming soft mud bricks need a 10 per cent water addition, this amounts to 100kg per
tonne. If the water were added at 100oC (i.e. containing 10kWh of sensible heat) to a
15oC clay mix, the temperature of the resulting mixture would be raised by 40oC. This
would be hot enough to reduce the moisture for forming (although the actual reduction
is not known and will be product and process dependant). But it would also mean that
less energy would be needed for drying, as the product would be hotter and the
moisture content lower.
Of course adding hot water would only work as an energy saving measure if the water
were heated using waste heat. There are two sources of waste heat in a brick works:
the kiln’s exhaust, which at 140oC is a potential source of hot water, and the dryer
exhaust. This is cooler, but has a higher moisture content and if condensed could
provide a supply of warm water to be added to a soft mud clay mix.
Key finding: Lower moisture content forming
Forming products at lower moisture content will reduce the energy needed for
drying. By simultaneously increasing the temperature of the clay mix it may be
possible to maintain constant forming consistency and also start the drying
process immediately after forming. To result in a net energy saving, the heat
would need to come from waste heat recovery such as the kiln or dryer.
4.6 Electricity consumption in clay preparation and
forming
Clay is prepared using crushing and grinding technologies along with storage and
conveyors, while forming uses mixing and extrusion equipment. Dust extraction
systems may also serve these areas. Figure 14 shows the pattern of electricity
consumption for this part of the process at Site 2, where consumption is high during the
week and lower at weekends.
In figure 15 we have re-plotted the time series data in order of the electricity consumed
every 15 minutes. The zero (or near zero) consumption when the plant is closed shows
that a good switch-off procedure is in place - the rapid drop in consumption from 60 to
zero shows that the plant is switched off quickly. For the remaining 50 per cent of the
time, the energy consumption varies fairly evenly between 60 and 90 kW. The
smoothness of the transition suggests that the variation is due to a combination of the
variable loading on plant as throughputs change, and the motor idling. Consumption
increases sharply at the end because an extra crusher is occasionally used for one
material.
Electricity may be able to be saved by changing the way the process equipment is used,
making the consumption profile more like that shown in the blue dotted line. Our time
on site suggested that it should be possible to increase the loading and use of the
equipment. The electricity saving would then correspond to the shaded region,
amounting to a saving of approximately 10 per cent. This would equate to savings of
8,000 kWh/year, equivalent to a CO2 saving of 55 tonnes per year. Across the sector
this amounts to a CO2 saving of 1,600 tonnes.
CARBON TRUST INTERNAL USE ONLY
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
Figure 4: Site 2. Power consumption in clay prep and forming

Figure 31: Site 2. Power consumption in clay prep and forming
CARBON TRUST INTERNAL USE ONLY
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Key finding: Advanced sequencing of clay preparation and forming
equipment
Improving overall equipment efficiency (OEE) through improved sequencing
control or production scheduling could reduce power consumption and CO 2
emissions. The pattern of consumption at Site 2 suggests that on modern plants
equipment is already well controlled, and savings could be difficult to achieve.
Nevertheless, advances in OEE methods could potentially save 10 per cent of
power consumption without investment in new technology. This would save the
sector 1,600 tonnes of CO2.
4.7
The impact
consumption
of
product
weight
on
energy
The greater the mass of an object, the more energy will be needed to heat it. This
suggests that the lower the mass of a brick, the lower the energy requirement. In
general bricks weigh between 2.0 kg and 2.5kg depending on their size, composition
and porosity. The mass of an extruded brick depends on the size of the perforations
than run through it, as shown. Soft mud bricks, which cannot have perforations, have
voids made by frogs.
In the UK, companies have recognised that larger perforations can improve energy
consumption (as long as other physical properties stay the same). The old British
Standard of BS3921 restricted the maximum perforation area to 25 per cent but this
has been superseded by BS EN 771-1 which allows a larger perforation area in some
circumstances. Many sites have increased perforation size. Sites 1 and 2 have both
increased the perforations on their products to 30 per cent of the area.
The mass of clay bricks can also be reduced by incorporating lighter materials into the
clay mix. These could be lightweight inert materials that survive the firing process, or
components that decompose to leave voids. If these additives have a calorific value
they can also reduce the fuel needed for the kiln by providing some of the heat
themselves.
Both of these approaches have an important role to play in the evolution of clay bricks
towards becoming a low carbon product.
CARBON TRUST INTERNAL USE ONLY
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4.8
The impact of
consumption
firing
temperature
on
energy
The peak temperature at which a brick is fired affects the energy requirement. If the
firing process were abandoned altogether, leaving only a drying process, all the energy
used for firing would be saved.
There is a very small but emerging demand for unfired bricks: an example of a product
available for inner leaf and partition wall construction is shown below. Used as a building
material in Mesopotamia as far back as 8,000 BC, such products are still used in hot,
dry countries. Their use in the wet climate of the UK, however, is likely to be limited,
particularly in the case of external walling where clay bricks are generally used.
The main barrier to their adoption is the reluctance of the market to use a product that
moisture will damage and which requires new construction techniques. It is possible to
add materials such as lime or cement to clay mixes to reduce their vulnerability to
water, but the CO2 saved by removing a firing process is replaced by the CO2 emitted
during the manufacture of lime or cement. One option would be to use a low carbon
alternative to cement such flue ash or blast furnace slag.

Figure 325: Dry clay block and lightweight clay block
In continental Europe, external walls are often made of lightweight clay blocks, although
the walls are generally rendered as well. These products are often fired at a lower
temperature and generally have a lower energy requirement per m 2 of walling. They are
already available in the UK but their adoption depends on an increase in demand for
rendered external walling and for clay internal blocks (a market currently dominated by
cementitious blocks).
Fuel consumption in the kiln can be reduced without changing the final properties of the
brick through the use of additives. Most of the work in this area has looked at adding
glass cullet, but other fluxes have also been tested such as flue gas scrubber waste and
other waste materials. Glass cullet can reduce the firing temperature if it is ground fine
enough and added in sufficient quantities; but the economics mean it’s not a sustainable
technique.
New waste materials or waste material processing methods may become available,
enabling brick manufacturers to work with material specialists and building contractors
to develop an even lower carbon masonry solution based on a clay brick.
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Key finding: Development of low carbon products
An alternative to making equipment more energy efficient is to manufacture
products that are less energy or carbon intensive. There are two basic approaches
to this strategy:
1. Modify an existing product so that it needs less heat by, for example,
increasing perforation size, adding materials that reduce firing temperatures or
incorporating biomass within the product that reduces the net carbon emission.
2. Develop a new product that may require a new manufacturing route such as
unfired bricks or lightweight blocks.
4.9 Alternative energy sources
We have seen from the heat balances and the theoretical minimum energy calculations
that even the most energy efficient plant will use a lot of heat to dry and fire bricks.
Although low carbon products could reduce this requirement they are currently niche
products and are likely to remain so for many years. As a result, CO2 emissions from the
sector can only be significantly reduced though the use of low carbon fuels.
Brick manufacture is an ancient craft, and for hundreds of years bricks were fired using
biomass. When coal extraction became a major industry, coal became the dominant
fuel, and it is only in the past 40 years that gas has taken over due to its convenience.
There are therefore no technical reasons why clay bricks cannot be fired using biomass.
Indeed biomass could be added to a clay mix to reduce the fossil fuel requirement with
very little change to the process. Hoffman kilns, a type of continuous chamber kiln, are
traditionally fired on coal but they are now very rare and are unlikely to be built in the
future due to their high cost of construction and labour intensive handling requirements.
The sector uses both mines gas and landfill gas. It is therefore used to altering
combustion systems to accommodate gases of lower and variable calorific value.
Integrating a biomass gasification system would be an innovative step for the sector,
enabling it to use current kiln technology while saving large amounts of CO2.
We consider that there is no good case for switching to electric kilns to fire bricks as
using biomass directly in a kiln is a more efficient use of resources and energy than
using it to generate power which is then converted to heat.
Key finding: The firing of tunnel kilns with biomass
If the brick sector is to halve its CO2 emissions, the use of zero carbon heat
derived from biomass should be considered. Improvement of process efficiencies
will only take the sector so far (perhaps a further 20 per cent). Low carbon
products are capable of delivering the savings required, but these products are
likely to remain niche for the foreseeable future. This means that low or zero
carbon fuel supplies must be adopted by the sector as a key part of its low carbon
strategy.
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4.10 Summary of key findings
1. Improving electricity consumption
Power consumption is responsible for 166,000 tonnes of CO2 - 19 per cent of the
sector’s emissions. We estimate that this could be reduced by 9.5 per cent, or 15,800
tonnes/year, by widely deploying best practice in energy efficiency. The main barrier to
this is the dispersed nature of the consumption, which makes it difficult to achieve large
CO2 reductions through the use of a single technology. The development of enabling
technologies that support the adoption of best practice may help the sector achieve this
saving.
2. Improving fuel consumption
Fuel consumption represents 82 per cent of the CO2 emitted in the brick sector. We
estimate that up to 100,000 tonnes/year could be saved by eliminating sources of heat
loss to improve kiln performance. Beyond this, low carbon solutions involving low
carbon products and fuel sources will need to be deployed.
3. Balancing airflow in kilns and dryers
The proportion of heat used for firing and drying appears to be constant, regardless of
the technology used. This suggests that a common airflow strategy (high or low air) is
adopted for both processes, with low airflow being associated with higher efficiency.
4. Keep kilns operating at high throughputs
Under normal operation, a 10 per cent change in throughput of the kiln and dryer will
change the specific energy performance by at least six per cent. So preventing periods
of avoidable slow kiln throughput is an important factor in maintaining the good energy
performance of a kiln.
5. Measure heat flows in the stack and to the dryers
The SEC of a kiln is primarily determined by the heat loss from the stack and the heat
recovered for drying purposes. So it makes sense to measure these inputs in the same
way that gas and electricity are measured to enable process control decisions to be
made and their overall heat consequences assessed.
6. Lower air flow in kilns means lower power and fuel consumption
By managing the air flows into and out of a tunnel kiln it may be possible to significantly
reduce the mass of air that leaves the kiln. This retains more heat within the kiln and
will reduce energy consumption. The challenge is to achieve this without losing the heat
transfer characteristics of the kiln and the physical properties of the fired products.
7. Improved control of cooling in kilns
Over-extraction from the kiln cooling zone leads to the transfer of hot gases from the
burner zone to the cooling zone, with increased energy loss.
CARBON TRUST INTERNAL USE ONLY
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8. Lower moisture content forming
Forming products at lower moisture content will reduce the energy required for drying.
By simultaneously increasing the temperature of the clay mix (using recovered heat) it
may be possible to maintain constant forming consistency and also start the drying
process immediately after forming.
9. Advanced sequencing of clay preparation and forming equipment
Improving overall equipment efficiency (OEE) through improved sequencing control or
production scheduling could reduce power consumption. The pattern of consumption at
monitored sites suggests that on modern plants the control of the equipment is already
good and savings could be difficult to achieve. Nevertheless, advances in OEE methods
could potentially save 10 per cent of power consumption without investment in new
technology. Thus would cut emissions across the sector by 1,600 tonnes of CO2/year.
10. Development of low carbon products
An alternative to making equipment more energy efficient is to manufacture products
that are less energy or carbon intensive. There are two basic approaches to this
strategy:
i. Modify an existing product to require less heat for its manufacture by, for example.
increasing perforation size, adding materials that reduce firing temperatures or
incorporating bio-mass within the product.
ii.
Develop a new product with a new manufacturing route such as unfired bricks or
lightweight blocks.
11. The firing of tunnel kilns with biomass
If the brick sector is to approach CO2 reductions of over 50 per cent, it should consider
the use of zero carbon heat derived from biomass. Improving process efficiencies will
only take the sector so far - perhaps a further 20 per cent. Low carbon products are
capable of delivering additional savings, but these products are likely to remain a niche
option for the foreseeable future. This means that low or zero carbon fuel supplies must
be adopted by the sector as a key part of its low carbon strategy.
CARBON TRUST INTERNAL USE ONLY
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5. Opportunities
5.1 Introduction
Low carbon and energy efficiency opportunities that can be applied to the clay brick
sector (and by extension elsewhere within the ceramic sector) have been identified from
a number of sources:
firstly, through the monitoring that has been carried out as described in section
4;
secondly, by reference to our existing knowledge from a wide range of Carbon
Trust surveys;
and thirdly via consultation with the industry and its supply chain.
In total we have identified over 30 distinct opportunities, which fall into two main
categories:


Opportunities that can be implemented now without any further support. These
will include technologies and actions considered best practice, as well as some
newer technologies with no adoption barriers such as LED lighting or new generation
motors and drives. We describe these as best practice opportunities and they
represent a valuable list of actions that organisations can adopt to reduce their
energy costs.
Opportunities where barriers exist for their adoption for which additional
intervention is required to enable or accelerate deployment. We describe these as
innovations. Within this category is a subset of opportunities which, although they
require support for deployment in the sector, are covered by other Carbon Trust
programmes, in particular CHP.
The two sets of opportunities are set out in the sections below, along with an estimate
of their costs to implement, their payback and the CO2 reduction potential for the
sector. In the case of the innovations we have also included a short analysis of the
barriers preventing their deployment.
5.2 Best practice opportunities
The projects detailed below represent opportunities for brick manufacturers to reduce
energy consumption. These are already readily available and have been implemented
and proven within the sector, or widely used in similar sectors.
Most brickworks have already made use of many of the opportunities listed here,
reflecting the sector’s relatively mature energy efficiency status. That is not to say all
sites would not benefit from a review of their performance and a rigorous application of
best practice. But it reveals that if the sector is to achieve the levels of reduction it
needs to over the next 5-20 years (i.e. CO2 reduction of 20-50 per cent) it will need new
low carbon technologies, products and energy supplies.
CARBON TRUST INTERNAL USE ONLY
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
Figure 33: Best practice opportunities
Opportunity
Process
Costs to
implement
(£ per
plant)
Payback
(years)
% of sites
where
applicable
Total
CO2saving
by sector
1
Automated and phased
switch off of plant when
production ceases
Whole plant
£10,000
2-5
25%
1,600
2
Use of VSDs on air
movement fans to
control speed
Kiln and
dryers
£25,000
2-5
25%
5,000
3
Automatic compressor
sequencer control
Compressors
£10,000
5
50%
1,000
4
Heat recovery from
compressors for
washroom water or
combustion air
Compressors
£5,000
10
100%
100
5
Maintaining kiln car
seals in optimum
condition through more
frequent maintenance
Kiln
£50,000/ye
ar
n/a
80%
10,000
6
Maintaining hot air
ductwork insulation
levels to a minimum of
two inches for
temperatures below
200C and four inches at
higher temperatures
Kiln and
dryer
£50,000
5
50%
5,000
7
Ensure burner dilution
air is maintained to a
minimum on dryer top
up burners
Dryer
nil
n/a
25%
1,000
8
Carry out daily check on
kiln burners to ensure
complete combustion at
point of entry
Kiln
nil
n/a
50%
5,000
9
Measure kiln O2 profile
and use to adjust the
burner air, kiln draft and
rapid cooling air to
return to optimum
setting
Kiln
10,000
1
50%
5,000
10
Check that the exhaust
fan speed reduces with
kiln thermal input i.e. at
the end of a push
period. If it doesn’t it
means fresh cold air is
being pulled into the
kiln, wasting heat
Kiln
nil
n/a
50%
5,000
11
Increase exit controvec
fan speeds to decrease
brick exit temperatures
Kiln
nil
N/A
50%
1,000
CARBON TRUST INTERNAL USE ONLY
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Opportunity
Process
Costs to
implement
(£ per
plant)
Payback
(years)
% of sites
where
applicable
Total
CO2saving
by sector
12
Minimise the standing
time between dryer and
kiln to avoid the reabsorption of moisture
Dryer
nil
N/A
20%
500
13
Upgrade of kiln
combustion system and
control
Kiln
>£1 million
>5 years
50%
20,000
14
Upgrade of kiln
structural insulation and
integrity
Kiln
£500,000
10 years
50%
10,000
15
Use of high velocity
recirculation (e.g.
cones) in the dryer
Dryer
250,000
2-5
years
25%
5,000
16
Replacing high bays
with efficient high
pressure sodium and T5
fluorescent for medium
heights
Whole plant
10,000
5 year
25%
500
17
Optimise throughput of
prep plant and forming
by minimising downtime
and optimising feed
rates
Prep plant
10,000
2-5
years
50%
1,000
18
Use of high emissivity
coating in kiln to
increase heat transfer.
(Still an emerging
technology)
Kiln
£100,000+
2-5
years
80%
20,000
Total with a payback
of less than five
years3
45,000
Our analysis in the table estimates that the total remaining opportunity for CO2
reduction by best practice is relatively low, at 45,000 tonnes CO2/year or five per cent
of current emissions. This is a low figure, although it excludes asset management and
design measures such as building a new factory or a new kiln as these are capital
investments driven by factors other than energy efficiency. It suggests a limited
remaining potential for best practice unless new technologies are developed for existing
factories. This modest saving is supported by an analysis of the savings in SEC that
have been achieved in the CCA milestones between 2002 and 2006. This has shown an
3
Although the CO2 saving potential in the sector is estimated some of the opportunities
tackle the same CO2 source and are not additive; some also have a payback well in
excess of five years and have very little chance of being implemented except in a new
factory situation.
CARBON TRUST INTERNAL USE ONLY
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energy efficiency improvement trajectory falling from over three per cent per year to
about one per cent per year. If this trajectory continues, it will take over 23 years to
reduce like on like carbon emissions by 20 per cent.
Figure 6: Energy efficiency improvement 2000 to 2006
energy effciency saving over previous
year

4%
3%
3%
2%
2%
1%
1%
0%
2002
2004
2006
year
5.3 Opportunities for innovation
Table 5 lists the identified energy efficiency and low carbon opportunities that require
further development or demonstration to overcome the barriers to their adoption. We
have indicated their potential in the table, using four key attributes to assess the
technologies:
the scope for CO2 saving in the sector;
the enthusiasm for the idea from the sector;
the nature of the barriers to its development and adoption in;
the cost and/or difficult of developing the technology within a two-year timeframe.
The savings and costs are estimates based on our own and the BCC’s knowledge of the
sector rather than on submitted costs by technology providers. However they are
considered to be reasonable. In some cases due to difficulty in estimating, the costs
have been omitted. More detailed costs are included in the business cases (section 6).
We have divided the ideas into five technology areas agreed at the industry consultation
event held on 6 July 2010:

Clay preparation and forming

Drying and firing (which includes heat recovery)

Low carbon products
CARBON TRUST INTERNAL USE ONLY
58

Alternative fuels and energy

Software tools for process and equipment efficiency
Please note that many of the innovations in the table tackle the same carbon source.
Therefore the opportunities cannot simply be added together to give an estimate of the
total savings potential of the sector. We have allowed for this overlap and estimate that
if all the innovations were developed and adopted the sector could save 350,000
tonnes/year.
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Opportunity
Cost to
implement
(per plant)
£
Payback
(years)
% of
sector
where
applicable
Total CO2
saving by
sector
Barriers to implementation
Strategy to address
barriers
Accelerator
potential
Clay preparation and forming
1
Elevated temperature
forming
Brick forming at elevated
temperatures using waste
heat to reduce the power
required for forming and
the heat for drying.
£200,000
2-4
20
(as most
applicable to
soft-mud
production)
10,000
Already carried out elsewhere within
Europe to reduce electricity
consumption and fuel for drying.
Main barriers are the recovery of
sufficiently high quality heat to raise
the temperature of the clay mix and
keeping its moisture content and
temperature consistent.
As one of the major barriers
to this project is the heat
recovery technology required.
Combining this with a heat
recovery project may be the
best way forward. Process
integration issues and
consistency can be readily
dealt with by an expert
supplier.
Medium
2
Rock wheel generators
Electricity generation
through the kinetic energy
of falling material, i.e. using
material falling from
elevated conveyors to
turn a small generator.
Not known
N/A
100
500
The main barrier here is the small
saving that would be generated and
the requirement for the technology
to be portable.
None recommended.
Low
Drying and firing
3
Dryer exhaust
heat recovery
Heat recovery of waste
heat in the dryer exhaust.
£300,000
2-5
100
10,000
The low temperature of the exhaust,
less than 100oC, making recovery of
the sensible and latent heat difficult.
The heat would be in the form of hot
water or air at 30oC to 40oC and of
limited use except for project 1.
Although over 20% of the
energy used in a brickwork is
contained in the dryer exhaust
it is in general at too low a
temperature to be recovered
usefully.
Low (medium
if combined
with
opportunity 1)
4
Kiln exhaust
heat recovery
Heat recovery of waste
heat from the kiln exhaust.
£300,000
2-5
100
10,000
The acidic nature of the exhaust
gases means durable materials are
required. There is a reluctance within
the sector to emit exhaust gases
below 120oC which will limit the
amount of heat recovered.
Improved material selection
such as stainless steel, plastic
or coated steels and a
business case that takes into
account a minimum exhaust
temperature.
High
65
Opportunity
Cost to
implement
(per plant)
£
Payback
(years)
% of
sector
where
applicable
Total CO2
saving by
sector
Barriers to implementation
Strategy to address
barriers
5
Microwave firing
Using microwaves in place
of combustion systems to
volumetrically heat products
rather than rely on
conduction from the
surface.
>£1 million
N/A
5%
not known
Unsuccessful attempts at technology
transfer by EA Technology and
CERAM in 1995.
Application mainly for intermittent
kilns and therefore low adoption
potential.
None considered at this stage.
Low
6
Preheat combustion air
using exhaust gases
Over 20% of the kilns heat
is lost through the stack,
preheating combustion air is
a viable method of
recovering that heat.
3
75
10,000
Heat recovery is the biggest
challenge.
Combine with a heat recovery
project.
High
7
Kiln car redesign
Redesign kiln car utilising
high U value materials and
kiln seal system to reduce
heat loss through the
structure and seal.
not known
N/A
80
20,000
A huge amount of heat is lost
through the kiln car and their seals,
possibly as much as 5%. The main
barrier is the amount of up-front
design and engineering work
required and the high expense of
conducting proving trails in an
existing kiln.
The incorporation of
lightweight materials will
reduce conductive heat loss
and a redesign of the seal for
existing kilns could reduce
loss by leakage. A water seal
kiln exists and has been
adopted by some sites but is
very expensive.
High
8
Reduced air flow
operation of kilns
Reducing the air flow in the
kin and dryer will reduce
power consumption and
also heat loss through the
stack.
£100,000 to
500,000
1-5
80
70,000
Applying the technology to existing
kilns may be difficult in some cases
but the main barrier is changing
established practices and long held
views on kiln operation. A new
robust measurement and control
system is also required.
Developing a new kiln design
with kiln manufacturer and a
retrofit option for existing kiln.
Demonstrating the retrofit to
prove savings and a
dissemination plan to change
attitudes towards air
movement management.
High
9
Integrating CHP into kiln
or dryer combustion
system
Two projects were put
forward by the sector, the
integration of CHP into the
brick making process and
N/A
5-10
50
N/A
The high cost and long payback of
CHP are barriers along with the
relatively modest potential CO2
savings.
The fact that the investment is
not adding value to the brick
product is also a barrier and
may mean such technologies
are best developed outside
the sector with the power and
heat sold into it through.
Low
£300,000
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66
Accelerator
potential
Opportunity
Cost to
implement
(per plant)
£
Payback
(years)
% of
sector
where
applicable
Total CO2
saving by
sector
Barriers to implementation
Strategy to address
barriers
Accelerator
potential
perhaps more process
specific was the
development of combined
micro-turbine and burners.
New products
10
Products with lower
firing temperatures
The development of new
clay body mixes with lower
firing temperatures which
consume less fuel.
not known
N/A
100
10,000
Concern that product quality and
colour are maintained; the cost and
availability of additives such as glass
cullet.
Rigorous physical testing
applied to of lab and longer
term industrial trials.
High
11
Unfired clay products
The development of new
niche low carbon clay
products that eliminate
firing altogether.
not known
N/A
5
35,000
Life expectancy of product and user
acceptability; current building
standards, some products already
exist.
Any project must include a
user (i.e. builder) that is
willing to test the construction
and jointly address the
barriers.
High
12
Lower mass products
Lightweight products
through increased
perforations or addition of
lightweight waste materials.
not known
N/A
25
10,000
Maintaining physical properties and
user acceptance. Current standards.
Either rigorous testing to
maintain current appearance
or partnership with builder to
develop a new product with
different appearance.
High
13
Hybrid products
New manufacturing
techniques that combine
fired and unfired materials
in a new product. e.g. high
insulation properties and
high durability; combined
brick tile with insulating
block; product with fired
outside face and unfired
interior.
not known
N/A
5
10,000
No known method of achieving the
result. Unknown properties of final
product.
Not known.
Medium
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Opportunity
Cost to
implement
(per plant)
£
Payback
(years)
% of
sector
where
applicable
Total CO2
saving by
sector
Barriers to implementation
Strategy to address
barriers
Accelerator
potential
200,000
5
100
2,000
Recovering the waste heat and selecting an
appropriate generation technology.
Combine with a heat
recovery project.
High
Alternative fuels/energy
14
Power generation from
waste heat
Over 20% of the energy
used in a brick factory is
lost as waste heat,
techniques such the organic
Rankine cycle or a Stirling
engine can convert low
temperature waste heat into
electricity.
15
Incorporation of
bio-mass fuel within
the product
Addition of bio-mass
material to clay mixes to
reduce the firing
requirement.
Not known
<2
50
70,000
Sourcing suitable material that will burn is a
manner that reduces the fossil fuel
requirement of the kiln. There may be some
unwanted emissions from the process.
Combine with a project
looking into developing
new products.
High
16
Co-firing of kilns
with syn-gas
If fired bricks are to remain
the most popular cladding
of our dwellings then heat
will always be required. The
integration of syn-gas into
existing kilns could
potentially deliver the
biggest CO2 saving of any
potential development.
Not known
5
100
250,000
The sourcing of suitable bio-mass; the
integration of the gasification process into a
brick site and the clean combustion of the
syn gas in the kiln.
An availability ministudy of bio-mass
should be a prerequisite of any project
application. The
integration should be
the main focus of the
project and clean
combustion achieved
by restricting syngas to
the burners in the
middle firing zones.
High
17
Bio-mass CHP
The integration of
established bio-mass CHP
systems into a brickworks.
£1,000,000
5-10
100
100,000
As well as sourcing bio-mass material the
main issue is using the low grade heat that
comes of the existing technology.
We consider the much
better solution is the
direct combustion of
bio-mass as an
ingredient in the
product or co-firing as
syn-gas.
Low
Process and equipment efficiency
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68
Opportunity
Cost to
implement
(per plant)
£
Payback
(years)
% of
sector
where
applicable
Total CO2
saving by
sector
Barriers to implementation
18
Process modelling for
minimum emissions
The development & use of a
process model that enables
the optimised use of
existing technology to be
determined through
simulation. To be used for
new factory design and
re-planning of existing
facilities.
100,000
3
50
10,000
The difficulty in obtaining data to
develop the simulation. The high
initial cost of developing a core
system which can then be modified
for use by the entire sector.
Support the development of
core system that will have a
much lower cost for
subsequent use.
High
19
Process fault elimination
The use of interactive
operator tools to determine
the causes of poor energy
performance and plan for
their solution.
100,000
3
50
10,000
Scepticism on the use of tools. The
low level of process data capture on
some sites may make it difficult to
determine waste opportunities.
Demonstration of success.
High
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Strategy to address
barriers
69
Accelerator
potential
5.4 Recommendations
By prioritising the 19 opportunities listed above we can recommend which would be an
appropriate focus of the Accelerator Challenge. We aim to recommend Challenges that
are based on real projects identified by the Phase 1 process, but are also broad enough
to allow alternative approaches.
The first move is to determine whether any of the projects can be combined with others
in a wider project idea without changing their scope or nature.
Project 1: elevated temperature forming: is best achieved in combination with a heat
recovery project, as the use of recovered heat is essential to achieve a low carbon
solution and is also its biggest technological hurdle. This is also true of project 14: the
generation of power from waste heat and project 6: the preheating of combustion air. A
heat recovery project may be able to provide enough heat to heat a soft mud clay mix,
pre-heating combustion and generating power through a micro waste heat generator.
The reason for combining these potential projects is that the main barrier to
demonstrating these ideas is the heat recovery step rather than its downstream use.
Although the kiln is the primary source of sensible heat, it would be perverse to have a
heat recovery challenge that could not be applied to a dryer exhaust. We therefore
recommend a single heat recovery challenge focused on developing a scalable
technology that is durable, does not impact the environmental consents of the site and
can provide enough recovered heat utilisation solutions to provide a payback of less
than five years.
Project 15: biomass addition to reduce fossil fuel requirement, can be seen as the
development of a low carbon product and readily combined with projects 10, 11, 12 and
13 which all seek to redesign product compositions to reduce CO 2 emissions. Although
each of these projects takes a different approach they are all tacking the same potential
CO2 saving and should be combined into one Challenge of developing a new low carbon
facing brick product. In order to encourage specific innovations that can be readily
adopted by the sector, and that do not require re-capitalisation, we think that the
products should be able to be produced in existing or modified plants.
Projects 18 and 19 are both concerned with developing tools that result in the more
efficient use of technology and less energy waste. As such they can be readily combined
into a single technology Challenge.
In addition to these consolidations we can eliminate any remaining potential projects
that have been rated as low or medium for accelerator potential. This eliminates four
projects, leaving a residual total of six possible Accelerator Challenges:
heat recovery
redesign of kiln cars and kiln car seals
low air movement kilns
low carbon clay products
co-firing of kilns with syn-gas
tools to improve overall equipment effectiveness
65
The two kiln projects could also be combined into a wider “efficient kiln” concept. This
would leave the door open to further innovations from organisations that have so far not
engaged with the Phase 1 project or have been unwilling to share their idea in an open
forum. On the downside it might detract attention from the two specific technologies
that have been identified as having large CO2 reduction potential. On balance we think
the areas should be kept separate. In section 6 we have therefore prepared the
business cases for supporting these six technology concepts.
It is perhaps surprising that there have been no nominations for drying technologies.
This is an energy intensive process within the sector (even allowing for the fact that
much of the energy is supplied as “waste” heat from the kiln). The explanation probably
lies in the fact that many of the actions that can be taken to improve a dryer are
already well known, being contained in section 5.2. as best practice options. Also,
before dryers can improve the kiln must be made as efficient as possible, which may
require unforeseen changes to the dryer operation.
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6. Next steps – business cases for
challenges4
In this section we have prepared the business cases for the six technologies identified in
section 5. Each business case takes the same format, containing the following
information:




a description of the concept and the CO2 emissions it is addressing;
the benefits of its development, why it represents an advance for the sector and
why it requires support;
one or more potential approaches or projects that would deliver the benefits;
an estimate of the project costs and an estimate of the cost of the developed
solution;

an estimate of the CO2 reduction for a site and for the sector; and

any key risks or barriers that may prove difficult to get over.
We have summarised the key numbers in the table below:
Challenge
Project
cost
Project
payback,
years
Maximum
sector
CO2
savings
Cost of
technology
once
mature, £
Annual
site
saving,
£/year
Annual site
CO2 saving,
tonnes/year
£1 million
16
200,000
£2 million
£244k
1,650
1
Co-firing of kilns
with syngas
2
Process heat
recovery &
utilisation
£400k
3.3
33,000
£400k
£140k
1,300
3
Redesign of kiln
cars
£150k
7.5
10,500
£100k
£20k
210
4
Low air
movement kiln
£250k
2.6
40,000
£200k
£90k
800
5
Low carbon
products
£150k
-
20,000
-
-
-
6
Tool to improve
process and
equipment
effectiveness
£150k
3.0
13,000
£100k
£40k
500
4
In this version of the report the business cases have been modified to reflect the
redraw of the Grants for Phase 2 of the Accelerator programme.
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6.1
Co-firing of kilns with syngas
Co-firing of kilns with syngas
Development
Description
Syngas is produced when biomass such as woodchip or agricultural
waste is heated without air. The decomposition of the material
generates CO and H2 (as well as other gases) while leaving behind a
char (which may or may not have calorific value). These gasifiers are
available at every scale of output but within the UK the market for them
is still immature and their use is non-existent in the brick sector.
Natural gas is the dominant fuel used in the brick sector and in most
cases it is introduced into the kiln via a simple metal tube at a
temperature above 800oC (the auto-ignition temperature of natural gas
is 580oC). Producer gas from coal was successfully used to fire bricks in
trials in the 1980s by the Coal Research Establishment in Stoke Orchard
and lower calorific value gas such as landfill gas is used to co-fire some
kilns in the UK. Substituting natural gas for a syngas is therefore
possible for the manufacture of bricks in a tunnel kiln.
Over 85 per cent of the emissions from the sector arise from the drying
and firing process. Even if these processes were made as
thermodynamically efficient as possible there would still be heat
requirements of some 3 million MWh/year, emitting over 500,000
tonnes /year of CO2. Substituting fossil fuel based heat with a
renewable heat source could eliminate much of this emission.
Utilising a syngas means that the sector can take advantage of current
gasifier technology and use its existing gas based combustion systems.
The project would therefore involve integrating the current state of the
art gasifiers and modifying the burner systems to accommodate a
hotter gas with a lower calorific value and different combustion
characteristics. The sensitivity of the integrated system to different
source biomass materials should also be explored.
In the consultation it was clear that developments in this area carried
the widest support and therefore there is considerable enthusiasm for
co-firing with a syngas. It also has the potential to deliver a very large
CO2 saving.
Technology
maturity and
need for support
The concept seeks to take small scale existing gasification technology
and link it to a combustion system currently deployed in the sector. This
has not been done in the UK before and no case studies exist elsewhere
in the world. Small and medium size biomass gasification is an
immature market in the UK and therefore some development of the
technology may be required for its integration into a brick process, the
starting point however should be existing technology. There is
considerable expertise in the UK in combusting syngas (although not for
brick manufacture) and the technology is fairly mature. However no-one
has put these systems together as an integral part of firing brick. The
complexity of the team required to deliver this project and the
development costs make it a project that is unlikely to proceed from the
sector itself without support.
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Co-firing of kilns with syngas
This concept has quite a narrow scope and the project approach is likely
to involve all of the following:

Selection and construction of gasifier to run off woody biomass
material and supply a syngas for one or two burner groups in a
tunnel kiln;

Possible project
approach


Modification of the existing combustion system to accommodate the
properties and combustion characteristics of the syngas
The integration of the gasifier and new combustion system into kiln
operation
Dealing with potential problems such as “tar” in the syngas,
residual char, controls and biomass supply and storage.
The project would need a host site willing to provide significant space
labour and process time to the project; an engineering company to
provide and commission the gasifier; a combustion engineer to modify
the existing burner system and a biomass supply company or market
expert to supply material that can meet the expected long term demand
from the sector.
Estimated
project cost
This is likely to take 18 to 24 months and a budget of £1 million for the
demonstration of a 250kW facility.
Payback to
project host site
The rhi rates published in March 2011 are not payable on kiln, furnaces,
ovens or dryers. Should the technology be eligible for the rhi in the
future, at 2p/kWh, this would generate an income of £43,500/year.
Current costs of virgin biomass are similar to the cost of natural gas
therefore in the current climate the fuel costs will be similar, but the
use of waste biomass will reduce fuel costs possibly by 0.5p/kWh,
giving an annual fuel saving of £11,000/year. An additional saving
comes from avoiding CO2 costs associated with taxes or other
regulations; assuming a price of £16/tonne for CO2 the annual saving
will be £6,500/year. The estimated saving for the host site of a 250 kW
trial unit is £61,000 giving a payback of 16 years.
Dissemination
Cost of
technology
(once mature)
Capital cost of £2,000,000 per site for 1 MW of thermal input. Running
costs will be dependent on biomass prices and the mix used
(incorporating waste will reduce the cost) but is expected to be similar
to using natural gas.
Saving
Basing the savings on those calculated for the 250kW development unit
the total savings for a 1MW system are estimated at £244,000/year.
Payback once
mature
Eight years
Project
persistence
10 years
CO2 saving
per site
A 1 MW installation (representing 20 per cent of the typical thermal
input of a kiln) would save 1,650 tonnes of CO2 per year and require
over 2,000 tonnes of bio-mass each year.
Over ten years a 1MW unit will reduce CO2 emissions by 166,000
tonnes and deliver a net saving of £440,000.
Sector CO2
saving potential
Assuming that 30 per cent of the current fossil fuel consumption could
be substituted by biomass gasification, the CO2 reduction potential is
200,000 tonnes/year.
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Co-firing of kilns with syngas
Market
penetration
The market penetration will depend on the economics of replacing
natural gas with bio-mass. But five per cent within five years and 25 per
cent within 10 are our current estimates based on the current drivers.
Sector forecast
CO2 saving
10,000 tonnes/year in five years
50,000 tonnes/year in 10 years
Barriers to
adoption
i) Sourcing suitable feedstock for the gasifier and security of supply;
ii) The high capital costs;
iii) The increased management control and maintenance required to run
a duel fuel system;
iv) Fears about product quality and increased levels of undesirable
emissions;
v) Storage of biomass on site
Risks
i) The high temperature of the generated syngas may make the
modification of the burner pipe work system more difficult than
anticipated.
ii) The lack of gasifier expertise/resources may be difficult to secure.
iii) The price ratio between fossil fuels and biomass may become less
favourable.
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6.2 Process heat recovery and utilisation
Process heat recovery and utilisation
Development
Description
The energy balances in section 4 have shown that over 50 per cent of
the heat supplied to the kiln and the dryer is lost through sensible heat
and latent heat in their exhausts. These exhaust streams are therefore
a rich source of heat that if harnessed could be used in a number of
ways e.g. to pre-heat combustion, heat the clay feedstock or to
generate electricity.
This challenge seeks to design and demonstrate a reliable means of
heat recovery from an exhaust stream and the re-use of that heat back
in the process. An ideal solution would be a modular package that can
be manufactured and installed at relatively low cost giving a scalable off
the shelf heat recovery solution.
Technology
maturity and
need for support
The sector has known for a long time that the kiln exhaust is a rich
source of waste heat. However there is no current proven recovery
method available for the sector to adopt. Although heat exchange is a
mature technology at high temperatures, its use at lower temperature
(below 200oC) remains a bespoke technology with correspondingly high
costs and few providers. For lower temperature heat recovery to
become widely adopted the sectors needs a packaged solution that can
be constructed off-site cheaply, installed at low cost and operated with
acceptable risks to the process. This will require a considerable amount
of engineering development on the drawing board, in material selection
and process integration for the utilisation of the heat. The high cost of
this work has meant that in the past it has not been carried out. This
may explain the failure of some past attempts (usually because of the
high costs of bespoke design or short life expectancy because of
corrosion). A joint funded project will decrease the financial risk to a
project team but also enable a project to cover the essential design and
replication criteria that have not been considered sufficiently before.
Possible project
approach
This project has a relatively wide scope in that it could attract a number
of alternative methods of heat recovery and a number of methods of
heat utilisation. We believe that a good project application would
involve:

A brick manufacturer committed to installing a full scale system on
a tunnel kiln and providing the resources required to integrate a
new system into their factory and deploy the utilisation
technologies;


An engineering company capable of designing, constructing and
installing the complete system;
A heat exchange expert to provide the “scalable solution” capable
of being mass reproduced.
Estimated
project cost
This is likely to take 18 to 24 months and a require a budget of
£400,000.
Project payback
to host site
Assuming an energy saving of £140,000/year and a running cost of
£20,000/year the payback for the development project would be 3.3
years.
Dissemination
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Process heat recovery and utilisation
Cost of
technology (once
mature)
Capital cost of up to £400,000 per site to recover 1 MW of thermal input
from an exhaust waste steam. Running costs will be dominated by
maintenance requirements and are estimated at £20,000/year.
Saving
Assuming 1 MW of heat recovery delivered 800 kW of heat or 150 kW of
electrical energy the energy saving will be £140,000 giving a net annual
saving or £120,000/year.
Payback
3.3 years
Project
persistence
10 years
CO2 saving per
site
A 1 MW unit would save 1,300 tonnes of CO2 per year.
Over ten years the CO2 saving will be 13,000 tonnes and the net saving
£900,000.
Sector CO2
saving potential
Assuming that 25 kilns could adopt this technology the maximum CO2
reduction potential is 33,000 tonnes/year.
Market
penetration
The market penetration will depend on the temperature and flow rates
of the current exhausts but 20 per cent within five years and 50 per
cent within ten are our current estimates based on the current drivers.
Sector forecast
CO2 saving
6,600 tonnes/year in five years
16,500 tonnes/year in 10 years
Barriers to
adoption
i) Temperature of exhaust gases. If they are too low there is increased
risk of acid condensation in the heat exchanger and stack;
ii) The high capital costs;
iii) The fears over corrosion and life expectancy;
Risks
A short life expectancy of a solution or existing ductwork and exhaust
stack due to acid condensation.
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6.3 Redesign of kiln cars and car seals
Kin car design
Development
The energy balances in section 4 show that a considerable amount of
heat (five per cent) is lost through the kiln car as a result of its high
thermal mass, conduction through its structure and also through a poor
seal between the kiln and the car itself. The figure below illustrates
these losses.
Heat loss
through
structure
Heat loss
through seal
with kiln wall
Description
Heat loss
through seal
with next car
A redesign of the kiln car could lead to the incorporation of more
lightweight materials, reducing thermal mass and conduction losses,
and an improved seal with adjacent cars and the kiln structure.
Technology
maturity and
need for support
Kiln cars are designed and supplied by the kiln builder, but maintenance
and repair is carried out by the operator, often involving changes in
material and/or design to improve their thermal performance or to
improve stability. This is normally carried out in conjunction with a
refractory material supplier but rarely involves the use of engineering
design tools to fundamentally redesign the concept. Such an exercise is
unlikely to be pulled together without external financial support.
The technologies required for a redesign are all relatively mature and
the project would seek to apply them in a new way to deliver a new
solution to an old problem of heat loss through kiln cars.
It is worth noting that there is already a high quality seal solution
available in the market from the French equipment manufacturer Ceric.
A water seal, it is very expensive and can only be supplied with a new
kiln i.e. it cannot be retrofitted.
This challenge should develop a solution that can be retrofitted to
existing kilns.
Possible project
approach
At the centre of this project will be an engineering designer able to
explore a range of potential new designs that can be integrated on a car
by car basis with existing kilns. Support will be needed from refractory
suppliers and kiln builders to ensure the designs are fit for purpose. One
or two of the designs could be tried out at a suitable tunnel kiln.
Project costs could be kept down by only trailing a relatively few kiln
cars (e.g. up to six). This represents a compromise between having
enough to measure an impact on energy consumption and risk to the
host brick manufacturer.
Estimated
project cost
The project is likely to take 12 to 18 months and a require a budget of
£150,000.
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Kin car design
Payback for
project host site
7.5 years
Based on a £20,000/year energy saving
Dissemination
Cost of
technology (once
mature)
The upgrading of 50 or so kiln cars in one go would be logistically
impossible as the kiln would need to be switched off for several months.
The technology would therefore be introduced gradually as part of an
accelerated car repair and maintenance programme. This makes the
cost of introduction lower than other projects but it means adoption
rates will be slower.
We estimate an increased cost of £100,000 over existing maintenance
costs.
Saving
Assuming that 25 per cent of the 500 kW of heat that is lost through
the kiln car is prevented with the new designs, 125 kW of heat can be
saved for each tunnel kiln or 1 GWh/year worth £20,000/year.
Payback
five years
Project
persistence
10 years
CO2 saving per
site
210 tonnes of CO2 per year
Over 10 years the CO2 saving will be 2,100 tonnes and the net saving
£100,000.
Sector CO2
saving potential
Assuming that 50 kilns could adopt this technology the maximum CO2
reduction potential is 10,500 tonnes/year.
Market
penetration
The market penetration will depend on the temperature and flow rates
of the current exhausts but 20 per cent within five years and 50 per
cent within 10 are our current estimates based on the current drivers.
Sector forecast
CO2 saving
2,000 tonnes/year in five years
5,000 tonnes/year in 10 years
Barriers to
adoption
i) The cost of the transition to the new design
ii) Reluctance to change current tried and tested design
ii) Changes required to the kiln interior to accommodate a new seal;
Risks
Compatibility with existing kiln cars may be difficult, either
compromising the potential savings or making it a “new build only”
technology.
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6.4 Low air movement kiln
Low air movement kiln
Development
Description
Section 4 has identified a link between air movement and kiln
efficiency, with high air movements being associated with lower
efficiencies. In spite of this, kilns and dryers do not measure their air
flows nor use them as a means of control.
Reducing air flows within the kiln reduces its thermal requirement and
also reduces the heat lost through the exhaust. Almost all existing kilns
will have considerable opportunities to reduce air flow but most either
do not recognise this as an energy saving opportunity or do not have
the knowledge or the confidence to make the necessary changes.
This challenge will design and test a kiln change programme that will
transform existing kilns into low air movement kilns with significant
lower energy consumption. The deliverable would be an expert
contractor capable of delivering the changes to existing kilns or a
detailed methodology to enable companies to implement the
programme themselves. An important part of the project will be the use
of robust flow measurement technology to help the continued operation
of kilns at low air flows.
Technology
maturity and
need for support
Most of the technologies required for low air movement kilns are
already in place on the modern kiln; technologies such as high velocity
burners that reduce the requirement to run kilns at high air flows to
heat the bricks in the early zones and variable speed drives on fans to
enable air flows to be precisely controlled. There is however a lack of
knowledge and confidence to use this technology to improve energy
efficiency. This may be partly due to the lack of instrumentation that
measures airflows to indicate whether excessive air is being admitted
into the kiln or exhausted from it in flue or to the dryer. The way a kiln
is operated may also need to change to maintain a good heat transfer
mechanism within the kiln.
Possible project
approach
We see three possible approaches to this project.
1. A design exercise for a new low air flow kiln through a kiln builder
and the application of those principles to an existing kiln through a
demonstration;
2. The adaptation of an existing kiln to a low air movement kiln by an
expert team and dissemination of the methodology through a
commercial service;
3. The development of a robust monitoring system that enables kiln
managers to reduce air movement themselves with demonstration at a
selected site.
In all cases the development of a process model that enables the
required changes to be designed and implemented is desirable.
Estimated
project cost
The project is likely to take 18 months and a require a budget of
£250,000
Payback for
project host site
2.6 years based on a 10 per cent energy saving in fuel and power.
Dissemination
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Low air movement kiln
Cost of
technology (once
mature)
The cost of the solution will vary considerably depending on the
capability of the kiln to accommodate the changes. Assuming the
combustion system needs no modification, the cost of implementation is
estimated at £200,000, plus increased maintenance costs of
£5,000/year due to the increased instrumentation.
Saving
We estimate a potential saving of 20 per cent for both fuel and power,
assuming that a refurbishment solution only achieves 50 per cent of this
potential due to limitation of the technology on the kilns. For a typical
site this will save 4,000 MWh/year of fuel (£80,000/year) and 150
MWh/year of Power (£15,000/year) a net saving of £90,000/year once
the increased maintenance costs are taken into consideration.
Payback
Two years
Project
persistence
Lower than the more technology based projects due to the dependence
on management commitment to maintaining the changes introduced.
Estimated at five years.
CO2 saving per
site
800 tonnes for a typical kiln.
Over five years the CO2 saving will be 4,000 tonnes and the net saving
£45,000.
Sector CO2
saving potential
Assuming that 50 kilns could adopt this technology the maximum CO2
reduction potential is 40,000 tonnes/year.
Market
penetration
The market penetration will depend on the temperature and flow rates
of the current exhausts but 10 per cent within five years and 25 per
cent within 10 are our current estimates based on the current drivers.
Sector forecast
CO2 saving
4,000 tonnes/year in five years
10,000 tonnes/year in 10 years
Barriers to
adoption
i) Lack of knowledge and resistance to changing established operation
practices
ii) Lack of resources to make the large number of changes required on
an existing kiln
ii) The quality and robustness of monitoring equipment
Risks
The ease with which changes can be reversed may make the
persistence of the saving low.
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6.5 Low carbon products
Low carbon products
Development
Description
This is perhaps the broadest of all the challenges recommended but also
the one with the greatest scope for innovation and the only project that
requires the engagement of the consumer.
The concept is to design new products or new formulation for existing
products that make them less carbon intensive to manufacture. The
concept could attract two different type of project:
1. A new clay based product that reduces or eliminates the need for
firing e.g. unfired blocks
2. Additives that reduce the firing requirement; e.g. flux addition to
reduce the firing temperature; a biomass addition to reduce the fossil
fuel requirement or a change in density/porosity of the product.
Technology
maturity and
need for support
This is an immature area in the UK although there are products meeting
the low carbon criteria made in Europe, Australia and in particular in the
developing countries (see section 5). Some of the larger brick
manufacturers are already engaged in developing “low carbon” products
and unlike the other projects we can expect progress in this area
without support for the Carbon Trust. However Carbon Trust support is
likely to increase the pace with which the developments progress.
Possible project
approach
There are a large number of possible approaches, but the involvement
of an end user i.e. builder would certainly increase the strength of a
project team and its chances of success.
We also believe that the projects with the best replication potential will
aim to use much of the current production technology (i.e. clay
preparation and drying).
Estimated
project cost
This project is likely to take 18 months and a require a budget of
£150,000.
Payback for
project host site
Not calculated as it is very project specific
Dissemination
Cost of
technology (once
mature)
It is not possible to estimate the cost of implementing the technology,
but manufacturing costs could reduce (due to a reduction in firing
requirement) and raw material costs are likely to increase in most
cases. New technology in preparation and forming is also likely to be
required.
For the basis of payback we have assumed a simple product formulation
project with a one-off cost of £200,000 for process changes.
Saving
We have assumed no saving, as the motivation for this project will be to
create new markets or new value in existing products.
Payback
Not calculated.
Project
persistence
For a successful product over 10 years. Fired bricks have been used for
2,500 years and dried clay bricks for 10,000 years.
CO2 saving per
site
Calculated at sector basis only.
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Low carbon products
Sector CO2
saving potential
Assuming that five per cent of the market could be displaced by a low
carbon product in which the CO2 emissions from firing are halved, the
maximum CO2 reduction potential is 20,000 tonnes/year. A similar
reduction would be estimated by assuming a 10 per cent substitution of
a product in which the firing carbon requirement was reduced by 25 per
cent.
Market
penetration
The market penetration may be slow as it will be driven by market
demand rather than a “push” mechanism from the manufacturer. We
estimate 10 per cent within five years and 50 per cent within 10 are our
current estimates based on the current drivers.
Sector forecast
CO2 saving
2,000 tonnes/year in five years
10,000 tonnes/year in 10 years
Barriers to
adoption
i) Lack of demand due to physical properties and current product
standards
ii) Quality problems and complaints
Risks
Higher embedded emissions from additives and life cycle in-use
emissions.
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6.6 Tools to improve overall equipment effectiveness
Tools to improve overall equipment effectiveness
Development
Description
Many manufacturing facilities are operated sub-optimally, particularly
when they are working at less-than-design throughputs. This means
that opportunities for efficiency improvements exist within most
processes. Production losses caused through waste, scrap,
overproduction, poor quality product and/or under-utilisation can result
in large energy inefficiencies.
This concept tackles the energy efficiency opportunities that exist in
many of the technologies deployed in the sector. Individually these
would not be cost effective to tackle, but if tackled collectively they
economic due to the accumulation of a number of marginal gains.
The concept is to provide IT tools to process managers and operators
that help them identify and implement process and equipment changes
that will bring about these marginal improvements.
Technology
maturity and
need for support
The concept of improving overall equipment effectiveness (OEE) is not
new and is a well-established technique to improve the return on
expensive assets. The use of modelling to do this or to improve process
configuration or production planning is also not new.
However the use of these techniques to improve energy performance is
new and will require the development of new systems, new skills and
new attitudes within the sector. For example, an improved OEE in one
area may push bottlenecks to other areas and reveal previously hidden
inefficiencies. This may have the undesired impact of actually increasing
energy consumption per unit of production overall. So an holistic tool is
needed to engage and educate managers to understand the relationship
between business, operational, energy and emissions performance.
The cost of generating the tools in the first place will be high but it is
expected that subsequent roll out cost will be low.
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Tools to improve overall equipment effectiveness
Possible project
approach
Two approaches are considered possible to deliver sufficient marginal
gains for a viable innovation:
1. In this project, a generic brick factory process model will be
developed, including energy consumption and CO2 emissions, and
combined with scenario and sensitivity analysis using advanced
modelling techniques. The model is applied to a site and the impact on
production, fuel requirements, CO2 emissions and unit costs is
determined. The model will also provide a means of sharing best
practice between sites whilst protecting commercially sensitive
information.
The generic simulation model is provided to process managers and
operators to help them experiment with, identify and implement
process and equipment changes that will find the optimum increase in
process efficiency that delivers the best reduction in energy
consumption and emissions per unit. By incorporating production,
energy and emissions, together with scenarios and sensitivities, the tool
will also enable capital investment decisions to be better underpinned.
2. A slightly different approach is to use existing production monitoring
to identify when a “fault” occurs that wastes energy (e.g. stopped
production) and collect operator generator data on the cause of the
fault (e.g. lack of feedstock material, broken wire). In this way a picture
of the causes of energy loss will emerge, and action can be introduced
to eliminate them.
Estimated
project cost
This project is likely to take 18 months and require a budget of
£150,000.
Payback for
project host site
Three years
Dissemination
Cost of
technology (once
mature)
The costs of adoption once the system is mature will include the
purchase of the system itself and the cost of the training and initial
consultancy which we estimate at £100,000 making this the lowest cost
solution to adopt. Running costs are likely to be £10,000/year.
Saving
Our estimate assumes that the average plant can make a power saving
of 10 per cent through the deployment of this technology. We have not
included fuel in this calculation and we believe our other
recommendations provide better methods of reducing fuel consumption.
This equates to a typical saving of £50,000 for a typical site.
Payback
2.5 years
Project
persistence
Persistence is likely to be relatively low due to the behavioural nature of
the improvement at around five years.
CO2 saving per
site
500 tonnes of CO2/year
Over five years the CO2 saving will be 2,500 tonnes with a net saving of
£100,000.
Sector CO2
saving potential
Assuming that 80 per cent of the power consumption in the sector could
be affected by this technology and a saving of 10 per cent the
maximum CO2 reduction potential is 13,000 tonnes/year.
Market
penetration
If the innovation is successful the market adoption should be fast,
though it may be limited by expertise on the supply side. We estimate
25 per cent within five years and 75 per cent within 10.
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Tools to improve overall equipment effectiveness
Forecast CO2
saving
3,250 tonnes/year in five years
9,750 tonnes/year in 10 years
Cost of CO2
savings to
Carbon Trust
£10/tonne CO2 in 10 years
Barriers to
adoption
i)Skills and commitment of the site
ii) Complexity of the developed solution
Risks
Changes identified may be much more expensive than forecast.
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Appendices
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Appendix A Sector wide opportunities
workshop
British Ceramic Confederation
Federation House, Station Road, Stoke-on-Trent. ST4 2SA Tel: (01782) 744631 Fax: (01782) 744102
E-mail: [email protected]
AGENDA
Carbon Trust
Industrial Energy Efficiency Accelerator
Brick Sector
Potential Accelerator Technologies
Workshop 6th July 2010 10.00 – 15.00
1. Introductions and Objectives
Dave Beardsworth, BCC
2. The Accelerator Programme
Al-Karim Govindji, Carbon Trust
3. Energy Consumption in the Ceramic Sector
James Beardmore, BCC
4. Discussion on the Potential Projects
John Fifer, SKM Enviros
5. Summary of Discussion
Dave Beardsworth, BCC
6. Next Steps
John Fifer, SKM Enviros
Lunch will be provided at 12.00
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Appendix B Calculations
Theoretical heat requirements
15 per cent moisture:
1000 * 15 per cent = 150kg water evaporated from 20oC
150 kg * 2600/3600 kWh/kg (total heat content of steam at 130oC)
108.33 kWh/0.9/0.76 to account for the irrecoverable latent heat in the
combustion of gas and the 25% estimated minimum loss through the stack and
structure
= 160.5 kWh/tonne
+ sensible heat in brick heated to 130oC
850 * 0.8 (specific heat of clay) * 120 (temperature rise 10oC to 130oc)
81,600/3600 kWh /0.9/0.76 to account for the irrecoverable latent heat in
the combustion of gas and the 25 per cent estimated minimum loss through the stack
and structure
= 33.6 kWh/tonne
Total
= 194.1 kWh/tonne
35 per cent moisture:
same as above
Firing a typical clay brick
Assume 5 per cent mass loss during firing and 25 per cent additional mass due to kiln
car base achieving the same temperature as the kiln. Fired to 1100oC from 50oC
1300 * 0.8 * 1050 /3600 kWh
303.33 kWh/tonne /0.9/0.76 to account for the irrecoverable latent heat
in the combustion of gas and the 25% estimated minimum loss through the stack and
structure
449 kWh/tonne
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Appendix C Flow meter specification
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