FEMS Microbiology Reviews 103 (1992) 355-364
© 1992 Federation of European Microbiological Societies 0168-6445/92/$15.00
Published by Elsevier
355
FEMSRE 00259
Use of renewable resources for non-food materials
M. E g g e r s d o r f e r , J. M e y e r a n d P. E c k e s
BASF Aktiengesellschaft, Ludwigshafen, FRG
Key words: Renewable resources; Non-food materials
1. I N T R O D U C T I O N
The use of renewable resources for non-food
materials is a topic under heated discussion in
various fields (Fig. 1).
The reasons for the public discussion are concerns about pollution of the environment, CO 2
emissions, limited petrochemical reserves, and
agricultural production surpluses.
Renewable resources are a source of energy,
and a feedstock for fuel or chemical reactions.
They seem to be intrinsically safe and clean, and
are regarded as unlimitedly available. The expectations of the public are high and opinions are
formed in an emotionally charged atmosphere.
As a matter of fact fossil raw materials are
used as the main source for energy supply in the
range of about 7 - 8 billion tons oil e q u i v a l e n t /
year. The world consumption of energy is about
3250 million tons of oil, 3430 million tons of coal
and 1900 billion m 3 of natural gas (Fig. 2).
On the other hand, biomass production is
about 170000 million tons a year. Theoretically
this biomass amount would be enough to replace
fossil fuels completely. However, realistically only
Correspondence to: M. Eggersdorfer,
sellschaft, W-7600 Ludwigshafen, FRG.
BASF
Aktienge-
3% or about 6000 million tons of plant material
can in fact be cultivated, harvested and processed. This amount includes about 2000 million
tons of wood, 1800 million tons of grain and
about 2000 million tons of oil seeds, sugar cane,
sugltr beet, fruits, beets and so on. This figure
comprises the food and non-food sectors.
As shown by the total-use figures, there would
not be enough renewable resources even if they
were all used exclusively to replace fossil f~els.
Replacement of fossil fuels by plants will not be
an objective at all in the near future.
Let us have a more detailed look at what our
resources are used for today.
The energy sector consumes large volumes of
fossil resources. Most renewable resources go into
nutrition.
To put this in perspective it is essential to look
at the total figures for the consumption of fossil
and renewable resources. Figures are available
for Germany.
Figure 3 shows that about 93% of West German consumption of fossil resources goes on energy generation and only 7% is used in the chemistry sector. Energy is consumed for heating and
by power stations and traffic.
The distribution of uses of renewable resources is similar. About 97% of agricultural production goes into the nutrition sector and only
356
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Fig. I. Selectionof newspaper headlines.
about 3% is processed into non-food materials,
including chemicals. Worldwide this is equivalent
to about 45 million tons of renewable resources.
A simple calculation demonstrates the influence
Renewable Resources
Fossil R e s o u r c e s
Total use. 6000 mill. tons / a
Total use. 7300 mill. tons OE* / a
on agricultural surplus reduction. Let us imagine
a doubling in the use of renewable resources in
the chemistry field. This would increase the cultiPercentage consumption of fossil resources and agricultural
products by the chemical i n d u s t r y
-
~
energy93%
fossilresources
wo¢
WaStGermann~m~alod
con,~mm~o,)
Oilseeds
Sugar-cane and Beets
Natural gas
agriculture
~"""".....
~
~
j~
chemcalindustry7%
nutritionsector97%
Fruits, Roots,Beets
Totalavailable: 170,000mill.tons/a
Totalavailable: 853.000mill.tonscoal
120.000mill.magus
135.000mill.tonsoil
* Oil equivalents
Fig. 2. Figures for renewable and fossil resources.
~ase~,O~w~Gend~mN~,~pl
e. x c l u d ~
no. . . . ,ritionsector 3°/.
(incl.chemicalindustry)
Fig. 3. Figures for the consumption of fossil and renewable
resources.
357
vation of farmland in Germany for chemical purposes to about 400000 hectares. However, in
Germany alone there is an excess of 2-3 million
hectares of farmland no longer needed for nutrition but which is usable for non-food materials.
This simple calculation indicates that the chemi-
cal industry cannot alone contribute to any significant reduction in German or European agricultural production surpluses. However, this could
be possible in the energy field, as will be discussed later.
With these arguments in mind the main appli-
Development of global energy demand
Million tons oil equivalent (OE)
8750
/_..
7500
6250.
5000
3750
O|1
o
1975
80
85
1990
b
Consumption of oil
in OECD countries
in non - OECD countries
Million tons
Million tons
750
ica
Australia
5OO
Lsla
OECD Europe
250
North A m e r i c a
. . . . .
~97s
laso
lm
laeo
0
lo7s
leao
leas
laeo
Fig. 4. a. Development of global energy demand, b. Comparison of oil consumption in O E C D and non-OECD countries.
358
cations of renewable resources in the non-food
sector which are broadly being discussed at the
m o m e n t are:
- in the energy field, for example as feedstock
for power stations or alternative fuels;
as a base for new materials in technical applications and polymers;
- and last but not least as a second feedstock for
chemical synthesis.
In the following sections, developments and
perspectives of renewable resources in these three
areas will be discussed.
-
2. R E N E W A B L E R E S O U R C E S IN T H E
ENERGY FIELD
a
Miscanthus as a source of energy
Growing o f
Miseanthus
Drying
Harvesting
30 t/ha
biomass
D u n n g winter
Special
machines 1o i
' be developed
in the fields
Transportation
and storage
Buming
Special local
.
_
_~wer~t~tjo,~
b
MISCANTHUS: ENERGY SOURCE FOR TOMORROW?
P R O D U C T IO N SCENARIO (Germany)
PRICE SCENARIO (Germany)
• Miscanthus (envisioned for 2000)
• Miscanthus I I 0 - 210DM/I
140 - 266 DM/t OE*
• Available area
2 mill. ha
• Yield
60 mill. t
• Energy
25 mill. t OE*
• Heating oil 200 - 400 DM/t OE*
• Fossil energy sources
• Total energy used 245 mill. t OE*
As already mentioned, the use of renewable
resources in the energy field would be the only
way to significantly save on fossil resources while
simultaneously reducing agricultural production
surpluses as a synergistic effect•
World energy demand has increased by more
than 40% over the past two decades (Fig. 4).
Symptomatically, global oil demand reached a
constant level after the first and second oil crises
in 1973 and 1979. However, beginning in the
early 1980s a significant and constant growth in
fossil fuel use is detectable• As a matter of fact
this is not the case for renewable resources• Renewable resources made no measurable contribution to world energy supply even in 1990.
The analzsis of oil consumption in O E C D a~d
n o n - O E C D countries will show in more detail the
development in energy demand•
Energy consumption in O E C D countries is
regarded as being virtually constant, whereas in
n o n - O E C D countries fossil resources consumption is rapidly increasing. For example, oil consumption in oil-producing countries and Southeast Asia is doubling. While figures show that
industrial countries have reached a level of constant oil consumption, programs for the development of alternative energy sources, for example
the use of renewable resources in the energy
field, have been started.
In the energy sector different possibilities for
renewable resources are being discussed and examined; for example whole-plant combustion,
• Possible contribution of Mi~..anthus
to German energy supplies
10%
* oa~ . ~
Fig. 5. a. Production of miscanthus, b• Figures for the use of
Miseanthus as energy source.
bioalcohol production and its use, especially as
gasoline for cars, or rape-seed oil and its methyl
ester as fuel for diesel cars.
The two projects that are most discussed,
widely published and funded with huge amounts
of money are the 'Alternative Energy Projects';
the use of Miscanthus or elephant grass as energy
sources in whole-plant combustion and the 'Biofuel Project' based on rape-seed oil or its methyl
ester•
The first is the subject of several different
evaluations by public institutions or industry in
different parts of G e r m a n y (Fig. 5).
The basic ideas are: to use Miscanthus as a
prototype of a perennial C4 plant with a very
effective CO2 fixation mechanism; to grow this
plant with a high biomass yield under optimal
agricultural conditions. The yield of biomass is in
the range of 30 t o n s / h a , compared to 6 t o n s / h a
for wheat, for example• The biomass dries during
winter in the fields and is harvested with special
machines. The biomass is collected and used for
combustion in local power stations•
To obtain an idea of the profitability of Miscanthus a production and price scenario will be
discussed. Given an acreage of about 11 million
359
hectares in Germany, and taking the 5-year crop
rotation system into account, about 2 million
hectares would be available for Miscanthus in
Germany. Assuming a yield of 30 t o n s / h a , a total
amount of 60 million tons of biomass would be
generated every year. This corresponds to about
25 million tons of oil equivalent. This rough estimation clearly shows, firstly, that Miscanthus will
not replace oil as a source of energy, and secondly, that the contribution made by Miscanthus
could be as significant as 10%.
The price scenario is based on first estimations
made by the German Federal Ministry of Energy,
Agriculture and Forestry (BMELF). With a reimbursement of DM 2000 per hectare the costs for
Miscanthus would be in the range of DM 110-210
per ton. This corresponds to DM 140-270 per
ton of oil equivalent. These figures compare to
DM 200-400 per ton of oil equivalent based on a
price of $15 per barrel. According to these figures
Miscanthus is competitive today. Provided that all
technological barriers are surmounted, Miscanthus could make a contribution to future energy
supplies.
a
Production of rape-seed oil methyl ester
1.Pressing
I
Rape
1Harcesti,i Rape-seed ~
I 0.92 ha
FTransRape-seed oil ~
2.75 t
1.1t
Rape-seed oil methyl ester
t
[
It
+
13
Rape-seed oil methyl ester: Biofuel of the future?
PRODUCTION SCENARIO (Germany)
PRICE SCENARIO (Germany)
• Rape-seed oil methyl ester
(envisioned for 2000)
• Rape seed oil methyl ester 2.00 DM/1
• Fuel
0.44 DM/I
• Available area
2.0 mill. ha
• Rape-seed oil methyl ester 2.2 mill. t
• Subsidization need for rape-seed oil
methyl ester
per 1:
• Fuel (1990)
• Total amount
• Farming
1.56 DM
22.0 mill. t
1.5 mill. t
• Possible contribution of rape-seed oil
methyl ester to fuel supplies
10%
Fig. 6. a. Production of rape-seed oil methyl ester, b. Figures for the use of rape-seed oil methyl ester as energy source.
360
The second project, 'Rape-seed oil methyl ester' (Fig. 6), aims at the use of plant oil as a fuel
substitute. Rape - in addition to sunflowers - is
today the only oil plant suitable for growth and
good yields in north-west Europe.
The process for the use of rape-seed oil comprises the following steps: harvesting, pressing,
and extraction. After extraction rape-seed oil is
converted to the corresponding methyl ester by
methanolysis. The esters are useful diesel substitutes. As the flow diagram (Fig. 6a) indicates, the
methyl ester yield is, at about 1 t o n / h a , relatively
low compared with the 30 tons of biomass yielded
by Miscanthus. Furthermore, by-products such as
1.6 tons of rape-seed meal and 100 kg of glycerol
should be taken into account. The production
and price scenario shows the potential of these
methyl esters. About 2 million hectares of rape
yield 2.2 million tons of ester. This volume could
replace about 10% of the total amount of diesel
fuel consumed in Germany.
The price of rape-seed oil ester is estimated at
about DM 2.-/I. This means that subsidies of
about DM 1.56/1 are needed to make rape-seed
oil methyl ester competitive to diesel fuel at DM
0.44/1. The bare figures do not give a fair description. Generally, rape-seed oil in Europe is
subsidized by about DM 0.80-0.90/1 to make it
competitive with soybean oil. Taking these subsidies into account, the price of the methyl ester is
about DM 1.15/1. This is the price range for
diesel fuel today. The scenario demonstrates that,
although it might not be realistic to produce and
subsidize large oil ester volumes, it could make
sense for a few applications, for example in city
centers or water-protection areas as well as
forests, to use rape-seed oil esters to reduce
environmental pollution.
3. R E N E W A B L E R E S O U R C E S
CHEMICAL INDUSTRY
FOR
THE
The chemical industry's raw materials base has
changed over the decades. At the beginning the
sole raw materials employed were renewable resources and coal. At the end of last century the
use of coal increased. In the 1930s oil was beginning to substitute coal as a feedstock. And it
replaced to an even. greater extent coal and renewable resources. This process was stopped by
the oil crises in the 1970s. At the beginning of the
1970s the German chemical industry used only 1
million tons of renewable resources. According to
b
Renewableresources
a
Feedstock consumption by the chemical Industry
in the Federal Republic of G e r m a n y (1985)
Change in the structure of the
chemical industry's feedstock base
Volume in tons
13 mi,.
Feedstock base
•N•a•ie•&
o,
mill.
2.7 mill.
/
~'~"
,,
,..:
I
/
I
1850
_~
"%.
"v'v'~'r~ .~.44 ~
/
coal
renewable resources
%#
Z'...... .... . . . J
I ....
1950
_,,q
"T
I
1980
2000
Year
Value in %
65
1.8 mill.
10%
5
approx
,
petroleum
•
natural gas
•
renewable resources
coan
Fig. 7. a. Structural changes in the chemical industry's feedstock, b. Feedstock consumption by the German industry.
22
361
new figures this amount has doubled within the
last few years (Fig. 7).
In G e r m a n y about 20 million tons of feedstocks are used in the chemical industry, made up
as follows: about 13 million tons of oil, about 1.5
million tons of natural gas, about 3 million tons
of coal and nearly 2 million tons of renewable
resources. Renewable resources thus account for
about 10% of total feedstocks, but represent
about 20% of their value.
Renewable resources used in the chemical industry are oil and fats, starch, pulp and sugar
(Fig. 8). Oils and fats are used for the production
of detergents, as raw materials for surface coatings, and textile, p a p e r and leather auxiliaries.
For the use of oil and fats standard reactions
such as saponification, hydrogenation and esterification have been established. Starch is an auxiliary in p a p e r manufacture, a carbon source for
biotechnological processes, and is used in packaging materials. Cellulose is employed in the textile
industry and other applications such as filters,
explosives, celluloid, etc. The use of cellulose has
decreased over the last few years. Sugar is used
as a feedstock for biotechnological processes, as a
building block for vitamins and for polyurethanes.
The use of renewable resources will increase in
the next few years because numerous research
programs have been started at universities and in
R & D in industry.
Uses of renewable resources
Oils and fats
Detergent base materials and detergents
Raw materials for surface coatings
Textile, paper and leather auxiliaries
Starch
Auxiliary in paper manufacture
Market prices of selected raw materials and chemicals
._
•
~=
• citric acid
• ethylene oxide
• propytene
• acetic acid
• ammonia
lactic a c i d
oxide
• acrylic acid
• ethylene
• ptopylene
*methanol • benzene
• ethanol
• starch
• melasses
~cmde *
oil
!
i
i
0
• sugar
• tallow • sunflower
oil
i
500
* c a s t o r oil
i
i
1000
1500
2000
i
I
2500
>
Dlvl~on
Fig. 9. M a r k e t prices of s e l e c t e d raw m a t e r i a l s a n d c h e m i c a l s
b a s e d on p e t r o c h e m i c a l s or r e n e w a b l e resources.
Two important prerequisites for the increasing
use of renewable resources are a competitive
price and the availability of conversion technologies. Figure 9 shows raw materials and chemical
products based both on petrochemicals and on
renewable resources of different upgrading levels
as a function of the price. If we compare world
market prices for raw materials, it is amazing that
renewable resources and their derivatives are in a
similar range to base products derived from
petrochemicals. Therefore, based on world market prices, renewable resources are a force to be
reckoned with. This is especially true and important in fields where we can make use of nature's
synthetic potential. For example sugars with their
high oxygen content might be interesting building
blocks for alcohols, polyols and other oxygen-containing compounds. The linear structure of oils
and fats may give opportunities in surfactants and
polymers. However, in all these calculations we
should not forget the amount of integration involved - from raw materials to the use of all
by-products.
Carbon source for biotechnological processes
Packaging materials
4.
Cellulose
Sugar
Fibers
FiLlers
Carbon source for biotechnological processes
Building block for vitamins
Polyurethanes
Fig. 8. R e n e w a b l e r e s o u r c e s and t h e i r fields of application.
RENEWABLE
RESOURCES
IN
THE
MATERIALS SECTOR
Use of renewable resources in the materials sector:
- Fibers
- Packaging materials
- Polyurethanes
362
Packaging materials based on renewable
sources:
- Starch/polyethylene
- Thermoplastically processable starch
- Starch/additives
- Starch graft polymers
- Cellulose diacetate
- Polyhydroxybutyrate
- Polylactides
re-
This area is rather heterogeneous as it consists
of natural fibers such as cotton for textile use.
Cellulose and derivatives are traditional raw materials for p a p e r and packaging or starch as
builder in p a p e r and detergents. Polyurethanes as
plastics are used for numerous technical applications.
In the last few years several new products
exhibiting biodegradability have been developed.
Examples are combinations of starch with other
polymers, cellulose diacetate, polyhydroxybutyrate, and polylactides. Some of these developments are on the threshold of commercialization.
Because this symposium deals with this topic 1
would like in this review to concentrate on one
special field that is closely related to chemistry:
the use of renewable resources in the production
of polyurethane.
All the processes for the production of
polyurethane follow basically the same route (Fig.
10).
A polyol is reacted in a polymerization step
with a diisoeyanate c o m p o n e n t to yield a
polyurethane. On this principle 4.6 million tons a
year of polyurethane are produced worldwide for
different purposes. As one can imagine, the favorite polyols are glycerol, sucrose, sorbitol or
starch. They are cheap starting materials with the
right set of functional groups. Polyurethanes
partly made from renewable resources are used
for bumpers for cars. The amount of renewable
resources consumed is estimated at 100000 tons
per year.
5. R E N E W A B L E
DUCTION
Use of renewable resources in the materials
sector
Polvurethanes as an e x a m o l e
HO . . . .
OH
+
O=C=N . . . .
polyol
.....
N=C=O
diisocyanate
o-
C-N
......
a
N-C-ta_J n
polyurethane
Polyol:
glycerol
saccharose
sorbitol
starch
Fig. I0. Production of polyurethanes based on renewable
resources.
RESOURCES
IN THE
PRO-
OF C H E M I C A L S
Two strategies can be differentiated for the
use of renewable resources for the production of
chemicals. The first strategy is the use of renewable resources for established product lines (Fig.
lla). New technologies have to be developed by
which renewable resources can be converted for
example into chemical intermediates. The advantage of this strategy is that it would follow established product lines in the chemical industry. This
might also enable high-volume products to be
synthesized from renewable resources.
The second strategy is to use nature's synthetic
potential for the development of new products
with new properties. Both strategies have already
been used successfully. Some selected examples
of both strategies will be discussed below.
Propanediol is a chemical intermediate for numerous applications such as polymers. It is produced worldwide in the range of about 2 million
tons per year. The established industrial synthesis
starts from propene. In a series of conversions
propene is oxidized to propanediol. A new route
to propanediol is the selective hydrogenation of
363
b
Intermediates based on renewable resources
a
Strategies for the utilization of renewable
resources in the chemical industry
PrgpanedioI as an example
•
Petrochemical-based production
OH
Development of technologies for the
j..
Naphtha
manufacture of established intermediates
OH
on the basis of renewable resources
•
Alternative route from renewable resources
CHzOH
rio _ ' ~,~~ ° \
HO "~""'~ V ' ' ~ - OH
oH
Development of new products having new
properties
OH
pressure,temperature
catalyst,H,
IOH
Fig. 11. a. Strategies for the use of renewable resources in the chemical industry, b. Propanediol based on renewable resources.
sugars in the presence of a catalyst under high
pressure and at elevated temperature (Fig. l lb).
This process yields propanediol in a single step,
but ethylene glycol, hexanetetrol and water are
produced as by-products. The yield of the different products is influenced by the reaction conditions, especially temperature. The selling price
for propanediol is in the range of DM 2300/ton.
a
Fine chemicals based on renewable resources
Vitamin B 2
Vegetable oil
Fermentation
i
b
Surfactants based on renewable resources
Separation
L
Drying
Examole
•
o
HN
Alkylpolyglucosides by reaction of glucosides and alcohols
.o
CH2-(CHOH)3-CH2OH
Vitamin B 2
o
o-~
o
a
~
"
N
•
Objective
Fully degradable nonionic surfactants
Fig. 12. a. Microbial synthesis of Vitamin B 2 based on renewable resources, b. APGs, surfactants based on renewable resources.
364
Depending on the sugar price and the reaction
selectivity there may be a chance for this process
to be competitive in the future.
Industrial applications for the hydrogenation
of sugars already exist, for example the hydrogenation of glucose to sorbitol. Sorbitol is an
intermediate for the production of vitamins and
numerous other applications. Another possibility
for renewable resources is as a carbon source for
fermentation processes. Biotechnological processes are increasing in importance for the synthesis of chemicals.
One example is vitamin B 2 (Fig. 12a). Vitamin
B 2 is used in the feed, food and pharmaceuticals
sectors. It can be produced - despite its complicated structure - in a single step starting from
vegetable oils by a biotechnological process. The
classical production sequence is a 5-step synthesis.
An example of the second strategy is the synthesis of detergents of the alkyl polyglucoside
type (Fig. 12b). These products are synthesized
from sugar and a fatty alcohol. Alkyl polyglucosides are fully degradable nonionic surfactants.
Worldwide capacity is at present in the range of
30000 tons per year. It is expected that alkyl
polyglucoside will replace petrochemical-based
surfactants.
There are numerous other applications for renewable resources which can only be mentioned
here. Paints and surface coatings use plant oils as
solvents. Here, linseed oil - due to its linoleic
acid content - is much in favor. Worldwide a few
hundred thousand tons of linseed oil are used in
non-food materials. Other products made from
renewable resources are for example crop protection agents, emulsifiers, cosmetics, aromas and
natural dyes.
To increase the use of renewable resources
there will have to be intensive cooperation between basic research, plant breeders, producers,
processors, industry and polities. For example, we
need to know more about chemical reactions with
renewable materials. The range of methods for
utilization as materials will have to be improved.
Plant breeding is essential to improve the crop
yield and the amount of desired constituents. In
this field the progress of biotechnology and genetic engineering is important. Worldwide production is necessary to ensure reliable supplies
with constant quality. Last but not least one of
the most important factors is competitive prices
for these renewable resources.
The potential of renewable resources for nonfood materials can be summed up as follows.
Renewable resources are a second feedstock; they
improve flexibility in feedstock selection and they
provide additional potential for innovation for
new products and processes. However, it should
not be forgotten that in the foreseeable future
fossil resources cannot be completely replaced by
renewable resources.
365
Fourth
Symposium
on
LACTIC
ACID
BACTERIA
Genetics,
Metabolism
and
Applications
To be held in Noordwijkerhout, The Netherlands, on 5-9 Sept. 1993
Sponsors: Netherlands Society for Microbiology and the Federation
of European Microbiological Societies (FEMS).
Information and Pre-registration: Please contact: International
Agricultural Centre, P.O. Box 88, 6700 AB Wageningen, The
Netherlands. Tel: +31-8370-90111 / Fax: +31-8370-18552