Titanium Use in the Geothermal Industry
Robert Houser, PE, MBA
ATI Wah Chang
An Allegheny Technologies Company
ABSTRACT
Geothermal power plants around the world experience diverse corrosive environments.
Some geothermal environments are so corrosive that titanium is one of the few
candidate materials that can survive past a standard 18 month test string casing. The
ability to survive these environments is critical when the design life spans of geothermal
power plants are typically over 20 years. Various grades of titanium tubular products
have been installed around the world and are doing very well in these highly corrosive
environments.
As the industry progresses to deeper wells and more corrosive conditions, the stand-by
product, steel, must be replaced with other specialty metals like titanium. Titanium’s
corrosion resistance and strength make it ideal for production wells and heat exchanger
tubing. Typical convective hydrothermal energy reaches temperatures in the 260-330°C
range. New advances in the geothermal industry could lead to magma-based energy
where temperatures exceed 500°C. Alaska and Hawaii are likely locations for magmabased applications. Titanium alloys, with the addition of palladium or ruthenium, are
ideally suited for these conditions.
Tubular goods are not the only application for titanium in the geothermal industry. High
strength and corrosion resistant specialty metals are required for parts such as springs,
snap-rings and the like.
This paper will look at the expanding geothermal industry and reflect on where titanium
can meet the needs of this growing industry.
INTRODUCTION
The geothermal industry can be broken up into three categories.
1. Direct Use
 Spas
 Snow melting
 Space Heating
2. Power Generation
 Greater than 150°C (300°F)
3. Enhanced Geothermal Systems (EGS)
 Experimental power generation
The direct use category typically uses plastic materials because the geothermal fluid is
not hot or corrosive enough for titanium. One indirect method to be aware of is coproduction fluids, which are hot usable fluids, such as oil and gas production fluids that
can have their heat converted to direct use applications or power generation. There are
presently two geothermal co-production demonstrations underway supported by the
U.S. DOE, at the Rocky Mountain Oil Test Center in Wyoming and the Jay oil field in
Florida. Another great example of geothermal heat use is in Iceland at the Blue
Lagoon. It is a large outdoor spa that serves 400,000 people annually.1 The spa is
sourced from the discarded water of two geothermal power plants pictured in the
background of photo 1.
Photo 1. Blue Lagoon in Iceland – Geographia
Power generation has the opportunity to utilize large quantities of titanium. This paper
will go into more details on applications where titanium has had great success.
The final category is Enhanced Geothermal Systems (EGS). EGS is power producing
technology based on creating engineered hydrothermal reservoirs in regions lacking in
fluid saturation and permeability. The EGS technique is to drill into the ground and then
inject high pressure fluid into the well in order to enhance existing fractures in the rock
and create an artificial reservoir that mimics a natural hydrothermal resource. Additional
"production wells" are then drilled to intersect the fractures and pump fluid, superheated by the heat in the rock, to the surface where it is used to power turbines and
create electricity.2
This technology has great potential but is still, after 36 years, experimental. In 2012 the
Cooper Basin facility in Australia is expected to be the first major operational plant at 50
MW. 2
GEOTHERMAL ENERGY PROCESS OVERVIEW
Magma from the center of the earth heats a natural underground convective reservoir of
water. The reservoir is replenished by rainwater through natural fractures in the ground.
Pictured below is a cutaway showing the process.
Figure 1. Geothermal Reservoir Process – Geothermal Energy Association
A production well pipe taps the hot water reservoir and as it proceeds up the pipe it
changes to steam. The steam and any remaining water are then separated. Water
from the process is re-injected down a second pipe. The hot steam pushes a turbine
resulting in electrical energy production. 3
Figure 2. Schematic of a Condensing Geothermal Power Plant. The flow of hightemperature fluid is indicated in red, and the cooling water in blue. – I.G.A.
TITANIUM APPLICATIONS
Every geothermal location has different environmental and operating conditions. What
generally works for one plant will not work for another. However, somewhere in every
process titanium is a very suitable and economical material choice. It could occur at the
production well head, turbine, re-injection or other equipment locations along the way.
The schematic does not show you the detail of the many different parts of the system
that could utilize titanium.
Application Considerations for Titanium Alloys
•Wellhead Components
–Valves, Gages, Piping, Blowout Preventers
•Turbine Components
–Blades, Rotor, Seals
•Brine Re-Injection
–Piping, Pumps, Impellers, Shafts, Seals
•Acid Addition Systems - Scale Prevention or Cleaning
–Tank, Piping, Mixers
•Equipment
–Separators, Condensers, Heat Exchangers, Flash Tank
•Production Well Casings
–Ti Grades 12, 29 and others with Palladium or Ruthenium
The following photo shows a geothermal production well head, where you will typically
find valves, gages, piping and blowout prevention devices. In the background is a tower
cooling hot brine before it is re-injected.
Photo 2. Well Head and Cooling Tower, Indonesia – Photo by R. Houser
In the photo below shows what happens to the inside of pipes as scale collects on the
walls. To prevent scaling, acid addition systems are used or frequent acid cleaning
must be performed. Where there is acid there is an opportunity for titanium tanks,
piping, mixers, and etc. to be considered.
Photo 3. Example of Scale Build-up – Photo by R. Houser
Titan Metal Fabricators recently fabricated the following heat exchanger with titanium
Grade 12 tubes and Grade 1 clad carbon steel tubesheets. The head is made of 2205
duplex stainless steel and the shell is painted carbon steel.
Photo 4. Titanium Tube Heat Exchanger – Photo by Tom Ukolowicz, Titan Metal Fabricators
Applications that have seen great success over the years include production wells that
have used grades 12, 29 and others with Pd or Ru additions.
ECONOMICS
This corroding pipe shown with massive peep holes is in use at an international
geothermal plant. On the ground shows evidence of what happens when the scale
build up is too great. The multiple holes cut out are to help maintenance clean the pipe.
The multiple issues pictured here could have been solved with better design and
material choices.
Photo 5: Geothermal Cooling Tower Discharge Pipe – Photo by R. Houser
The material decision process involves factoring in the cost of different materials,
maintenance and replacement costs. As of April, 2010, the relative cost to make
vessels and heat exchangers is shown in the cost index tables below. 4,5 The benefits of
longer life with titanium to get lower total life cycle cost are covered in other papers.
Engineers will find the cost to install the equipment are relatively the same.
Table 1. Vessel Material
Cost Index4
Table 2. Heat Exchanger Material
Cost Index5
Alloy
$ Factor
Alloy
$ Factor
316L
1.0
316L
1.0
Alloy 2205
1.2
Ti Gr 2
1.5
Alloy 2205
1.01
Ti Gr 12
1.6
Ti Gr 2
1.16
Ti Gr 9
1.8
Ti Gr 12
1.43
Ti Gr 16
1.8
AL-6XN®
1.45
Ti Gr 7
2.1
Ti Gr 7
1.67
Alloy 825
2.2
Alloy 625
1.92
AL-6XN®
2.4
C-276
2.04
Alloy 625
3.6
C-276
3.6
Zr 702
4.0
Cost index numbers shown in Table 1 represent a vessel or tank made entirely out of
each alloy. The index is based on equivalent section thickness of fabrication. Higher
strength alloys in some pressure/temperature applications can reduce wall thickness
and overall cost. Table 2 index values will have less spread between the index
numbers because the carbon steel shell of a 1150 square foot heat exchanger is
included in the baseline cost for the different alloy tubes represented.
Even though nickel Alloy 625 and nickel Alloy C-276 are somewhat equivalent in
corrosion resistance to titanium Grade 7, they are more expensive. Looking at titanium
versus the 316L stainless steel option for a large tank (table 1), the initial cost for
titanium alloys is 1.5 to 2 times the price of 316L stainless steel. The upfront cost is
more; however, the savings will come in over time, due to maintenance and later
replacement costs.
Much of the geothermal industry perception on titanium is a high priced solution used as
a last resort. The International Titanium Association needs to educate the industry on
the competitive pricing and long term benefits that titanium provides.
INDUSTRY STATUS
Geothermal energy supplies more than 10,000 MW to 24 countries worldwide and now
produces enough electricity to meet the needs of 60 million people. The Philippines,
which generates 23% of its electricity from geothermal energy, is the world’s second
largest producer behind the U.S. 6
Figure 3. A world-wide overview detailing the current power capacity of each country. 6
In the geothermal community, Iceland is widely considered as a success story. The
country of just over 300,000 people is now fully powered by renewable forms of energy;
with 17% of electricity and 87% of heating needs provided by geothermal energy (fossil
fuels are still imported for fishing and transportation needs). Iceland has been
expanding its geothermal power production largely to meet growing industrial and
commercial energy demand. In 2004, Iceland was reported to have generated 1465
gigawatt-hours (GWh) from geothermal resources; geothermal production is expected to
exceed 3000 GWh in 2010. 6
The five countries with the highest energy production are: USA, Philippines, Indonesia,
Mexico and Italy. Also important is where industry expansion is occurring. Table 3
below shows the US leading the expansion with Iceland and Turkey making large
improvements over their existing capacity as well.6 The industry is proactive in
launching new projects, and the economical environment is strongly positive in terms of
incentives and supporting measures.
Table 3. Top Five Country Geothermal Growth Amounts, 2005 - 2010
COUNTRY
MW
% MW
USA
496
19
INDONESIA
400
50
ICELAND
373
184
NEW ZEALAND
193
44
TURKEY
62
308
Current U.S. geothermal electric power generation totals approximately 3100 MW or
about the same as three large nuclear power plants. Over the past 5 years California
has led the way in increasing capacity and growth with Nevada close behind. Utah also
had an impressive 20 MW added. Over the next 5 years we should see significant
growth from several states. The growth in Wyoming and Florida are expected to occur
from co-production studies mentioned earlier.6
Table 4. U.S. Capacity and Growth
STATE
2005 MW 2010 MW 2015 MW
ALASKA
0
0.7
30
CALIFORNIA
2,239
2,553
3,400
FLORIDA
0
0
0.2
HAWAII
30
35
60
IDAHO
0
16
130
NEVADA
239
442
1,300
NEW MEXICO
0
0.2
20
OREGON
0
0.3
200
UTAH
26
46
240
WYOMING
0
0.2
0.2
USA TOTAL
2,534
3,093
5,400
Figure 4. World Geothermal Electricity Production, 1950-2050
The graph (figure 4) presents the world geothermal electrical production history and
forecast from 1959 to 2050.6 The electrical production over the past 50 years has been
steadily increasing. It is expected that EGS will experience exponential growth over the
next 40 years. Without EGS, experts predict the trend will continue slightly higher
(linearly). However this growth with or without EGS will result in more aggressive
corrosive conditions and require additional engineering that today’s plants do not
experience. The easily accessible hot reservoirs are gone and facilities will require
more robust materials to handle higher corrosion rates, temperatures, and strength
requirements. The materials commonly used today such as carbon steel will not always
be sufficient and titanium is a good candidate for many applications in the geothermal
process.
CONCLUSION
Geothermal power production may be quiet and unseen, but the industry is alive and
well. With recent incentives being given around the world, the industry is proactively
growing and should continue to do so for many years to come. The industry will find
more aggressive conditions than they’ve seen in the past; however, there are plenty of
material options to choose from and titanium has proven itself to be one used in many
historical successful applications. The industry currently utilizes operating experiences
from the oil and gas industry, which in most cases amply applies. However, knowledge
about titanium does not fully transfer over. The industry would benefit from more
education on titanium’s suitability for applications and availability options. A new
perception in regards to the cost of titanium compared to other more common materials
would also be beneficial. The price index charts shown were a surprise to many
individuals attending the World Geothermal Congress this year in Bali Indonesia. The
participants had no idea that titanium was so competitively priced.
REFERENCES
1. Geographia website: www.geographia.com
2. International Partnership for Geothermal Technology website:
www.Internationalgeothermal.org
3. International Geothermal Association website: www.geothermal-energy.org
4. Philippon P., Tricor Metals, Personal communications with author April 2010.
5. Zentil N., Titan Metal Fabricators Inc., Personal communications with author April
2010.
6. Bertani, R., Geothermal Power Generation in the World – 2005-2010 Update
Report, World Geothermal Congress 2010, Bali, Indonesia, 25-30 April 2010.
CONTACT
Robert Houser is a professional engineer working at ATI Wah Chang within the
technical services group. He is a mechanical engineer with 15 years experience in
manufacturing of materials and equipment for harsh environments. Some of those
materials include titanium, zirconium, ceramics, and composite plastics. He holds a
B.S. and MBA from Oregon State University. Robert recently attended the World
Geothermal Congress in Bali, Indonesia and presented a paper on “Performance of
Eleven Ti Alloys in High Temperature, High Brine Solutions”. He can be contacted at
[email protected]
ADDITIONAL SOURCES
 The Geothermal Education Office: http://geothermal.marin.org Great education
materials about all types of geothermal energy uses.
 The Geothermal Energy Association: www.geo-energy.org Information about
geothermal power, including companies developing new technologies and building
new projects in the U.S.
 The Geothermal Resources Council: http://www.geothermal.org Links to information
about U.S. and world geothermal information, and annual U.S. technical conference
on geothermal energy.
 The U.S. Geological Survey: http://www.usgs.gov/science/science.php?term=477
 The International Ground Source Heat Pump Association:
http://www.igshpa.okstate.edu Local to national information about geothermal heat
pumps, including directory of businesses. You can search for heat pump designers,
installers and dealers in your area.
 The Geothermal Heat Pump Consortium: http://www.geoexchange.org Geothermal
Heat Pump industry information and events. Check out the fact sheets and
brochures under their publications tab.
 Geo-Center of the Oregon Institute of Technology: http://geoheat.oit.edu U.S. DOE
funded information center on geothermal energy, particularly unique site for
information on geothermal “direct uses” such as greenhouses and building heating.
You can click on their interactive map to see geothermal projects in your state.
Titanium Use in the
Geothermal Industry
Robert Houser, PE, MBA
Applications Engineer
© ATI 2010. All Rights Reserved.
TITANIUM 2010, Oct 3-6 – Orlando, Fl.
Geothermal Industry Segments
• Direct Use
– Spas
– Snow melting
– Space Heating
• Power Generation
– > 150°C (300°F)
• Enhanced Geothermal
Systems (EGS)
– Experimental
© ATI 2010. All Rights Reserved.
Blue Lagoon, Iceland -National Geographic
2
Converting Heat into Electricity
-BBC.co.uk
© ATI 2010. All Rights Reserved.
- International Geothermal Association
3
Application Considerations for Titanium Alloys
• Wellhead Components
– Valves, Gages, Piping, Blowout Preventers
• Turbine Components
– Blades, Rotor, Seals
• Brine Re-Injection
– Piping, Pumps, Impellers, Shafts, Seals
• Acid Addition Systems - Scale Prevention
or Cleaning
– Tank, Piping, Mixers
• Equipment
– Separators, Condensers, Heat
Exchangers, Flash Tank
© ATI 2010. All Rights Reserved.
Photos by: R. Houser
4
Titanium Applications
• Production Well Casings
– Ti Grades 12, 29 and others with Pd or Ru
• Heat Exchangers
– Ti Grade 12 tubes, 2205 Duplex SS Head, Ti
Grade 1 Clad CS Tubesheets, Painted CS Shell
TITAN
Metal Fabricators Inc.
www.titanmf.com
© ATI 2010. All Rights Reserved.
5
Material Cost Index
Large vessel
Alloy
$ Factor
316L
1.0
Alloy 2205
1.2
Ti Gr 2
1.5
Alloy
$ Factor
Ti Gr 12
1.6
316L
1.0
Ti Gr 9
1.8
Alloy 2205
1.01
Ti Gr 16
1.8
Ti Gr 2
1.16
Ti Gr 7
2.1
Ti Gr 12
1.43
Alloy 825
2.2
AL-6XN®
1.45
AL-6XN®
2.4
Ti Gr 7
1.67
Alloy 625
3.6
Alloy 625
1.92
C-276
3.6
C-276
2.04
Zr 702
4.0
Courtesy of:
TRICOR METALS
Fabrication and material
for 1150 sqft shell and
tube heat exchanger
Courtesy of: TITAN
Metal Fabricators Inc.
Photo by: R. Houser
Geothermal Brine Return Line
*Cost valid as of April 2010
© ATI 2010. All Rights Reserved.
6
Status of the Geothermal Industry
© ATI 2010. All Rights Reserved.
* World Geothermal Congress 2010 – Power Generation Report Update
7
Growth - Top Five Countries
2005 - 2010
© ATI 2010. All Rights Reserved.
COUNTRY
MW
% MW
USA
496
19
INDONESIA
400
50
ICELAND
373
184
NEW ZEALAND
193
44
TURKEY
62
308
* World Geothermal Congress 2010 – Power Generation Report Update
8
USA Geothermal Energy Capacity
STATE
2005 MW
ALASKA
2015 MW
0
0.7
30
2,239
2,553
3,400
0
0
0.2
HAWAII
30
35
60
IDAHO
0
16
130
239
442
1,300
NEW MEXICO
0
0.2
20
OREGON
0
0.3
200
26
46
240
0
0.2
0.2
2,534
3,093
5,400
CALIFORNIA
FLORIDA
NEVADA
UTAH
WYOMING
USA TOTAL
© ATI 2010. All Rights Reserved.
2010 MW
* World Geothermal Congress 2010 – Power Generation Report Update
9
World Geothermal Electricity
© ATI 2010. All Rights Reserved.
* World Geothermal Congress 2010 – Power Generation Report Update
10
Conclusion
• Geothermal industry is stable and
proactively growing
• Many areas for titanium usage
• Industry needs titanium education
– Suitability
– Availability
– Price perception correction
© ATI 2010. All Rights Reserved.
11