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 magma-based 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 co-production 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, super-heated 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 high-temperature 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

Alloy $ Factor

316L 1.0

Alloy 2205 1.2

Ti Gr 2 1.5

Ti Gr 12 1.6

Ti Gr 9 1.8

Ti Gr 16 1.8

Ti Gr 7 2.1

Alloy 825 2.2

AL-6XN® 2.4

Alloy 625 3.6

C-276 3.6

Zr 702 4.0

Table 2. Heat Exchanger Material Cost Index5

Alloy $ Factor

316L 1.0

Alloy 2205 1.01

Ti Gr 2 1.16

Ti Gr 12 1.43

AL-6XN® 1.45

Ti Gr 7 1.67

Alloy 625 1.92

C-276 2.04

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 Robert.Houser@ATImetals.com 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.

© ATI 2010. All Rights Reserved. TITANIUM 2010, Oct 3-6 – Orlando, Fl.

Titanium Use in the

Geothermal Industry

Robert Houser, PE, MBAApplications Engineer

2© ATI 2010. All Rights Reserved.

Geothermal Industry Segments

• Direct Use– Spas

– Snow melting

– Space Heating

• Power Generation

– > 150°C (300°F)

• Enhanced Geothermal Systems (EGS)– Experimental

Blue Lagoon, Iceland -National Geographic

3© ATI 2010. All Rights Reserved.

Converting Heat into Electricity

-BBC.co.uk - International Geothermal Association

4© ATI 2010. All Rights Reserved.

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

Photos by: R. Houser

5© ATI 2010. All Rights Reserved.

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

TITANMetal Fabricators Inc.

www.titanmf.com

6© ATI 2010. All Rights Reserved.

Material Cost IndexLarge vessel

Alloy $ Factor

316L 1.0

Alloy 2205 1.2

Ti Gr 2 1.5

Ti Gr 12 1.6

Ti Gr 9 1.8

Ti Gr 16 1.8

Ti Gr 7 2.1

Alloy 825 2.2

AL-6XN® 2.4

Alloy 625 3.6

C-276 3.6

Zr 702 4.0

Fabrication and material for 1150 sqft shell and tube heat exchanger

Alloy $ Factor

316L 1.0

Alloy 2205 1.01

Ti Gr 2 1.16

Ti Gr 12 1.43

AL-6XN® 1.45

Ti Gr 7 1.67

Alloy 625 1.92

C-276 2.04

Courtesy of:

TRICOR METALS

Courtesy of: TITAN

Metal Fabricators Inc.Geothermal Brine Return Line

*Cost valid as of April 2010

Photo by: R. Houser

7© ATI 2010. All Rights Reserved.* World Geothermal Congress 2010 – Power Generation Report Update

Status of the Geothermal Industry

8© ATI 2010. All Rights Reserved.

Growth - Top Five Countries 2005 - 2010

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

9© ATI 2010. All Rights Reserved.

USA Geothermal Energy Capacity

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

* World Geothermal Congress 2010 – Power Generation Report Update

10© ATI 2010. All Rights Reserved.

World Geothermal Electricity

* World Geothermal Congress 2010 – Power Generation Report Update

11© ATI 2010. All Rights Reserved.

Conclusion

• Geothermal industry is stable and proactively growing

• Many areas for titanium usage

• Industry needs titanium education– Suitability

– Availability

– Price perception correction