Geothermal Energy


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Geothermal Energy

  1. 1. Geothermal Energy Stephen Lawrence Leeds School of Business University of Colorado Boulder, CO 80309-0419
  2. 2. AGENDA – Geothermal Energy <ul><li>Geothermal Overview </li></ul><ul><li>Extracting Geothermal Energy </li></ul><ul><li>Environmental Implications </li></ul><ul><li>Economic Considerations </li></ul><ul><li>Geothermal Installations – Examples </li></ul>
  3. 3. Geothermal Overview
  4. 4. Geothermal in Context U.S. Energy Consumption by Energy Source, 2000-2004 (Quadrillion Btu) 0.143 0.115 0.105 0.070 0.057 Wind Energy 0.063 0.064 0.064 0.065 0.066 Solar Energy 2.845 2.740 2.648 2.640 2.907 Biomass d 0.340 0.339 0.328 0.311 0.317 Geothermal Energy 2.725 2.825 2.689 2.242 2.811 Conventional Hydroelectric 6.117 6.082 5.835 5.328 6.158 Renewable Energy 8.232 7.959 8.143 8.033 7.862 Nuclear Electric Power 0.039 0.022 0.078 0.075 0.115 Electricity Net Imports 40.130 39.047 38.401 38.333 38.404 Petroleum c 23.000 23.069 23.628 22.861 23.916 Natural Gas b 0.138 0.051 0.061 0.029 0.065 Coal Coke Net Imports 22.918 22.713 21.980 21.952 22.580 Coal 86.186 84.889 84.070 83.176 84.965 Fossil Fuels 100.278 98.714 97.952 96.464 98.961 Total a 2004 P 2003 2002 2001 2000 Energy Source
  5. 5. Advantages of Geothermal
  6. 6. Heat from the Earth’s Center <ul><li>Earth's core maintains temperatures in excess of 5000°C </li></ul><ul><ul><li>Heat radual radioactive decay of elements </li></ul></ul><ul><li>Heat energy continuously flows from hot core </li></ul><ul><ul><li>Conductive heat flow </li></ul></ul><ul><ul><li>Convective flows of molten mantle beneath the crust. </li></ul></ul><ul><li>Mean heat flux at earth's surface </li></ul><ul><ul><li>16 kilowatts of heat energy per square kilometer </li></ul></ul><ul><ul><li>Dissipates to the atmosphere and space. </li></ul></ul><ul><ul><li>Tends to be strongest along tectonic plate boundaries </li></ul></ul><ul><li>Volcanic activity transports hot material to near the surface </li></ul><ul><ul><li>Only a small fraction of molten rock actually reaches surface. </li></ul></ul><ul><ul><li>Most is left at depths of 5-20 km beneath the surface, </li></ul></ul><ul><li>Hydrological convection forms high temperature geothermal systems at shallow depths of 500-3000m. </li></ul>
  7. 7. Earth Dynamics
  8. 8. Earth Temperature Gradient
  9. 9. Geothermal Site Schematic Boyle, Renewable Energy, 2 nd edition, 2004
  10. 10. Geysers Clepsydra Geyser in Yellowstone
  11. 11. Hot Springs Hot springs in Steamboat Springs area.
  12. 12. Fumaroles Clay Diablo Fumarole (CA) White Island Fumarole New Zealand
  13. 13. Global Geothermal Sites
  14. 14. Tectonic Plate Movements Boyle, Renewable Energy, 2 nd edition, 2004
  15. 15. Geothermal Sites in US
  16. 16. Extracting Geothermal Energy
  17. 17. Methods of Heat Extraction
  18. 18. Units of Measure <ul><li>Pressure </li></ul><ul><ul><li>1 Pascal (Pa) = 1 Newton / square meter </li></ul></ul><ul><ul><li>100 kPa = ~ 1 atmosphere = ~14.5 psi </li></ul></ul><ul><ul><li>1 MPa = ~10 atmospheres = ~145 psi </li></ul></ul><ul><li>Temperature </li></ul><ul><ul><li>Celsius (ºC); Fahrenheit (ºF); Kelvin (K) </li></ul></ul><ul><ul><li>0 ºC = 32 ºF = 273 K </li></ul></ul><ul><ul><li>100 ºC = 212 ºF = 373 K </li></ul></ul>
  19. 19. Dry Steam Power Plants <ul><li>“ Dry” steam extracted from natural reservoir </li></ul><ul><ul><li>180-225 ºC ( 356-437 ºF) </li></ul></ul><ul><ul><li>4-8 MPa (580-1160 psi) </li></ul></ul><ul><ul><li>200+ km/hr (100+ mph) </li></ul></ul><ul><li>Steam is used to drive a turbo-generator </li></ul><ul><li>Steam is condensed and pumped back into the ground </li></ul><ul><li>Can achieve 1 kWh per 6.5 kg of steam </li></ul><ul><ul><li>A 55 MW plant requires 100 kg/s of steam </li></ul></ul>Boyle, Renewable Energy, 2 nd edition, 2004
  20. 20. Dry Steam Schematic Boyle, Renewable Energy, 2 nd edition, 2004
  21. 21. Single Flash Steam Power Plants <ul><li>Steam with water extracted from ground </li></ul><ul><li>Pressure of mixture drops at surface and more water “flashes” to steam </li></ul><ul><li>Steam separated from water </li></ul><ul><li>Steam drives a turbine </li></ul><ul><li>Turbine drives an electric generator </li></ul><ul><li>Generate between 5 and 100 MW </li></ul><ul><li>Use 6 to 9 tonnes of steam per hour </li></ul>
  22. 22. Single Flash Steam Schematic Boyle, Renewable Energy, 2 nd edition, 2004
  23. 23. Binary Cycle Power Plants <ul><li>Low temps – 100 o and 150 o C </li></ul><ul><li>Use heat to vaporize organic liquid </li></ul><ul><ul><li>E.g., iso-butane, iso-pentane </li></ul></ul><ul><li>Use vapor to drive turbine </li></ul><ul><ul><li>Causes vapor to condense </li></ul></ul><ul><ul><li>Recycle continuously </li></ul></ul><ul><li>Typically 7 to 12 % efficient </li></ul><ul><li>0.1 – 40 MW units common </li></ul>
  24. 24. Binary Cycle Schematic Boyle, Renewable Energy, 2 nd edition, 2004
  25. 25. Binary Plant Power Output
  26. 26. Double Flash Power Plants <ul><li>Similar to single flash operation </li></ul><ul><li>Unflashed liquid flows to low-pressure tank – flashes to steam </li></ul><ul><li>Steam drives a second-stage turbine </li></ul><ul><ul><li>Also uses exhaust from first turbine </li></ul></ul><ul><li>Increases output 20-25% for 5% increase in plant costs </li></ul>
  27. 27. Double Flash Schematic Boyle, Renewable Energy, 2 nd edition, 2004
  28. 28. Combined Cycle Plants <ul><li>Combination of conventional steam turbine technology and binary cycle technology </li></ul><ul><ul><li>Steam drives primary turbine </li></ul></ul><ul><ul><li>Remaining heat used to create organic vapor </li></ul></ul><ul><ul><li>Organic vapor drives a second turbine </li></ul></ul><ul><li>Plant sizes ranging between 10 to 100+ MW </li></ul><ul><li>Significantly greater efficiencies </li></ul><ul><ul><li>Higher overall utilization </li></ul></ul><ul><ul><li>Extract more power (heat) from geothermal resource </li></ul></ul>
  29. 29. Hot Dry Rock Technology <ul><li>Wells drilled 3-6 km into crust </li></ul><ul><ul><li>Hot crystalline rock formations </li></ul></ul><ul><li>Water pumped into formations </li></ul><ul><li>Water flows through natural fissures picking up heat </li></ul><ul><li>Hot water/steam returns to surface </li></ul><ul><li>Steam used to generate power </li></ul>
  30. 30. Hot Dry Rock Technology Fenton Hill plant
  31. 31. Soultz Hot Fractured Rock Boyle, Renewable Energy, 2 nd edition, 2004
  32. 32. 2-Well HDR System Parameters <ul><li>2×10 6 m 2 = 2 km 2 </li></ul><ul><li>2×10 8 m 3 = 0.2 km 3 </li></ul>Boyle, Renewable Energy, 2 nd edition, 2004
  33. 33. Promise of HDR <ul><li>1 km 3 of hot rock has the energy content of 70,000 tonnes of coal </li></ul><ul><ul><li>If cooled by 1 ºC </li></ul></ul><ul><li>Upper 10 km of crust in US has 600,000 times annual US energy (USGS) </li></ul><ul><li>Between 19-138 GW power available at existing hydrothermal sites </li></ul><ul><ul><li>Using enhanced technology </li></ul></ul>Boyle, Renewable Energy, 2 nd edition, 2004
  34. 34. Direct Use Technologies <ul><li>Geothermal heat is used directly rather than for power generation </li></ul><ul><li>Extract heat from low temperature geothermal resources </li></ul><ul><ul><li>< 150 o C or 300 o F. </li></ul></ul><ul><li>Applications sited near source (<10 km) </li></ul>
  35. 35. Geothermal Heat Pump
  36. 36. Heat vs. Depth Profile Boyle, Renewable Energy, 2 nd edition, 2004
  37. 37. Geothermal District Heating Boyle, Renewable Energy, 2 nd edition, 2004 Southhampton geothermal district heating system technology schematic
  38. 38. Direct Heating Example Boyle, Renewable Energy, 2 nd edition, 2004
  39. 39. Technological Issues <ul><li>Geothermal fluids can be corrosive </li></ul><ul><ul><li>Contain gases such as hydrogen sulphide </li></ul></ul><ul><ul><li>Corrosion, scaling </li></ul></ul><ul><li>Requires careful selection of materials and diligent operating procedures </li></ul><ul><li>Typical capacity factors of 85-95% </li></ul>
  40. 40. Technology vs. Temperature <ul><li>Direct Fluid Use </li></ul><ul><li>Heat Exchangers </li></ul>Direct Use Water Low Temperature 50-150 o C (120-300 o F). <ul><li>Binary Cycle </li></ul><ul><li>Direct Fluid Use </li></ul><ul><li>Heat Exchangers </li></ul><ul><li>Heat Pumps </li></ul>Power Generation Direct Use Water Intermediate Temperature 100-220 o C (212 - 390 o F). <ul><li>Flash Steam </li></ul><ul><li>Combined (Flash and Binary) Cycle </li></ul><ul><li>Direct Fluid Use </li></ul><ul><li>Heat Exchangers </li></ul><ul><li>Heat Pumps </li></ul>Power Generation   Direct Use Water or Steam High Temperature >220 o C (>430 o F). Technology commonly chosen Common Use Reservoir Fluid Reservoir Temperature
  41. 41. Geothermal Performance Boyle, Renewable Energy, 2 nd edition, 2004
  42. 42. Environmental Implications
  43. 43. Environmental Impacts <ul><li>Land </li></ul><ul><ul><li>Vegetation loss </li></ul></ul><ul><ul><li>Soil erosion </li></ul></ul><ul><ul><li>Landslides </li></ul></ul><ul><li>Air </li></ul><ul><ul><li>Slight air heating </li></ul></ul><ul><ul><li>Local fogging </li></ul></ul><ul><li>Ground </li></ul><ul><ul><li>Reservoir cooling </li></ul></ul><ul><ul><li>Seismicity (tremors) </li></ul></ul><ul><li>Water </li></ul><ul><ul><li>Watershed impact </li></ul></ul><ul><ul><li>Damming streams </li></ul></ul><ul><ul><li>Hydrothermal eruptions </li></ul></ul><ul><ul><li>Lower water table </li></ul></ul><ul><ul><li>Subsidence </li></ul></ul><ul><li>Noise </li></ul><ul><li>Benign overall </li></ul>
  44. 44. Renewable? <ul><li>Heat depleted as ground cools </li></ul><ul><li>Not steady-state </li></ul><ul><ul><li>Earth’s core does not replenish heat to crust quickly enough </li></ul></ul><ul><li>Example: </li></ul><ul><ul><li>Iceland's geothermal energy could provide 1700 MW for over 100 years, compared to the current production of 140 MW </li></ul></ul>
  45. 45. Economics of Geothermal
  46. 46. Cost Factors <ul><li>Temperature and depth of resource </li></ul><ul><li>Type of resource (steam, liquid, mix) </li></ul><ul><li>Available volume of resource </li></ul><ul><li>Chemistry of resource </li></ul><ul><li>Permeability of rock formations </li></ul><ul><li>Size and technology of plant </li></ul><ul><li>Infrastructure (roads, transmission lines) </li></ul>
  47. 47. Costs of Geothermal Energy <ul><li>Costs highly variable by site </li></ul><ul><ul><li>Dependent on many cost factors </li></ul></ul><ul><li>High exploration costs </li></ul><ul><li>High initial capital, low operating costs </li></ul><ul><ul><li>Fuel is “free” </li></ul></ul><ul><li>Significant exploration & operating risk </li></ul><ul><ul><li>Adds to overall capital costs </li></ul></ul><ul><ul><li>“Risk premium” </li></ul></ul>
  48. 48. Risk Assessment
  49. 49. Geothermal Development
  50. 50. Cost of Water & Steam Table Geothermal Steam and Hot Water Supply Cost where drilling is required 10-20 Low Temperature (<100 o C) 20-40 3.0-4.5 Medium Temperature (100-150 o C) 3.5-6.0 High temperature (>150 o C) Cost (US ¢ /tonne of hot water) Cost (US $/ tonne of steam)
  51. 51. Cost of Geothermal Power Normally not suitable 4.0-6.0 2.5-5.0 Large Plants (>30 MW) Normally not suitable 4.5-7 4.0-6.0 Medium Plants (5-30 MW) 6.0-10.5 5.5-8.5 5.0-7.0 Small plants (<5 MW) Unit Cost (US ¢ /kWh) Low Quality Resource Unit Cost (US ¢ /kWh) Medium Quality Resource Unit Cost (US ¢ /kWh) High Quality Resource
  52. 52. Direct Capital Costs Direct Capital Costs (US $/kW installed capacity) Normally not suitable Exploration : US$100-400 Steam field:US$400-700 Power Plant:US$850-1100 Total: US$1350-2200 Exploration:: US$100-200 Steam field:US$300-450 Power Plant:US$750-1100 Total: US$1150-1750 Large Plants (>30 MW) Normally not suitable Exploration: : US$250-600 Steam field:US$400-700 Power Plant:US$950-1200 Total: US$1600-2500 Exploration : US$250-400 Steamfield:US$200-US$500 Power Plant: US$850-1200 Total: US$1300-2100 Med Plants (5-30 MW) Exploration : US$400-1000 Steam field:US$500-900 Power Plant:US$1100-1800 Total:US$2000-3700 Exploration : US$400-1000 Steam field:US$300-600 Power Plant:US$1100-1400 Total: US$1800-3000 Exploration : US$400-800 Steam field:US$100-200 Power Plant:US$1100-1300 Total: US$1600-2300 Small plants (<5 MW) Low Quality Resource Medium Quality Resource High Quality Resource Plant Size
  53. 53. Indirect Costs <ul><li>Availability of skilled labor </li></ul><ul><li>Infrastructure and access </li></ul><ul><li>Political stability </li></ul><ul><li>Indirect Costs </li></ul><ul><ul><li>Good: 5-10% of direct costs </li></ul></ul><ul><ul><li>Fair: 10-30% of direct costs </li></ul></ul><ul><ul><li>Poor: 30-60% of direct costs </li></ul></ul>
  54. 54. Operating/Maintenance Costs Operating and Maintenance Costs 0.4-0.7 0.6-0.8 0.8-1.4 Total 0.25-0.45 0.35-0.45 0.45-0.7 Power Plant 0.15-0.25 0.25-0.35 0.35-0.7 Steam field O&M Cost (US c/KWh) Large Plants(>30 MW) O&M Cost (US c/KWh) Medium Plants (5-30 MW) O&M Cost (US c/KWh) Small plants (<5 MW)
  55. 55. Geothermal Installations Examples
  56. 56. Geothermal Power Examples Boyle, Renewable Energy, 2 nd edition, 2004
  57. 57. Geothermal Power Generation <ul><li>World production of 8 GW </li></ul><ul><ul><li>2.7 GW in US </li></ul></ul><ul><li>The Geyers (US) is world’s largest site </li></ul><ul><ul><li>Produces 2 GW </li></ul></ul><ul><li>Other attractive sites </li></ul><ul><ul><li>Rift region of Kenya, Iceland, Italy, France, New Zealand, Mexico, Nicaragua, Russia, Phillippines, Indonesia, Japan </li></ul></ul>
  58. 58. Geothermal Energy Plant Geothermal energy plant in Iceland
  59. 59. Geothermal Well Testing Geothermal well testing, Zunil, Guatemala     
  60. 60. Heber Geothermal Power Station 52kW electrical generating capacity
  61. 61. Geysers Geothermal Plant The Geysers is the largest producer of geothermal power in the world.
  62. 62. Geyers Cost Effectiveness Boyle, Renewable Energy, 2 nd edition, 2004
  63. 63. Geothermal Summary
  64. 64. Geothermal Prospects <ul><li>Environmentally very attractive </li></ul><ul><li>Attractive energy source in right locations </li></ul><ul><li>Likely to remain an adjunct to other larger energy sources </li></ul><ul><ul><li>Part of a portfolio of energy technologies </li></ul></ul><ul><li>Exploration risks and up-front capital costs remain a barrier </li></ul>
  65. 65. Next Week: BIOENERGY
  66. 66. Supplementary Slides Extras
  67. 67. Geothermal Gradient
  68. 68. Geo/Hydrothermal Systems
  69. 69. Location of Resources
  70. 70. Ground Structures Boyle, Renewable Energy, 2 nd edition, 2004
  71. 71. Volcanic Geothermal System Boyle, Renewable Energy, 2 nd edition, 2004
  72. 72. Temperature Gradients Boyle, Renewable Energy, 2 nd edition, 2004
  73. 73.
  74. 74. UK Geothermal Resources Boyle, Renewable Energy, 2 nd edition, 2004
  75. 75. Porosity vs. Hydraulic Conductivity Boyle, Renewable Energy, 2 nd edition, 2004
  76. 76. Performance vs. Rock Type Boyle, Renewable Energy, 2 nd edition, 2004
  77. 77. Deep Well Characteristics Boyle, Renewable Energy, 2 nd edition, 2004
  78. 78. Single Flash Plant Schematic
  79. 79.
  80. 80. Binary Cycle Power Plant
  81. 81. Flash Steam Power Plant
  82. 82. Efficiency of Heat Pumps Boyle, Renewable Energy, 2 nd edition, 2004
  83. 83. Recent Developments <ul><li>Comparing statistical data for end-1996 (SER 1998) and the present Survey, it can be seen that there has been an increase in world geothermal power plant capacity (+9%) and utilisation (+23%) while direct heat systems show a 56% additional capacity, coupled with a somewhat lower rate of increase in their use (+32%). </li></ul><ul><li>Geothermal power generation growth is continuing, but at a lower pace than in the previous decade, while direct heat uses show a strong increase compared to the past. </li></ul><ul><li>Going into some detail, the six countries with the largest electric power capacity are: USA with 2 228 MWe is first, followed by Philippines (1 863 MWe); four countries (Mexico, Italy, Indonesia, Japan) had capacity (at end-1999) in the range of 550-750 MWe each. These six countries represent 86% of the world capacity and about the same percentage of the world output, amounting to around 45 000 GWhe. </li></ul><ul><li>The strong decline in the USA in recent years, due to overexploitation of the giant Geysers steam field, has been partly compensated by important additions to capacity in several countries: Indonesia, Philippines, Italy, New Zealand, Iceland, Mexico, Costa Rica, El Salvador. Newcomers in the electric power sector are Ethiopia (1998), Guatemala (1998) and Austria (2001). In total, 22 nations are generating geothermal electricity, in amounts sufficient to supply 15 million houses. </li></ul><ul><li>Concerning direct heat uses, Table 12.1 shows that the three countries with the largest amount of installed power: USA (5 366 MWt), China (2 814 MWt) and Iceland (1 469 MWt) cover 58% of the world capacity, which has reached 16 649 MWt, enough to provide heat for over 3 million houses. Out of about 60 countries with direct heat plants, beside the three above-mentioned nations, Turkey, several European countries, Canada, Japan and New Zealand have sizeable capacity. </li></ul><ul><li>With regard to direct use applications, a large increase in the number of GHP installations for space heating (presently estimated to exceed 500 000) has put this category in first place in terms of global capacity and third in terms of output. Other geothermal space heating systems are second in capacity but first in output. Third in capacity (but second in output) are spa uses followed by greenhouse heating. Other applications include fish farm heating and industrial process heat. The outstanding rise in world direct use capacity since 1996 is due to the more than two-fold increase in North America and a 45% addition in Asia. Europe also has substantial direct uses but has remained fairly stable: reductions in some countries being compensated by progress in others. </li></ul><ul><li>Concerning R&D, the HDR project at Soultz-sous-Forêts near the French-German border has progressed significantly. Besides the ongoing Hijiori site in Japan, another HDR test has just started in Switzerland (Otterbach near Basel). </li></ul><ul><li>The total world use of geothermal power is giving a contribution both to energy saving (around 26 million tons of oil per year) and to CO2 emission reduction (80 million tons/year if compared with equivalent oil-fuelled production). </li></ul>