Session 13 geothermal energy

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Session 13 geothermal energy

  1. 1. Session 13 – Geothermal Energy T. Ferguson, University of The Nesjavellir Geothermal Power Plant in Iceland, Gretar Ívarsson. Wikipedia
  2. 2. Session 13 Outline • • • • • • • Definitions Renewable Status, Sustainability Geothermal Resource Types Utilization Advantages/Disadvantages General Status; Potential in Minnesota R&D T. Ferguson, University of
  3. 3. Geothermal Definitions • • • • • Geothermal Energy Crustal Heat Flow Core, Mantel, Crust of the Earth Geothermal Gradient Types: Spontaneous Hot Fluid Production & Non-spontaneous T. Ferguson, University of Source: EIA
  4. 4. Sustainable/Renewable Status • • • • Large and well-distributed resource base Crust heat conduction rate: 10 yr recharge Local depletion occurs Replenishment – Conduction from adjacent crust – Decay of radioactive isotopes – Fluid-base convective heat transfer T. Ferguson, University of
  5. 5. Geothermal Resource Types • Four Types – Natural Hydrothermal – Iceland – Geopressurized – sedimentary rocks – Hot Dry Rock (HDR) – Drill and circulate – Magma - Yellowstone T. Ferguson, University of
  6. 6. Utilization Modes • Electrical Generation – For electrical delivery – For hydrogen production • Process Heat • Space Heating T. Ferguson, University of Source: EIA
  7. 7. Hydrothermal Process (from Chevron) http://www.chevron.com/stories/#/stories/re_geo/geo_hiw/ T. Ferguson, University of
  8. 8. Pros and Cons of Geothermal Energy Conversion Advantages – – – – – Enormous Stored Energy Dispatchable Multiple “products” Access uses proven oil/gas technology Simple and safe operationally; quick startup Disadvantages – 9 of 10 largest US Cities: >800km from hi-temp sources; only electrical gen possible – Only high-grade, hydrothermal reservoirs are economic – 5-20% Carnot cycle efficiencies – Treatment of dissolved gases – Geothermal wells are 2-4 times oil/gas well costs T. Ferguson, University of
  9. 9. Status 5% of 7% T. Ferguson, University of Source: EIA
  10. 10. The Geysers Northern California • Calpine owns 19 of 22 Geysers power plants • 850 MW • Largest geothermal electrical gen in world • Energy output declining ~7-8%/yr • About 7% of California’s electrical energy is geothermal T. Ferguson, University of Sources: The Geysers; Geysers Geothermal Association
  11. 11. Status of Geothermal Energy • US Geothermal Output: ~17 million MWh in 2004; 69% capacity factor • About 10,000 MW capacity worldwide (2000); ~8 % annual growth • Chevron claims top spot with 1273 MWe • Competitiveness with other sources: – Low grade geothermal (20-40°C): 8-200 c/kWh busbar price – High grade (80 °deg +): 4-9 c/kWh T. Ferguson, University of Sources: Text; Canadian Geothermal Energy Association; Chevron
  12. 12. Minnesota’s Geothermal Potential From DOE’s EERE: “Minnesota has vast low-temperature resources suitable for geothermal heat pumps. However, Minnesota does not have sufficient resources to use the other geothermal technologies.” T. Ferguson, University of EERE: Energy Efficiency and Renewable Energy Office

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