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GEOTHERMAL ENERGY: A reliable, renewable energy source IANAS Workshop: Toward a sustainable energy future GEOTHERMAL ENERGY: A reliable, renewable energy source OUTLINE Origin of geothermal energy Classification of geothermal resources Utilization of geothermal resources Geothermal power generation around the world Virtues of geothermal technology Barriers to further development IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 2 Depth km The heat flows toward the external layers. The crust is a very good thermal insulator. The mantle is partially melted and supports convective heat transport. The external nucleus is postulated to be in a liquid state and the internal nucleus is in a solid state. In addition to the heat flowing to the crust from the inner layers of the Earth, the concentration of radioactive isotopes in the crust and upper mantle, mainly 40K, 232Th, 235U and 238U, generate an estimated 4.7x1020 cal/year. IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 3 Volcanos and island arcs align on the plate boundaries. IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 4 New crust is formed from rising magma in divergent plate boudaries. One plate slides under another in convergent plate boundaries. IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 5 Thermal gradient along the Earth’s radius As a result of tectonic processes, the thermal gradient in the crust varies enormously from one site to another. A “normal” thermal gradient is considered to be about 30oC/km(depth). However, in some sites it could be as high as 800 oC/km. IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 6 Geothermal resources classified on the basis of temperatures found at “reasonable” depths: High temperature (220 oC – 320 oC) Mid temperature (120 oC – 220 oC) Low temperature (50 oC – 120 oC) IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 7 Geothermal resources classified on the basis of geological and hidrological factors: IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 Hidrothermal Hot, dry rock Geopressurized Marine Magmatic 8 A hydrothermal reservoir contains all the elements: hot rock, source of water, permeability. IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 9 Use of Geothermal Energy IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 10 High Temperature Hydrothermal Systems Electric power generation by direct separation of steam Electric power generation through organic Rankine cycles, utilizing "spent" fluids Large-area thermal conditioning of living and commercial quarters Direct uses of heat in "spent" fluids in industrial or agricultural processes IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 11 Medium temperature hydrothermal sources Electric power generation through organic Rankine cycles Large-area thermal conditioning of living and commercial quarters Direct uses of heat in industrial or agricultural processes IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 12 Geothermal resources classified on the basis of geological and hidrological factors: IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 Hidrothermal Hot, dry rock Geopressurized Marine Magmatic 13 Incipient: Engineered hot-dry rock resources Electric power generation from heat delivered to the surface by circulating exogenous water through the hot rock IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 14 Power generation with geothermal energy IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 15 Virtues of Geothermal Energy Reliable and continuous Flexible; could be used as base generation or load-following mode Low CO2 emissions Competitive costs IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 16 AVERAGE PLANT FACTORS PLANT FACTORS Technology Plant factor Ref. Coal 0.75 1 Other fossil fuels 0.55 1 Geothermal 0.85 1 Hydro 0.40 1 Nuclear 0.90 1 0.18 - 0.45 2 Wind References: 1.- Calculated from installed capacities and power generated (Jan-Sep, 2008). Data from CFE webpage. 2.- NEA&IEA (2005) “Projected costs of Generating Electricity: Update 2005” IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 17 Virtues of Geothermal Energy Reliable and continuous Flexible; could be used as base generation or load-following mode Low CO2 emissions Competitive costs IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 18 IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 19 Virtues of Geothermal Energy Reliable and continuous Flexible; could be used as base generation or load-following mode Low CO2 emissions Competitive costs IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 20 Levelised Costs LEVELISED GENERATION COSTS Technology Cost (cUSD/KWh) Ref. Coal (2.5) 3.5 - 6.0 (6.8) 1 Gas 4.0 - 5.5 (6.4) 1 5.0 - 5.3 2 4.2 1 4.5 - 4.8 2 Geothermal (New Zealand) 3.7 - 5.2 (8.1) 3 Hydro 6.5 - 10 (24) 1 Nuclear 3.0 - 5.0 (6.8) 1 Fuel oil 6.3 - 10 2 Solar 20 - 75 (190) 1 Wind 4.5 - 10 (14) 1 Gas, combined cycle Geothermal (USA) Geothermal (Mexico) References: 1.- NEA&IEA (2005) “Projected costs of Generating Electricity: Update 2005” 2.- CFE (2005) “Costos y parámetros de referencia para la formulación de proyectos de inversión” 3.- Barnett, P. (2007) “Cost of Geothermal Power in New Zealand: 2007 Update”, New Zealand Geothermal Workshop, November 2007 IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 21 Disadvantages of Geothermal Energy A measure of uncertainty Capital-intensive initially IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 22 www.iie.org.mx IANAS Workshop, Buenos Aires, República Argentina, 30-31 October 2008 23