A Brief Introduction to Geothermal Energy and its Utilization for Electric Power Generation G. W. Huttrer OAS Consultant Michela Miletto OAS Staff GEO = Thermal means THERMAL = The Earth Crust M Mantle Outer Core Inner Core Temperatures in the Earth Depth in Temperatures Kilometers in degrees C 2,000 4,000 C 4,000 6,000 C 6,000 Plate Boundaries “Ring of Fire” Plate Tectonic Processes Volcanoes (as in the Caribbean) SpreadingSpreading Center Rising Magma Continental Oceanic Plate Plate Subduc ting ConvectionConvection Cells Mt. Kiluea Hawaii Permeable Reservoir Rocks Magma Geothermal Exploration Surveys • Satellite imagery and aerial photography • Volcanological studies • Geologic and structural mapping • Geochemical surveys • Geophysical surveys • Temperature gradient hole drilling Geochemistry Thermal Gradient Measuring Geology Geophysics Thermal Gradient Drill Sample Temperature Gradient Temp. (C) Data 50 100 150 200 250 Depth/Ft 500500 10001000 1500 Depth 1500 (Feet) 20002000 2500 30003000 Bottom hole temperature 265˚C (509˚F) Deep Well Drill Well Test in Progress Turbine-Generator Power Plant & Flash Tanks Cooling Towers Injection Production Well Well Dry Steam Power Plant Turbine Generator Electricity Condense Steam d Steam (Water) Flash Steam Power Plant Generator Electricity Turbine Steam Flash Tank Condense d Steam (Water) Separated Hot Water Water Binary Cycle Power Plant Binary Generator Turbine Vapor Generator Electricity Binary Liquid Heat Exchanger Heat Exchanger Injection Production Well Well Hot Water Cooled Water CO2 Emissions Comparison (lbs/MW-hr) Coal 2000 Oil 1500 Natural Gas 1000 500 Geothermal 0 Source EIA 1998; Bloomfield and Moore 1999 Benefits of Geothermal Power • Provides clean and safe energy using little land • Is renewable and sustainable • Generates continuous, reliable “baseload” power • Conserves fossil fuels and contributes to diversity in energy sources • Avoids importing and benefits local economies • Offers modular, incremental development and village power to remote sites.