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Home , Geothermal energy, Geothermal exploration, Geothermal power

A Brief Introduction to Geothermal and its Utilization for 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

“” Plate Tectonic Processes Volcanoes (as in the Caribbean)

SpreadingSpreading Center Rising 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 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 & Flash Tanks Cooling Towers

Injection Production Well Well Dry Steam Power Plant

Turbine Generator

Electricity

Condense Steam d Steam () Flash Steam Power Plant

Steam Turbine Generator

Flash Tank

Condense Hot Sep d Water ara Steam W ted ater (Water) Power Plant Binary Generator Turbine Vapor Generator Electricity

Binary Liquid Heat Exchanger Injection Production Well Well Hot Water Cooled Water CO2 Emissions Comparison (lbs/MW-hr) 2000 Oil 1500 1000

500 Geothermal

0

Source EIA 1998; Bloomfield and Moore 1999 Benefits of

• Provides clean and safe energy using little • Is renewable and sustainable • Generates continuous, reliable “baseload” power • Conserves fossil and contributes to diversity in energy sources • Avoids importing and benefits local economies • Offers modular, incremental development and village power to remote sites