Mechanical EngineeringME217 Energy, Environment & Society

ME 217: Energy, Environment & Society Fall 2015

Geothermal energy

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Clicker question

What will be the dominant source of electricity in 2050?

Nuclear fusion

Fossil fuels

Solar

Wind

Biofuels

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Voyage to the Center of the Earth

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Temperature gradients in the U.S.

3.5 kmdepth

6.5 kmdepth

10 kmdepth

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Potential of geothermal resources

remember: the U.S. uses 100 quads per year of primary energy

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Tectonic plate motion

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Geothermal resources worldwide

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Structure of water / steam reservoir

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The dry steam cycle

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The flash steam cycle

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Typical plant layout

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Early geothermal electricity

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Still going after many years

the dry steam plant at Larderello, Italy now

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The Geysers plant in California

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A flash steam plant

Imperial Valley geothermal project in California –combined capacity 370 MW

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The binary cycle (ORC)

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A binary / flash power plant

30 MW Puna power plant in Hawaii – a hybrid flash steam andbinary geothermal system

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Efficiency vs. resource temperature

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Geothermal electricity to date

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direct uses of geothermal energy

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Direct use of geothermal to date

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Where to now?The Future of Geothermal Energy

An Interdisciplinary MIT Study

http://mitei.mit.edu/publications/reports-studies/future-geothermal-energy

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The Hot Dry Rock concept

schematic of HDR plant experimental HDR plant atFenton Hill, New Mexico

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“Geothermal” heat pumps

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How much does geoelectricity cost?

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How much does geoheat cost?