Geothermal Energy for Electric Power Generation

Samuel A. Gray

Source of Geothermal Energy

Yellowstone magma chamber: Wikimedia [5]

• Geothermal Energy is sustainable and renewable energy• For commercial use, only useful reservoirs are those that produce

hydrothermal• Steam is created beneath Earth surface when water comes in

contact with hot bodies such as magma chambers, and hot rocks

Geological Regions with Rich Hydrothermal Resources

U.S. Geothermal map [8].

Global Energy Institute [10]. Hottest geological regions of the world.

Estimated Subterranean temperature at depths of 6 km.

Geothermal Energyfor Electric Power Generation

• Larderello, Italy, in 1904 as an experiment.. Became commercial in 1913 with a capacity of 250 KW. Currently, it has 487 MW capacity

Photograph courtesy of ENEL SpAPosted 30 Sep 2001

• In the U.S. the first geothermal power plant was built in Geysers in 1960.

Types of Geothermal Power Plant Designs

Dry Steam Power Plant

Flash Steam Power Plant

Source: Energy Almanac: [7]

Types of Geothermal Power Plant Designs

Binary Cycle Power Plant.

Source: Energy Almanac: [7]

Geothermal Energy Association, [1]

Total U.S. Geothermal Installed Capacity by Technology (MW) 1975-2012

Geothermal Power Plant Capacity by Technology

California Geothermal Power Plant

• It is the largest complex of geothermal power in the world

• Geysers geothermal power plants use Dry Steam technique.

• Today, total of 14 power plants, draw steam from 350 wells, and produce 725 MW enough to power 725000 homes

Geysers condensers of geothermal power plants. [4]

Global Installed Geothermal Capacity

Established Geothermal Power Installed Capacity (MW) [February 2015].

February 2015 Annual U.S & Global Geothermal Installed capacity [7]

• Globally, 12.8 GW online at geothermal power plants in 24 countries as of February 2015.

Geothermal Power Plants Advantages

• Geothermal power plants are reliable and predictable. [1].

• They are considered baseload plants because they are available 24/7 regardless of environmental conditions

• They are dispatchable. Capacity is available when you need it

• High Capacity Factor

Comparison of Energy Sources

Renewable Energy World http://www.renewableenergyworld.com [1]

Benefits and Main Issues

• Benefits:- No burning fossil fuel - High Capacity Factor- Very low operating expense

• Main issues- Areas with idle geology are very rare; most places require

deep holes be drilled- Very high initial investment. Many places, it is not

economically viable- Steam from geothermal reservoirs carry some dangerous

gases like H2S- Some geothermal wells suddenly stop producing steam or

hot water.- Overtime, the heat of geothermal well runs out.

References

[1] Annual U.S. Geothermal Power Production and Development Report. April 2011 http://www.geo-energy.org/pdf/reports[2] Union of Concerned Scientists. How Geothermal Energy Works. http://www.ucsusa.org/clean_energy/our-energy-choices[3] Renewable Energy World. http://www.renewableenergyworld.com [4] Calpine Corporation: http://www.calpine.com/media/Geysers_Factsheet.pdf[5] Wikimedia:

http://commons.wikimedia.org/wiki/File:Yellowstone_magma_chamber.jpg[6] Geothermal Energy Association: http://geo-energy.org/reports/Gea-GeothermalBasicsQandA-Sept2012_final.pdf[7] Energy Almanac: http://energyalmanac.ca.gov/renewables/geothermal/types.html[8] U.S. Geothermal map. http://en.wikipedia.org/wiki/Geothermal_energy_in_the_United_States[9] Renewable and Sustainable Energy Reviews, Arif Hepbasli [10] Global Energy Institute: http://www.geni.org/globalenergy/library/renewable-energy-resources/geothermal.shtml