Advantages and Disadvantages

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Unlike wind, solar, or tidal plants, geothermal power plants can deliver power continuously and thus provide base-load electricity (1). Furthermore, geothermal plants are not vulnerable to weather changes, no storage is needed, and distribution is not an issue. Geothermal reservoirs are, however, limited to specific geographical areas. Depending on the resources and on power demand, geothermal plants can be constructed in any size-- as small as 100 kW (convenient for local grid applications and rural electrification) to many hundreds of megawatts for base-load and load-demand applications and for national grids. Modular plants can be built so that capacity can be added as the need for power increases.

Like most renewable energies, direct-use systems require a larger capital investment as compared to traditional systems, but the lack of fuel cost and lower operating expenses offset the initial investment in only a few years. The cost of power production varies greatly from 2.5 to 10 cents per kilowatt-hour, depending on such factors as the size, depth, location, and temperature of the reservoir. As the price of petroleum and other fossil fuels increase, geothermal sources become more competitively priced or even cheaper than fossil plants. The currently installed US capacity of direct-use systems totals to 470 MW, enough energy to heat 40,000 average-sized houses.



(1) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005

Additional Comments

(a) Base-load refers to minimum electricity needs, independent of the time of the day.

Further Reading

Dipippo, R., Geothermal Power Plants: Principals, Applications and Case Histories, Elsevier, 2005.

Dickson, M. H., Fanelli, M., Geothermal Energy: Utilization and Technology, Stylus Pub., 2005.

Ochsner, K, Geothermal Heat Pumps: A Guide for Planning and Installing, Earthscan Ltd, 2007.

Gupta, H. , and Roy, S., Geothermal Energy: An Alternative Resource for the 21st Century, Elsevier, 2007.

Geothermics, Direct Science Elsevier Publish. Company, publishes articles on geothermal energy resources and technologies.

Geotimes, Journal of the American Geological Institute.

Geo-heat Center Quarterly Bulletin, covers how-to articles on various geothermal applications and equipment, progress in research and development activities of direct heat utilization

Journal of Volcanology and Geothermal Research, an international journal on the geophysical, geochemical, petrological, economic, and environmental aspects of volcanology and geothermal research.

External Links

National Renewable Energy Laboratory Geothermal Energy Program (

Idaho National Laboratory Geothermal Program (

US Department of Energy Geothermal Technology Program (

California Energy Commission ((

Geothermal Resources Council (

Geothermal Energy Association (