Introduction of Geo-Thermal Energy
Geo-thermal Potential
Geo-thermal Locations
Prominent countries worldwide with geothermal potential:
India hot springs
Geothermal energy is energy extracted from heat stored in the earth. This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. It has been used for space heating and bathing since ancient times, but is now known for both heating as well as for generating electricity.
Geothermal power is cost effective, reliable, and environmentally friendly, but has previously been geographically limited to areas near tectonic plate boundaries. Recent technological advances have significantly expanded the range and size of viable resources, especially for direct applications such as home heating.
Geothermal energy has shown signs of considerable growth over the last few years. Global geothermal installed capacity (for electricity) has escalated from 7,972 MWe in 2000 to around 9,700 MWe in the year 2007 (generating about 0.3% of global electricity demand) and is expected to reach around 13,600 MWe by 2012.
The US
By mid 2008, worldwide installed
capacity of geothermal energy for electricity generation had crossed the 10 GW
mark. Worldwide, about 30 GW of direct geothermal heating capacity is installed
for district heating, space heating, spas, industrial processes, desalination
and agricultural applications. If heat recovered by ground source heat pumps is
included, the non-electric use of geothermal energy is estimated at more than
100 GWt (gigawatts of thermal power) and is used commercially in over 70
countries.
Geothermal (ground-source) heat pumps
(GHPs) have become a major growth area of geothermal energy use in the United States , Canada
and Europe . The number of GHPs has steadily
increased over the past 10 years. By 2008, an estimated 800,000 equivalent 12
kW (3.4 ton) units have been installed in the United States
and about 50,000 in Canada
Geothermal energy supplies more than 10,000 MW to 24 countries worldwide and now produces enough electricity to meet the needs of 60 million people. The Philippines, which generates 23% of its electricity from geothermal energy, is the world’s second biggest producer behind the U.S. Geothermal energy has helped developing countries such as Indonesia, the Philippines, Guatemala, Costa Rica, and Mexico. The benefits of geothermal projects can preserve the cleanliness of developing countries seeking energy and economic independence, and it can provide a local source of electricity in remote locations, thus raising the quality of life.
Iceland is widely considered the success story of the geothermal community. The country of just over 300,000 people is now fully powered by renewable forms of energy, with 17% of electricity and 87% of heating needs provided by geothermal energy. Iceland has been expanding its geothermal power production largely to meet growing industrial and commercial energy demand. In 2004, Iceland was reported to have generated 1465 gigawatt-hours (GWh) from geothermal resources; geothermal production is reached 3000 GWh in 2009.
According to some experts, the most likely value for the technical potential of geothermal resources suitable for electricity generation is 240 GWe (This is about 5% of total global installed capacity for electricity in 2008). Theoretical considerations, based on the conditions in Iceland and the USA, reveal that the magnitude of hidden resources is expected to be 5-10 times larger than the estimate of identified resources. If this is the case for other parts of the world, the upper limit for electricity generation from geothermal resources is in the range of 1-2 TWe.
Prominent countries worldwide with geothermal potential:
- Russia
- Japan
- Eastern China
- Himalayan Geothermal Belt
- The Philippines
- Indonesia
- New Zealand
- Canada
- United States
- Mexico
- Central American Volcanic Belt
- Andean Volcanic Belt
- The Caribbean
- Iceland and other Atlantic Islands
- Northern Europe
- Eastern Europe
- Italy
- Eastern and Southern Mediterranean
- East Africa Rift System
Geothermal Energy - How it works
There are three main types of geothermal energy in use currently:
- Direct Use Heating Systems – these use hot water from springs or reservoirs near the earth’s surface.
- Electricity from Geothermal Energy – Electricity generation in power plants require water or steam at very high temperature. Geothermal power plants are generally built where geothermal reservoirs are located within a mile or two of the surface. Thus, these plants use the geothermal heat for generating steam that run a turbine to produce electricity.
- Geothermal Heat Pumps – These heat pumps use stable temperatures under the ground to heat and cool buildings.
Geothermal Electricity Production
Geothermal Electricity: This geothermal power plant generates electricity for the Imperial Valley in California.
This geothermal power plant generates electricity for the Imperial Valley in California. Credit: Warren Gretz
Most power plants need steam to generate electricity. The steam rotates a turbine that activates a generator, which produces electricity. Many power plants still use fossil fuels to boil water for steam. Geothermal power plants, however, use steam produced from reservoirs of hot water found a couple of miles or more below the Earth's surface. There are three types of geothermal power plants: dry steam, flash steam, and binary cycle.
Dry steam power plants draw from underground resources of steam. The steam is piped directly from underground wells to the power plant, where it is directed into a turbine/generator unit. There are only two known underground resources of steam in the United States: The Geysers in northern California and Yellowstone National Park in Wyoming, where there's a well-known geyser called Old Faithful. Since Yellowstone is protected from development, the only dry steam plants in the country are at The Geysers.
Flash steam power plants are the most common. They use geothermal reservoirs of water with temperatures greater than 360°F (182°C). This very hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam are injected back into the reservoir, making this a sustainable resource.
Binary cycle power plants operate on water at lower temperatures of about 225°-360°F (107°-182°C). These plants use the heat from the hot water to boil a working fluid, usually an organic compound with a low boiling point. The working fluid is vaporized in a heat exchanger and used to turn a turbine. The water is then injected back into the ground to be reheated. The water and the working fluid are kept separated during the whole process, so there are little or no air emissions.
Small-scale geothermal power plants (under 5 megawatts) have the potential for widespread application in rural areas, possibly even as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system.
In the United States, most geothermal reservoirs are located in the western states, Alaska, and Hawaii.
Geothermal Direct Use
Geothermal Direct Use: Geothermally heated waters allow alligators to thrive on a farm in Colorado, where temperatures can drop below freezing.
Geothermally heated waters allow alligators to thrive on a farm in Colorado, where temperatures can drop below freezing. Credit: Warren Gretz
When a person takes a hot bath, the heat from the water will usually warm up the entire bathroom. Geothermal reservoirs of hot water, which are found a couple of miles or more beneath the Earth's surface, can also be used to provide heat directly. This is called the direct use of geothermal energy.
Geothermal direct use dates back thousands of years, when people began using hot springs for bathing, cooking food, and loosening feathers and skin from game. Today, hot springs are still used as spas. But there are now more sophisticated ways of using this geothermal resource.
In modern direct-use systems, a well is drilled into a geothermal reservoir to provide a steady stream of hot water. The water is brought up through the well, and a mechanical system - piping, a heat exchanger, and controls - delivers the heat directly for its intended use. A disposal system then either injects the cooled water underground or disposes of it on the surface.
Geothermal hot water can be used for many applications that require heat. Its current uses include heating buildings (either individually or whole towns), raising plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes, such as pasteurizing milk. With some applications, researchers are exploring ways to effectively use the geothermal fluid for generating electricity as well.
In the United States, most geothermal reservoirs are located in the western states, Alaska, and Hawaii.
Indian Geo-thermal Energy Program
Potential
It has been estimated from geological,
geochemical, shallow geophysical and shallow drilling data it is estimated that
India
Rocks
covered on the surface of
Potential
Sites:
- Puga Valley (J&K)
- Tatapani (Chhattisgarh)
- Godavari Basin Manikaran (Himachal Pradesh)
- Bakreshwar (West Bengal)
- Tuwa (Gujarat)
- Unai (Maharashtra)
- Jalgaon (Maharashtra)
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