Geothermal Power Unleashed:
Mostly untapped, the Earth’s reserves of heat energy are estimated at a potential 42 million megawatts of produced power—equivalent to the energy supplied by 25,000 large power plants. Deep Inside the EarthHow Does Geothermal Energy Work
The Earth’s core has temperatures reaching 10,800 degrees Fahrenheit (6,000° Celsius). The core is surrounded by a layer of rock, the mantle, and molten rock, or magma. The outer layer of Earth, the crust, is made up of large continental plates that float on the mantle. Nuclear reactions below the Earth’s crust release heat energy to the surface. The areas where these continental plates overlap or bump into each other are the known earthquake and volcanic activity zones. These are the areas with the greatest potential for the use of geothermal power.
As groundwater seeps into the ground it becomes trapped and heated to extreme temperatures. In areas around the earth where there are cracks or the crust is thin—usually areas with volcanic activity—this heat is released through hot springs, geysers and volcanoes. As with everything else, man has been able to tap into this renewable clean energy source, and put it to use. By drilling wells, steam is extracted and used as an energy source. How Is Geothermal Energy UsedGeothermally-heated waters can only be found close to the Earth’s surface in few parts of the world—including Iceland, northern California, Japan, the Philippines and New Zealand. For this reason, geothermal energy is not one of the biggest sources, but it has great potential uses. It can: 1) Provide heat by pumping the heated water through buildings as they do in some parts of the world. In Iceland, this is the method used by 85 percent of the population. Geothermal Energy History
Geothermal Power PlantsThe first geothermal power plant using naturally-occurring steam was built in Larderello, Italy in 1904. The steam in this area reaches a temperature of about 430° F (220° C). Dry steam reservoirs are very rare. The Larderello facility currently produces 10 per cent of the world’s geothermal energy providing power to one million homes. In 1960, the first successful geothermal electric power plant in the United States began operation at The Geysers in California. It is currently the largest geothermal power plant in the world.
About 60 million people worldwide get their electricity from geothermal energy. In the United States, 3.5 million homes are powered by the Earth’s energy—equivalent to the amount of power generated by a fossil-fuel power plant using 60 million barrels of oil per year. Twenty-four countries are currently using geothermal power including the United States, Iceland, New Zealand, Japan, Australia, Kenya, and Mexico. As of 2004, five countries—El Salvador, Kenya, the Philippines, Iceland, and Costa Rica—generate more than 15% of their electricity from geothermal sources. Disadvantages of Geothermal EnergyTapping into the Earth’s heat energy can release small amounts of greenhouse gases as well as other toxic elements. However, these levels are a small fraction of that released by burning fossil fuels, and emission control systems are installed to reduce pollution. Advanced carbon capture and storage technology can be used to contain these pollutants and inject them back into the earth. Advantages of Geothermal EnergyThe known geothermal energy facts support geothermal power as a cost effective, reliable, and environmentally friendly alternative energy resource . Geothermal energy cost considerations include drilling and exploration of deep sources. Fuel cost fluctuations, however, are not an associated cost since no fuel is used. Technological advances have widened the range and output of viable geothermal energy sources worldwide which are less and less limited to earthquake-prone areas. Geothermal power plants can pump cold water deep underground where the water is heated and returns as hot water and steam. The steam is used to generate electricity and the hot water to heat buildings. One of the best geothermal energy advantages is that since geothermal power does not rely on variable sources of energy, such as wind or solar, a plant’s capacity factor—the ratio of actual output over a period of time and its output if operating at 100 percent the entire time—is very high—up to 90 percent. Future of Geothermal Energy
Worldwide, geothermal power plants have the capacity to generate about 10 GW of power as of 2007, and generate 0.3% of global electricity demand. An additional 28 GW is produced by direct geothermal heating.
In countries with no natural oil or coal reserves, geothermal energy is becoming a major source of energy. As new technology emerges, the potential for drilling deeper wells to access higher temperatures is increasing. Geothermal Energy is just one more viable resource in our renewable, clean energy arsenal—along with solar, wind, biomass, and hydropower—that can be used to mitigate the effects of global warming, and help to save planet Earth for future generations to come. Return to Top of Geothermal PowerPage
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