As energy prices soar and reserves dwindle, the industrialized world is coming under increasing pressure to find new ways of providing the energy on which our society depends. Solar power, wind energy, refuse burning, alcohol and methane production all show promise, but each is not without its limitations and disadvantages. One source of future power being given serious consideration is geothermal energy. About 20 miles below the crust of the earth, there exists a hot molten mass called magma. In some places the magma is relatively close to the surface (five to ten miles down). In a geothermal field, water trapped in fractures in the near-surface rocks is heated by the magma. This results in hot water and steam, which often can escape along fractures to the surface of the earth. Usually the steam is under considerable pressure, and when such a reservoir is tapped by drilling, the steam can be used to drive a turbine. Actually, geothermal energy is not new. Roman documents 2,000 years old tell of a steam field west of what is now Florence, Italy. Today, Italy produces some 4,000,000 kilowatts of geothermal electricity. The United States has the largest geothermal steam system in the world, located about 90 miles north of San Francisco. Known as the Geysers Power Plant, it currently produces nearly 1,000,000 kilowatts of electrical power and may eventually double that capacity. Since the fuel for geothermal power is free, the cost of producing electricity from it is only that of tapping the steam and maintaining the equipment. Total operating cost (fuel plus capital) for geothermal electricity at the Geysers plant is well below nuclear power, coal, and fuel oil. Each 100,000 kilowatts of geothermal energy replaces one million barrels of oil per year. Since the Geysers plant may eventually produce 2,000,000 kilowatts of electricity, some 20 million barrels of oil could be saved each year at a monetary savings of about half a billion dollars per year. However, geothermal energy does have several drawbacks. First, fairly pure steam from the earth is quite rare. The less useful hot water (with more impurities) is much more common, but steam is far more desirable. Also, almost all the geothermal sources worldwide have the noxious odor of hydrogen sulfide gas associated with them. Special equipment must be used to reduce the hydrogen sulfide odor where geothermal plants are located near inhabited areas. In spite of these difficulties, geothermal power does have many advantages. Unlike power plants fueled with coal, oil or natural gas, there are no combustion products emitted to contribute to air pollution and smog. There are no long-lived and dangerous waste products as in the case of nuclear power. Moreover, fossil fuels and nuclear fuels, diminishing in supply, are rapidly increasing in cost; by contrast, the steam of geothermal plants appears virtually inexhaustible. Unlike hydroelectric power plants, geothermal plants do not require that rivers be dammed. Condensed steam from the geothermal system can be recycled in the cooling process and reinjected underground into the steam reservoir. Geothermal resources are not the total answer to man's energy demands, but in an increasingly energy-hungry world, geothermal power will undoubtedly make a lasting contribution to energy needs in the world is of tomorrow.