ALTERNATIVE TECHNOLOGIES

Though still small, contributors to the world's electrical grid.

wind, geothermal, biomass. solar, and fuel cell technologies may

nonetheless represent the power of the future, given the economic,

geopolitical, and environmental costs of power generation in

operation today.

Wind power has been used for centuries, but instead of turning

mill stones it now involves large, fan like blades geared to turn

turbines. Wind farms, concentrated installations of power-

generating wind turbines, have found their most extensive use in

California. Wind power plants operate in northern Europe, Saudi

Arabia, and India, and more have been proposed for the U.S.,

offshore on the Atlantic coast and on the mid-western plains.

Geothermal systems tap Earth's underground heat. Like sunlight,

this is a free and limitless resource, but one that for large-

scale use requires the user to be near an area where volcanic

activity or radioactive decay is producing heat close enough to

the surface to be used efficiently. Single dwellings can benefit

from geothermal heat just by conscientious design.

Biomass fuels are typically distilled from corn, sugarcane, or

other plants high in sugar. They have recently gained popularity,

but the local and global economic effects of redirecting

agricultural production for fuel rather than food raises

concerns,does the amount of fossil fuels use grow such crops.

Solar energy reaches that a rate about 200,000 times the daily

capacity of existing power plants, and available technology

harnesses it for heat or electricity. Solar pan else work by

absorbing heat from the sun and transferring it into circulating

fluid. Photovoltaic cells made of silicon, boron, and other

substances convert sunlight into electricity. As with geothermal

energy, individual buildings can be designed to benefit from the

sun's heat without complex equipment, a technique called passive

solar.

Fuel cell technologies hold great promise. Research agencies,

private companies, and the world's major automobile manufacturers

are exploring these new ways of converting chemical energy

directly to electricity, possibly providing a battery-operated

alternative to the conventional automobile.

WHAT IS GEOTHERMAL ENERGY

Temperatures at the centre of the Earth may reach as high as 7000°F. That energy radiates out in the form of underground hot springs, volcanoes, geysers, fumaroles , and other geologic phenomena, and it has become an important source of power in more than 20 countries of the world, including New Zealand, Japan, Iceland, Mexico, and the United States.

The oldest modern geothermal power system was built in Larderello, Italy, in 1904, and it still operates to day. Reykjavík, Iceland, uses geothermal energy for district heating in the city, which has significantly cut back on pollution. The first U.S. city to install geothermal district heating was Boise, Idaho. The world's largest geothermal development is the Geysers, north of San Francisco, a complex of 22 power plants that serves 725,000 homes.

Major geothermal plants are limited to sites where sources of under ground heat are intense and shallow enough to be tapped economically. By contrast, geothermal heat pumps take advantage of the Earth's relatively constant




 temperature even ten feet below ground—a way to produce air that is, relative to the surface, cooler in the summer and warmer in the winter.