Solar Energy

Report Outline
New Interest in Solar Development
Progress Toward Tapping Sun Power
Uncertainty in Development Efforts
Special Focus

New Interest in Solar Development

Enormous Abundance of Energy From the Sun

Solar energy is by far the most abundant energy source available to earth. The sun generates such an enormous amount of energy that the facts and figures are almost incomprehensible. Only an infinitesimal fraction of the sun's radiant energy strikes this planet, but our share still equals about 180 trillion kilowatts of electricity, or more than 25,000 times the world's present industrial power capacity. A few comparisons help to illustrate the awesome potential of solar energy. The energy in the sunlight falling on the surface of Lake Erie in a single day is greater than current annual U.S. energy consumption. The amount of solar radiation striking only 1 per cent of the nation's land area each year is more than projected national energy needs to the year 2000. The solar energy reaching the surface of the entire United States annually is greater than the total amount of fossil-fuel energy that, scientists say, will ever be extracted in this country.

The sun is already the indirect source of most of the energy used on earth—from wood, wind and falling water to the coal, oil and natural gas deposits formed centuries ago. But today, with fossil-fuel resources rapidly being depleted, nuclear energy plagued by cost and safety problems, and hydropower and geothermal resources limited, interest in wider use of solar energy is soaring. Solar power is seen as the clean, safe, pollution-free and virtually inexhaustible energy source that can meet the nation's—and the world's—energy supply needs for the foreseeable future. A wide variety of technologies are being pursued, from direct use of solar energy to heat water and buildings or generate electricity to indirect use through the wind, ocean thermal layers or bioconversion of organic material (see boxes, pp. 828 and 830).

But there are many problems. For one thing, sunlight is so diffuse that collecting it and concentrating it present serious difficulties. Solar energy varies greatly with latitude, season, time of day and weather conditions. Moreover, it cannot be converted to useful power at 100 per cent efficiency, and it cannot be stored easily for later use or transported to other areas. There are numerous technical problems with most existing solar-energy equipment, although progress has been rapid in recent years and more refinements or scientific breakthroughs seem imminent. Perhaps the greatest barriers to the acceptance of solar energy are political, social and economic. But none of these problems appears insoluble and it is increasingly likely that solar energy will emerge in the decades ahead as a major energy source for the United States and for other nations.