Environment: The Gift from the Sun

And pluck till time and times are done… The golden apples of the sun.

Long before William Butler Yeats wrote these words, scientists dreamed of harnessing and storing the awesome energy of the sun. For Donald Hyde, a Stow, Mass., manufacturer, and thousands of other Americans, those dreams are becoming a reality. The sun provides most of the heat for Hyde’s modern cedar-walled house, keeping its temperature at a comfortable 68° to 70° F. during even the coldest days of a New England winter. Solar energy also warms the water in Hyde’s 16-ft. by 30-ft., kidney-shaped swimming pool. Putting the sun to work saves Hyde money on his fuel bills. His prototype solar system meets most of the house’s space and hot-water heating needs, and cuts his energy bills by about 75%.

No More Ifs. Houses like Hyde’s, their sharply pitched roofs covered by glassy-looking solar collectors, are still uncommon but may soon be familiar sights across the nation. On lots from Maine to California, in downtowns as well as rural areas, architects are erecting houses and office buildings designed to capture the sun’s radiation for heating purposes. Schools in increasing numbers are also using solar energy to keep classrooms comfortable. The Government is seriously studying ways of using sunshine to generate electricity for utility customers. Though the current high costs of capturing the sun’s energy make it uncompetitive with more conventional fuels, there is no doubt that solar energy is slowly coming of age. “There are no ifs involved with solar energy any more,” says Bradley University Professor Y.B. Safdari, who has built a solar house in Eureka, Ill. “It’s merely a question of when.”

As recently as a decade ago, the whole idea of directly tapping solar energy was considered by many to be little more than a form of permissible idiocy, a harmless pursuit for a handful of engineers and tinkerers. Only six years ago, the Federal Government budgeted a mere $1 million for solar-energy research; this year the sum will be almost $180 million.

Abundant Energy. The growing popularity—and respectability—of solar-energy systems stems in part from the price of oil, which has quadrupled during the past five years, and is likely to climb still higher after the Organization of Petroleum Exporting Countries (OPEC) meets in December. The prices of natural gas and coal have also increased, and reserves of all three fuels have dwindled, forcing economists to look ahead to the day when they might be unavailable at almost any price. “We eventually will have very little left but solar energy,” says Erich Farber of the University of Florida at Gainesville. “Therefore we must learn to convert solar energy into every kind of energy we use in our daily lives.” Nuclear-power proponents would disagree with Farber’s philosophy, but concerns over safety and rising costs have slowed the rush toward fission power. Nuclear fusion plants, which promise virtually unlimited power, are probably decades away from becoming a reality.

Solar power has many attractions. It produces neither pollution nor radioactivity. It is inexhaustible; the sun is expected to burn with undiminished brightness for billions of years. Finally, it is abundant, though diffuse and difficult to collect. The amount of solar energy reaching the earth averages 126 watts per sq. ft. Even in a northerly location such as Madison, Wis., the amount of solar energy striking an acre of ground is equivalent to 10 bbl. of oil per day, while that hitting a roof is in most cases more than enough to meet the energy needs of the building below.

Solar energy is being tapped in many strange and wondrous ways. In New Mexico, where the sun is seldom obscured by clouds. Inventor Steve Baer heats his futuristic-looking home by means of a “passive” solar system that has a minimum of mechanical components. The south-facing walls of Baer’s home outside Albuquerque are floor-to-ceiling windows, and behind these glass panels are walls composed of water-filled 55-gal. steel drums. The drums absorb the sun’s heat by day, radiate it at night when the windows are covered by huge clamshell-like shutters to slow cooling. Similar systems work almost as well in colder climates. In Bedford, N.H., Ralph Tyrrell and Holly Anderson share a three-bedroom house that obtains its heat directly from the sun. South-facing windows catch the sun’s rays during the day; foot-thick cement walls absorb heat and help prevent heat loss at night.

Hot Rocks. “Active” systems, which work more like conventional gas or oil heating arrangements, are also becoming popular. George Löf, director of the Solar Energy Applications Laboratory at Colorado State University, uses an original installation in his home in Denver. Löf’s house is fitted with plate-type solar collectors, sandwiches of glass and black-painted, heat-absorbing metal that warm trapped air like a series of shallow greenhouses. Fans then force the heated air through ducts to cylinders filled with rocks that hold the heat. When warmth is needed, air from the rooms is circulated through the rocks and directed into the heating ducts.

Other active systems use water or various antifreeze solutions as a heat-conducting medium (see diagram). In Hyde’s house, water heated by the sun to around 200° F. is stored in a 2,500-gal. tank. Hot water then circulates through a heat coil over which air is blown by a fan and ducted to every room in the house. At Harry Evans’ new home in East Hampton, N.Y., heat from solar panels in the roof is collected in a bin containing 1,000 sealed, plastic bottles of water, which can hold the heat for as long as three sunless days. The system provides between 50% and 75% of Evans’ home heating requirements. Alden and Margaret Krider of Manhattan, Kans., have fashioned their own solar collectors from discarded aluminum printing plates, storing solar heat in discarded paint cans filled with water. They are delighted with the results. Says Krider: “Every 1,000 cu. ft. of gas I don’t burn now is 1,000 cu. ft. that I or someone else can have in the future.”

Power Tower. New York Telephone’s central exchange in Cutchogue, N.Y., gets up to 70% of its heat from the 170 solar collectors that cover its roof. Sunlight is expected to provide up to one-third of the energy requirements of the new Norris Cotton Federal Building in Manchester, N.H. The sun also warms most of the hot water for a 16-story high-rise apartment for the elderly in Brookline, Mass.

The practicality of photovoltaic cells —thin sandwiches of silicon or metals that generate current when struck by light—has been amply demonstrated by the space program. Solar cells power satellites that orbit the earth and drive the instruments on the Viking orbiters currently circling Mars. They are used on earth to power digital watches, remote weather stations and navigation buoys at sea—and may some day save gasoline. Researchers at the University of Florida have outfitted an experimental Volkswagen bus with an electric motor that runs on batteries charged by current generated by solar cells.

At Odeillo, in the Pyrenees, French officials have constructed a parabolic mirror half the size of a football field (TIME, May 18, 1970) that focuses the sun’s rays on a single point. The solar furnace has already been used to melt tungsten, which must be heated to nearly 6,000° F. before it liquefies, and has also been used to test boilers for a power-generating plant. The Energy Research and Development Administration (ERDA) is planning to fund an experimental program in which 100 acres of mirrors would direct sunlight at a “tower of power,” where the sun’s rays would be concentrated and used to heat water in a boiler, thus generating steam for a turbine. ERDA believes such an arrangement could generate up to 10,000 kw., or enough to supply a town of 5,000 to 10,000 people with electricity.

Engineers at NASA have gone even further, embracing an idea originally proposed by Peter Glaser of the Cambridge, Mass., consulting firm Arthur D. Little, Inc. He suggested mounting huge arrays of solar cells on a space satellite that would be exposed to sunlight for almost 24 hours a day. The cells would generate electricity that could be beamed to a ground receiver in the form of microwaves, then transformed back into electrical current for transmission to power customers.

Sun Rights. The major obstacles to any of these far-out schemes are more economic than technological. Harnessing solar energy is currently far more costly than burning fossil fuels. ERDA estimates that tower-supplied electricity would cost from six to ten times more than electric power generated from fossil fuels. Electricity from solar cells, which costs from 50 to 100 times as much as that produced by more conventional means, is still far too costly for anything except specialized applications. Even home heat tends to be uneconomical for widespread use. A solar heating system adds from $5,000 to $10,000 to the cost of a new house, an investment that could take from ten to 20 years to amortize at current fuel prices. Says an ERDA official simply: “The economics are not good.”

Other problems stand in the way of large-scale conversion to solar energy. Engineers have yet to figure out effective ways to store heat from the sun for more than three days or to tap solar energy for power production without filling huge tracts of land with reflectors or photovoltaic cells. Even legal technicalities must be resolved before use of solar energy can become practical. A study by Arthur D. Little suggests that the courts might be required to decide whether everyone has an equal right to sunlight, a question that will certainly arise the first time someone tries to put up a building that casts a shadow on a neighbor’s solar collector.

With all of these obstacles yet to be overcome, ERDA does not expect solar power to provide more than 1% of U.S. energy needs during the next quarter-century, or even as much as 25% by the year 2020. But solar radiation may yet become a major means of meeting the needs of the earth for energy. Regardless of how great they may be, the earth’s supplies of coal, oil and natural gas are finite. Long after these resources have been exhausted, the sun’s golden apples will still be ripe for harvesting.