most embarrassing variety of valid ways to accomplish the feat exist. And they’re all done with mirrors. Proposals for large-scale application of any of these ideas, however, have yet to be built or tested. Because all such schemes would cost big, big money. The large U.S. companies in the solar energy field are going after ERDA research grants to build large, central electric power generating plants. Martin-Marietta says it can have one operating by the end of 1977 to generate 1 Megawatt of electricity, and by 1985 a plant of 100 Megawatt size. For comparison, San Antonio currently uses about 1,400 Megawatts. Itek Corporation proposes a field array of parabolic troughs; General Atomics proposes a field array of parabolic troughs of a different size, shape, and orientation. McDonnell, Honeywell, and Boeing are all working on the central-tower scheme. For a 100 Megawatt capacity, this envisions the following: a central receiving tower about the height of the Empire State building, surrounded by acres and acres of heloistatsmirrors, about 15,000 of ’email tracking the sun in two dimensions, each at a slightly different angle than its neighbors, reflecting a portion of the sun’s rays up to the top of the central tower, where water flashed into steam by the intense heat will push turbines to produce electricity. Now that’s style . . . nothing penny-ante about it. Out of a 1977 budget of $2,400 million, ERDA plans to devote $120 million about 5 percentto solar research and development; it’s easy to see how a tower 300 meters tall, surrounded by a square mile of tracking heliostats, could soak up most of the money. ERDA is sticking with the central tower plan because it appears to be the least costly to construct$1,360 per megawatt of electric power capacity. All the other big-time solar schemes are in the neighborhood of $2,000 per MWe. Recall, for comparison, the current cost of a boiling-water nuclear plant is around $1,000 per MWe. The justification nuclear advocates offer for the high cost of construction can be invoked on behalf of solar electric power, too, and with better credibility: over the years, fuel costs will be miniscule. The Australians may make us pay handsomely for yellowcake, but old Sol can be relied upon never to increase the price of his energy. Dr. Albert Wortham of A&M, when asked his opinion of ERDA’s central-tower plan, responded with an Emperor-has-noclothes question of his own: what happens to all those delicate, shiny mirrors, he wondered, if you build your plant out in the wide open spaces and along comes a good ole West Texas dust storm, or some golfball sized hail? Still another solar electric power scheme was presented April 2nd at the St. Mary’s University Engineering Seminar, by Dr. Robert Walters of E-Systems, Inc. It’s the Fixed Mirror Distributed Focus device, or FMDF. E-Systems, of Dallas, builds radiotelescopes, and has installed several hundred of them world-wide, including, most pertinently, the giant at Arecibo, Puerto Rico. The idea is: rather than building mirrors to track the sun, build a gigantic, fixed, inverted hemisphere of a mirror to reflect the sun back up to a long absorber tube, and let the absorber track the sun so as to always remain at the focus of the reflected rays. Much simpler, much cheaper, and very similar to existing radiotelescopes already constructed. Degree of concentration attainable: about 1,000 times, resulting in steam at temperatures greater than 700 degrees F, and pressures of many hundreds of pounds per square inchsuperheated steam, in fact, the kind modern steam turbines are designed for. The price, said Dr. Walters, is well under that for the tower system ERDA wants to test. Ultimately, 3 cents per kilowatt electricity would be available. A 5 MWe system could be constructed within five years; a 100 MWe system could be ready by 1985, consisting of an array of smaller, optimum-sized devices, each about 1,000 feet in diameter and generating about 15 MWe, with a solar-to-thermal conversion efficiency of 67 percent. No basic research or development needed. Just build one and test it. How about the dust-storms and hailstones? The Arecibo radiotelescope has a catch-tank under its lowest point, where rain-water is collected, mixed with a little detergent, and periodically flushed over the surface of the reflectors like water running down from the rim of a toilet-bowlnot exactly an esthetically appealing image, but a very effective method of keeping the mirrors dust-free. The hailstone threat was minimized by building the reflector in segments of impact-resistant plastic. What about days when the sun doesn’t shine? Various methods of storing energy during solar peak hours are available: caves in which heated air could be retained are a good possibility around San Antonio; dissociating hydrogen from water and storing it for fuel in another one. Now . . . who will put up the money to build one? San Antonio City Public Service? No. ERDA? Applications had been submitted already, Dr. Walters said, for sites at Hobbs, New Mexico, a site in North Texas, and on the U.T.S.A. campusfor which last an elegant artist’s conception drawn on a photograph of the campus was available. But ERDA had not approved any of them, yet. Councilmen Neilsen, Hartman, Pyndus, and Rhode of the San Antonio City Council had been given the same presentation Dr. Walters gave the St. Mary’s audience; other council members had been unable to attend. But the Council was reluctant to consider radical departures from the tried and true. It preferred to go along with CPS advice and remain a part of the South Texas Nuclear Project. Plus, it thought becoming the location for ERDA’s projected Solar Energy Institute would be a dandy thing. Dr. Arthur Tamplin, authority on somatic and genetic effects of nuclear radiation, and long-time critic of the U.S. nuclear program, who also spoke at the St. Mary’s seminar on March 26th, was scornful of the Institute idea. What’s the need for an Institute, he asked, when the scientific facts on solar energy have been available for a century? The effort would pay off better if devoted to constructing demonstrations and testing ,them. If a Solar Energy Institute, why not a Horse-manure Institute, a Pigmanure Institute? A Chicken Institute? That would give more American cities some distinctions to vie for. But with all these alternative designs to weigh, and considering the high cost of building them, it’s no wonder the U.S. Government should be regarded as the likeliest source of construction capital. And, with the uncertainty as to future prices of fuels, including uranium, it’s no wonder the possibility of generating electricity from solar power plants should be both attractive, and doubtful. This very same economic question, indeed, is the one that has held back serious large-scale development of solar energy for fifty years. Some students of the energy situation feel it’s possible the difficulty in adapting solar energy to producing electric power lies not on the sunny side of the question, but over on the side of large central generating plants. Solar energyfor electric power, they say, might be better developed by a decentralized approach, utilizing plants of modest size to serve neighborhoods of 1,500 homes or so. Such installations would require capital investment in smaller, more manageable bites. It could be implemented in a modular fashion, adding only as much generating capacity as was needed at a given time. If this turned out to be true, it could mean that solar energy applications would never rise to the leval of standardized, ponderous corporate style. It could mean that tapping the energy of the sun would continue to be a matter of imaginative application of engineering and scientific principles to particular needs on a human scale, requiring that people using solar technologyrather than being specialized, regimented, and obedientbe informed, thoughtful, and resourceful. Sort of adapted for survival, one might say.
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