What's New Under the Sun?

There was a sun before there was an earth, and it is easy to understand the primitive worship of that magnificent fire in the sky. Life flourishes in and because of the sun. Our food, textiles, and wood are produced by the sun, as are rain and wind and tides. In essence, the sun is a nuclear fusion powerplant, converting 4 million tons of hydrogen to helium each second, and beaming incredible amounts of radiant energy, a tiny portion of which is intercepted by the earth. In the year 214 B.C. Archimedes foiled an attacking Roman navy at Syracuse by setting it afire with a solar furnace, evidence of the potent force in sunshine. For many decades the Crookes radiometer and its spinning black and white vanes have intrigued us and constantly reminded us of the energy content of the gentle rays of the sun. A few pioneers built solar stills in Chile and solar steam engines in France and America a century ago. Dr. Charles G. Abbot used a solar engine to power a radio transmitter for a nationwide broadcast in 1936! Solar energy is the oldest thing on earth, but its wide application is just beginning. The few solar heated and cooled homes, pumps and solar battery installations are just an exciting preview of the age of solar energy, a bountiful and safe age that has been put off too long.

As is being proved every day as new solar residences and other buildings begin operation, the sun can heat and cool, and provide hot water. Fortunately for a nation battling energy woes that seem to get worse each year, space heating and cooling, and water heating for domestic and industrial purposes, represent about 45 percent of our total energy demand. Without developing solar power generators we can take care of nearly half our requirements. And very efficiently too, for we do not burn fuel at elevated temperatures merely to heat our homes to 80 degrees, nor do we have to transmit energy over long distances with resulting high losses.

This is not to say that the sun can't or won't provide electricity too. It has already proved it can do this, both with the elegant "solar battery" that simply sits in the sun and converts light to electric power, and with a variety of mechanical engines that then produce electricity in more or less conventional ways. The problems thus far are those of scope and cost. The solar battery, for all its elegance and simplicity, exacts a high price for these advantages. Today it costs from $20 to $50 per watt for solar cells. A 1-kilowatt power supply would thus cost up to $50,000, a price we can afford only for such applications as Skylab, or a few specialized uses here on earth. If the cost can be cut tenfold, we might be in business with solar electricity. If it could be cut by a factor of 100, there would be no question about it. So work goes on toward that wonderful goal.

Three of Arizona's major utilities are proceeding with solar thermal electric projects. This is more logical than remarkable, for if we are one day to operate "solar power farms" such as the 5,000-square-mile giants proposed by Drs. Aden and Marjorie Meinel of Tucson, it will be the utilities that must fund and build them. The Meinel designs and the Arizona Public Service/Arizona State University/Gulf Atomic solar-electric power plant are described elsewhere.

Another proposed solar-power project seems to be ideally suited to helping Arizona's electric power utilities meet their peak load demands in summer and to reduce their conventional energy demands throughout the remainder of the year. The proposed system originated in the mind of Floyd Blake of the Martin-Marietta Company of Denver, who learned most of his high-temperature solar technology during his years of serVice at the laboratory which was formerly operated by the General Electric Company at their Black Canyon facility near Phoenix. Blake's concept, which may some day be built near Apache Lake and Horse Mesa Dam, uses a large number of movable mirrors, called heliostats. These reflect a tremendous amount of sunshine into the opening of a steam generator, where the sun's radiant energy is converted into heat at very high temperatures. The only energy which is transported is the reflected radiation from the sun, and the heliostats would be automatically guided to track the sun's motion and reflect its rays into the boiler cavity. Martin-Marietta has made computer studies covering the year 1973, using the actual power-generating statistics from the Salt River Project. The original idea was to save water for the hydroelectric plant at Horse Mesa Dam, shown in the background of the general view of the solar power plant. The computer studies show that the current importance of the program lies in its ability to save oil which would otherwise have to be burned in steam boilers or gas turbines.

Arizona is ideally adapted to the erection and operation of large solar-steam power plants because of our very large number of sunny hours (85 to 90% of the maximum possible!) and the existence of a highly developed electrical distribution system which will use the solar power when it is available and eliminate the need for the storage of huge quantities of heat to run the solar plants at night when they will not be needed.

Future developments of solar apparatus for Arizona will inevitably come because this area will continue to attract an ever-increasing population and their energy needs must be met. The sun can go far towards doing just that.

Beyond the huge desert solar power farm, and the sea thermal energy plant tapping the heat stored in the oceans themselves, is the possibility that some day solar scientists and engineers will move their collectors nearer the sun. The orbiting solar power plant may be a reality and produce electric power for our grandchildren. And someday spacemen may hurtle through space at fantastic speed on a vast "solar sail" such as has been proposed not by science fiction writers but