Solar Energy in Arizona ...Some Historical Facts

SOLAR ENERGY IN ARIZONA ...some historical notes

The most widespread use of solar energy is one in which, until quite recently, man let nature do the job of plant production in its own way. For more than 2,000 years, the diligent, intelligent, and hard-working Hohokam made use of irrigation in the valleys of the rivers that we call the Verde, the Salt, and the Gila. Then as now, rainfall in these valleys was inadequate to support the relatively large populations which migrated to these sun-rich lands, and extensive irrigation channels were employed which compared in extent with those in use today. These hardy folks had neither pumps nor permanent dams, yet they managed to maintain a population which was not exceeded in numbers until after World War I.

Primitive peoples have always relied upon the sun to warm their dwellings whenever it was available. The great structure which so impressed the Spanish explorers that they called it "Montezuma's Castle" is unquestionably one of the finest naturally heated and cooled apartment buildings that this continent has ever produced. Located in the south-facing center of a great white limestone cliff, in a recess with a massive overhanging cliff, this structure receives the full force of Arizona's sunshine upon its outer walls during the winter months when the sun is relatively low. The masonry and adobe walls of the "Castle" are warmed by the sun and, after the sun has set, heat continues to make its way through the walls into the many rooms which are contained within this seven-story structure.

During the summer months, the face of the building is completely shaded by the overhanging ledge. The walls, cooled by the breezes which flow down the valley and by radiation to the sky, do not attain the high temperatures reached by sun-heated surfaces and the rooms remain comfortable. According to the tree-ring dating, construction of Montezuma's Castle began about 700 A.D. and the last logs in its uppermost ceilings were cut early in the 1300s. No one knows today why it was abandoned, but it was quite empty when the first white men came to the Verde Valley and no larger structure was built in the Arizona Territory until early in the present century.

The inhabitants of Arizona first made technical use of the sun's radiation a century ago, when the U.S. troops, under the command of General Nelson A. Miles, employed the heliograph to establish a communication system which could not be cut by Geronimo and his wily Apaches. The heliostats which General Miles used first in Montana and then in South Dakota employed mirrors mounted on tripods, equipped with shutters which could be used to flash long and short bursts of brilliant light that could be seen over distances of 50 to 60 miles. The Morse code, familiar to all telegraphers, was used and the equipment was readily portable, a feature which made possible the establishment of heliograph stations on a chain of mountain tops which ranged from Fort Huachuca in the south to Whipple Barracks in the north and to Fort Stanton in New Mexico on the east.

The telegraph line which the army endeavored to maintain across the Arizona Territory was readily interrupted by the Apaches, who did not understand the "singing wires" but knew that when the poles were chopped down and used for firewood the wires ceased to sing. The heliograph system with its 27 stations could not be interrupted, since its transmitting and receiving equipment was operated by well-trained soldiers, protected by detachments of cavalry.

The clear, dry air of the southwest, unpolluted by any manmade contaminants, was ideally suited for heliography, and General Miles made good use of it and its operators to observe and report on the movements of Geronimo and his warriors. It is reported that a successful demonstration of the heliograph's ability to permit rapid communication among the whiteman's forts convinced Geronimo and Natchez, the hereditary chief of the Apaches, that further fighting was futile. The simple little heliograph, with its bright flashes of dots and dashes, in telegraphic language, brought about the end of the Apache wars on September 5, 1886, when Geronimo, Natchez and their warriors capitulated. In its turn, the heliograph was displaced by radio, which could function by night as well as by day.

man's forts convinced Geronimo and Natchez, the hereditary chief of the Apaches, that further fighting was futile. The simple little heliograph, with its bright flashes of dots and dashes, in telegraphic language, brought about the end of the Apache wars on September 5, 1886, when Geronimo, Natchez and their warriors capitulated. In its turn, the heliograph was displaced by radio, which could function by night as well as by day.

The next major development in solar energy technology in Arizona came nearly forty years after General Miles had shut down his heliograph stations. An English inventor named Aubrey G. Eneas, then a resident of Boston, devised and patented a remarkable solar-powered steam engine which consisted of a gigantic inverted cone, lined with thousands of flat glass mirrors which concentrated the sun's rays upon a boiler located at the center of the concentrator. An ingenious clockwork mechanism, powered by a great weight which was raised each morning to the top of the supporting tower, caused the concentrator to follow the sun across the sky. The operator had only to crank the weight to the tower top, adjust the concentrator to face the sun when it rose, and then turn it loose, letting the clockwork cause the necessary rotation of fifteen degrees per hour.

The first of these machines, and the best known in the technical literature, was installed at the Ostrich Farm in South Pasadena, California, in 1901, where it ran successfully for a number of years. The Arizona engine, identical in design to the California prototype, had a much more fascinating history. Edwin Cawston of Pasadena owned the Ostrich Farm on which the first Eneas machine was erected. His brother was a "wealthyLondon banker" and, according to the Arizona Republican for July 9, 1904, he put up the funds needed to patent the Eneas invention in fifteen nations. The Bostonians, led by Frank J. Post, put up the funds needed to build the Arizona version of the Eneas engine. The cost of the solar engine shown here, in 1904 dollars, was $2,500, and, on a bright sunny day, it could pump enough water to irrigate 80 acres of dry but fertile Arizona land. Following a demonstration in Tempe, where the photograph was taken, it was sold to John May of Willcox and operated on his ranch during most of 1905. It was then removed to the McCall ranch near Cochise, according to Arizona Range News, March 2, 1906.

There are conflicting stories about the demise of the Arizona Eneas engine. One account credits a bolt of lightning with its destruction while another and more likely story attributes its end to a hail storm which "broke every mirror in the collector." Whatever the cause, there were no more Eneas engines in Arizona or elsewhere, because small gasoline engines and electric motors were beginning to become available and they, with much less cost and greater reliability, soon eliminated the solar engine. Only now, when oil has quadrupled in price, when natural gas is again becoming as scarce as it was in 1907, and when electricity is rising in cost, are thoughts turning again to using the sun's energy to pump and heat water and to generate steam. The necessity for developing a solar power water pump has suddenly become urgent in Arizona. Hundreds of farmers now using gas-powered engines to irrigate thousands of acres Owners of agricultural land are faced with having to use alternative sources of energy, and these are increasingly difficult to find. During the two generations which followed the Eneas era, many Arizonans provided hot water for their homes by simple but reliable solar heaters. In some cases these were simply blackened barrels mounted on rooftops or other elevated, exposed locations. They were filled with water in the morning and by the end of a sunny day the water was hot enough for showering and dish washing. Later the somewhat more costly but far more efficient glass-covered thermosyphon heater was introduced and it provided more and hotter water during most of the year. The invention of simple kerosene and later gasfired heaters put an end to the solar heater industry in Arizona and in California and today the few remaining examples are regarded as curiosities. The impending end of the natural gas era in Arizona, as far as new installations are concerned, has renewed interest in solar heating, and house heating and cooling by solar energy are once again under active consideration. After World War II a few solar enthusiasts continued to work in the fields of their particular interest and at their own expense. Among these pioneers were Mr. and Mrs. Raymond Bliss, who resided at that time in a ranch house near Amado. They "retrofitted" the house for solar heating and natural cooling by use of an ingenious solar air heater which combined a south-facing, glazed collector using a black mesh to trap the sun's rays. This collector heated air which was drawn through the system by a small fan. Since storage of day-collected heat for use at night is an essential feature of any solar heating system, Ray and Mary Bliss used a rock bin to which heat was transferred by the sun-warmed air during the day. At night, the dampers were shifted and the house air was circulated through the heated rocks. This simple but inexpensive and fool-proof system, in various modifications, is now in use in most of the solar houses throughout the world which use air as their heat-transfer fluid. Night-time cooling was accomplished at the Amado residence by simply drawing cool night air through the rock bed and then circulating air from the house through the rock bed during the warmer daylight hours. Later, Mr. and Mrs. Bliss transferred their activities to the Solar Laboratory which the University of Arizona built on the land which now contains the Medical School. The University's extensive solar program, described elsewhere in this issue, was moved to permanent quarters adjacent to the Tucson International Airport.

Renewed interest in solar energy was aroused in Arizona in the mid-1950s, when the formation of the Association for Applied Solar Energy was announced and a World Conference on Solar Energy was organized for the new Association by Stanford Research Institute of Menlo Park, California. A week-long series of meetings was held, attended by more than a thousand delegates from ninety nations. The first three days of the week of November 1, 1955, were devoted to scientific conferences at the University of Arizona in Tucson. The next three days featured a series of meetings in Phoenix and a great exposition of solar apparatus on the lawn north of the Phoenix Public Library, where the Fine Arts Museum stands today.

Of greatest permanent importance in that exposition were the Bell Laboratories' silicon solar cell, which now powers all of our satellites, and the Tabor solar water heater from Israel, which demonstrated for the first time the selective surface which traps the sun's shortwave radiation but permits very little longwave heat radiation to escape.

Doctor Aden Meinel proposes this 1,000 foot long solar concentrator to power a conventional 200 H.P. irrigation pump. - DON COWEN