SOLAR ENERGY. Because the amount of solar radiation received by Texas is considerably above the average received by the United States, the use of its energy has been a matter of interest for centuries within the state and the Southwest. Unfortunately, although the availability of this energy is unquestionable, its utilization has been quite low because the state's energy policy has been based on the apparent cost of solar energy; policy makers have not yet reckoned with the time when fossil fuels will become scarce. By far the best known applications of solar energy technology are those using passive techniques for residential purposes. The large public and private buildings of nineteenth-century Texas are good examples of passive applications; they have thick walls, high ceilings, floor-to-ceiling windows, southern frontage, few north-facing windows, screened porches and verandahs that shade the house in summer, and cross ventilation. Twentieth-century updating adds ceiling fans and double-paned windows to provide houses, which, throughout most of Texas, would not require supplementary heating or cooling for eight or nine months out of the year.
Although water and homes were successfully heated by controlled use of solar energy as early as May 1882, active solar heating of houses in the United States and in Texas is largely a development of the twentieth century. Details of the development of active solar heating in Texas are sketchy, but solar houses that used glass-enclosed porches to capture the winter sun's heat and flat plate collectors for water-heating purposes were relatively familiar in Texas during the 1920s and 1930s, before most houses had natural gas. Solar energy can also be utilized for agricultural grain drying purposes and is economically viable for small and large installations provided that the equipment used for small-scale drying is available for direct connection to the farmstead's residential heat supply during periods of nonagricultural use. The suitability of solar heat for this purpose has been demonstrated in the drying of rice and evaluated positively in several studies.
Because of the heat and humidity in Texas, however, what the state needs is a way to cool houses using a source of heat. Solar cooling is feasible but much more complicated than solar heating because it requires an indirect procedure to extract heat through the use of heat. The first installation of large-scale heating and cooling through the use of solar energy was at Trinity University, San Antonio, in 1977, although in 1976 an experimental residence had been built by the University of Texas at Arlington, and College House, a small cooperative residential dormitory in Austin, had installed solar heating and cooling in the same year. These uses of solar energy are based on the supply of relatively low-temperature heat, not much hotter than 300° F. For industrial purposes much higher temperatures are needed, and they can be produced only by the use of concentrating solar collectors. Texas Tech University, in cooperation with the city of Crosbyton, developed a sixty-five-foot diameter bowl-shaped reflector with a linear power receiver in order to produce the high temperature (1000° F) needed to run an electricity-generating turbine, which provides power to the city as a replacement for diesel-fueled generators. It is the first moderate-scale solar-electric power plant in the United States. The device is relatively inexpensive to construct and maintain. A modification of the dish is being used at the Johnson and Johnson plant in Sherman. Recent studies have shown it to be operational during 97 percent of available sunshine and to have an average thermal efficiency of 20 percent, lower than expected but significantly economical nonetheless.
Wind energy is not commonly thought of as solar energy, but because it is the result of the differential heating of the earth's surface by the sun it too must be considered a solar resource. Windmills, a striking and prominent characteristic of the Texas High Plains landscape, have been a feature of Texas since the middle of the nineteenth century, as the historical collection at Texas Tech University in Lubbock demonstrates. These devices were used as a convenient source of power to pump water and, through the use of gearing and power takeoffs, to run small sawmills and farm machinery. After the invention of the electric generator wind chargers brought electric power to the countryside. This use died out as a result of rural electrification efforts in the late 1930s. Although windmills are being used in experimentation for a variety of purposes, the present primary use of these devices is to pump water for stock and irrigation, as in the nineteenth century. There is considerable potential for the development of large-scale electricity generation from "wind farms," which are expected to grow rapidly.
Photovoltaic power in significant quantities first became possible with the discovery of the silicon cell in 1954 and its development for use in space vehicles. A twenty-kilowatt photovoltaic power system for El Paso was designed in 1979–80 in conjunction with a combined use of standard silicon cells and cadmium-sprayed glass photocells developed by Photon Power of El Paso. Other uses of photovoltaics are commonly encountered as power sources for Park Service radio-telephones in Guadalupe Mountains National Park and Big Bend National Park, as well as for railroad block control power by the Missouri Pacific and the Santa Fe systems. Such sources of power are common enough as electricity supply to electric fences. Nonetheless, there was only slight use of photovoltaics for large-scale power generation in 1985, due in large part to the cost, poor economy, and the elimination of solar tax credits. The city of Austin, in the late 1980s and early 1990s, began to experiment with two methods of solar power using photovoltaics: the broad-scale, centralized system of large plants, and the dispersed method, which provides solar power to individual houses or buildings. The city built the Decker solar power plant in 1986 at a cost of $3 million, the first of its type in Texas. Its primary function was as a demonstration plant, but it does produce energy. On a sunny day it can generate about 300 kilowatts of electricity, enough for 50 to 100 homes. Austin, along with 3M Corporation, Entech Incorporated of Dallas, the state of Texas, and the United States Department of Energy, built another plant in northwest Austin in 1990. This plant also cost $3 million and can generate 300 kilowatts of electricity; it is used to power lights at the 3M garage, and some flows into the city's utility grid. Although still in the experimental stages the two solar plants produce less than one-half of one percent of Austin's electricity needs. The dispersed method met with slightly more success. Photovoltaic systems were installed in the Austin Youth Hostel in 1990 for $26,000 and in ECHO Village, a housing project for the elderly, in 1991 for $30,000. The Hostel saves an estimated $700 to $1,000 per year in electricity costs. Although both projects had problems with their inverters, which change direct current (DC) to alternating current (AC), and were not as successful as first hoped, the small-scale dispersed system appeared to be more feasible than solar power plants in terms of cost and efficiency. The future of solar power depends on the ability to bring the cost down. Once this is accomplished, however, many believe it will be one of the biggest growth industries in the twenty-first century.
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The following, adapted from the Chicago Manual of Style, 15th edition, is the preferred citation for this article.Handbook of Texas Online, John G. Bordie, "Solar Energy," accessed February 21, 2017, http://www.tshaonline.org/handbook/online/articles/dos09.
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