High performance in this case means an efficiency of only 6%, al though with further research the cells likely can be pushed closer to their theoretical maximum of 15%. Consumption ( 1 0 Btu) 1977 1978 On the other hand, the amorphous 36.94 38.66 Petroleum liquids material appears to be very stable. It Natural gas 19.81 19.81 is fabricated in a low-temperature Coal, including 15.82 16.09 process (glow discharge), it has a high optical absorption, which makes it anthracite 2.67 3.04 effective in extremely thin layers (a Nuclear electricity 2.70 2.86 few micrometers), and it can be made Hydroelectricity into cells of quite a large area (1-foot 77.94 80.46 TOTAL squares, compared to the 3-inch a Revised estimate. Source: Institute of Gas wafers of conventional crystalline Technology cells). In a word, says Carlson, amor phous silicon cells will be cheap. In the RCA process, a glow dis fuel, related products, and power index (1967 = 100) as published by charge chamber is filled with silane the Bureau of Labor Statistics, ad gas (SiH4) at low pressure. Dop justed to a 1972 = 100 basis and di ants—diborane (Β2Ηβ) for p-type and vided by the implicit price deflator for phosphine (PH3) for n-type—also can the gross national product for the be added at this stage. The discharge year 1972. For its current assessment, deposits a thin film of amorphous IGT used a preliminary value of 181.3 silicon, containing up to 20% hydro for 1977. Noting that many current gen, on a substrate of glass or metal. uncertainties made it difficult to as The hydrogen serves as a bond ter sess, IGT assumed a 7% increase to minator and thus minimizes the atomic defects. 194 for the index for 1978. At the GE Research & Develop Employment, IGT points out, is the most important factor in energy ment Center in Schenectady, N.Y., consumption. IGT figured the aver researchers have developed what age labor force for 1978 at 99.5 million appears to be a practical device for and chose a value of 7% for unem storing energy in substances with a IGT forecasts higher high latent heat of fusion. ployment. GE's efforts have focused mainly In focusing on energy supply, IGT energy use for 1978 notes that imports of crude oil, al on Glauber's salt (sodium sulfate U.S. energy consumption in 1978 though increasing for some time, are decahydrate), a material that can will reach 80.46 quadrillion Btu not expected to rise substantially in store more than seven times the en (quads), a 3.2% increase over the 77.94 1978. It estimates total imports of ergy of an equal volume of water. It quads estimated for 1977, which was petroleum liquids for 1977 at 3205 also is cheap (1.5 cents per lb in bulk), itself a 4.9% increase over 1976 con million bbl. Subtracting exports of 80 and has a convenient melting tem sumption. These figures are the bot million bbl, this amounts to a net of perature of 90.3° F (32.2° C). In the past, however, use of this salt tom line in what has become an an 3125 million bbl. IGT anticipates the nual energy supply and consumption 1978 import level at 3260 million bbl for heat storage has been hampered forecast by the Institute of Gas (3180 million bbl net)—only a little by a tendency for crystals to build up Technology using an IGT economet less favorable, it says, thanks to on container walls, impeding heat Alaska North Slope production. D transfer, and by an encapsulation ef ric model. fect that prevents complete solidifi In preparing its 1978 forecast, IGT cation of the material after five to 10 also has revised its 1977 forecast on freeze-thaw cycles. the basis of published estimates for New solar cell, way to In the GE rolling cylinder device, the first several months of 1977. Its however, Glauber's salt is contained prediction of 78.65 quads for 1977, store heat developed in a horizontal tank that turns at made a year ago, has been revised Two new developments have been three revolutions per minute. This downward to 77.94 quads. IGT points out that the difference made in solar energy research. RCA action provides just enough stirring to in the original and revised 1977 pre has found a cheaper way to collect keep the temperature of the salt uni dictions is due largely to unpredict solar energy, and General Electric has form and to prevent wall crystalliza tion and encapsulation. able circumstances. Drought kept the found a better way to store it. The GE team is now planning a value of hydroelectricity below that A U.S. patent (4,064,521) on the forecast, for example. And wildcat RCA solar cells, made from hydroge- 30-month scaleup effort, with partial coal mine strikes during the past nated amorphous silicon, was granted sponsorship by the Department of summer hindered coal production, last month to Dr. David E. Carlson, Energy. According to the GE re while, at the same time, there was head of photovoltaic development in searchers, one possible commercial considerable substitution of coal and the RCA Energy Systems Research system would be a tank 22-feet long foreign oil for natural gas in electric Laboratory, Princeton, N.J. Dr. by 2 feet wide, holding 800 gal of power consumption. Brown Williams, director of that Glauber's salt and storing 1 million IGT's econometric model uses laboratory, says that Carlson's silicon Btu of thermal energy. Such a system employment, population, and a de is "the only amorphous material we could heat an average older home flated fuel and power price index as know of that has been used success (one requiring 15,000 Btu per degree the explanatory variables. The price fully to make high-performance solar day) for 24 hours when the outside temperature was 0° F. D index used by IGT is the wholesale cells." tered in startup and design of chem ical plants arise from lack of under standing of how particles of this size will behave, he explains. The institute also will sponsor research in other areas of mechanical processing such as surface chemical engineering, liq uid-solids separation, and rheology. Turner is chairman of the orga nizing committee of the new institute and the only industrial representative lined up so far. Other committee members include Dr. Robert Pfeffer of City College of New York, Dr. Frank M. Tiller of the University of Hous ton, Dr. Brian Scarlett of the Uni versity of Loughborough, England, and Dr. Kurt Leschonski of the Technical University of Clausthal, West Germany. Research proposals from these and other universities are being screened by the committee. In June, when the committee will have a better idea of the research that can be supported immediately, it will begin soliciting industrial members. Turner says he would like to attract 10 to 20 com panies as members each contributing $10,000 to $15,000 per year to support this research. G
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C&ENJan. 2, 1978
Use of petroleum for energy far surpasses other sources 15
a
