Evening Star Newspaper, July 12, 1931, Page 77

THE SUNDAY STAR, WASHINGTON, D. C, JULY 12, 1931 | —ccmeem— _ 13 | T e Harnessing the Sun 1n a Sandwich, = Only One Two-Billionth Part of the Sun’s Great Energy Beucfits the Earth Today, but This New Invention of a Young German Scientist Converts Direct Sunlight Into an Electric Current That May Be Developed toSupply the World’s LPower. BY D. LINDSAY WATSON. HE sun, worshiped as a god by sav- ages, is well on the way to becoming the hidden servant of civilized man. Thanks to the efforts of several American and German inventors, the most successful of whom is Dr. Bruno Lange of the Kaiser Wilhelm Institute of Berlin, mankind may be able to achieve the age-old dream of harnessing sunpower di- rectly and making it turn the wheels of indus- try even before the arrival of that great and final power famine, which economic prophets predict will follow the exhaustioly of the world's coal mines about 4,000 years hence. Dr. Lange's invention is still in its infancy; but it is a healthy and promising infant just the same. For a tiny sun-catcher which he made, with a surface only about three inches square, has for several months now been keep- ing a small motor turning round and round— and at that it has had no better juice to feed on than Berlin’s somewhat thin .and watery sunchine. Wwhat a bigger apparatus could do in the full-bodied light of the Mohave Desert of Cali- fornia must for the present be left to specu- Jation. But, at least, Dr. Lange has already brecught the infant measurably toward ma- turity. Talking pictures, television and automatic control devices for machinery will certainly use the new light-sensitive cell even before it can be adapted to large-scale power production. The light-sensitive vacuum tubes containing potassium or caesium, which have played suca a fundamental part in recent engineering de- velopments, will probably be replaced in most of their uses by the cheaper and simpler Lange device. Here are some of the other uses on which expcrimentation is being carried on: Control of steel rolling mills, transmission of phono- graph records, fire prevention on ocean-going steamships, telephonic fog-signalling and as a direction finder for aircraft. In scientific work it will find application in light-measuring fnstruments; for instance, in the determination of photographic exposures. Y a curious bit of poetic appropriateness, the key stuff in Dr. Lange’s sun-catching device is a chemical element dedicated to the moon, that classic, age-old mirror of the sun. It is the somewhat uncommon element selenium, which got its name from the Greek goddess Selene. - e P i Selenide of silver now best holds the secret of catching the sun's light and turning it into electric power. By another coincidence, silver is also connected with the moon. The al- chemists talked of silver as the moon element; “Junar caustic” is another name for nitrate of silver. The selenide of silver is spread on a sheet of metal in a very thin layer and then a second layer of metal only, a few atoms thick, is spread on this. Light falling on this device from above sets up an electric current between the two layers ¢! the metallic “sandwich.” It is not much of a current—Iless than what would be needed to light a flashlight bulb— yet this is the most promising way now known for getting electric current directly from sun- light. Actually the selenide cell is about a hundred times better than the cell that im- mediately preceded it. This predecessor cell A toy that became the ancestor of today’s giant power generators. Franklin’s famous ex- periment with a kite identified lightning with electricity and a toy be- came a great invention. Prof. Lcnge's “electric® sandwich” toy of today ‘may eventually become another highly valuable invention. consisted of a plate of copper on which aie placed successively a layer of cuprous oxide and a thin layer of copper. The copper oxide sandwich was first in- vented in this country by Dr. L. O. Grondahl and Paul H. Geiger and patented by the Westinghouse company. Lange's invention is patented in the name of the Siemens Halske Co. of Berlin. The Grondahl cell is much Jess efficient than the Lange cell, chiefly be- cause of the way in which the upper electrode is attached. Ten to 20 square yards of the copper oxide sandwich produce 50 watts of electricity in full sunlight, and thus could run an ordinary electric lamp. What prospect is there of such a device being cheap enough and practicable enough to be used on a large scale as a source of power? An old wood cut showing Otto von Guericke's electrical machine of 1740, a rotating sulphur ball in which electricity was pr against the globe. oduced by iriction of the hands held Dr. Bruno Lange of the Kaiser Wilhelm Institute, Berlin, inventor of the sele- nide plate that draws power from the sun. Dr. Lange himself sums up this interesting possibility as follows: IITHE application of these cells to the produc= tion of energy seems to bz possible, but, of course, this is a task that can be accom- plished only step by step. “Apgregates of a large number of cells of this kind connected with each other seem to o the direction of the next development. There are still many difficulties of manufacture and circuiting to be overcome. Even if these prcbi~ms are succescfully solved, the direct pro- duction of sun-generated power will be able to go into compctition with the methods of fuel burning or water power only in tropiced and subtropical climates, where a steady, strong radiation exists.” Some $25,000 per kilowatt is Dr. Lange’s esti- mate of the cost of installing the copper sand- wich on a large scale. A water-power plant can be profitably operated if the cost of in- stallation is $125 per kilowatt, while it is economic to put up a coal-steam generating plant at a capital cost of $75 to $90 per kilo- watt. This does not look very hopeful for sun- power, one must admit. In addition you have to remember that the cost of producing the power is only a fraction of the total cost of the power as delivered to the consumer. Stepping up the voltage so that the current can be economically transmitted, the erecticn and up- kecp of transmission lines, stepping-down trans- former stations and distribution networks to the ultimate consumer have all to be added to the cost of generation itself. In addition the relation of the peaks in the supply and demand curves has to be consid- ered. Col. William Kelly of the Buffalo, Niagara and Eastern Power Corporation has recently estimated that the overall cost of capi- tal construction to the distribution substations for the industrial consumer is $177 per kilowatt. For the domestic consumer it is $256. Forty- two dollars and $101 per customer has to be added to these figures before the current is ready for use. N the other hand, silver selenide s detem, clared to be about a hundred times more efficient than the cuprous oxide device. True, silver is more expensive than copper, but recent industrial history shows that when there is a sure field for a material of definite proper- ties he would be a rash man who would predict that a cheap enough substance would not be discovered or devised. Konel, the metal newly invented at the West- inghouse laboratories for making the filaments of radio tubes, is at least a hundred times cheaper than the platinum which it has re- placed throughout the entire radio industry. Platinum was considered irreplaceable before this invention. Despite tbese reservations, generator costs are of extrerme importance in the economics of the power industry, which is at the heart of modern civilization. The largest power coms= pany in America generates 7,000,000,000 kilo- watt hours per year, so that a saving of only & tenth of a cent per kilowatt hour would result in a saving of $7,000,000 to the company. Serious problems will be raised by the fact that the supply of sunpower will be intermit- tent throughout the day. Water power is open to a similar objection, though in this case the fluctuation is seasonal. Ne satisfactory means of storing power on a large scale has yet been devised, except perhaps by using a dam and the water level behind it, or a novel method just perfected in connection with the use of tidal power. If the storage problem is not solved in a satisfactory way the present riethod of linking up power supplies into large chains wilMflave to be still further extended. The demand for power is at its greatest dur- ing a great deal of the time when the sun is above the horizon. However, from 5 to 8 in the evening the amount of power being used is still near its maximum, and the sunlight would, of course, be greatly reduced at this time, par- ticularly in the Winter months. The sun is par excelience the power house of the world and of the solar system. The sun- light falling on the earth and at present largely wasted, so far as human purposes are confi provides some hundred shousand times gr energy in a yeAr than all the coal that is . burned in, she seme: time—some 1;500: sniltfon tons.