S c i e n c e has reached its full majority working apart in mysterious laborain the minds of all men. In the broad tories, a n d occasionally running forth domain of human endeavor, butcher, baker, a n d candlestick maker now view science as a vital and necessary element of daily life. As a landmark in human history, the foundation for full public awareness of science was laid down with the control of nuclear energy. T h e capstone of recognition and acceptance was cemented on October 4, 1957, with the literal appearance of Sputnik I. This man-made moon stirred the final, deep thoughts a n entire society must feel before something new becomes significant in a culture. Sputnik I stirred these thoughts, a n d men began looking at the works of science with a new perspective. T h e y saw the biochemical science behind the reduction of beef prices with tranquilizers given in the feed lots a n d railroad yards. T h e y saw the scientist in the Salk vaccine victory over polio. T h e y saw the interplay of nuclear a n d missile technology in the Nautilus undersea crossing of the Narth Pole, utilizing advanced navigation gear from a guided missile system. This very year has been pivotal for sheer technical drama and for its profound impact on the minds of men. T h e public is calling upon science with greater and greater directness to serve the material a n d social needs of our society. We are beyond the time w h e n the average citizen thinks of scientists as akin to bright children,
with a shiny new creation that comforts-r frightens. T h e relationship is now basically different. And this new mature partnership of science and society promises much and demands much for the years ahead. Science and scientists are ready to bear these larger responsibilities. T h e wide field of p u r e and applied science is now linked together so well that we can utilize the whole fabric of technical knowledge to gain a material objective, We have demonstrated this truth in the recent development of highly complex technologies that draw upon virtually every field of modern science. Their significance is even more pointed when we recall that these systems were not accidents, b u t were deliberately constructed on existing knowledge. T h e Golden Anniversary Lectures that follow were commissioned to mark a n occasion significant in the history of the American Chemical Society. T h e authors of these articles are informed experts: Their immediate purpose is to suggest new technical developments that can be achieved within the next 10 years with basic knowledge now in hand. Their broader goal is to document the great creative power of modern science and technology, and to encourage its utilization for the higher purposes of mankind-an endeavor in which every reader of these pages can contribute. DeWitt 0.Myatt
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Energy Sources Prologue to Engineering Advances
WITHOUT
abundant energy, modern engineering is unthinkable and advances in engineering are impossible. Only 20 years ago we had an extraordinary breakthrough in atomic energy, using uranium fission. We look forward to an enormous new source of energy in the fusion of hydrogen nuclei a t temperatures of the sun. We are still trying to solve the related problems of radioactivity and international control. Less spectacularly we also are trying to find ways to use the sun’s radiation. Solar energy is abundant, ample for our needs, gentle, and harmless, but diffuse and intermittent.
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I t deserves far more research effort than it has received. We can hardly expect to get energy more cheaply than we do now at a few tenths of a cent per kilowatt-hour from electricity and a few cents per million B.t.u. from coal, petroleum, and natural gas. Cheap electricity and fuel have done much to give the United States its industry and wealth. But there is an ever-increasing demand for more fuel and power in the United States and a rapidly growing demand in the countries that have not yet become industrialized. Not only our supplies, but world supplies, will diminish. Shale oil and lignite will be exploited. The chemist will convert solid coal into gas and liquid fuel,
but the price of fuel will increase and in the distant future become prohibitive. What are we doing now to prepare for fuel substitutes? Only with the assurance of an abundant supply of energy can we expect to have engineering advances in the future. We can have this assurance through the new materials, and the bold research which is familiar to chemists and chemical engineers. New Fuels
One would think that gasoline furnishes as much energy in a small volume as could be needed. But it is not enough for requirements of outer space. All our past fuels have involved the oxidation of carbon- and hydrogen-containing substances, but now chemical reactions are needed which have larger heats of reaction per mole and smaller molecular weights, so that the heat per gram and the number of gaseous molecules produced per gram are both large. \.$’e turn to elements like hydrogen, lithium, boron, and fluorine. Particularly the boron hydrides are under intensive study. I n what other ways can we get fuels with greater energy? Theoretically, we can use fuels that already contain additional sources of energy. For example, hydrogen atoms burnt in air would give off heat corresponding to the heat of combustion of molecular hydrogen, 34,000 calories per gram, plus the heat or recombination of hydrogen atoms, 50,000 calories per gram. This gives a total of 84,000 calories per gram, which is more than ten times the heat of combustion of carbon per gram. Again, free radicals, such as CI-13, would give much more heat than methane when oxidized. Gaseous ions, too: will add their heat of ionization to any chemical reactions in which they take part. But tve don’t know how to stabilize and package in a small volume hydrogen atoms, free radicals, or ionized gases. This is a n important field for basic research. ‘There is a possibility of increasing the heat of reaction of solids by subjecting crystals to high energy, such as radioactivity, which displaces atoms within the lattice. We have measured the stored energy in certain “metamict” crystals, which have high uranium and thorium contents and complex lattice structures. They are so old geologically that the accumulated effects of alpha-particles have completely destroyed the crystal lattice. They show no x-ray diffraction pattern, but when heated, the atoms go back into place with evolution of heat and restoration of the x-ray diffraction pattern. When some of these crystals are heated or react chemically, they evolve over 100 cal. per gram. This is still too small to be
interesting in comparison with TNT, which evolves 1000 cal. per gram. When, graphite is submitted to intensive neutron exposure in a nuclear reactor, some of its atoms are displaced and it is possible to store u p several hundred calories per gram. If sGch carbon is mixed with a solid oxidizing agent, as in gunpowder or other propellant, the graphite will give its normal heat of oxidation, plus the several hundred calories per gram which has been stored in the distorted crystal lattice. These are possible ways toward advances in superfuels,, but practical applications are difficult.
materials, which the chemist is able and eager to supply. Like fossil fuels, the supply of uranium and thorium is finite. But the reserves in terms of available energy are great. Thermonuclear power from the fusion of hydrogen nuclei is, of course, the greatest challenge in the power field. The supply of hydrogen in sea water is practically unlimited and disposal of the radioactive wastes is easier than for the fission of uranium and thorium. But the requirements for producing a tewperature above that of the sun and for providing suitable containing vessels are indeed formidable.
Atomic Power
Solar Energy
Atomic power will be a vital factor in the future. T h e bottlenecks in economic atomic power are chemical in natureelimination of corrosion, reprocessing of the partially spent atomic fuel, and practical storage and use of the radioactive waste fission products. Most of the developments to date in nuclear power reactors have used metals, cooled with water. This is standard engineering practice. I t is likely that more radical types of nuclear reactors will be more economical. Operation a t high temperatures above the melting points of metals is possible through the use of graphite and other ceramic materials. Such reactors eliminate the corrosion problem due to water, they increase the efficiency of heat transfer and cooling because of their higher temperature difference and reduce the pumping costs, they are safer because there is nothing to melt, and there is no possibility of an explosion such as may occur when water changes rapidly into steam. The cost of chemical processing is greatly reduced because there is no large excess of enclosing metals to be dissolved in the nitric acid. Some radioactive fission products will escape slowly into the gas-cooling system, but they can be removed constantly, as they are formed, by passing part of the gas continuously through a purifier. These ideas were proposed in Chicago in 1944 and reports on a complete engineering study a t Oak Ridge are now declassified. An unclassified proposal along these lines was published in 1956. These early attempts to build a gascooled high temperature nuclear reactor were auddenly canceled, and we lost the chance to have the first peacetime atomic power plant, which might have been operating in 1948 or 1949. This high temperature ceramic reactor is now under renewed study and designs are on the drawing boards. These developments are cited to stress a point-engineers have been so tied to their experience with metals and water that they have been slow to branch off into imaginative ventures with new
Solar energy will be important within the next 10 years in certain areas, particularly in sunny sparsely populated countries. Unlike atomic energy, it can be used in small, inexpensive units and research can be carried out safely and cheaply by scientists and engineers who have not had highly specialized training in nuclear fields. The difficulty with solar energy is its low intensity, it requires large collecting areas. Its first fields of application are in solar water heating, cooking, house heating, refrigeration, house cooling, operation of heat engines, and distillation of sea water. T h e new things are that the chemist has developed new materials, including weatherable plastics which will withstand long exposures to the sun. Plastics can be made so thin and strong that they can cover large areas cheaply. I n the United States, solar air conditioning is an attractive possibility. Apparently, satisfactory cooling should be obtained for a given room if a solar collector of a n equal area is used. A system of absorption-desorption of a gas in a Liquid or the adsorption-desorption of vapor by a solid adsorbing agent .is possible. The heat of the desorption may be produced either intermittently or continuously. I know of no solar aircooled rooms a t present, but I will be disappointed if we don’t have a t least one operating by next summer. Air conditioning and refrigeration can be carried out in nonindustrialized areas where electricity and fuels are not available and where our present mechanical type of refrigeration is not possible, and they can be used in the United States to reduce the peak loads on public utility power plants in hot weather. Before solar power can be widely used in small units, it is necessary to develop both a very cheap solar collector and a more efficient steam engine, or a device which converts heat directly into electricity. No large engineering project is yet in sight for producing solar power, but it is technologically possible. A square mile of bright sunshine operating through
heat engines or other devices, which convert 10% of the heat into work, could theoretically produce 190,000 kw. of electricity (150 sq. feet at 10% conversion gives about 1 kw.). There are countless square miles of cheap land with effective sunshine which could be used for such a purpose. Even though the fuel is “free,” the capital investment will be much higher than that of a conventional fueldriven power plant, particularly if the plans include operation at night. Bold new ideas and much research are needed here. Thermoelectric converters of semiconductors with junctions heated by focused solar radiation appear very promising. Ten per cent conversion of sunlight directly into electricity is already possible, using a silicon photovoltaic cell (Bell solar battery) in which no materials are used up. But these cells, which are now made with single crystals of highly purified silicon, are much too expensive. Experiments are under way to determine ho.w much can be gained by concentrating a large area of sunlight with plastic focusing mirrors onto a water-cooled photoelectric cell. The photochemical use of sunlight is a possibility. A committee of the National Research Council is attempting to encourage research in this area, and the report of a symposium will soon be published. We cannot leave solar energy without pointing out the advances which it makes possible in reaching very high temperatures, over 3000’ C., by large and perfect focusing mirrors. Several are now in use and larger ones are being constructed in the United States, chiefly for research tools. Professor Trombe held a world symposium on solar furnaces this summer a t his laboratory in France. H e plans to build a 100-foot reflector which can be used for the semiproduction of highly refractory materials. There are unique features about a solar furnace, including extremely high temperatures, freedom from contaminating materials, and very quick heating and cooling. Conservation of Fossil Fuels
For the sake of future generations we should conserve our reserves of gas, petroleum, and coal. Even before they become scarce, there are other impelling reasons why we should be actively searching for new sources of energy. Atomic and solar energy can give heat and power, but they cannot provide great quantities of cheap organic materials. Our carbon-containing fuels are worth more as a source of petrochemicals than as fuelsand some day we will not have enough for both uses. Another way to conserve our fuel is to operate our engines more efficiently at higher temperatures. Chemists and chemical engineers will try to provide VOL. 51, NO. 1
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JANUARY 1959
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suitable materials and it is likely that high-temperature gas turbines will come into general use. I n connection with the use of heat in chemical operations, the effectiveness of pebble beds for inexpensive heat exchangers should be emphasized. The tortuous path of a gas through a bed of pebbles, perhaps a n inch in diameter. provides extremely efficient heat transfer and quick chilling. This type of heat exchanger could well find much wider acceptance in cbemical engineering. An operating plant was built at Lawrence. Kan., which actually produced 40 tons of nitric acid per day, by heating air with natural gas to 2100”C. and chilling it a t the rate f more than 20,000” per second. With two beds of magnesium oxide spheres, it is possible to preheat the air in one bed, and then conserve the heat in a second pebble bed, so that the waste gas going to the chimney is no higher than 200’ C. Storage
of Energy
Fuel has been so cheap that there has been no incentive to store low-temperature heat. As fuel becomes more expensive and as the intermittent solar energy comes into general use it will be important to devise economical ways of storing heat. Heat and cold can be stored physically in systems with high heat capacity, such as highly insulated water tanks, or pebble beds. The storage capacity of this type is not large. Better results are obtained with systems which undergo a change of phase, such as the melting of ice o r the transition of hydrated crystals of sodium sulfate. Still more heat can be stored per gram, or per dollar, in twocompartment systems which make use of distillation or chemical reactions. For example, water can be vaporized in a sealed vessel from one compartment into another which contains sulfuric acid. Another example is the distillation of ammonia in a closed system between two compartments which contain a nonvolatile solute a t different concentrations. But what is really needed is a chemzcal reaction involving many hundreds of calories per gram, which is easily and fully reversible over the temperature range desired-endothermic in one direction, and exothermic in the other. I n competition with present fuel, it must be realized that the combustion of coal gives 8000 calories per gram and wood gives 4000. But these are irreversible and can be used but once. The engineer of the future will have to be content with energy contents per gram much less than this when he uses a “heat storage” chemical fuel, but he can use this less efficient chemical fuel over and over again indefinitely. After the chemicals are separated, they d o not lose their stored energy as does a water tank or
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other hot system and they can store the potential heat indefinitely. International Aspects
Advances in engineering have immediate implications in international relations. The need for a n uninterrupted supply of petroleum, for instance, is still a cause of political tensions. .4nother cause of international tensions is the unequal standards of living in different parts of the world. The nonindustrialized nations can improve their economic and social conditions through more abundant supplies of energy and these can be supplied through atomic energy and solar energy, particularly in countries far removed from coal and oil supplies. T h e new weightless fuel substitutes, atomic and solar energy, can help to overcome some of the handicaps of geography. LVith the help of a grant from the Rockefeller Foundation, our solar energy laboratory has been trying to develop inexpensive solar cookers made of plastics for use in sunny nonindustrialized regions where fuel is expensive. There are three tests to be made in a n introduction of such a n innovation, as the solar cooker-Is it technologically possible? Is it economically profitable? Is it sociologically acceptable? We are finding that the third test is perhaps the most difficult. We are adding an anthropologist to our staff to help us understand the habits of an established civilization. I n thinking of the world-wide impact of new sources of energy and the engineering and economic advances that go with them, we will do well to realize that our national economy and planning are concerned with 170,000,000 people, but that there are 2.5 billion people in the world. When many of these peoples develop beyond the subsistence level, the world’s limited reserves of fossil fuels will be used u p much more rapidly and the world-wide market for manufactured goods will be increased enormously. Future Advances
O u r research efforts are continuously reducing the cost of manufactured goods, but there is still a large cost itemnamely, the transportation costs to every part of the United States and the world. Either the goods have to be transported to the consumer, or the coal and oil have to be taken to the place of manufacture. These transportation costs may set a minimum below which further economies are not possible. Atomic and solar energy have the great advantage of not being subject to transportation handicaps. The universities are primarily involved in basic resexch without emphasis on practical applications. Only a few of the largest companies can invest heavily
in the long-range research which does not involve practical applications. There is a gap here which has to be filled by the Government. Fortunately, the Government of the United States has accepted this responsibility. We rely on all three, the universities and research institutions and government laboratories, for basic, long-range projects which involve defense. public health, and the economic welfare of future generations. it’e will not go forward fast enough if we are tied to the economic present and have to wait for the technological ceilings to rise naturally. Diesel engines were introduced as locomotives after they had been produced for the navy without the handicap of economic justification, and atomic energy is now available to the world because of vast government spending on an emergency basis. Electric batteries for special purposes and exotic fuels for rockets have been made possible through government research contracts. These fields would not be developed anywhere near to their present level if we had waited for the normal spontaneous rrsearch programs of universities and industry, without government encouragement and support. The chemical industries are among the most vigorous and successful of all our manufacturing enterprises. There are several reasons for these outstanding achievements. Among them are bold, pioneering vision and strong reliance on research. Chemical industry accepts obsolescence and does not hesitate to scrap old methods when better ones are devised. The research emphasis in chemical industries is very high. This is partly because the executives and the men a t the decision-making level are largely drawn from the technical, professional men of the organization, many of whom have grown u p through the companies’ research laboratories. Another important item in the success of chemical industries is the close cooperation between industry and the universities. The industries support fellowships in the universities and occasionally employ academic personnel as consultants. T h e representatives of industry attend scientific meetings and read the chemical literature, both basic and applied. They are quick to translate the abstract findings of the academic laboratories into practical reality. In this close and effective partnership, the American Chemical Society exerts a strong influence. Both in the centralized national meetings and in the publication of its journals, the ACS plays a n important part in bringing these groups closer together for their mutual benefit and for the public welfare.
FARRINGTON DANIELS Department of Chemistry, University of Wisconsin, Madison, Wis.
