2 Prime Movers and Prime Metals
3.1Phase 2. Review and analysis of world energy resources–differentiation between ’income’ and ’capital’ energies–design of more efficient energy utilization. Analysis of circulation and scrap recycling of prime metals. Redesign towards comprehensive and more efficient use and reuse ’assemblies’ with higher extraction of performance per unit of all invested prime metals in use. (R. B. Fuller, 1964)
3.2 Man is, of course, a ’prime mover’–like all living systems–and functions basically as an energy converting organism. Energy is absorbed in one form or another, e.g., food, and transformed for internal and external purposes. Part goes towards maintaining the internal processes of the organism, and part is available for external use, e.g., to find more food. In terms of external mechanical work energies, man is, however, a relatively inefficient energy converter. Operating at less than 20 per cent efficiency, he can only deliver about one horsepower hour of work per day.30
3.3 His own mechanical energy conversion capacity has been, possibly, the least important factor in his progress. Man’s unique evolutionary pattern has been predicated rather as his ability to convert energies externally.
3.4 Through his intellectual capacity, he has designed and employed tools which enable him to do this on a much greater scale than may be accomplished solely by his own unaided metabolism. This gain in energy output through the use of technical advantages has increased enormously in the past hundred years, as the conceptual tools provided by the scientific revolution were phased into new technological tools giving higher degrees of energy conversion than were possible for man before. Though many millions of men still function in the lesser developed countries as ’mechanical’ energy converters as their own prime source of survival energy, man increasingly functions namely as controller and designer of high energy conversion systems.
3.5 It is the type and quantity of energy conversion which sharply distinguishes the highly developed countries from the less advanced. About 80 per cent of the high grade machine energies available are presently preoccupied in maintaining the industrially advanced countries. The lesser developed countries still depend largely for the major part of their work energy on low grade energy converts–animal and human energies converting various agricultural yields through craft tools of various types.
3.6 All energy derives from three main sources–one, the radiant energy from the sun; two, the kinetic and potential energy of the earth from the gravitational system; three, energy conducted from the interior of the earth, geothermal energy. All other energy sources are subcycles of these prime sources, and may be divided into ’income’ energies and ’capital’ energies.
3.7 30 Cottrell, Fred, Energy and Society, McGraw-Hill Book Co., Inc., N.Y., c1955. Man can convert about 3,500 calories per day. About 20 per cent of this is available for mechanical work–roughly one half to one horsepower hour per day per man.
3.8 Income energies are those which we may use by converting naturally recurring energies by ’tapping in’ to regenerative cycles. Examples of these would be:- one, water power–deriving from the gravitational relation of the earth, sun and moon system–we have the ocean tides and currents; related to this and to the hydrological cycle, there are the rivers as flowing and lakes as impounded income energy sources. Both of these enormous sources are still hardly used. Two, solar energy directly impinging upon the earth–we are just beginning to design means of more efficient conversion of this source for specific purposes; three, wind energy from atmospheric circulation related to earth spin, etc., has long been in use for ’sail’ power in ships’, through windmills for direct mechanical work and in wind-powered electrical generators; four, geothermal energies–available from hot springs and volcanoes, are, to an extent, income energies, though theoretically they could be used up in time. Little use has been made so far of such sources.
3.9 Capital energies are those which may be depleted through use as they are derived mainly from the ’fossil’ fuels–coal, oil and natural gas. They are all deposits of solar energy converted by organisms during a 500 million year period of geological time and buried in the earth’s crust. Since the onset of the industrial revolution, these energy sources are those which have been, and still are, used most prodigally. Wood is used as a prime energy source, through burning as fuel, in many parts of the world. This is by far the least efficient way of using the stored photosynthetic energy which it represents, particularly in relation to the relatively slow growth cycle through which it may be restored. As it is grown, and therefore, ’regeneratively cycles’, one could consider it to be an ’income’ source, but its present usage tends to be capital as forests used up are not replaced at the same rate. Nuclear energy, the most recent source becoming available to man, results from two processes - one, the fission of heavy element isotopes in the atomic scale, and two, the fusion of lighter elements. Based mainly on uranium ores in the earth, at present, this could be regarded as a ’capital’ energy, but in terms of isotope sources available, and the extension of the process to a wider range of elements, suggest that, in anything but the longest term, this may be referred as an ’income’ energy process. It does have, however, at the present time, certain demerits of waste product disposal problems.
3.10 If these problems can be dealt with, this may prove to be an extraordinary energy source. Large scale production of power from uranium isotope fission has already been accomplished, and as one ton of rock containing appropriate fission material is equivalent in energy to 150 tons of coal (or 650 barrels of petroleum), this affords man an energy reserve hundreds of times greater than that of his fossil fuels.
3.11 As commented upon briefly, the present use of these various energy sources varies enormously. Our current uses tend to favor capital sources and, therefore occasion great concern over the possible depletion of these. Since most of these depletable sources are unequally distributed around the world, access to them, and their control by one nation or another, tends to be the mainspring of many of major international tensions; however, these may be ultimately explained in other terms.
3.12 The role of energy consumption available per capita in differentiating between high and low standards of living has been touched on. A full analysis of the world energy population distribution in these terms will be found in Document One in this series. Eighty-eight per cent of the world’s energy is presently consumed by less than half of the world’s population. Of that eighty-eight per cent representing high grade industrial energy conversion, approximately forty-seven per cent is solid fuels, thirty per cent liquid fuels, fifteen per cent natural gas and about eight per cent only is hydro-electric power representing use of ’human’ energy. The location of ninety per cent of the proved and estimated fossil fuel sources are as follows:
3.13 49
3.14 1961 ENERGY SLAVES AND NATIONAL INCOME
3.15 Per Capita National Income (in U.S. Dollars)
3.16 Man/Energy Slaves (based upon Energy Consumption)
3.17 USA 2,308 192 CANADA 1,461 135 UNITED KINGDOM 1,148 117 AUSTRALIA 1,237 96 W. GERMANY 1,114 87 USSR 800 69 NETHERLANDS 868 65 FRANCE 1,035 60 JAPAN 402 31 ARGENTINA 413 28 BRAZIL 129 8 INDIA 67 3
3.18 Source: Energy and Economic Growth. Haig Babian. N.Y. University, 1964.
3.19 50
3.20 Coal - U.S.A. (35%); U.S.S.R. and China (50%); Europe (13%). The three continents of Africa, South America and Australia share the remaining 2%.
3.21 Oil - Middle East (60%); U.S.A. (13%); U.S.S.R. and China (11%); South America (8%) Africa (3%); Others (5%).
3.22 Natural Gas - North America, Middle East, U.S.S.R., North Africa and Netherlands.31
3.23 Estimates of natural gas reserves vary considerably, as do coal and oil reserve estimates over the years. We do not know, with any real certainty, how much we have of these reserves or how far we can rely upon them in the future.
3.24 In terms of rendering world resources adequate to the service of all men, it is interesting to speculate that if we were simply to extend our present rate of consumption of energy at the present level and efficiency, in the highly developed countries this would mean an approximate 40 per cent rise in our present consumption of fossil fuel reserves. The latest estimate of such reserve exhaustion at a four per cent annual rise is given at 120 years. By simple sharing we would possibly reach the end of such fuels in 12 years!
3.25 In view of the amount of atmospheric contamination and other types of pollution involved in the use of fossil fuels, authorities have suggested that serious consideration be given to a planned world shift to other energy sources. In the lay term sense, apart from the obvious depletion of irreplaceable fossil fuel reserves which could then be kept in emergency store, this seems the wiser comprehensive solution.
3.26 Our available ’continuous’ or income energy sources have much greater potential with much less hazard. They also have much greater flexibility in, for example, pro- ducing electrical power directly which may be easily transformed, specially transmitted over great distances and meets the largest number of varying power needs.
3.27 It has been calculated, for example, that if the world water power, were fully developed, the electrical energy produced per year would be equivalent to six times our electrical power production in 1959–to produce this amount of energy would require about ten times our present coal production.32 Realizing the full use of the world’s water power energies would redraw the world energy map to quite an extent, e.g., Africa has the largest power resources and South America the second largest of the continents. Solar energy, tidal and geothermal capacities are still relatively untouched.
3.28 Of course, the key to the use of resources are the tools to convert them to required purposes. Energy of the types reviewed was always available, but high conver- sion rate tooling has only recently become so. The development of technical efficiency in
3.29 31 Energy Resources: Publication 1000 D. National Academic Sciences, Wash., D.C. 1962. Fuel and Power in 1984: Sir H. Hartley FRS, New Scientist (Eng.), May, 1964. 32 Energy Resources: Publication 1000 D, New Academic Sciences, Wash., D.C., 1962.
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3.31 1950 POPULATION, INCOME, AND CONSUMED ENERGY
3.32 area | population in millions | income per capita | energy consumed per capita (kw-hrs.) —|—|—|— World | 2,497 | 223 | 1,676 Africa | 199 | 75 | 686 North and Central America | 219 | 1,100 | 10,074 South America | 112 | 170 | 741 Asia | 1,380 | 50 | 286 Europe | 393 | 380 | 3,117 U.S.S.R. | 181 | 310 | 1,873 Oceania | 13 | 560 | 3,543
3.33 Source: The Population Crisis and the Use of World Resources. Ed. by Stuart Mudd. (p. 109 Demographic Dimensions of World Politics, by P.M. Hauser) World Academy of Art and Science, 1964.
3.34 WORLD WATER POWER CAPACITY
3.35 Potential (10,000 Megawatts) | Development (1,000 Megawatts) —|— Percent of total Megawatts produced | Percent developed
3.36 Africa 780,000 27% 2,000 South America 577,000 20% 5,000 U.S.S.R. 466,000 16% 16,000 3% South East Asia 445,000 16% 2,000 North America 313,000 11% 59,000 19% West Europe 158,000 6% 47,000 30% Australia 45,000 2% 2,000 Far East 42,000 1% 19,000 Middle East 5,000 5%
3.37 Source: Conference on Energy Resources. Frances L. Adams. Committee on Natural Resources, National Academy of Science, N.Y. 1961.
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3.39 high energy converters belongs more properly in our Tool Evolution phase, but some mention may be pertinent here. Modern power begins with Watt’s modification of the Savery-Newcomen Steam Engine. This might well be studied as a prototype example of design invention of the type with which we are engaged. Finding the Newcomen again wasteful of fuel, Watt redesigned this so as to extract three times as much work from the same input! Still the Watt steam engine had a technical efficiency below five per cent. Parallel in development to the steam engine, but of later date, the steam turbines produced, for example, forth to fifty times as much energy per unit of coal as the Newcomen engine. Modern steam turbines are now around 40 per cent efficient. The present range of energy conversion efficiency available to us at present ’prime mover’ design levels, are roughly as follows:
3.40 Steam Locomotive 7% Automobile engine 10 - 15% Reciprocating aero engine 23% Turbo (at 40,000 feet) 24% Ram jet (at 1,300 mph) 21% Gas (general) 30% Diesel locomotive 35% Electrical Generating Steam Turbines 40% Fuel Cells (potential) 80% Hydro-electric turbines (water wheel) 90%
3.41 Apart from consideration of specific area efficiencies worked out on total machine plants’ processing world energy is presently used at a very low overall efficiency rate. At best only 20 per cent of the energy in the world’s full consumption is utilized! The recent World Power Conference, held in September, 1964, had as its main theme, "Ways of Redesigning to Combat this 80 per cent Loss of Energy."33
3.42 Such redesign for higher performance per unit of invested energy is mandatory if we are to attempt to raise world living standards and represents a key direction for the ’extension’ of even present resource use to all.
3.43 A prime example of higher energy performance towards greater service is discussed in Buckminster Fuller’s ’Geosocial Revolution’,34 the development of ultra-high voltage; UHV electrical transmission now render economically possible great intercontinental linkages from relatively isolated generating sources at vastly decreased auxiliary energy transport inputs. Africa and China could be the world’s main energy producing and transmitting sources within a not too distant period!
3.44 Apart from the large scale engineering of such high performance gains, our program should concern itself with the comprehensive review and correlation of the fuel of energy conversion discoveries which are being made available through rapidly advancing science and technologies in this area. At the present stage of knowledge accumulation and specialization barriers, such discoveries are often mislaid despite the efforts of governments, industries and other agencies to maximize their economic advantage. (Many so-called, unconventional energy sources and conversion capacities belong in this category.)
3.45 33 "The Times", London, Eng., Sept. 9, 1964.
3.46 34 Document Three (1965), "Comprehensive Thinking", R. B. Fuller.
3.47 53
3.48 PERFORMANCE PER ENERGY UNIT INVESTED
3.49 INDUSTRIAL KILOWATTS kw/man-hr.
3.50 WHEAT man-hrs./acre
3.51 LUMENS PER WATT lumens/watt
3.52 COTTON man-hrs./acre
3.53 BITUMINOUS COAL tons/man-hr.
3.54 HOGS man-hrs./CWT
3.55 COMBUSTION lbs. coal/kw-hr.
3.56 CATTLE man-hrs./CWT
3.57 U.S. FIGURES
3.58 Based on: Chart series of R.B. Fuller. Fortune Magazine, Feb, 1940.
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3.60 Among recent space technology developments, for example, was a fuel cell unit weighing one-fifth of an ounce and producing two watts of electricity. In developing fuel cells for the Gemini spacecraft, a similar energy unit was reported which weighed less than a man, yet replaced a ton of batteries and could produce drinking water as well. Fuel cell-driven surface vehicles have already been built.
3.61 Portable gas turbin generators with remarkable power to size ratio, developed initially for aircraft use, are now available and deliver comparable power for a diesel engine four times their size. With per capita garbage output averaging from 500 to 1,000 pounds per day in advanced countries, German engineers have evolved a ’clean fume’ incinerator which gives high power output as an auxilary power station. Experiments in bio-electricity using the organisms’ own potential to power artificial arms, legs, etc., are proving successful, and in the same area considerable work has also been done in ’microbial’ fuel cells in which micro-organisms generate electrical energy in their food processing.
3.62 Such examples might be extended for many pages. A program of development such as we are planning depends closely on comprehensive review of material of this nature, and the maintenance of ’efficiency-rated’ inventories of all high performance technologies appropriate to various environ control requirements. Students should keep trend charts of energy conversion efficiencies in various fields and cross relate such developments against average requirements and possible performance augmentation in other areas.
3.63 Considerable insight into overall energy efficiencies may be afforded by the analysis of those operable in ’house’ as a major environmental control. The industrial energy conversion components for heating, lighting, cooking, etc., presently incorporated in ’high standard’ dwellings are technologically far in advance of the enclosing ’shell’. The advance in housing standards has been achieved almost entirely through the introduction of such mechanical services and is reflected in the relative costs invested in shell and mechanics. In 1900 such costs were approximately 97 per cent for shell and 3 per cent for mechanics–today this is closer to 50 per cent each way. The dependence of ’house’ services on local input/output through power lines, piping, sewers, garbage service, etc., is one of the largest ’hidden’ costs of housing. Their piecemeal unrelated function also downgrades the overall performance of the system. The ’Universal Requirements’ schedule of R.B. Fullerş may be used as a guide here in such studies as:- one, overall systems analysis or energy flow sheet, of present conventional operation; two, redesign of the system towards maximal performance; three, redesign of individual components toward coupling of services into a fully linked integral system giving maximal performance for energy invested.
3.64 On larger scale environment control systems the same comments may be made. Little overall systems analysis has been accorded multiple dwelling units, and even less attention has been given to the operation of the whole ’services’ system at the larger community level. Thence to the overall input/output energy accounting for regional and larger systems.
3.65 35 Document Two (1964), "The Design Initiative".
3.66 55
3.67 Prime Metals
3.68 The use of energy and the development of high performance energy conversion is tied closely to the development of metallurgy and the availability of large supplies of the prime metals.
3.69 Iron and steel constitute about 95 per cent of the world’s metal production. The non-ferrous metals closely associated with steel production, i.e., through use in alloying to give special mechanical or physical properties, are vanadium, molybdenum, manganese, tungsten, chromium and cobalt.
3.70 Five other main metals, not directly dependent on steel technology are copper, lead, zinc, tin and aluminum. Among these, copper production and use is a sensitive barometer of technological and industrial change through its efficiency as an electrical conductor, its ductibility, alloying properties, etc.36
3.71 Such division, of course, tends to be somewhat arbitrary and related specifically to current uses and technologies which are in process of constant change. The so-called ’rare’ metals, for example, have come into increasing prominence and importance recently, both as extraction and isolation technics improve and as the demand for their particular characteristics emerges, i.e., in space technology. Many of the ’rare’ metals are included above, others are titanium, beryllium, mercury, antimony, tantalum, columbium, etc.
3.72 As with all major resources necessary to the maintenance of industrial civilization, the large metal ore reserves are distributed inequally around the earth. No one country is wholly self-sufficient in the full inventory of metals required to sustain advanced industrial processes. Document One (1963) is our series contained a charting of forty major metals and minerals production for most of the countries in the world. Noted relative to this was the present and past patterns of world tension associated with the control of seemingly backward and valueless areas which, on inspection, turn out to be key sources for various major metals or minerals.
3.73 The production and overall reserve picture is, however, not as critical as it may seem. One factor which changes the actual natural resource location is the progressive recycling of metals, the scrapping and re-use cycle which constantly increases and re-distributes the metals in our above ground ’mines’ as industrial development tends to do more with less in each successive use. The second factor is the increasing capacity to process ores of decreasing metal content at less energy input cost.
3.74 Scrap metal now accounts for over half the input into iron and steel production plants. Conservative sources suggest that 60 per cent of the copper in use is now recoverable, and, since three quarters of all the known consumption of copper has occurred since 1900, scrap copper recovery would be about one million tons per year and would then constitute about one half the total available supply of copper. Though reducing the ’critical’ aspects of the overall resource position, etc., this still leaves our major task unfulfilled as the consumption of metals per capita goes higher, then more and more specific design attention will have to be paid to increased overall performances per pound of metal used–even to maintain the present disparity in living standards. A key factor, as has been reiterated, in raising the general world living standard is, therefore, the tripling or quadrupling of the performance of metals in use.
3.75 36 See Copper: The Energy Highway of Industrialization, p. 125, Document Two, 1964.
3.76 MAJOR RAW MATERIALS IN THE STANDARD U.S. DESK TELEPHONE SET
3.77 RAW MATERIAL SOURCE LOCATION 1 ALUMINUM United States, British Guiana, Dutch Guiana, Jamaica 2 ASPHALT United States, Venezuela, British West Indies 3 BERYLLIUM Brazil, Argentina, India, South Africa, Australia 4 CARBON United States 5 CHROMIUM Turkey, South Africa 6 COBALT Republic of Congo, Canada 7 COPPER United States 8 COTTON United States 9 GOLD United States, Canada, South Africa, Australia 10 LACQUER United States 11 LEAD United States, Canada, Mexico 12 MOLYBDENUM United States 13 NICKEL Canada, Norway 14 NYLON United States 15 PALLADIUM Canada, South Africa 16 PAPER Canada, Sweden
3.78 RAW MATERIAL SOURCE LOCATION 17 PHOSPHORUS United States 18 PLASTICS United States 19 RAYON United States 20 RUBBER Indonesia, Malaya 21 SILICON United States 22 SILVER United States, Canada, Peru, Mexico 23 STEEL United States 24 TIN Indonesia, Malaya 25 VANADIUM United States 26 WAX United States 27 ZINC United States
3.79 Source: Western Electric Co., Inc. Sept. 1963.
3.80 57
3.81 In relation to the large scale planning of the ’metal economy’, it is worth noting that steel, so far accorded first priority in such planning, may not always retain its prime place. Apart from the fact that through improved transportation, etc., countries are no longer dependent on their locally available raw material resource, or confined to a particular technological development process, there is also the progress in light metals, composites and plastic technologies which have displaced steel as prime requirements in many areas.37 ’Steel is losing its historic role as the symbol of economic potency" as it is replaced by the light metals, structural composite materials and plastics.38 For example, in automobile production, plastics used per car doubled between 1954 and 1960, and the aluminum is expected to triple or replace steel as the main metal in the near future.39 Within the steel industry itself this leads to the increased performance development of stronger and lighter steel alloys. In general, the displacement of many of our traditional ’key’ materials through more efficient substitutes and replacements requiring less weight and energy pro- cessing is proceeding at a considerable rate. The copper ’trending’ referred to above gives some insight into this process where aluminum replaced copper in high tension electrical lines–though not as good a conductor, aluminum’s weightsaving allowed support towers to be more widely spaced, thus giving an accompanying performance economy in steel used.
3.82 Various other developments affect this changing metals use picture also. Pro- gressive weight saving, overall performance gains and reduction in maintenance energy are being affected to an astonishing degree in the sub and micro-miniaturization of com- ponents in the space and communications industry.40 Composite materials, i.e., ’powdered’ and sintered metal/mineral alloys, are coming to play an increasingly important role in space materials, as well as new methods of ’filament-wound’ structures which give great strength-to-weight ratio advantage. Molecular engineering–the designing and restructuring of materials to any prescribed range of properties–is advancing to the point where we may order a ’metal’ or metallic composite with the combination of precise performance criteria required. To the resource reserve, we may now add the availability of metals discovered as accumulating in large nodular deposits on the ocean bed–these are estimated to contain 25 to 30 per cent of manganese, 1 per cent of cobalt, copper and nickel plus other metals in varying proportion.41 These may be available in the next ten or twenty years. Off shore dredging of continental shelf sands for magnetite, tin and other ores is already in process.
3.83 Despite these increasing capacities, it is essential to bear in mind that the overall consumption and amortization of metals in varying use cycles is still increasing also. The newer capacities, if incorporated within the present distribution and use patterns, will only further increase the discrepancy of living standards in the world. Our task still remains to integrate and implement these capacities in high performance use–assemblies so as to render all resources adequate to the service of all men.
3.84 37 e.g.: Development of the Steel Industry in Japan 38 "Technology and Economic Development": Scientific American, Sept., 1963. 39 "The Challenge of Abundance": Theobald, Mentor, 1961. 40 "Tool Evolution", Chapter for further discussion of this area 41 "The Research Frontier", Roger Revelle, Saturday Review, Oct. 3, 1964. 58
3.85 In redesigning towards comprehensive and more efficient use and reuse ’assemblies’ with higher extraction of performance per unit of invested metals, it will be necessary to study these in ways not customarily thought of. For example, in designing a large scale miltiple dwelling environment control though much thought is applied to the ease and efficiency of construction, i.e., to the energy required to build the unit or units, little thought is given to that required to dismantle them. We still tend to build permanently even though the use-cycle of many such systems grows steadily shorter. In our designs, therefore, we should include the energy inputs and materials ’wastage’, etc., to be incurred in the dismantling of such structures when they are no longer needed.
3.86 The design scientist must think beyond the ’static’ assembling of the ’end product’ of the unit, as designed, built, and used to its place in a regenerative changing of usage cycle, not only of materials, but of requirements. We are required to design not only for use but also for reuse. Our urban centers, for example, are clogged with obsolete buildings whose dismantling costs prohibit their removal. The new environmental control systems will not be ’end products’ in this manner, but will be subject, like aircraft, to progressive obsolescence and redesign as technological capacities develop, and as changing social needs require them to change in many ways to man’s own changing requirements. If we need cities they will be expendable, expandable and swiftly alterable to the full requirements of their users. There are no final permanent end use assemblies only certain more or less temporal configurations of materials whose value, function and worth may only be gauged relative to overall satisfaction of human functions and needs.
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3.88 READINGS LIST
3.89 Phase 2. Prime Movers and Prime Metals
3.90 Energy from Fossil Fuels. M. K. Hubbert. Science, Vol. 109, February 4, 1949.
3.91 Energy in the Future. P. C. Putnam. Van Nostrand, New York, 1953.
3.92 Energy for Man. Hans Thirring. New York & Evanston: Harper & Row, 1962.
3.93 Energy Resources of the World. N. B. Guyol. Department of State Publication 3428, U. S. Government Printing Office, Washington, D. C., 1949.
3.94 Energy and Society. Fred Cottrell. McGraw-Hill Book Company, Inc., 1955.
3.95 Energy Sources – The Wealth of the World. E. Ayres and C. Scarlott. McGraw-Hill Book Company, Inc., 1952.
3.96 Heat Pumps and Thermal Compressors. S. J. Davis. Constable, London, 1950.
3.97 International Conference on the Peaceful Uses of Atomic Energy, Geneva, 1955. Reports published in 1956.
3.98 Man and Energy. A. R. Ubbelodhe. Penguin Books Ltd., 1963.
3.99 Power from the Wind. P. C. Putnam. Van Nostrand, New York, 1948.
3.100 Resources for Freedom. A Report to the President. W. S. Paley. U. S. Government Printing Office, Washington, D. C., 1952.
3.101 Solar Energy Research. Daniels, Farrington and John A. Duffie, (eds.). University of Wisconsin Press, 1955.
3.102 Tidal Power and the Severn Barrage. H. Headland. Proceedings of the Institution of Electrical Engineers, Vol. 96, Part 2, June, 1949.
3.103 World Symposium on Solar Energy, Phoenix, 1955. Published in 1956.
3.104 Metals
3.105 History of Metals. L. Aitchson. MacDonald and Evans, 1960.
3.106 History of the Strength of Materials. S. P. Timoschenko. London, 1953.
3.107 Iron and Steel Scrap, Survey and Analysis of Availability. Department of Commerce, 1957.
3.108 Metals in the Service of Man. W. Alexander and A. Street.
3.109 Mineral Resources. Dean F. Frasche. National Academy of Sciences, ’962.
3.110 60