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SE-022 608 AOTROR' Hates, Denis 'rtmiAt Energy: The Solar P'rosnect.Worldwatch Paper 11,,,, IdTxuTION Worldwatch Inst., Washington, P.C. Mar .71 VA".4.CDAtE iegible due to small 1141$ 83p.; Parts may be mar inally type ;AVAILABLE FROM Worldwaich Institute, 776 Massachusetts Avenue, ; W.W., Washington, D,C.20038 ($2.:00 BIM PRICE MP-$0.83 P/us Postage. HC Not Available from EDRS DESCRIPTORS Depleied Resources; *Energy; Environment; *Environmental Influences; Fuels; *Futures (of .Society); Natural Resources; *Solar Radiation; *Technology; *World Problems TDENTIFIERS *Solar Energy ABSTRACT 0 T Tliis paper, one of 'a series published by the Worldwatch Institlite to identify i.snd focus atteption onglobal . problemsi is adapted fro..the .author's book, "Rays of Hope: rhe Transition to a Post-etr.eum World.v The author examines the qurtent energy problems of the world, and determines thatthe 'energy patterns of the past dare not the prologue to the future. The inadequacies associated with energy alternatives-to petrole9m,sxch as coal and nuclear fusion, areidentified and discusSed. Thus, soctety- is left with only the, solar oPtions: wind,falling water, biomass, and dtrect sunlight. The ;historical dévelopmept,rtechnol'ogy, 'and current status of each' of the sdlar options' isdetailed. The social and politiCal ramifications. of theconversion to a society based On solar energy are hypotheized.The.author° concludes tthat 'the conversion to °solar energy is tec'hnically feasible,ecoltiomically sound, and environmentally' attractive. (BT) / _> 4********4F******************************(****4i*********1*******,********** * * Documents, acquired by ERIC inClide maiy,informal uni*nblished * materials not,available from other source4 .ERIC makes every ef fort * * ;to obtain the best copy available..Neve14heless, items of marginal , * * reproducibility are oftenencOuntered a'#this affects the quality * * o'c the microfiChe and hardcopyreproluet ons BRIC makes available -* * via the ERIC Document ReproduotionServi e(EDRS).. EDRS is not. * jp-r4sponsible fpr the quality of the opoigi l document. Reproduction's"* I' ssioPlied bY DDRS are thebest that can be made from the originil. * *********************************************************************** t "IS ner rjisott,..-4 `o dLV t. 1-1,t.' v Energy: TheSolar Prospect Denis tiayes Worlawatdaaper 11 Macch 1077 4 tt Thls paper Is, adapted 'from the author's forthcoming book, Rays of Hope: The Transition to a Post-Petroleum World . W .Norton, 1977). The section on "Plant Power" is ,adapted from an article that will appear in BioScience in mid- '1977. The remainder Of the paper may be partially repro- duced with acknowledgement to VVorldwatch Institute. The views- andaconclusions contained in this document are thoseV the author and do not tAecessarily represent those of Worldwatch Institute, its directors, offioers, or staf. f. - Copyright Worldwatch _ Instite. 1977 Library of Congress Catalog Card Number 77-72418 . ISBN 0-91646840-0 'Printed on recycled paper 5 Tableof Contaiti tawn of an Era 5 Solar Heating and Cooling 13 Electricity from the Sun 21 Catching the Wind 28 Falling Water 35 Plant Power 40 Storing Sunlight 5,7 Turning Toward the Sun 61 Notes 67 of an Era ' , tiout one-fifth of all ener y usedaround the world now comes from solar resoiirces:ind power, water power, biomass, and . direct sunlight. By t e year 2000, such renewable°energy sources could provi e 40 percentof the global energy budaet; by 2025, humanity cou d 'obtain 75 percentof.its energy from, solar resources. Suoh a transiti n would not becheap or easy, but its benefiti -would far outweigh t es.costs anddifficulties. The proposed timetable would require an un recedentedworldwide commitment of resources and talent, but thecOnsequences of failure are similarly un: precedented. Every essential feature of theproposed solar transition' has already proven technically viable:if the 50-year timetable is met, the roadblocks will have bleenpoliticalnot technical.' ,\ ..4 Different solar sources will see theirfullest development in different regions. Wind poyver potential is greatescin- the temperate zones while Viomass Flourishes in the tropics.Direct sunligh t is ',most in- teusi in-ke cloudless desert, while water powerdepends upon moun-. tam rpins. -However, most countrieshave some potential to harness all these renewable resources, and manysands have begun to explore the feasibility of doing so.2 .4 major eneigy transition ofsomeld is inevitable. For richands!,, . and poor alike, the energy patterns oftip past are not prolog' to1 the future..The oil-based societies ofthPindustrial world cann t be sustained and cannot be replicated;their spindly foundationsan- Middle East, have begun to Irode. ." chored in the shifting sands of the Until recently most poor countrieseagerly looked forward to entry. into the oil era .With its geirplants,,diesel tractors, and ubiquitous automobiles. However, the fivefoldincrease in oil prices since 1973 9 .virtually guarantees that the ThirdWorld Will never derive most of its energy from petroleum. Both worlds thus face an awesome diston- tinuity in the production and use of energy. In the past, such energy transformations invariahly 'produced far- ieaihing social chadge. The 18th-century substitution of /coal for It wood .and wind in Europe, for example accelerated and refashioned the industrial -revolution. Later, the shiftto petroleum altered the nature of travel, shrinking the planet and reshaping its cities. The coming energy transitipn can be countea upon to itinclaItally alter tomorrow's. world. Moreover, the quantity of.energy avable may, in the long rit9, ptrove much less important than where and how this energy is obtained. Since many energy sources besides the sun coulreplace oil and gas, ,we need to kriow now what consequences the choices we make. today will have in 50 years. While we can obviously possess n9. detailed information about the state of the world 50 years from now, even rough calculations may, yield insights of importance for energy6 policy. If we optimisticaPy assume that the world's population will level off after one more doubling and stabilize at eight billion by 2025, and if we conservatively assume that per capita energy use will then amount to one-third the current U.S. level, we can broadly assess different ways of trying to meet this aggregate demand.3 - If this energy were all provided by coal, an absolutely intractable jproblem Would result. Coal combustion necessarily produces carbon 'dioxide and adding COi to the air. raises the earth's temperature by ,retarding the radiation of heat into spge (a phenomenon known as' the greenhouse effect). Since CO2 remains in the atmosphere for hundreds, or, perhaps thousands of years, the' impact of CO2 emis- sions is cumulative and irreversible on any relevant time scale. At our projected level of coal consumption, the atmospheric inventory of ca would increase about 4 percent aen; such growth In atmos- pheric carbon dioxide 4ould, virtually all nutteorologists agree, soon alter the heat balance of the entire plan t dramatically,., 4. If the postulated energy derhand, were met with nuclr fission, about 15,000 reactors as large as the biggest builtwou ave to be Con- / 8 J 14 * e I struitedone new reactor a day for 50 )9ears. Sustaini these re c- tort would require the recycling of 20million kilograms annuallyi Everysyear, enough plutonium would be recckd a nd 7 ch. world to *fabriCate four million Hiroshima-sitebo s. uch a plowed cannot sanely be gieeted with equanimity. Nuclear Antion is it speculativeteihnolopla,No one knows what it wilrcqst, how it will worl, or even whether work. The deuteri- um-tritium rtactionthe 'simplest- fusion reactionand the focus of almost all current researchwill produce large amountsof radioactIve iwaste artecan be 'ailed tobteed plutonium. Some advanced fusion cyclesaroit nqtably those that woul4 fuse twodeuterium nuclei or that would fuse a protiin with a boronatomcould, theoretically, provide a nearly inexhaustible supply of -relativelyclean power. Ilut such reactions will be vastly,-more difficult toachieve than the deu- terhsm-tritium.reaction. In short, there is no chancethat most of 4the world's energy demand will be met by fusion in 2025.4 Thus we are left with the solar options: wind,fallinif w.r, biomass, and direct sunlight. Fortunately, they arerather attractive. Solar' sources_ _add no new heat tothe global environment, andwhen in egglibriumthey make no net contribution toatmospheric carbon .diide. Solar technologies fit well into a political systemthat empika- apes decentralization, pluralism, and localcontrol. §unlight is abundant, dependable, 'and free. With someminor fluctu- ations, the sun has been bestowing itsbounty on the earth for more than four .billion years, 'and it is expeikl to continueto do so for several billion more. The suns inconstancy is'regional and seasonal, not arbitrary Of political, and it can.therefole be anticipated and plannsd for.3 Qur ancestors captured the sun's energy indirectlyby gathering wild vegetation. Their harvest became more reliablewith the revolutionary shift to planned cultivation and the, domesticationof animals. As civilization developed, reliance upon The sun grewincreasingly cir- cuitous$ Slaves alid draft animals provided aroundabout means of . .hatnessing large quantities of phbtosynthetic energy.Breezes and 9 . Currentsboth solar-powered phenomenadrove mills and invited overseas travel. 8 In earlier era& people were intensely