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Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. Sustainable Energy — without the hot air Version 3.5.2. November 3, 2008. This Cover-sheet must not appear in the printed book. high-resolutionedition. Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. Thequest for safe, secure and sustainable energy poses one Thisisareallyvaluablecontributiontothecontinuingdis- of the most critical challenges of our age. But how much cussion ofenergy policy. Theauthoruses a potent mixture energy do we need, and can we get it all from renewable of arithmetic and common sense to dispel some myths and sources? DavidMacKaysetsouttofindtheanswerthrough slay some sacred cows. The book is an essential reference a forensic numerical analysis of what we use and what we workforanyonewithaninterestinenergywhoreallywants can produce. His conclusions starkly reveal the difficult tounderstandthenumbers. choicesthatmusturgentlybetakenandreadersinterestedin LordOxburghKBEFRS howwewillpoweroursocietyinthefuturewillfindthisan Former Chairman,RoyalDutchShell illuminatingread. Foranyonewithinfluenceonenergypol- icy,whetheringovernment,businessoracampaigngroup, This is a brilliant book that is both a racy read and hugely this book should be compulsory reading. This is a techni- informative. cally precise and readable account of the challenges ahead. ProfDavidNewberyFBA It will be a core reference on my shelf for many years to come. So much uninformed rhetoric is thrown about on climate TonyJuniper changeand energysystemsthatthereisanurgent needfor FormerExecutiveDirector,FriendsoftheEarth an authoritative study setting out just what can and can- notrealisticallybedonetoachievesustainableenergy. This Engagingly written, packed with useful information, and hugely important book fills that gap both technically and refreshinglyfactual. highlyreadably. Itshouldbea‘mustread’notonlyathome PeterAinsworthMP and in industry, but on each Government Minister’s desk, ShadowSecretaryofState andnotjustintheUK. forEnvironment, Food, andRuralAffairs MichaelMeacherMP FormerEnvironment Minister DavidMacKaysetsouttodispelthehalftruths,distortions and nonsense which make up so much of what we’re told DavidMacKay’sbooksetsthestandardforallfuturedebate about climate change and our energy needs. This book is onenergy policy and climatechange. His dedicationto the readable, accessible and thorough. He cuts through un- facts and to rational argument is admirable in a field beset founded opinion and takes us to facts and figures which bypropagandaandwishfulthinkingonallsides,andevenif speak for themselves. It’s a useful guide for both layman hisconclusionseventuallydate,asallscientificworkmust, andexpert. Iheartilyrecommendit. hisapproachwillliveonforaverylongtime. GrahamStuartMP DavidHowarthMP Thisremarkablebookfromanexpertintheenergyfieldsets The choices that we make (or fail to make) in the coming out, with enormous clarity and objectivity, the various al- years about sustainable energy will determine what world ternative low-carbon pathways that are open to us. Pol- future generations will inherit. How do we arrive at ratio- icymakers, researchers, privatesectordecisionmakers, and nal decisions? In his book, David MacKay does not tell us NGOs,allwillbenefitfromthesewordsofwisdom. what to choosebut how to. Basic arithmetic is all it takes SirDavidKingFRS to distinguish between viable strategies and pipedreams. ChiefScientificAdviser Anybody who feels responsible for the future of our society totheUKGovernment, 2000–08 shouldreadthisbook. ProfDaanFrenkelFRS Startedreadingyourbook yesterday. Tookthedayoffwork today so that I could continue reading it. It is a fabulous, Atotaldelighttoread. Extraordinarilyclearandengaging. witty, no-nonsense, valuable piece of work, and I am busy ChrisGoodall sendingittoeveryoneIknow. AuthorofTenTechnologiestoSavethePlanet MatthewSullivan CarbonAdviceGroupPlc continuedonnextpage Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. DavidMacKay’sbookisanintellectuallysatisfying,refresh- At last a book that comprehensively reveals the true facts ingcontributiontoreallyunderstandingthecomplexissues aboutsustainableenergyinaformthatisbothhighlyread- of energy supply and use. It debunks the emotional clap- ableandentertaining. A“mustread”forallthosewhohave trap which passes for energy policy and puts real numbers aparttoplayinaddressingourclimatecrisis. intotheequations. Itshouldbereadbyeveryone,especially RobertSansom politicians. DirectorofStrategyandSustainableDevelopment Prof IanFellsCBE EDFEnergy FounderchairmanofNaREC, theNewandRenewableEnergyCentre So much has been written about meeting future energy needs that it hardly seems possible to add anything use- Preventingclimatechaoswillrequiresophisticatedandwell ful, but DavidMacKay has managed it. His new book is a informed social, economic and technological choices. Eco- delighttoreadandwillappealespeciallytopracticalpeople nomicandsocial‘laws’arenotimmutable–politicianscan who want to understand what is important in energy and and should reshape economics to deliver renewable energy whatisnot. LikeLordKelvinbeforehim,ProfessorMacKay and lead cultural change to save energy – but MacKay re- realisesthatinmanyfields, andcertainlyinenergy,unless mindsusthateventhey“cannachangethelawsofphysics”! youcanquantify somethingyoucanneverproperlyunder- MacKay’s book alone doesn’t have all the answers, but it stand it. As a result, his fascinating book is also a mine of provides a solid foundation to help us make well-informed quantitativeinformationforthoseofuswhosometimestalk choices,asindividualsandmoreimportantlyassocieties. to our friends about how we supply and use energy, now andinthefuture. DuncanMcLaren ChiefExecutive,FriendsoftheEarthScotland DrDerekPooleyCBE Former ChiefScientistattheDepartmentofEnergy, MacKay brings a welcome dose of common sense into the ChiefExecutiveofthe UKAtomicEnergyAuthority discussion of energy sources and use. Fresh air replacing andMemberoftheEuropeanUnionAdvisoryGroup hotair. onEnergy ProfMikeAshbyFRS AuthorofMaterialsandtheenvironment The need to reduce our dependence on fossil fuels and to find sustainable sources of energy is desperate. But much Byfocusingonthemetricsofenergyconsumptionandpro- ofthediscussionhasnotbeenbasedondataonhowenergy duction,inadditiontotheaspirationweallshareforviable is consumed and how it is produced. This book fills that renewable energy, David MacKay’s book provides a wel- need in an accessible form, and a copy should be in every comeadditiontotheenergyliterature. “SustainableEnergy household. – without the hot air” is a vast undertaking that provides Prof RobertHindeCBEFRSFBA bothapracticalguideandareferencemanual. Perhapsiron- ExecutiveCommittee, PugwashUK icallyforabookonsustainableenergy,MacKay’saccountof thenumbers illustrates just how challenging replacing fos- What a lovely book ... I feel better in a way that a cancer silfuelwillbe, and whybothenergy conservationandnew patient might feel after reading something in-depth about energytechnologyarenecessary. hisdisease. DarranMessem RichardProcter Vice PresidentFuelDevelopment RoyalDutchShell Beautifullyclearandamazinglyreadable. Prof WillyBrownCBE This is a must read for anyone who wants to help heal our world. Itookittothelooandalmostdidn’tcomeoutagain. CarolAtkinson MatthewMoss ChiefExecutiveofBREGlobal Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. Sustainable Energy — without the hot air Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. Sustainable Energy — without the hot air David JC MacKay UIT CAMBRIDGE, ENGLAND Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. FirstpublishedinEnglandin2009. UITCambridgeLtd. POBox145 Cambridge CB41GQ England Tel: +441223302041 Web: www.uit.co.uk Copyright©2009DavidJCMacKay Allrightsreserved. ISBN978-0-9544529-3-3 (paperback) ISBN978-1-906860-01-1 (hardback) TherightofDavidJCMacKaytobeidentifiedas theauthorofthisworkhasbeenassertedbyhim inaccordancewiththeCopyright,Designsand PatentsAct1988. Whilethispublicationintendstoprovide accurateandauthoritativeinformationinregard tothesubjectmattercovered,neitherthe publishernortheauthormakesany representation,expressorimplied,withregard totheaccuracyofinformationcontainedinthis book,nordotheyacceptanylegalresponsibility orliabilityforanyerrorsoromissionsthatmay bemade. Thisworkissuppliedwiththe understandingthatUITCambridgeLtdandits authorsaresupplyinginformation,butarenot attemptingtorenderengineeringorother professionalservices. Ifsuchservicesare required,theassistanceofanappropriate professionalshouldbesought. Manyofthedesignationsusedbymanufacturers andsellerstodistinguishtheirproductsare claimedastrade-marks. UITCambridgeLtd acknowledgestrademarksasthepropertyof theirrespectiveowners. 10987654321 3.5.2 Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. to those who will not have the benefit of two billion years’ accumulated energy reserves Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. Preface What’s this book about? I’m concerned about cutting UK emissions of twaddle – twaddle about sustainableenergy. Everyonesaysgettingofffossilfuelsisimportant,and we’re all encouraged to “make a difference,” but many of the things that allegedlymakeadifferencedon’taddup. Twaddle emissions are high at the moment because people get emotional (for example about wind farms or nuclear power) and no-one talks aboutnumbers. Oriftheydomentionnumbers,theyselectthemtosound big, to make animpression, and to score points in arguments, rather than toaidthoughtfuldiscussion. This is a straight-talking book about the numbers. The aimis to guide thereaderaroundtheclaptraptoactionsthatreallymakeadifferenceand topoliciesthataddup. This is a free book Ididn’twrite this book tomake money. Iwrote itbecausesustainable en- ergyisimportant. Ifyouwouldliketohavethebookforfreeforyourown use,pleasehelpyourself: it’sontheinternetatwww.withouthotair.com. Thisisafreebookinasecondsense: youarefreetouseallthematerial inthis book, exceptfor the cartoons andthe photos with anamed photog- rapher,undertheCreativeCommonsAttribution-Non-Commercial-Share- Alike 2.0 UK: England & Wales Licence. (The cartoons and photos are exceptedbecausethe authors havegenerally givenme permission only to includetheirwork,nottoshareitunderaCreativeCommonslicense.) You areespeciallywelcome to use my materialsfor educationalpurposes. My website includes separate high-quality files for each of the figures in the book. viii Copyright David JC MacKay 2009. This electronic copy is provided, free, for personal use only. See www.withouthotair.com. How to operate this book Somechaptersbeginwithaquotation. Pleasedon’tassumethatmyquot- ingsomeonemeansthatIagreewiththem;thinkofthesequotesasprovo- cations,ashypothesestobecriticallyassessed. Manyoftheearlychapters(numbered1,2,3,...) havelongertechnical chapters(A,B,C,...) associatedwiththem. Thesetechnicalchaptersstart onpage254. At the end of each chapter are further notes and pointers to sources andreferences. Ifindfootnotemarksdistractingiftheylitterthemaintext ofthebook,sothebookhasnofootnotemarks. Ifyoulovefootnotemarks, youcanusefullyaddthem–almosteverysubstantiveassertioninthetext will have an associated note at the end of its chapter giving sources or furtherinformation. The text also contains pointers to web resources. When a web-pointer ismonstrously long, I’veusedthe TinyURL service, andputthe tinycode in the text like this – [yh8xse] – and the full pointer at the end of the book on page 344. yh8xse is a shorthand for a tiny URL, in this case: http://tinyurl.com/yh8xse. A complete list of all the URLs in this book is providedathttp://tinyurl.com/yh8xse. Iwelcomefeedbackandcorrections. IamawarethatIsometimesmake booboos, and in earlier drafts of this book some of my numbers were off by a factor of two. While I hope that the errors that remain are smaller thanthat,IexpecttofurtherupdatesomeofthenumbersinthisbookasI continue tolearnaboutsustainableenergy. Howtocitethisbook: DavidJ.C.MacKay. SustainableEnergy–withoutthehotair. UITCambridge,2008. ISBN978-0-9544529-3-3. Availablefreeonline fromwww.withouthotair.com. ix