Sustainable Energy – Without the Hot Air, written by David MacKay, Professor in the Department of Physics at the University of Cambridge is available for free as a download. Addressing the sustainable energy crisis in an objective manner, the book analyzes the relevant numbers and organizes a plan for change on both a personal level and an international scale—for Europe, the United States, and the world. In case study format, this informative reference answers questions surrounding nuclear energy, the potential of sustainable fossil fuels, and the possibilities of sharing renewable power with foreign countries. While underlining the difficulty of minimizing consumption, the tone remains positive as it debunks misinformation and clearly explains the calculations of expenditure per person to encourage people to make individual changes that will benefit the world at large.

The book presents the information needed to answer critical questions such as:

  • How big do renewable energy facilities have to be, to make a significant contribution?
  • Do new much-hyped technologies such as hydrogen or electric cars reduce energy consumption, or do they actually make our energy problem worse.
  • Which efficiency measures offer big savings, and which offer only 5% or 10%?
  • How big would our energy consumption be if we adopted strong efficiency measures?

“The public discussion of energy options tends to be intensely emotional, polarized, mistrustful, and destructive. Every option is strongly opposed: the public seem to be anti-wind, anti-coal,anti-waste-to-energy, anti-tidal-barrage, anti-fuel-duty, and anti-nuclear,” said Mc Kay.

He adds, “We can’t be anti-everything! We need an energy plan that adds up. But there’s a lack of numeracy in the public discussion of energy. Where people do use numbers, they select them to sound big, to make an impression, and to score points in arguments, rather than to aid thoughtful discussion.”

He continues, “My motivation in writing “Sustainable Energy – without the hot air” is to promote constructive conversations about energy, instead of the perpetual Punch and Judy show. I’ve tried to write an honest, educational and fun book. I hope the book will help build a cross-party consensus in favour of urgently making an energy plan that adds up.”

On why he made the book available for free

I didn’t write this book to make money. I wrote it because sustainable energy is important. If you would like to have the book for free for your own use, please help yourself to any of the electronic versions on this website. There’s pdf and html versions (thanks to William Sigmund!); we are working on other formats.

Download  the Free Ebook: Sustainable Energy – Without the Hot Air

About the Author

David MacKay FRS is a Professor in the Department of Physics at the University of Cambridge. He studied Natural Sciences at Cambridge and then obtained his PhD in Computation and Neural Systems at the California Institute of Technology. He returned to Cambridge as a Royal Society research fellow at Darwin College. He is internationally known for his research in machine learning, information theory, and communication systems, including the invention of Dasher, a software interface that enables efficient communication in any language with any muscle. He has taught Physics in Cambridge since 1995. Since 2005, he has devoted much of his time to public teaching about energy. He is a member of the World Economic Forum Global Agenda Council on Climate Change. He was elected a Fellow of the Royal Society on 14 May 2009.

Reader Reviews

It stood out for me that the book got five stars across the board from all 15 reader reviewers on Amazon who purchased the hardback.  Below are a few of those reviews.

Do the numbers!, Robert Hargraves, Hanover NH, March 4, 2009
This book is essential for anyone thinking about energy policy. It excels because MacKay does not espouse one specific solution, but rather teaches the reader how to create solutions and evaluate them. He emphasizes that the numbers must add up — total energy production must equal total energy consumption.  In a way the book is very simple. He leads the reader by the hand in estimating the energy requirements of society – transportation, heat, food, gadgets, and so on. He similarly helps you make credible estimates of achievable production from sources such as sunlight, tides, hydro, nuclear, wind, coal, and oil. Like a good physicist, MacKay is able stand back and estimate these numbers top-down from first principles, with just enough depth to generate numbers that are credible to you and good enough for policy making. The charts, graphs, tables, and pictures are extensive and clear. If you have a particularly loved energy source [wind?] or a particularly hated one [coal?] you can “do the numbers” and build your own energy policy. The only requirement is that the numbers add up!

Long Overdue Discussion, By Herbert W. Lorber (Denver, CO USA), June 4, 2009

This discussion of sustainable energy without dependence on burning fossil fuels is unique and valuable in that it is general, covering all non-fossil sources of energy, but doing so quantitatively. Prof. MakKay works to allow the numbers to speak for themselves and to distance himself from narrow advocacy. The book is available for download online, gratis, but I find the convenience and high production values of the paperback edition well worth the price on Prof. MacKay helpfully divides the book into two parts: the first a broad, quantitative analysis of renewable energy sources for various needs (e.g., transportation, heating and cooling, electric power), the second a more detailed analysis that develops the scientific basis for the results presented in the first. The second part requires a background in the physical sciences but is nonetheless accessible.

Please. Read This Book!, By   Gaurav S. Shah “orion” , May 18, 2009

And then we can pass a law saying that all elected representatives must read this book. And pass a test based on it. The author is logical, sensible, clear and unbiased (and has a great sense of humor, to boot). It is no surprise that these qualities make it a great contribution to the field of alternative energy writing. If you want to be an informed citizen, read this book. If you want to understand what we can do to help, read this book. Even if you disagree with everything he says, read the book.

A stimulating and numerate guide to alternative energy options, By Graham (Palo Alto, CA) , May 2, 2009
Prof MacKay’s starting point is that there is a great deal of vague flummery talked about energy production and consumption. It is easy to make vague claims of “huge” potential green sources or to obsess over what turn out to be very minor energy savings. His goal in this book is to have a hard-nosed discussion of real numbers, so that there can be a more sensible discussion of options. He avoids making explicit recommendations, but his one continual plea is that we create a plan that “adds up” rather than merely reflecting wishful thinking. The world currently consumes enormous quantities of fossil fuel, so any viable alternative plan also has to deal with very large numbers, either as savings or as alternate sources.  MacKay writes in a very readable and entertaining style. But he is also very careful to explain his numbers and to build his scenarios from the ground up. I found his analyses convincing and stimulating. Sometimes more detailed or more mathematical analysis is pushed off to supplementary appendices, but those are also well worth reading.  I learned many things. One key factor I hadn’t appreciated was the enormous land areas required for renewable sources, such as wind, solar, biofuel, or geothermal to make a substantial difference. For example, MacKay calculates that it would probably require 10% of the UK’s surface to be dedicated to wind farms in order to make a significant contribution to the UK’s current energy needs. Even larger areas are required to generate meaningful quantities of biofuel. If an area the size of Africa were dedicated to growing biofuel, that might only replace a third of current world oil needs. But MacKay also points out there may be places where building vast energy farms makes sense. For example, a 20,000 square km solar power farm in the Sahara could be one way to meet the UK’s energy needs.

MacKay explains how technologies such as electric cars or heat pumps reduce energy needs, independent of how the electricity is generated. He shows us that because electric motors are extremely efficient, burning oil in a central power plant and using the electricity to run an electric car actually requires much less energy than traditional cars. Similarly, he shows how using a central electric power station to power home heat pumps is a significantly more efficient way to heat houses than burning gas or oil at the house. (I had definitely not understood this before!) MacKay would prefer we use green technology to create the electric power, but it is interesting that even using fossil fuel power stations, electric cars and heat pumps still reduce overall fossil fuel consumption.  In his concluding chapters, MacKay outlines several possible plans that “add up”. All of them have significant negatives, either through reliance on nuclear power, or enormous environmental impact, or enormous expense. He doesn’t pick a winner from among these options, but he emphasizes that we need to chose a plan rather than simply saying “no” to every possible option.

Regardless of whether you agree with Prof Mackay’s goal of shifting to alternative energy supplies, this book is definitely worth reading. MacKay succeeds admirably in explaining the raw numbers, so we can see what realistic energy choices are available.

Having read this book (and having it available as a reference) I now feel much better equipped to read the plethora of ideas, plans, suggestions, trivia, wishful thinking and occasional good sense that circulate around energy policy. MacKay is right that numbers matter, and plans need to add up!

© 2009, Tracey de Morsella. All rights reserved. Do not republish.

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Author: Tracey de Morsella (323 Articles)

Tracey de Morsella started her career working as an editor for US Technology Magazine. She used that experience to launch Delaware Valley Network, a publication for professionals in the Greater Philadelphia area. Years later, she used the contacts and resources she acquired to work in executive search specializing in technical and diversity recruitment. She has conducted recruitment training seminars for Wachovia Bank, the Department of Interior and the US Postal Service. During this time, she also created a diversity portal called The Multicultural Advantage and published the Diversity Recruitment Advertising Toolkit, a directory of recruiting resources for human resources professionals. Her career and recruitment articles have appeared in numerous publications and web portals including Woman Engineer Magazine,, Job Search Channel, Workplace Diversity Magazine, Society for Human Resource Management web site, NSBE Engineering Magazine,, and Human Resource Consultants Association Newsletter. Her work with technology professionals drew her to pursuing training and work in web development, which led to a stint at Merrill Lynch as an Intranet Manager. In March, she decided to combine her technical and career management expertise with her passion for the environment, and with her husband, launched The Green Economy Post, a blog providing green career information and covering the impact of the environment, sustainable building, cleantech and renewable energy on the US economy. Her sustainability articles have appeared on Industrial Maintenance & Plant Operation, Chem.Info,FastCompany and CleanTechies.