Sustainable Energy – Without the Hot Air

David MacKay’s Sustainable Energy – Without the Hot Air is a remarkably engaging book; it has certainly kicked off and contributed to some very energetic discussions here. The book, which was written by a physics professor at Cambridge and is available for free online, is essentially a detailed numerical consideration of renewable forms of power generation, as well as technologies to support it, and to reduce total power demand. MacKay concludes that the effort required to produce sustainable energy systems is enormous, and that one of the most viable options is to build huge solar facilities in the world’s deserts, and use that to provide an acceptable amount of energy to everyone.

The book has a physics and engineering perspective, rather than one focused on politics or business. MacKay considers the limits of what is physically possible, given the character of the world and the physical laws that govern it. Given that he does not take economics into consideration much, his conclusions demonstrate the high water mark of what is possible, with unlimited funds. In the real world, renewable deployment will be even more challenging than it is in his physics-only model.

Here are some of the posts in which the book has already been discussed:

I have added relevant information from the book to the comment sections of a great many other posts, on everything from wind power to biofuels.

Even if you don’t agree with MacKay’s analysis, reading his book will provide some useful figures, graphs, and equations, as well as prompt a lot of thought. It is certainly one of the books that I would recommend most forcefully to policy makers, analysts, politicians, and those interested in deepening their understanding of what a sustainable energy future would involve.

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. In the fall of 2005, I began reading for an M.Phil in IR at Wadham College, Oxford. Outside school, I am very interested in photography, writing, and the outdoors. I am writing this blog to keep in touch with friends and family around the world, provide a more personal view of graduate student life in Oxford, and pass on some lessons I've learned here.

23 thoughts on “Sustainable Energy – Without the Hot Air

  1. No power cuts danger – Miliband

    There is “no danger” of mass power cuts in the UK during the next decade, Energy Secretary Ed Miliband has said.

    He told the BBC it was possible to meet the country’s energy needs while using more “sustainable” sources such as wind farms and nuclear stations.

    Last week the government’s new energy adviser warned that the UK could face blackouts by 2016 as green energy is coming on stream too slowly.

    But Mr Miliband said building projects would be completed in time.

    Cambridge University researcher David MacKay, who takes up his post as adviser at the Department of Energy on 1 October, has warned that the public will keep objecting to facilities such as wind farms and nuclear power stations being constructed near their homes.

  2. From Turbines and Straw, Danish Self-Sufficiency

    “Last year, the Danish island of Samso (pronounced SOME-suh) completed a 10-year experiment to see whether it could become energy self-sufficient. The islanders, with generous amounts of aid from mainland Denmark, busily set themselves about erecting wind turbines, installing nonpolluting straw-burning furnaces to heat their sturdy brick houses and placing panels here and there to create electricity from the island’s sparse sunshine. By their own accounts, the islanders have met the goal. For energy experts, the crucial measurement is called energy density, or the amount of energy produced per unit of area, and it should be at least 2 watts for every square meter, or 11 square feet. ‘We just met it,’ said Soren Hermansen, the director of the local Energy Academy, a former farmer who is a consultant to the islanders.”

  3. December 1, 2009, 8:12 am

    100 Percent Renewables by 2030?

    Could the world get to 100 percent renewable energy by 2030? Not a chance, say most analysts.

    But in an article last month in Scientific American, two California academics outline a path to this amount through “millions of wind turbines, water machines and solar installations.”

    The paper, by Mark Jacobson, a professor of civil and environmental engineering at Stanford University, and Mark Delucchi, a research scientist at the Institute of Transportation Studies at the University of California, Davis, envisions 3.8 million large wind turbines, accounting for just over half of electricity demand in 2030. These would be augmented by 90,000 solar plants and other renewable technologies like tidal and geothermal power.

    The turbines “would occupy about 1 percent of the earth’s land, but the empty space among turbines could be used for agriculture or ranching or as open land or ocean,” the paper states. Solar plants (not counting rooftop installations) would take up 0.33 percent of the earth’s land.

  4. This is why I think MacKay’s book is so valuable, because of news stories like this:

    “Nearly all the energy we use on this planet starts out as sunlight that plants use to knit chemical bonds. Now, for the first time, researchers at the Massachusetts Institute of Technology have created a potentially cheap, practical artificial leaf that does much the same thing—providing a vast source of energy that’s easy to tap. The new device is a silicon wafer about the shape and size of a playing card coated on either side with two different catalysts. The silicon absorbs sunlight and passes that energy to the catalysts to split water into molecules of hydrogen and oxygen. Hydrogen is a fuel that can be either burned or used in a fuel cell to create electricity, reforming water in either case. This means that in theory, anyone with access to water can use it to create a cheap, clean, and available source of fuel.”

    Even if your artificial leaf is 100% efficient at turning sunlight into electricity, you would need to cover an enormous area with them to meet today’s energy demand.

    Most journalists seem to have no appreciation for scale, when it comes to energy. Yes, you can make biofuel out of discarded fry-cooking oil from fast food restaurants, but that isn’t a technology that scales cheaply to replace gasoline…

  5. Opinion: Every little bit doesn’t really help
    Wednesday, May 25, 2011
    By MARQ DE VILLIERS, The Ottawa Citizen

    There is no easy way to cut the necessary emissions. We do need to be green, but it is not nearly as simple (or as cheap) as the greenies would have you believe. What is required are big changes in demand, and big changes in supply. We’re talking countrywide scales — hundreds of thousands of wind turbines, thousands of square kilometres of solar panels, massive cuts in demand, wholesale switches in technology, gigantic investments. You won’t hear these numbers from politicians, or not very often. Nor will you hear them from business leaders. And hardly ever from environmentalists.

    Here are a few lamentable numbers to remember:

    Every year our global civilization digs up, transports, heats and pummels and shapes and processes and sells half a trillion tons of materials. Only six per cent of all those tons ends up in products — the rest is used to mine and make and move them. And only one per cent — a single measly per cent — is still a useful product six months later.

    Only 37 per cent of primary energy production is put to any real use. The rest is lost to conversion inefficiencies and waste.

    About four-fifths of all energy used in transportation, including trains and planes, is spent on road traffic — and about half of that is for moving light vehicles and people. Worse, only about five per cent of the energy we expend in transportation actually gets us from one place to another. The rest is just to shift our inefficient internal combustion vehicles or is sent out the tailpipe as waste heat. Ninety-five per cent of the energy we use to get to Wal-Mart is wasted. So much for so-called “savings.”

    The International Energy Agency estimates that somewhere around $45 trillion, or an average of one per cent of annual global economic output, needs to be invested between now and 2050 to make any real difference — which sounds unlikely in this era of “jobless recoveries” and multiple fiscal crises.

  6. One Third of World’s Energy Could Be Solar by 2060, Predicts Historically Conservative IEA

    The International Energy Agency is notoriously conservative on projections for renewable energy. The agency has embraced the need for more clean electricity and fuels to address climate change and peak oil, but its outlook for the future is usually far more conservative than how reality plays out.

    So when an official at the IEA says we could get up to one third of our global energy supply from solar photovoltaics, concentrating solar power, and solar hot water by 2060, that’s a fairly big piece of news. But even that projection may be conservative.

  7. Version 3 of the 2050 Pathways Calculator

    In December 2011, DECC published the Carbon Plan and version 3 of the 2050 Pathways Calculator.

    As before, this open-source engineering-based tool is intended to support grown-up conversations about our possible energy futures. The user can choose any combination of demand-side and supply-side actions over the period to 2050, and the calculator computes and displays various consequences – energy flows, areas of land use, greenhouse gas emissions, and some security-of-supply indicators. The significant new feature in version 3 is the inclusion of costs, for the first time. Version 3 of the calculator also includes an air-quality calculator, which, like the costs calculator, is under development. Expert feedback is welcome.

  8. Germany’s energy transformation
    German plans to cut carbon emissions with renewable energy are ambitious, but they are also risky

    The micro-level works almost too well. Schleswig-Holstein plans to generate three times as much renewable energy as it consumes and to export the surplus south and west. Southern states are keen to produce their own renewable power, too. Bavaria talks of self-sufficiency. The states’ windpower targets add up to double the federal government’s goal of 36 gigawatts by 2020.


    Enough Wind to Power Global Energy Demand: New Research Examines Limits, Climate Consequences

    ScienceDaily (Sep. 9, 2012) — There is enough energy available in winds to meet all of the world’s demand. Atmospheric turbines that convert steadier and faster high-altitude winds into energy could generate even more power than ground- and ocean-based units. New research from Carnegie’s Ken Caldeira examines the limits of the amount of power that could be harvested from winds, as well as the effects high-altitude wind power could have on the climate as a whole

  10. Intermittence of Wind Energy Hardly Affects CO2 Emissions in Spain

    Oct. 16, 2013 — Researchers at the UPM have found that real contribution to emissions targets is positive even in energy markets with high penetration of wind energy.

    The finding has generated the first comprehensive analysis on interaction between wind parks and thermal power plants in Spain and has concluded that global balance of CO2 reduction is still significant. Besides, the study suggests how to enhance effectiveness of potential sources that can be helpful for promoters of renewable technologies.

  11. David MacKay, a physicist at Cambridge University, once posed the question of what would need to happen for the United Kingdom to entirely stop using fossil fuels. He arrived at this instructive hypothetical: even if the country cut energy consumption by half, it would still require a wind farm the size of Wales, along with fifty new nuclear-fission plants, and photovoltaic cells with twice the surface area of Greater London—but situated in a far-off desert, with the electricity somehow delivered to British consumers.

  12. The genesis of the book was a campfire discussion in Africa in the mid-2000s, about sustainable sources of energy. Most people present said that wind and wave power are so abundant that there’s no need for fossil fuels. Only one person (from South Africa?) dissented, saying that wind and wave were plentiful, but on nowhere near the scale needed to power the world. That was the end of productive discussion; without real data about energy use and calculations of possible energy sources, any debate was bound to be hot air, producing more heat than light. So David decided to produce the data and do the calculations — to cut out “the twaddle” and produce “a straight-talking book about the numbers”. (His interest in the environment was longstanding. When he was at Caltech for his PhD around 1990, he instigated a recycling scheme, and Caltech now has sophisticated recycling across the campus.)

    Over the next three or four years, David produced several drafts of his book, and published them on the web for people to comment on. This had three important effects:

    He got feedback from people interested in the subject, on which topics to cover, and information about those topics. (The Acknowledgements in the book list about 350 people who helped one way or another.)
    Readers commented on how readable and how understandable the written material was.
    A growing number of people became aware of David’s work, (which was to prove important when the book was finally published).

    Later on when I got to know David, I realized that doing things this way stemmed from his particular character. He wanted to get things correct. He was neither falsely modest nor conceited, so he accepted suggestions and corrections without any intrusion of ego. If someone else was right, their contribution was very welcome, because it improved the book.

  13. Similarly, reader comments made it clear that how clearly the material was expressed was crucial to people’s understanding. This is why he eventually expressed all energy use in kilowatt hours, per person per day (kWh/p/d). Superficially this a minor issue, but in fact it’s very important because his book is essentially quantitative. However, national energy use is so huge that ordinary people can’t relate to it. (“The electricity generating capacity of the UK is 92 gigawatts.”). David’s insight was to choose units where the numbers involved were (a) familiar – kWh are the units on our electricity and gas bills (b) small enough to be understandable, i.e. mostly units and tens, which the “per day” gives us, and (c) easily related to an individual’s own activities, which is why “per person” is so important. For example, in the UK, a person’s average energy consumption in a day is 125 kWh. “Taking a bath uses about 5kWh … a shower uses 1.4kWh”. Expressing consumption in simple numbers likes these gives you a true understanding of your own behaviour. Driving a car 30 miles a day uses about 40kWh/day — about a third of the 125 kWh average — so reducing your driving can make a big difference to your overall energy consumption. At the time of publication, there had been a big campaign for people to save energy by switching off their phone charger. The book pointed out that switching off your charger for a year would save the same amount of energy as one hot bath. Choosing the right units gave people a handle on the numbers and showed how campaigns like these were like “bailing the Titanic with a teaspoon”.

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