Wednesday, September 30, 2009

Book: Sustainable Energy - Without The Hot Air

David MacKay, the future government energy adviser and professor at Cambridge University's department of physics, warns us in his new book Sustainable Energy - Without the Hot Air that plans for energy production in the future will not come fast and will not come cheap.

We have an addiction to fossil fuels, and it’s not sustainable. The developed world gets 80% of its energy from fossil fuels; Britain, 90%. And this is unsustainable for three reasons. First, easily-accessible fossil fuels will at some point run out, so we’ll eventually have to get our energy from someplace else. Second, burning fossil fuels is having a measurable and very-probably dangerous effect on the climate. Avoiding dangerous climate change motivates an immediate change from our current use of fossil fuels. Third, even if we don’t care about climate change, a drastic reduction in Britain’s fossil fuel consumption would seem a wise move if we care about security of supply: continued rapid use of the oil and gas reserves will otherwise soon force fossil-addicted Britain to depend on imports from untrustworthy foreigners.

We need a plan that adds up. The good news is that such plans can be made. The bad news is that implementing them will not be easy.

Part I – Numbers, not adjectives

The first half of this book discusses whether a country like the United Kingdom, famously well endowed with wind, wave, and tidal resources, could live on its own renewables. We often hear that Britain’s renewables are “huge.” But it’s not sufficient to know that a source of energy is “huge.” We need to know how it compares with another “huge,” namely our huge consumption. To make such comparisons, we need numbers, not

Where numbers are used, their meaning is often obfuscated by enormousness. Numbers are chosen to impress, to score points in arguments, rather than to inform. In contrast, my aim here is to present honest, factual numbers in such a way that the numbers are comprehensible, comparable, and memorable. The numbers are made accessible by expressing them all in everyday personal units. Energies are expressed as quantities per person in kilowatt-hours (kWh), the same units that appear on household energy bills; and powers are expressed in kilowatt-hours per day(kWh/d), per person.

Part I of Sustainable Energy – without the hot air builds up an illustrative red consumption stack, enumerating the energy cost of a range of energy-consuming activities; and a complete green stack, adding up all the potential renewable resources available in Britain.

The first half gives two clear conclusions. First, for any renewable facility to make an appreciable contribution – a contribution at all comparable to our current consumption – it has to be country-sized.

Second, if economic constraints and public objections are set aside, it would be possible for the average European energy consumption of 125 kWh/d per person to be provided from these country-sized renewable sources. The two hugest contributors would be photovoltaic panels, which, covering 5% or 10% of the country, would provide 50 kWh/d per person; and offshore wind farms, which, filling a sea-area twice the size of Wales, would provide another 50 kWh/d per person on average.

Such an immense panelling of the countryside and filling of British seas with wind machines (having a capacity five times greater than all the wind turbines in the world today) may be possible according to the laws of physics, but would the public accept and pay for such extreme arrangements? If we answer no, we are forced to conclude that current consumption will never be met by British renewables. We require either a radical reduction in consumption, or signficant additional sources of energy – or, of course, both.

Part II – Energy plans that add up

The second part of Sustainable Energy – without the hot air explores six strategies for eliminating the gap between consumption and renewable production identified in the first part, then sketches several energy plans for Britain, each of which adds up.

The first three strategies for eliminating the gap reduce energy demand:
  • population reduction;
  • lifestyle change;
  • changing to more efficient technology.
The other strategies for eliminating the gap increase energy supply:
  • “Sustainable fossil fuels” and “clean coal” are names given to carrying on burning coal, but in a different way, with carbon capture and storage. What power could we get from coal, “sustainably”?
  • Nuclear power is another controversial option; is it just a stop-gap?
  • A third way to get extra carbon-free power would be to live on renewable energy from other countries – in particular, countries blessed with plentiful sunshine, large areas, and low population densities. What is the realistic potential of the Sahara desert?
Part III and Part IV

The third part of the book drills down to the physical foundations of energy consumption and energy production. Eight appendices show from first principles where the numbers in the first two parts come from.

The final sixteen pages of the book contain further reference data and conversion factors, useful for applying the book’s ideas to other countries, and for translating to and from units used by other organizations.

This is a free book. David MacKay didn't write this book to make money. He 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.

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