Sustainable Energy – without the hot air

Thanks to Urban Ziegler of RETScreen for putting me onto this fascinating book by David JC MacKay, a Physicist at Cambridge University.  Sustainable Energy – without the hot air sets out to crunch the numbers on a potential sustainable energy future for the UK. You can download the entire book (in three sections) or a 10 page summary, from the website at, where you can also order a hard copy.

Cover to Sustainable Energy - without the hot air, by David JC MacKay
Cover to Sustainable Energy - without the hot air, by David JC MacKay

MacKay wants to know if we can get off our fossil fuel addiction but seems to be fed up with two things: firstly, the unhelpful suggestions that will save small amounts of energy but allow people to think they’ve done something positive. His favourite bad example is the common exhortation to unplug mobile phone chargers when not in use. He says that doing so will save as much energy in one day as you use driving your car for one second.

In other words, don’t focus on the little things if you aren’t going to make big changes. As he puts it, our energy consumption is huge, so ‘every big helps.’

Secondly, he’s angry that the discussion about renewable energy is conducted with adjectives rather than numbers. He says the latter are mainly used (especially in the media) in a confusing way for political point scoring.

His idea to cut through the fog is simple in concept, though it must have taken a while to pull all the information together. He converts all energy to the same unit (he chooses kilowatt hours per person per day) and in one column draws up a representation of the average person in the UK’s usage (the red one on the cover), and in another column draws up the potential capacity for different types of generation (the green one). In this graphic way he aims to show whether renewable energy can meet our demands and get us off our fossil fuel addiction.

The result? Yes, in theory (and with some big decisions about energy efficiency, e.g. converting to electricity for all transport). However, there’s a catch…

We will only get there by giving over vast areas of land and sea to electricity generation or growing crops for biofuels. Really vast areas, like an area of sea twice the size of Wales for offshore wind production. He’s worried, probably with justification, that the British public simply won’t wear it.

So what can we do? Is the situation hopeless? MacKay doesn’t think so. He just thinks there are some difficult choices ahead, and he aims to steer the conversation in the right direction for us all to take those decisions. He therefore offers a number of options of energy plans that add up. He makes some suggestions on how to reduce the demand, and proposes different mixes for low carbon supply. Some include nuclear power, some include clean coal (with carbon capture and storage technologies) and one is for the purists, using neither of these ‘controversial’ sources, just pure renewable energies.

There’s a proviso on any such plan, he warns: without nuclear or clean coal we’ll need to import renewable energy produced elsewhere. The most promising technology to his mind is concentrating solar power produced in desert regions.

Sustainable Energy – without the hot air is written in an engaging and easily readable style. It’s about the UK, but MacKay hopes similar calculations will now be done for other countries. As I said at the start, it’s free to download, so I don’t intend to precis it any further. I recommend you go straight to the source and start thinking about your own preferred answers to those difficult questions.

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