Opinion A topflight science brainbox at Cambridge University has weighed into the ever-louder and more unruly climate/energy debate with several things that so far have been mostly lacking: hard numbers, willingness to upset all sides, and an attempt to see whether the various agendas put forward would actually stack up.

Professor David J C MacKay of the Cambridge University Department of Physics holds a PhD in computation from Cal Tech and a starred first in Physics, so we can take it that he knows his numbers. And, as he points out, numbers are typically lacking in current discussion around carbon emissions and energy use.

MacKay tells The Reg that he was first drawn into this field by the constant suggestion — from the Beeb, parts of the government etc — that we can seriously impact our personal energy consumption by doing such things as turning our TVs off standby or unplugging our mobile-phone chargers.

Anyone with even a slight grasp of energy units should know that this is madness. Skipping one bath saves a much energy as leaving your TV off standby for over six months. People who wash regularly, wear clean clothes, consume hot food or drink, use powered transport of any kind and live in warm houses have no need to worry about the energy they use to power their electronics; it’s insignificant compared to the other things.

Most of us don’t see basic hygiene, decent food and warm houses as sinful luxuries, but as things we can reasonably expect to have. This means that society as a whole needs a lot of energy, which led MacKay to consider how this might realistically be supplied in a low-carbon fashion. He’s coming at the issues from a green/ecological viewpoint, but climate-change sceptics who are nonetheless concerned about Blighty becoming dependent on Russian gas and Saudi oil — as the North Sea starts to play out — will also find his analysis interesting. Eliminating carbon largely equates to eliminating gas and oil use.

“I don’t really mind too much what your plan is,” MacKay told The Reg this week. “But it’s got to add up.”

He says he’s largely letting his machine-learning lab at Cambridge run itself these days, and is personally spending most of his time on trying out different energy scenarios.

MacKay sets out his calculations in a book, Sustainable Energy — Without the hot air . You can download it here. As he says:

The one thing I am sure of is that the answers to our sustainable energy questions will involve numbers; any sane discussion of sustainable energy requires numbers. This book’s got ’em, and it shows how to handle them.

He emphasises that the book isn’t quite finished yet, and says he’s always glad to hear from someone who has something to add or has spotted a mistake.

In Without the hot air , MacKay examines our total energy usage in the UK, and then tries to provide a similar amount of energy but without using any oil and gas. He’s willing to consider windpower on a thoroughly heroic scale, as it is probably the renewable technology best suited to the UK climate. As a benchmark for wind, he writes:

Our conclusion: if we covered the windiest 10 per cent of the country with windmills, we might be able to generate half of the energy used by driving a car 50 km per day each. Britain’s onshore wind energy resource may be “huge,” but it’s not as huge as our huge consumption. I should emphasize how audacious an assumption I’m making. … The windmills required … are fifty times the entire wind hardware of Denmark; seven times all the windfarms of Germany; and double the entire fleet of all wind turbines in the world. This conclusion – that the greatest that onshore wind could add up to, albeit ‘huge’, is much less than our consumption – is important …