How much energy do we consume? Does it matter? Robert Butler considers the numbers in his latest Going Green column ...
From INTELLIGENT LIFE Magazine, Summer 2009
Two years ago, the Independent columnist and former Sunday Telegraph editor Dominic Lawson wrote an article saying man’s contribution to climate change was very slight and any attempt to reduce it was “megalomania”. He backed his argument with figures about the gigatonnes of CO2 released by human fuel-burning compared with the far larger number of gigatonnes released by the oceans or the flow from the biosphere into the atmosphere.
A Cambridge physicist, David J.C. MacKay, was not impressed. All three figures were “wrong”. When Lawson said we burn seven gigatonnes, it should have been 26; when he said the biosphere sends out 1,900 gigatonnes, it should have been 440; and—almost comically—when he said the oceans send out 36,000 gigatonnes, it should have been 330. More than that, listing the natural flows into the atmosphere without also listing natural flows out of the atmosphere and back into the biosphere and the oceans—for millennia these two figures have cancelled themselves out—is “terribly misleading”.
In an effort to cut “UK emissions of twaddle”, Professor MacKay has now written a 383-page book that lays out the numbers we need to take part in a grown-up discussion about energy use. As he says, “we need to stop the Punch and Judy show”.
MacKay doesn’t like big numbers, he likes small ones that we can get our heads round. “Simplification”, he says, “is a key to understanding.” If you’re concerned about your personal finances, or energy security or climate change, and you want to cut down on your use of fossil fuels, “Sustainable Energy—Without the Hot Air” explains which actions make a significant difference and which make very little. The Economist described the book as “exemplary” and the place to start “for anyone seeking a deeper understanding of the real problems involved”. You don’t even have to buy it. It’s a £45 hardback and a £19.99 paperback, but can be downloaded free (www.withouthotair.com).
The tone is surprisingly playful, sidestepping the oughts, musts and shoulds of most eco-guides in favour of breezy sums. MacKay favours “numbers, not adjectives” and he presents them with a jaunty mix of photos, diagrams, maps, cartoons, timelines, bar charts, algebraic equations, pull-out quotes, tiny URL links, chummy headings (“gadgets that really suck”, “the war on leakiness”) and a generous dollop of exclamation marks. It’s geek heaven: full of killer stats that you immediately want to pass on—from the annual bird deaths in Britain caused by cats (55m) to the average winter-time temperature in a British house in 1970 (13 Degrees Celsius).
MacKay is tough on things that don’t do very much: his motto is “every big helps”. The energy you save by switching off your phone charger for a whole day is used up in one second driving a car. To focus on the phone charger is like “bailing the Titanic with a teaspoon”.
For his basic unit of measurement, MacKay uses the rate at which we use energy in kilowatt hours per day (kWh/d). So if you leave a 40-watt lightbulb on all day, that’s 40 x 24 = 960, or roughly 1kWh/d. The average British citizen uses 125kWh/d, while the average American uses 250 (and these figures exclude embedded energy in imports and in natural food). In the Middle Ages, it’s estimated, the average Briton consumed 20kWh/d.
How do we reach that 125? MacKay breaks the figure down into crisp chunks. If you boil the kettle for a total of 20 minutes, that’s 1kWh/d. If you buy the Independent, that’s 2kWh/d. If you have a bath, that’s 5kWh/d. If you drive a car 30 miles, that’s 40kWh/d. Heating and cooling accounts for another 37kWh/d, light for 4, gadgets for 5, food for 15, stuff—from drinks cans and batteries to computers and cars—for 48, transporting stuff for 12, and defence for 4. If you take one long return flight a year (to Cape Town, say), that trip will average out at 30kWh/d—the same as running an electric fire, day and night, all year round.
MacKay doesn’t consider changes in attitude, only in energy sources. He crunches the numbers on wind, solar heating, solar photovoltaics, biomass, hydro, tide, waves and geothermal and shows how massive each would need to be if, added together, they were to meet current demand. He factors in public consultation (our national tendency to say no) and decides about a seventh of our needs could be met through renewables. We can’t do it alone. “Europe needs nuclear power, or solar power in other people’s deserts, or both.” For Britain, that area in someone else’s desert would have to be the size of Wales.
MacKay puts a figure on almost everything: he tells us that a cat consumes 2kWh/d, a dog 9kWh/d, and a horse 17kWh/d. He likes to base his sums on personal experience. As a milk drinker who also likes cheese, he personally requires one sixteenth of a cow a day. By personalising energy use, we can take significant steps to reduce it. MacKay’s house in Cambridge used to consume 50kWh/d, so he replaced the gas boiler with a condensing boiler, put thermostats on the radiators, installed cavity-wall insulation and had the back door double-glazed and the door to the front porch extra-double-glazed. His home now consumes 13kWh/d.
He takes a genial delight in making things clear to non-scientists (perhaps even columnists). But the fun doesn’t mask a sense of urgency. He dedicates the book “to those who will not have the benefit of two billion years’ accumulated energy reserves”.
Picture credit: mandiberg (via Flickr), Sam Barker
(Robert Butler is a former theatre critic. He now blogs on the arts and the environment at the Ashden Directory and writes the Going Green column in Intelligent Life. His last article for More Intelligent Life was about climate change on stage.)