How to Save The Planet, in one easy step
Hippies would have you believe that you can Save the Planet and your wallet by unplugging your devices instead of leaving them on stand-by. They are wrong. If we assume that each of twenty devices in my flat is wasting 2W for the 23 hours a day that they're not in use (all of which are pessimistic estimates), then that's wasting 3.3 mega-Joules a day. That sounds like quite a lot. It is, however, just under 1kWh (the unit in which electricity is metered) so costs about 10p a day, or £3 a month.
Here's a much better way of saving energy, emitting less "carbon" (carbon is in fact Just Fine, it's carbon dioxide that will destroy the planet), and coincidentally saving quite a bit more money.
Drive slower.
I recently took a round trip of about 500 miles, most of it on motorways and other fast free-flowing roads. By driving at 60mph instead of 85, I got 45 miles per gallon instead of my normal 33-ish. That means I burned 4 gallons less fuel, or 18 litres, or £24.50. Given that the energy density of diesel is about 38MJ/l, I saved 684MJ or 192 kWh. That is, in one weekend I Saved the Planet as much as I would in nearly eight months of unplugging the hifi, phone charger, etc.
And never mind how much my back thanks me for not having to do all that bending over to plug and unplug things.
Anyway, now let's see what happens if we apply my wisdom to the whole country. Let's conservatively assume that there are 1,000,000 cars, each doing 10,000 miles a year, and that they all normally do a quite good 50mpg. That means they burn 200,000,000 gallons of fuel, or about a billion litres. If everyone slows down by the same amount I did, that billion litres becomes 700 million litres, saving 300 million litres of petrol (which is cheaper than the diesel I use), or 354 million quid. That's also a saving of 12,000,000,000,000,000 joules of energy. Which is about the annual output of the Enfield power station.
What's really interesting about this is that Enfield is a very small power station, about a twelfth of the size of Drax. So while driving slower is a fuck of a lot better than unplugging your phone charger, it's also still not very effective at Saving the Planet. You should still do it though, cos it'll annoy the BMW driver behind you.
[updated to ignore engine efficiency - even if your engine is really inefficient you're still turning each litre into 38MJ of energy, just not very usefully]
I'm a BMW driver, and a Hippy so nerr!
The 318 tourer is actually pretty impressive on MPG - even beating our previous Focus C-Max, which was diesel and had automatic gears tuned for "economy".
On top of that there is a dial under the rev counter showing your MPG, it's a very good reminder that you're driving like an arse sometimes :)
But yes - taking your foot off the accelerator earlier and braking less, starting journeys with low speeds and low revs, etc all not only save fuel, but reduce wear on the parts in your car.
Posted by Aaron Trevena on Fri, 27 Jun 2008 at 09:12:46