There's no denying it: sustainability is a hot topic. And, as most sane people would agree, rightfully so. But there is little agreement on what the right measures would be to deal with our current climate crisis (which would be more aply be labelled as a "energy crisis", in my opinion, but that's a whole different subject).
The current trend in sustainability seems to be based on the adagium "every little bit helps", combined with "fake it until you make it". Every little bit is made to sound large, by using numbers that to many a laymen sound vast, blurring the discussion with fake facts and unclear figures.
That's where David MacKay, professor at Cambridge University's department of physics steps in. His main argument is that there should be a clear measure for energy consumption. His basic concept is very clear, as could be seen in this quote "We need to understand how much energy our modern lifestyles use; we need to decide how much energy we would like to use in the future; and we need to choose where we will get that energy from."
Ok, it sounds simple, but how? For him, the starting point is starting to measure everything in a single unit. In the case of energy, of course, Kilowatt-hour: a measure that most people know from daily use.
To give some examples: One kilowatt-hour (1 kWh) is the electrical energy used by leaving a 40 watt bulb on for 24 hours. Or driving an average European car 50km uses 40kWh of fuel. In total, the british lifestyle allegedly uses approximately 125 kWh a day.
Good. Once the basic units and a reference point are established, it's time to see how actual measures add up.
The first example is simple: switching off phone chargers when not in use. It's included in lists of "things to do to go green" all around the world, and sounds like a sensible idea. The truth is that leaving a phone charger switched on uses about 0.01kWh per day – 100th of the power consumed by a lightbulb. Or better yet: switching off a phone charger for an entire day is the equivalent of driving a car for about 1 second!
This being said, it's not that switching off phone chargers is a bad idea. Just note that it's only a tiny bit of improvement. So in this case a tiny bit only helps a tiny bit...
Another example: think about vehicles. Most people consider hydrogen cars one of the sane solutions - they certainly have a "green" feel to them. The odd thing is, that if you really measure it, most prototype hydrogen-powered vehicles use more energy than the fossil-fuel vehicles they replace. The average fossil car in Britain uses 80 kWh per 100 km, the BMW Hydrogen 7 uses 254 kWh per 100 km.
Electric cars, is a different story alltogether: Even if the electricity for electric vehicles comes from traditional fossil-fuel power stations, electric cars are still more efficient than petrol cars; and if in the future we switch over the nation's electricity production from fossil fuels to greener sources, then electric vehicles will win by a mile.
And now the big question: how can we use more (preferably only) renewable energy sources? "As a thought experiment, let's imagine that technology switches and lifestyle changes manage to halve British energy consumption to 60kWh per day per person. How big would the wind, nuclear, and solar facilities need to be to supply this halved consumption? Here is the scale that is required if (for simplicity) we wanted to get one-third from each of these sources: we would have to build wind farms with an area equal to the area of Wales; we would have to build 50 Sizewells of nuclear power; and we would need solar power stations in deserts covering an area twice the size of Greater London."
The interesting thing about the argument David MacKay brings across isn't about solutions, it's about measuring. About carefully looking at actual effects, and cutting away all the hot air surrounding sustainable arguments.
This is uncomfortable for anybody who's making money spreading half-truths about green issues (or green-washing unecological ideas).
He put forth his ideas in a book, aptly called "without the hot air". The cool thing is that the entire book is available as a PDF from (t)his website. It's worth your time, because he delivers a refreshing take on sustainability and energy consumption, and gives an insight that is mostly left out of the equation. There's no politics in this book, only arthmatics. And that's definitely wise for such a widely used and misused theme.