Occasionally, I hear someone talking about how it makes more sense to make power stations more efficient rather than making incremental improvements to efficiency at the point of use.
Obviously I’m in favour of efficiency improvements anywhere (except maybe in the NHS where they are “efficiency improvements”). I’m going to use what’s called an Energy Flow Diagram (I prefer the other name, Sankey Diagram, it has more character). This one is from the British Government and shows where our energy came from and where it was used in 2010.
On the diagram, you start on the left with all your energy inputs, 314.7 Million Tonnes of Oil Equivalent of (top to bottom) Gas, Coal, directly produced electricity (mostly Nuclear with a little Hydropower and Wind), Biofuels, Petroleum (oil).
Anything that turns and scoots off the bottom of the diagram is either being exported or represents the energy lost in converting energy into another form. The Green ones at the start are oil exports, the big Light Purple one is power station losses and the Skinny Multicoloured one like an old school data ribbon is losses incurred moving energy around our gas and electricity networks.
Now, moving left to right, you follow the fuel (and electricity) through the system until on the right you reach the 159.1 Million Tonnes of Oil Equivalent of users.
There are two big yellow blocks in the middle. We can pretty much ignore the first one, oil refineries but it’s worth mentioning because this is where the diagram really gets started once we close the system to imports and exports. Our total national demand for energy inputs is 227.5 Million Tonnes of Oil Equivalent.
WARNING: This next bit (the second yellow block, power stations) is me going all information overload and explaining a bit of the diagram I wasn’t going to write about. It explains what it means in interesting but unnecessary detail. If you want to skip it I’ll let you know when it’s over.
The second big yellow block is power stations, people are right to care about this bit. Looking at this diagram they produce 31.3 Mtoe of electricity and waste 46.of Mtoe of the energy that was in the fuel for an average efficiency of about 40%. This seems pretty rubbish but it’s not all that bad. At the moment you can’t get much past 60% efficiency for a gas fired power station. More efficient basically means burning hotter and if we want to go any hotter than we already do, we’ll have to invent some pretty magnificent materials. Coal power stations are less efficient. To start with if someone gives you the choice of coal or gas to burn, take the gas every time. Coal is a solid. If you want to burn it efficiently you have to smash it to smithereens first (think flour, only you wouldn’t want to eat that cake). That process takes energy and even then, coal just won’t burn like gas does so your power station is running colder (remember that’s the same as less efficiently). There are a bunch of improvements you can make to the sort of 1960s and ’70s coal power stations we have in Britain and, if you use them all (expensive) then you might get a bit more than 50% efficiency.
THE BIT WHERE I WENT OFF AT A TANGENT IS OVER NOW.
So here we are at the right of the diagram. As you can see, there are three big end points in the diagram. The first is industry, the second is transport and the third is domestic.
The really cool thing is you can look at the colours of the arrows to see what fuels end up where.
The first thing you will have noticed is that we pretty much don’t use oil except for transport and we pretty much use nothing else for transport (it’s not easy to get the energy sources for walking and cycling onto this chart but it hardly matters, they’re tiny in energy terms).
The second thing I hope you’ll notice is that we use way more gas than electricity. At work it might be about 50:50 but at home it’s more like 80:20.
So there are two points I’ve been taking a while to make. The second has a caveat. Sorry.
1. For every 1% saving in energy consumption at the end of this diagram this amplifies as you go back across the diagram so saving that one percent over here means we save 1.43% of the fuels we need to feed in on the left of the diagram, an extra 0.43%! If we make power stations 1 percentage point more efficient we’d get another 0.78 Million Tonnes of Oil Equivalent out of the fuels we put in, 0.34% of the energy we needed at the start.
2. Our homes are leaky as a rusty bucket. George Monbiot once said they have a thermal performance only marginally better than tents. Sad but true. If we want to reduce our energy usage we need to be looking at heat about four times as hard as we look at electricity. Perhaps, given that it’s relatively difficult to make some of those savings from electricity (replacement of cyclical goods or wholesale lifestyle changes) we should try even harder on the heat side where the answer is simple and it’s keeping the heat in our buildings.
I said there would be a caveat on the second one and here it is: Gas is about three times less carbon intensive (and about the same or even more for money) than our electricity so from an environmental point of view any of these electricity vs. gas numbers can be divided by three. Household greenhouse gas emissions from energy are 57% gas, 43% from electricity and only a quarter of industrial emissions.
What am I doing? Well, I live in a rented flat so I do what I can which is mostly being energy conscious; turning off lights, closing doors to the warmer rooms and replacing old bulbs (there will be a blog about LEDs, my friend solar power’s distant cousin in future). I have learned how to use what passes for heating controls in my house, they’re not the worst but they could be better. But what I need to do that I’ve been lining up is to buy an egg-timer so I don’t spend too long in the shower. It’s probably the easiest change I could make, I’ll get to work earlier and I’ll be cutting down on both gas and water usage so it’s an all round win.