In light of my recent studies into transportation energy efficiency I’ve learned a lot more about the energy budget of the USA and the world.

One conclusion from those investigations is that if you are serious about greening the world, there are really only a few areas worthy of serious effort. Yes, you can make a difference anywhere, and if all you’re going to make is a personal difference there are scores of things you can change in your life to reduce your own footprint. But if you want to make a real difference, by affecting groups of people and whole sectors, the choices are few and clear.

Cars

The footprint of cars and light trucks is so large — 63% of transportation energy — that I am tempted to say that if you’re not working on cars, you’re not working on being green. Freight trucks are another 17% of transportation energy. Transit is in the noise — it only has bearing in that it can, in the rare cases it is done well, take people out of cars to make their travel greener. These numbers are huge, so of course differences can be made in the other transportation areas, but if the question of cars and trucks is not fixed, the rest of transportation barely matters in comparison. The one exception is jet airliners, which at 9% take the next largest shot of the energy budget.

However, transportation is “only” 28.5% of the total U.S. energy budget, so it’s not quite the only place to go. However, adding the energy cost of manufacturing cars bumps them up to around a third.

Electricity Generation

The rest of the energy budget is split 32% industrial (including making cars,) 18% commercial and 21% residential. But 70% of residential energy, 78% of commercial energy and 34% of industrial energy comes from electricity. (Just .3% of transportation energy does, but that will change if we move to electric cars.)

All these energy uses are quite diverse. There are many targets to attack, all worthy within their own scope but there’s only one truly big target, and that’s electricity generation. In the USA that’s currently 50% coal and 20% natural gas. So if you’re working to fix this — with renewable energy or nuclear — then you’re working on one of the big problems. Right now hydro and nuclear are the largest non-fossil power generators. All the other renewables are currently in the noise.

Agriculture

One of the biggest commercial users of energy is agriculture. It’s estimated that the equivalent of 400 gallons of gasoline per person in the USA is used to grow our food. Part of that is that 5% of all natural gas goes into making fertilizer. This makes this a particularly large non-electrical target. In addition, most of the methane we emit comes from livestock. I need to do more research but currently agriculture looks like another big target.

So it’s not quite true that if you’re not working on cars, you’re not working on being green, but it does suggest that projects like the Automotive X-Prize and DARPA Grand Challenge are among the most important projects in the world for going green.