## Conservation of Energy - Part II

Erratum. There was a mistake in my code. I have re-done the figure and the text in this post to reflect the correction. We are doing a little bit worse than I thought, compared to Western Europe and Japan.

In an earlier post, I wrote

... energy conservation of say 20% would only buy us about 7 1/2 years before we are right back in the same boat. This is assuming a modest growth rate of 3% for the economy. My guess is that 20% is a lot, in that it would take a lot of effort and belt-tightening to gain that sort of efficiency.
I would like to go back and try to get a handle on that 20% conservation, which I said was a lot. I recently found this very nice graph at the Wikipedia page on "Energy Consumption."

to which I have added the colored rays shooting out of the origin and the legend at top right (click image to zoom).

The underlying graph plots per capita energy consumption vs. per capita Gross Domestic Product (GDP). The first thing that stands out with this graph is how much GDP per person the US produces vs. nearly every other country. Yes, the US uses a lot of energy, but that is mostly because we produce a lot of stuff per person. More than twice what Spain produces per person. Roughly 50% more per person than Germany. Only Japan has higher per capita output. The second thing to notice is that the US is not that inefficient. There are many countries that do worse than we do, and we are better than the world average. We are roughly as efficient as Spain. If we could get by with 90% of the energy we use, without decreasing GDP, we would be like France. That would buy us 3.6 years before we were consuming as much energy as we are today. Conserving 20% would make us as efficient as Germany, and buy us 7.5 years. The UK is doing well. We would have to cut about 32% of our energy use to get their level of efficiency, and we would gain 13 years in doing so. All of these calculation assume 3% annual growth in our GDP. Japan is doing very well in this regard. Cutting 50% of our energy would get us to where they are, and gain us 23 years. That's not nothing.

Japan and those western European countries have an advantage in that they are not as spread out as we are. They have less transportation costs, for people and freight. They may also have milder weather, I'm not sure. I doubt that many Americans would be willing to adopt a Japanese style of living. Very high population density, with a high percentage of people living in small (by American standards) apartments.

So the bottom line, I think, is that we can do better with our energy use. I still think that 20% would be an ambitious goal, gaining us about 7.5 years. Not earth changing, but not bad.