Efficiency is Cheaper But…

I keep running across the idea that it’s cheaper to reduce greenhouse gas emissions by improving efficiency, so we shouldn’t do this other stuff, one of which is nuclear power. To see why this doesn’t work, consider an analogy:

You weigh 140 pounds, 20 of it excess fat, and you want to reduce your weight to 28 pounds over the next 4 decades or so. This is comparable to lower estimates for reductions we want to make in GHG emissions – 60% reductions or more or much more as total energy use more or less doubles (or would without improved efficiency). So per unit energy, we need to reduce carbon emissions by 80%. (Or reduce the amount of energy we use and reduce carbon emissions per unit energy.)

[An aside: improved efficiency is crucial to reducing GHG emissions. All policy recommendations stress that we can’t possibly succeed without aggressively getting rid of waste in energy use, or without carbon cap and trade. Research and development must be better funded to improve efficiency more rapidly.]

There are several options. One includes walking 1.5 miles/day, to lose a pound+ a month. Other ideas are likely to be more expensive, such as replacing bones with lighter weight versions.

The people who say that we should really only start with improving efficiency point out how cheap walking is compared to any of the alternatives, many of which have other downsides. What I have heard, and maybe this isn’t what they are saying, is why not just keep walking, and in 9 or 10 years, you will have achieved your goal – down below 30 pounds.

Some choices have valuable but limited roles in the solution. No question that walking may be the best choice for the first 20 pounds and it would be silly to do expensive operations. Similarly, the best way to satisfy much of our energy needs is to reduce our energy use.

Energy analysts often graph from left to right all solutions in order of cost. Many solutions have negative costs, such as compact fluorescent bulbs (where the lights are on for a while), and more efficient cars. Many will hopefully achieve this negative cost status soon, with technological breakthrough or economies of scale, for example, hybrid cars, trucks, and buses. The graph also shows the reduction in GHG emissions each technology can achieve. It doesn’t make sense to dismiss solutions that will have a small effect if they are cheap or free.

So why not list all energy sources in this manner and pick only those that are needed?

First, we don’t have enough information. No one knows how expensive solar power will be, whether technological breakthroughs will occur more or less rapidly than hoped for. The costs of using biofuels, crops for fuels, may change as crop productivity goes up a little (more carbon for some crops in some areas of the world), and then goes down with climate change, because of dryer soils and reduced water availability.

We know a lot about wind power, but the effects of wind on climate – wind helps spread heat and humidity from the equator and windmills interfere with that process more than telephone poles in the same location – are still being evaluated. If wind power turns out to be more or less damaging to the climate than current estimates indicate, the relative benefit of wind power will change. Wind power appears to have a much stronger effect on the local climate than on the global climate, so wind power may make sense for some areas of the world, but better analysis may lead some peoples to reject an energy source they once considered important.

Secondly, things may change. We can plop our windmills down, and then see wind patterns change. The energy obtained from wind power varies with wind speed cubed, so doubling or halving the speed of wind changes wind power by a factor of 8. On the other hand, if wind speed is too high, windmills are turned off. Crops for biofuels are much easier to move, if we forget such details as land ownership and national borders. One of the likely major effects of a changing climate, however, is not just increased temperature and more or less precipitation, but a new climate regime. Now we can look at world map and predict the climate in places we don’t know much about, based on latitude, and distance from oceans and mountains. Variability is likely to increase as well as temperature: what crops should farmers grow in an area that averages 1/3 as much rain as the current average 3 years out of five and twice as much 2 years out of five?

These are the kinds of arguments that lead policy people to recommend pursuing all technologies that reduce GHG emissions. Perhaps in 2050 or 2100 people will look back and note that we wasted money and effort, that we didn’t have to work this hard. Few policy people worry about this scenario.

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