How Many Windmills Does It Take?

In the last post, we estimated that the U.S. would need to double (more or less) the electric generating capacity, 1,000,000MW, in order to power a fleet of 135,000,000 electric cars. Remember, we left out trucks and buses.

Currently, at the end of 2007 there was about 15,600MW of wind generating capacity. Let's estimate, for argument's sake, that at the end of 2008 there was 20,000MW of wind capacity in the U.S. So how many windmills would it take to charge 135,000,000 automobiles?

Let's orient ourselves with some criteria. There are a number of wind turbine sizes available from manufacturers but for our purposes let's assume that we use the largest size--2.5MW. We also assume that each of these wind turbines is running full tilt (no pun intended) during the six hours we're charging the fleet. The fleet is charged at the same time of day, let's say overnight, and that there is sufficient wind to run the turbines at maximum output. None of this is realistic but we're trying to estimate an order of magnitude.

So, how many? Simplistically: 1,000,000MW divided by 2.5MW per turbine results in 400,000 new wind turbines. If we assume our existing fleet were composed of 2.5MW turbines (which it is not), we would have approximately 8000 wind turbines (20,000 divided by 2.5). There are more wind turbine units in the country because the original sizes were smaller, so it could be 2 or 3 times that number. A truly national study of the number of units required might be significantly larger to account for all of the changing variables.

The point is this: there is no time soon or possibly ever that the U.S. will increase the number of wind turbine units by one or two orders of magnitude. Not feasible.

Of course, one could argue that wind turbines are only one source of renewable energy that could be used, and I concede that. But we could make similar calculations for all of the renewable energy sources combined--and as much as we all would like it to--it's just not going to get us there. Moreover, as I argued in a previous post, electric cars are too inefficient and the infrastructure to support them too capital intensive to pursue this ill advised course. It's not sustainable.

The realistic solution in a future post.