Wednesday, September 29, 2010

Mythbuster busted: Tom Gray and the hard facts of wind energy

The unflagging Tom Gray of the American Wind Energy Association has now presented a story about Kodiak Island, Alaska, as a "mythbuster".

It's a mythbuster only if you characterize, as Gray does, the problems with wind on the grid in the most simple-minded way.

1. First, he harps on the charge that backup power units must be kept running, noting (actually, asking tauntingly like a brat in a schoolyard) that Kodiak Electric Association (KEA) burned 930,000 fewer gallons of diesel fuel in the first year of three 1.5-MW wind turbines operating, so emissions must have been reduced.

2. For the same reason, fossil fuel use was reduced.

3. Finally, taking on the charge that wind is unreliable and hard to integrate into utility systems, he notes that KEA did it.

Now let us look at the facts.

The 4.5 MW of wind went into operation in July 2009. The data provided by KEA on diesel fuel saved is estimated as proportional to the net energy produced by the wind turbines. That is not a record of actual fuel savings, which is affected by the diesel generators' efficiency, which is affected by more frequent ramping and switching on and off to balance the wind feed.

As Gray knows, the charge that other plants have to be kept running primarily applies to large coal (and nuclear). Smaller coal plants may be able to ramp their production as needed (at a cost of efficiency). Natural gas plants may be able to switch very quickly on and off (again, at a cost of efficiency, like city versus highway driving). Diesel plants, too, can switch on and off quickly. On an island, they act very much like the backup generator that an off-gridder keeps ready.

So points 1 and 2 dodge the issue of exactly how much diesel fuel is saved by using an estimate rather than actual data. In a similar example from East Falkland, Islas Malvinas, less than one-fourth of the estimated fuel savings was actually seen. And it has still to be documented how less cleanly the remaining three-fourths is being burned.

Again, emissions may have been reduced, but by very much less, if any, than hoped or claimed. And fossil fuel use was reduced, but likely by very much less than estimated.

As for point 3, an island system is a simple closed system, with fast-responding diesel generators (as well as in this case hydro) to adjust quickly to changing demand. They continue to operate in the same way with the addition of wind turbines, which are essentially "negative demand". Being a "small, isolated" utility system is precisely why it is easy to integrate wind there, not, as Gray implies, an example of particular challenge.

wind power, wind energy, environment, environmentalism