Re: theWatt Podcast 75

Ben:

I guess I did exaggerate a bit. The bottom line of my below computations and assumptions is 1280 turbines, not 2000.

While I accept the numbers that result from your assumptions, I just wanted to provide mine. While there are a lot of smallish coal fired power plants still in commission in the US, most of the projects that I have been reading about recently are closer to 800-900 MWe per unit.

I have heard about 5 MWe wind turbines; they are physically imposing machines. Depending on the wind pattern in their local area, they will have their turbines mounted somewhere between 90-120 Meters above the surface and have blade diameters in excess of 120 meters. These machines are probably not the ones that you saw located next to what appeared to be coal fired power stations; they would dwarf all structures at most coal plants except the cooling towers and stack.

(http://www.ecotality.com/blog/2007/five-mw-wind-turbines-going-up/)

Therefore, my mental gym number for wind turbine size is 2 MW with an annual capacity factor of 25%. Quite a few land based turbines are still in the 1.5-2.0 MWe class since they are easier to transport and install than the more massive machines because they need smaller, more readily available cranes.

The average coal capacity factor in the US is about 70%, but newer plants tend to operate in excess of 80% - the average is brought down by some older plants that only run during high usage seasons.

If the coal plant is 800 MWe and operates at 80% CF, its annual electricity production is 5.6 Billion KW-hrs.

It would take 1280 of the nominal 2 MWe machines to produce that amount of electricity, but the big difference for the grid operator is the degree to which that production can be scheduled. The wind blows when it wants to, coal production can generally be more predictable.

Mind you - I am not defending coal - it is a messy substance that just happens to be useful to produce something that humans apparently want badly enough so that we put up with the mess that results from burning about 6 BILLION tons of coal each year.

One other comment about wind turbines - though many people talk about wind as something local and distributed that shifts power from the hands of large corporations, when they perform economic computations to talk about how cheap wind power is they assume the use of massive machines produced by companies like GE, Siemens, and Vestas. None of those companies seem to be in need of taxpayer subsidies or market mandates anymore than do nuclear plant producers.

Separate topic - Ben; thank you for inviting me onto the show. It was a lot of fun to engage with such a well informed group.