Mountaintop activists visit Maine

Wikipedia stock photos of a mountaintop removal mine in Appalachia and the Kibby wind farm in Maine.

The Natural Resource Council of Maine has been a steadfast supporter of Maine wind power for several years now, and has resisted every attempt by local "environmental" interests to convince or force them to withdraw that support.

For good reason. NRCM is one of the more reasoned environmental organizations there are, and is capable of understanding some economics and drawing reasoned and quantitative comparisons.

Most recently they bought some Appalachian activists to Maine to see our wind farms and to highlight the comparison. I for one was blown away by the picture of pure happiness on the one activist's face when he contemplated the notion of making clean energy on a mountaintop.

I suggest you watch the video. It's Channel Five, so they'll make you watch an ad first, but it's worth it.

Joy is a beautiful thing to watch.

But we're tougher thinkers than that at Unity College. Let's just run the numbers implied by this admitted PR stunt, so we can see exactly which system is actually a more efficient use of land.

If you take a 2,000 or 3,000-foot tall mountaintop in Maine and put a shiny American-made GE 1.5 MW/hour rated turbine on it, you will make on average 500KW/hour from your nice new turbine. This is due to the fact that the wind doesn't blow strong enough to run the turbine all the time. We call this ratio, which in this case I assume to be 33%, the "capacity factor." To get the best performance, to make sure the turbines don't interfere with one another, you should put one turbine roughly every 1,000 feet. If we calculate the area each turbine sits on as a 1,000 foot square, we get an energy/land ratio of 4.4 KW/square feet/year.

(500KW/hr x 365 days/yr x 24 hrs/day ÷ 1 turbine/1,000,000 square feet)

The Appalachian coal mine, on the other hand, will have a seam depth of anything from a few feet to several tens of feet. I don't know, and couldn't find at short notice the average depth of an Appalachian coal seam, but if we calculate on the basis of a ten-foot seam, we can easily multiple or divide by various factors to suit our own favorite biases. A pound of bituminous coal carries around 12,500 BTUs, which is about 3.7 KW. Solid bituminous coal is about 80 pounds per cubic foot. Our ten-foot seam delivers, then, around 3,000 KW per square foot.

(3.7 KW/pound x 84 pounds/cubic foot x 10 cubic feet/square foot of land)

Seemingly, coal is several orders of magnitude more efficient than wind in terms of the amount of mountaintop land that is needed.

But wait: Coal is typically burned in relatively inefficient power plants of about 35% thermal efficiency. In other words, 65% of the heat energy goes up the chimney before we can convert it to electricity. Newer "combined cycle" plants are more efficient, and the EPA's "cap-and-trade" acid rain regulation is driving the adoption of the newer technology (an example of a successful cap-and-trade system), but there are still quite a few of the older plants in use. Combined cycle plants have about a 55% thermal efficiency.

What to do? If we split the difference at 45% we might have a good average thermal efficiency for coal-to-electricity.

Then we need to understand that the amount of land needed to actually access the energy value of coal-bearing land increases by a factor of two or three or more. There has to be room to bulldoze all the overburden, the land that was previously on top of the coal. And then there's rail lines and power plants and a place to put the coal ash. This last is an enormous waste disposal problem. The Guardian just did an interesting exposé of the difficulties in China, while a major disaster occurred at at least one storage site in the US recently.

Meanwhile, while this is all happening, the wind power plants are quietly producing, year upon year, for a couple of decades. You'd be amazed how little maintenance is needed. Sometimes I wish they needed more, because that would create more jobs. But they just sit there for twenty years or more. Then the turbines get refurbished, and the plants produce for some more years.

But of course, initial fabrication-and-construction costs consume some energy, and even some coal. Coal makes coke which makes steel which makes wind turbine towers and generators and trucks and trains to transport turbines. The energy return on investment for moderately well-sited, properly managed wind power plants is typically around 80 to 1, or just 80.

Whereas we already decided our coal mine can only deliver 45% of it's energy as electricity. That's an EROI of 0.45. And we haven't even calculated the energy costs of delivering the coal to the plant or mining it or disposing of the ash..

For the purposes of comparing energy return per unit land, however, we can just assume on the one hand that the energy costs of producing wind turbines and refurbishing them every twenty years, if they are only one-eightieth of the actual energy produced by the turbine, are negligible. We might then, even-handedly, assume that the energy costs of transporting coal and disposing of ash are also negligible. Generous, maybe, but for arguments sake....

So we need to divide the energy per square foot for coal by a factor of three or four because there's that much more land involved, especially in waste disposal. If we use a factor of 3, we get 1,000 KW/square foot of land.

Which still compares very poorly to the 3.7 KW per square foot of land for wind turbines.

Except for one thing: the wind power plant is renewable, and delivers 3.7 KW every year.

And we already accounted for the turbine costs themselves, albeit rather crudely, by balancing them against those hidden coal costs of transportation and disposal of ash.

When the coal is gone, its gone.

So yet another correction factor is needed. And it's a very subjective one. We'd be well within our analytic rights, if we had any, to multiply the wind power output by an infinite number of years because, well, renewable is renewable.

That's what it means.

But it's unreasonable to think that any energy supply technology will stick around forever. This is the mistake that is being made by advocates for fossil energy, and their climate denialist apologists. They imagine that there's no scientific or engineering progress, or to be more accurate, they can't conceive of such progress. A lack, rather than a presence, of imagination.

More than likely, we'll invent a better solar panel, or a new bio-diesel producing algae, or a Mark II Bloom Box, and the clean green wind turbines and the coal plants will become as obsolete as steam engines.

So if instead of using an infinite number, or even a big number, we use a number related to the number of years this particular kind of energy supply technology might be expected to last before it's superseded by a newer kind, we might come up with a more reasonable comparison. I like the number 20, because 20 years is about the rest of my working life as an energy wonk, and I sure want to live to see the day when the denialists and fossil fuel advocates get their comeuppance.

So...

3.7 KW/square foot x 20 years possible viability = 74/KW per square foot of land committed to wind power use.

While...

1,000 KW/square foot x 0.45 thermal efficiency = 450/KW per square feet committed to coal mining use.

450 KW is still eight times as much as 74 KW, but it is a comparable number, almost in the same order of magnitude. That was the point of the NRCM stunt, to show that coal and wind are comparable use of mountaintops. They're quite correct, although we'll need somewhat more mountaintops to have wind turbines do the work than we would if we had coal mines.

And my assumptions of the energy costs of coal extraction and land use were generous. I gave coal the benefit of the doubt, while I didn't inflate the time period during which wind power might be relevant. If anything, I underestimated it.

So, dear readers, given that the land efficiency is at least comparable if you make certain assumptions, what it might boil down to is this: assume you're a total NIMBY: What would you rather live next to, a wind turbine or a coal mine?

And which mess will be easier to clean up, when all is said and done?

And which one contributes most to climate change?

I generally don't think like a NIMBY, but if you use your imagination, from a national point of view, both wind power and coal mining are economic "bads". The NIMBY question is irrelevant, if you're the nation thinking as a whole. All bads are local bads to someone. We should choose to minimize both.

However, as I've pointed out in other articles, we still need a base load power supply. So wind power may not displace coal power in production. It's more likely to displace natural gas, at least until we develop the kind of grid-scale wind forecasting that will allow us to power down coal plants in a timely manner. Such forecasting is in place in some grid areas, but it isn't ubiquitous.

But if we could choose one over the other, based on these numbers alone, the numbers implied by NRCM's latest PR effort with these Appalachian activists, we'd choose wind.

And it's very unreasonable to complain about the "blight" of wind turbines on Maine mountaintops, once you begin to think nationally, and contemplate the blight of mountaintop removal mining. That blight will still be with us in hundreds of years. If Maine's wind turbines are still around in twenty or thirty years, well, I'd be very surprised.

But it would only be because they are still useful.

And once they are not, they'll be much more easily removed and the land restored.

If we don't use the most cost-effective means to reduce climate emissions, our Maine mountains will change forever, as tree species and birds and other animals leave us, to be replaced by species more adapted to a warm climate.

Ironically, it will a climate more like southern Appalachia. Read Maine's Climate Future for the full prognosis.

I don't expect anyone to be convinced by all of this number-crunching. Least of all, one of Maine's anti-wind activists. Such folk are in many ways like the apologists for the coal industry. They are arguing uncomplicatedly for the protection of a small way of life for a very small number of people, the pleasure of seeing a view unmarred by turbines, the hope not to have Maine's still nights punctuated by the regular woosh of a turbine blade. I can sympathize a little. But like the coal industry apologists, like Knut, they're desperately holding back a turning tide.

And the real comparison is much more complicated.