The recent TGDaily article “Wind farms could raise temperatures” [Posted March 12, 2010 – 04:27 by Emma Woollacott] presents a possible surprise environmental concern about using millions of wind turbines to generate clean electrical energy.
It seems that wind turbines change how heat dissipates in the areas downwind of them, because they slow the wind as it spins their propellers. Once one begins to think about it, this makes perfect sense.
In a world where everything was the same temperature, you would have no wind. Wind is the heat transport mechanism. It takes heat from hot places to cooler places, where eventually it radiates out into space.
When wind turbines interfere, that thermal energy changes into kinetic energy (motion, in the form of spinning propellers). That motion is transferred to generators where it’s converted into electrical energy. Any waste heat then simply turns back into thermal energy, and is dissipated back into the nearby environment.
The net effects in terms of the local environment are at least two:
- Heat is now collected in the neighborhood of the turbine, and
- Heat downwind of the turbine is less effectively dissipated by the reduced wind, and therefore remains longer.
So as the article points out, the ‘microclimate’ in that local area may change in ways that cannot be entirely predicted: “…[U]sing wind turbines to meet 10 percent of global energy demand in 2100 could cause temperatures to rise by one degree Celsius [or about 2 degrees Fahrenheit] in the land regions where they’re installed.” [Emphasis and temperature conversion are mine – MH].
Wind turbines are carbon neutral, since they don’t use carbon-based fuel. In terms of the ‘MACROclimate’ (or ‘global climate’), they don’t contribute to global warming through CO2 exhaust, so this suspected local effect does NOT increase global average temperature. The Earth’s net ‘energy budget’ would be unchanged.
On the other hand, they may affect MICROclimates (small, localized ‘pockets’) through redistribution of heat in their local areas in ways that are technically unnatural.
New York City is a perfect example of a microclimate. You have so many people, buildings, vehicles, buried steam pipes, etc. in one, small concentrated area, that it’s long been recognized that the City has its own microclimate, and is generally a couple of degrees warmer than the surrounding suburbs. This is especially noticeable in winter. Areas surrounding Manhattan may get several inches of snow, while New York City just gets rain or maybe some sleet. When the City gets a couple of inches of snow, right across the river in New Jersey they get 2 or 3 times that. The same is true of the southern tier counties and eastern Long Island. (Western Long Island consists of Brooklyn and Queens.) It’s those couple of degrees that makes all the difference.
So you can’t simply dismiss the microclimate argument of those who live near the turbines. If you’re a farmer in an area experiencing microclimate change, your local rain and/or wind pattern might change. It might affect how well or poorly your crops grow, and how much you earn at the end of your growing season. There would be winners and losers. And there’s no way to entirely predict it, since our knowledge of climate (micro OR macro) is nowhere near good enough to model with extreme accuracy.
So the locals may have a right to be concerned.
I’ll also throw this out as a random thought…
If we ever fly Solar Power Satellites (SPSs), like the wind turbines they will also be carbon neutral, but they won’t be entirely neutral. They’ll capture sunlight that would have by-passed the Earth and beam it down as another form of energy; say, microwaves that will then be converted to electricity. Electricity’s waste product is heat. (Try touching a lit incandescent bulb if you need a simple example.) This has the effect of slightly increasing Earth’s net solar heating budget for each working satellite. That heat now has to somehow be radiated back into space, in addition to all the other heat radiating back into space… Or it won’t be, depending on the effect of greenhouse gases in the atmosphere.
So … As Rosanne Rosannadanna (aka, Gilda Radnor) used to say: “It’s always somethin’. If it’s not one thing, it’s anotha.”