Mighty Winds Meet
Energy Needs


getmedia/ceedba49-5d13-49dc-ab7f-44a2a571652e/Mighty_Winds_Meet_Energy_Needs-thumb.jpg.aspx?width=60&height=60&ext=.jpg

There’s no energy source that doesn’t have its naysayers. Though it’s not likely that wind turbines will add any carbon dioxide to the atmosphere, or strip the earth of forest or mountaintop, perhaps, some say, there’s only so much of it. If we start relying on the air currents for all our power, could there be a day when those currents fail and all sailboats are dry-docked, all kites grounded, and all wind socks limp?

The answer is blowing in the climate model. “The big question that we were trying to get at was basically how much wind can you take out of the atmosphere? Is wind a renewable resource?” says Kate Marvel, a researcher at Lawrence Livermore National Laboratory. “There’s been chatter in the popular press saying, if you have too many turbines, it’ll slow down the winds, that there won’t be any wind.”

Marvel’s model is simple to understand. Take the atmosphere with all its dynamics and add drag all over the place. “We had a parameter that allowed us to crank up that density,” says Marvel. That meant she could take a look at how wind power might change the winds and the weather if it met our current energy needs (18 terawatts), our future energy needs (something like 40 terawatts by the end of the century), or absurdly high energy needs (1,800 terawatts or more).    

Meeting Energy Needs

Marvel is quick to point out that, whatever the effect on the atmosphere, actually trying to meet all our energy needs with wind is probably not a good idea. Aside from the fundamental efficiency issue, high-altitude turbines that tap the jet stream would impact anything that flies—planes, birds, bats. To build anything that high on a large scale would require an enormous amount of resources. Then, there’s the transmission issue for less breezy lands. And, of course, some people just don’t want to look at them. “No one is seriously saying let’s satisfy all our energy demands with wind,” says Marvel.

That said, the results of her model are simply put. “If you generated all electric needs, electrified all transport, and put turbines everywhere, it would basically have no effect,” says Marvel.

Full steam ahead, then.

Wind turbine farm in Netherlands.

Increasing the Drag

Crank up the drag, though, and things start to happen. With the winds and the climate at their current state, hot air rises at the equator and moves toward the poles. The air sinks before it gets to either pole, which is why we have jet streams. “If you increase the drag to crazy levels, you mess with that circulation pattern,” says Marvel. “You can force the air to go all the way to the poles. You get this really interesting one cell pattern.”

Needless to say, “Something like this would have massive effects on everything,” she says. Storm systems would be disrupted, the churning of nutrients in the ocean would be reduced, plankton and marine life would die off. Luckily, we’re not likely to need 100 times our current energy consumption any time soon . . . right?

Marvel’s calculations can test out even more extreme scenarios. What if we did use all the energy our winds had to offer? If we increase the drag to the point where there’s truly no wind left we’d end up with a slightly faster spinning planet, to the tune of .007 seconds a day. “This is about how much the tidal forces from the moon slow down the Earth every 400 years,” says Marvel. “So, you could think that stopping the atmosphere might return us to the day length that Columbus experienced.”

For those nostalgic individuals who yearn for the day length of years past, Marvel has only bad news: “Obviously you can’t go out and cover the entire atmosphere with wind turbines.” For those of us focused on more contemporary needs, don’t worry. “We’re not going to run out of wind,” she says.

Michael Abrams is an independent writer.

If you generated all electric needs, electrified all transport, and put turbines everywhere it would basically have no effect.

Kate Marvel, researcher, Lawrence Livermore National Laboratory.

getmedia/ceedba49-5d13-49dc-ab7f-44a2a571652e/Mighty_Winds_Meet_Energy_Needs-thumb.jpg.aspx?width=60&height=60&ext=.jpg

December 2012

by Michael Abrams, ASME.org