Wind Power Has its Limits, But It’s Not the Sky

From the climate’s point of view, wind turbines are a great way to generate electricity. The energy source is absolutely free, and turning breezes into kilowatts releases precisely zero heat-trapping greenhouse gases. Sure, it takes energy to build and transport and assemble turbines — some of it, undoubtedly, derived from fossil fuels — but once that giant pinwheel is up and turning, emissions drop off the map. The other thing people like about wind power is that it’s essentially limitless.

Limitless, that is, unless you’re a scientist who thinks hard about such things. Three of those scientists have been thinking hard about the limits of wind power — and their thoughts have turned into a paper just published in Nature Climate Change.

In principle, they argue, the very existence of wind turbines could slow the planet’s winds to the point where they couldn’t generate any more energy. In practice, fortunately, that’s not likely to happen anytime soon.

The analysis considers both conventional, ground-based wind turbines and futuristic flying turbines that could take advantage of the steadier, stronger winds that blow at high altitudes. In both cases, a big enough fleet would slow the wind and limit the total energy available for electricity making.

For the flying windmills, that limit would be 1,800 terawatts, or 1.8 billion watts — 100 times more electricity than the entire planet currently uses. The ground-based turbines would top out at a mere 400 terawatts, or 20-ish times current demand.

“It is likely,” write the authors drily, “that wind power growth will be limited by economic or environmental factors, not global geophysical limits.”

That’s not to say that switching entirely to wind power would have no effect on the atmosphere. The climate models the scientists used show that a worldwide wind-based energy economy could decrease global precipitation slightly, by altering weather patterns.

On balance, however, the conclusion is pretty straightforward: we can build as many wind turbines as we could possibly want, and the Earth will be able to handle it just fine.