Giant wind turbines that generate fossil fuel–free power add a little heat of their own to the planet.
If the United States sprouted enough wind turbines to meet its entire demand for electricity, the turbines would immediately raise the region’s surface air temperatures by 0.24 degrees Celsius, on average, scientists report online October 4 in Joule. In the short term, that’s not a negligible amount: Current global greenhouse gas emissions are projected to warm the contiguous United States by 0.24 degrees Celsius by 2030.
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Harvard University applied physicists Lee Miller and David Keith postulated a parallel world in the years 2012 through 2014: In it, a wind farm region across the central United States generates 0.46 terawatts of electric power — as much as the country currently uses. With those hypothetical turbines in place, surface air temperatures during those years were warmer than average across the contiguous United States, particularly near the center of the wind farm region, Miller and Keith (who also started the Vancouver-based carbon capture company Carbon Engineering) found.
Wind turbines alter climate by increasing atmospheric mixing within the boundary layer, the layer of atmosphere just above Earth’s surface. The turbines’ churning increases temperatures, particularly at night, by pulling warmer air from the upper part of the boundary level down toward the cooler air just above the land surface (SN: 10/16/04, p. 246). And the turbines can redistribute moisture as well as heat: A recent study in Science reported that wind farms could increase precipitation and, therefore, vegetation in the Sahara.
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The turbines’ warming impact on the atmosphere is instantaneous, but it has a long tail: It might take a century for reductions in greenhouse gas emissions to counteract that amount of extra heat, the study finds.
Still, the study’s scenario is unlikely: Even within a fossil fuel–free world, power generation would probably include a mix of wind, solar and geothermal energy sources. And eliminating fossil fuels would reduce carbon dioxide emissions, ultimately conferring long-term benefits to the planet.