Wind energy is some of the cleanest energy there is. It's relatively cheap to produce and easy to install, and produces power fairly reliably. So, but what happens if we transition to nothing but wind power? As dumb as it sounds, will we run out of wind? The answer seems to be "probably not," but there will be consequences.
When asking the question of whether we'll run out of wind to power wind turbines, what we're really asking is whether we'll run out of areas with wind that are powerful enough (and reliable enough) to produce a consistent and economically viable amount of energy. Researchers from the Carnegie Institution Department of Global Ecology and the Lawrence Livermore National Laboratory have taken a look at just how much wind energy it would be possible to extract from the atmosphere with wind turbines, and we're happy to report that there's a lot more wind out there than we're likely to be able to harness in the near future.
The level of present global primary power demand is approximately 18 terawatts. The researchers have calculated that, if we were to populate the entire Earth with an even distribution of wind turbines (or, in an abstract sense, things that cause drag and extract kinetic energy from moving air), the geophysical limit on wind power availability is somewhere north of 400 terawatts. If we were to use atmospheric "kite" turbines, which operate high up in the sky where the winds are stronger and more reliable, that number jumps to well over 1,873 terawatts, or more than 100x the present global demand for energy.
As fans of physics will point out, you can't get something from nothing, and wind energy is no exception. When we extract kinetic energy from moving air, that air will end up moving slower than it was before. This has the potential to mess with climate on a scale proportional to the amount of energy we're trying to extract, and the researchers modeled what would happen to global temperatures and precipitation if we were to completely cover the Earth's surface with wind turbines:
[This figure] shows zonal mean temperature change and percentage change in zonal mean precipitation for cases [of 400+ terawatt wind energy extraction at the surface and in the atmosphere]. At the scale of global energy demand [just 18 terawatts], uniformly distributed wind power would produce zonal mean temperature changes of ~ 0.1 K and changes in zonal mean precipitation of ~ 1%. Thus, reliance on widely distributed wind turbines as an energy source is unlikely to have a substantial climate impact.
So the good news is that transitioning completely to wind power right now would have a minimal effect on global climate, and would be easy to do without running out of wind, especially if we use atmospheric generators. If we need substantially more power, though, we could see localized climate changes, some of them fairly substantial: a 20 percent change in precipitation is a lot.
The thing to do, of course, is to not rely entirely on any one source: wind energy is great, but so is solar energy and tidal energy. And anyway, by the time we're sucking down 400 terawatts, we'll probably be relying on fusion and microwaves from space.