0204 GMT July 16, 2019
The current claims that they do stem from a misreading of a scientific study, which does not show anything of the kind, forbes.com reported.
The study in question was conducted by Lee Miller and David Keith at Harvard University. The pair simulated what would happen if the US's entire electricity demand was supplied solely by wind turbines. This is not a plausible scenario, because the electricity grid is easier to run if it has a mix of sources rather than just one, but let's set that aside: It's a ‘what if’ question, designed solely to examine how the turbines affect the surrounding environment.
Miller and Keith estimated that this many wind turbines would heat up the surface area over the continental US by 0.24°C. The study was published in the journal Joule.
At first glance, 0.24°C seems like quite a lot — particularly when you consider that we are being told that we must do everything possible to limit global warming to 2°C or even 1.5°C. But that is where the misreadings come in.
For starters, that warming is only occurring over the US — a rather small fraction of the Earth's surface. It would take much more energy to warm the entire planet's surface by 0.24°C.
But that is almost beside the point, because the wind turbines are not generating extra heat. Instead, they are moving the existing heat around. Normally, the air just above the ground cools at night, but the rotating turbine blades draw down warmer air from higher up. So things get warmer just under the turbines at night while they're on, but they also get cooler elsewhere. The planet as a whole does not warm at all.
This is very different to what greenhouse gases are doing. They trap heat from the Sun, which would otherwise escape into space, so the entire planet warms up.
By using wind turbines instead of fossil fuels like coal, we avoid this long-term warming effect. Miller and Keith make it clear in their paper that this trumps the localised, temporary warming they describe.
At this point, you might ask what is the point of the study. In fact it has useful things to tell us, but they are subtle points.
The first is that we will need a mix of zero-carbon energies if we're to keep our society running and avoid dangerous climate change. Putting all our eggs in one basket will lead to the sort of unwelcome consequences that Miller and Keith found. That means solar, tidal, wave, bioenergy, nuclear, wind, geothermal and anything else we can think of.
For this reason, anyone who says ‘wind is better than solar’ or ‘solar is better than wind’, or any such comparison, is just being daft. It's like saying cabbages are a better food than bananas. Different energy sources will suit different places.
Second, we will need to be smart about which energy sources to place where, and how to deploy them. If an area is home to threatened wildlife that are sensitive to temperature changes, building a wind farm might be a bad idea because of the localized warming they cause — or maybe the farm could be redesigned to reduce the effect. Similarly, there is much research on how to space out the turbines on a wind farm so they don't interfere, ensuring that the farm as a whole captures more energy.
Finally, while climate change is happening at the global scale, the consequences will be local. All the talk of incremental changes in temperature can make it seem rather abstract and remote. But the real impacts are things like floods, storms, higher food prices and widespread droughts - and that's all alarmingly real.