A quick search turned up this paper: https://wes.copernicus.org/articles/5/1623/2020/wes-5-1623-2020-discussion.html https://wes.copernicus.org/articles/5/1623/

A quick search turned up this paper: https://wes.copernicus.org/articles/5/1623/2020/wes-5-1623-2020-discussion.html https://wes.copernicus.org/articles/5/1623/2020/wes-5-1623-2... Is this the one you're thinking of? If so it sounds like wind shear has a surprising amount of impact on it. This article also suggests up to 40% losses in downstream wind turbines in a wind farm, which might be addressed by having some turbines rotating the other way: https://www.inverter.com/the-efficiency-of-wind-turbine-in-different-direction https://www.inverter.com/the-efficiency-of-wind-turbine-in-d...