This paper, published in the Proceedings of the National Academy of Science in 2012, explores the limits of wind energy extraction on Earth. The bad news is that one cannot indefinitely add more and more wind turbines and obtain more and more wind power and electricity because the atmosphere reaches a saturation point passed which no additional wind energy can be extracted, no matter how many new turbines are added. The good news is that this "saturation point" is very very high, on the order of 70 TW (1 TW = 1 TeraWatt = 10E12 W). Even for wind energy penetrations that are high for today's standards, like 50% of global electricity demand, the impact on the atmosphere's energy cycle is miniscule. Thus humanity does not need to worry about extracting too much wind power, there is plenty of it and it will remain renewable!
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