Stress
Let's say Wind City—no relation to The Windy City—depends on wind for forty percent of its electricity. Now let's say Wind City has a particularly slow day for wind. It just ain't blowing. But it's hot, it's humid, and the people want their air conditioning on full blast.
You can't just go to the good people of Wind City, and say, "Sorry, but we just don't have any wind. You guys don't need refrigeration, or lights, or computers, do you? Wind City Hospital, you don't really need working defibrillators or those machines that keep you breathing, right?"
Wrong. You'll be scrambling like a madman to make sure the pumped hydroelectric storage and the compressed air energy storage systems are in good shape. And then you'll be checking in with the various flexibility sources Wind City has on hand for moments like this: hydroelectric and natural gas plants (source). If you sweat enough bullets and work your rear end off, the people will never need to know the wind went on strike.
Oh, and did we mention that you'll have to climb all the way up the super tall turbines? If you haven't conquered your fear of heights, having to do that could certainly prove to be a tad stressful.