I know there is a big concern about wind and solar in which their intermittent nature may cause problems. The propaganda being pushed on the net is that they have to make back up coal burning power stations to go along with every wind farm to take up the slack when the wind isn't blowing. This sounds right at first glance but after careful consideration just doesn't hold up.
In reality, the wind farm is there to augment the existing electrical production so it offsets the use of fossil fuels. In other words, no backup coal power plant is needed. The wind farm means that whenever the wind is blowing then there is less coal or natural gas being burned. This is a good thing.
The only time it becomes a problem is when you get close to 20% of your power production coming from wind. Right now we are only at about 1.3%. But when that time comes, there are much better ways to deal with downtime than just making more coal power plants. One example is pumping air underground.
There are two ways to do it. The picture above shows the more inefficient way. But this is the only cheap way to retrofit an existing wind farm. It feeds the grid with electricity from the windmill and uses some of the power to pump air under ground into a empty natural gas well. When the wind isn't blowing, the compressed air will turn air motors or turbines that spin generators to make electricity.
The second way is to use wind turbines that have the air compressor built in instead of the generator. You can read more about it here.