The problem with wind power is that electric utilities have to be prepared at any time for their power production to just stop on short notice. So they must keep fossil fuel plants on hot standby, meaning they are basically burning fuel but not producing any power. Storage technologies and the use of relatively fast-start plants like gas turbines mitigates this problem a bit but does not come close to eliminating it. This is why wind power simply as a source contributing to the grid makes very little sense. Here is Kent Hawkins of Master Resource going into a lot more depth:
How do electricity systems accommodate the nature of wind and solar? They do this by having redundant capacity almost equalling the renewable capacities as shown in Figures 5 and 6 for two jurisdictions that have heavily invested in wind and solar – Germany and Ontario, Canada.
Figure 5 – Duplicate capacity requirements for Germany in 2015.
Source: See note 4, sub point a.
Figure 6 – Duplicate capacity requirements for Ontario, Canada, in 2018
Source: Ontario Power Authority
In both figures, the left-hand columns are peak demand requirements and include all the dispatchable capacity that is required to reliably meet demand and provide operating reserve. In the right-hand columns, if you look very carefully, you can see the capacity credit for wind by the slight reduction in “Peak Demand + Op Reserve.” In summary, when wind and solar are added, the other generation plants are not displaced, and, relative to requirements, wind and solar are virtually all duplicate capacity.
Wind might make more sense in niche applications where it is coupled into some kind of production process that can run intermittently and have its product stored. I think T Boone Pickens suggested having wind produce hydrogen from water, for example, and then store the hydrogen as fuel. This makes more sense because the total power output of a wind plant over a year can be predicted with far more certainty than the power output at any given minute of a day. This is one reason why the #1 historic use of windpower outside of transportation has been to pump water -- because the point is to fill the tank once a week or drain the field over a month's time and not to make absolutely sure the field is draining at 10:52 am. The intermittent power is stored in the form of water that has been moved from one place to another.