It depends entirely on pricing. Most "coal" plants switch between coal and natural gas based on current market trends. And even if coal is burned, the fuel to g

It depends entirely on pricing. Most "coal" plants switch between coal and natural gas based on current market trends. And even if coal is burned, the fuel to get the coal to the plant is petroleum-based. There are a lot of complexities involved. Of course, working in the natural gas industry, I only have limited knowledge. :)