Why the huge drop off? The two main factors are natural gas and wind energy, with solar and hydro also playing a part.
Texas is by far the largest producer of natural gas in the U.S., more than doubling the production of the #2 state, Pennsylvania. Texas is now producing so much natural gas, that a pipeline is being built that will send a significant amount of natural gas to Mexico to be used by their electricity generators.
Texas also produces more electricity via wind energy than any other state. There have already been days when the state saw more electricity produced from wind than from coal.
It is expected that by 2020, more than half of all coal-burning power plants in Texas will be shuttered.