Gas power plants on the grid are pretty inefficient. Like a modern furnace they are pretty efficent at getting the heat energy out of the gas. However the effic

Gas power plants on the grid are pretty inefficient. Like a modern furnace they are pretty efficent at getting the heat energy out of the gas. However the efficiency of turning the heat into electricity is low. They get something like an average of 40% overall efficiency. The best gas turbine plants on the market can get about 60% efficiency max. If the power plants were able to provide the excess heat to nearby businesses and the like, they could be a lot more efficient overall, and there are some that have tried to do that, but transporting heat itself is not an easy thing to do efficiently, and many plants are things like peaker plants, which don't run consistently, making it even harder to sensibly use the "waste" heat in the nearby communities. Then there is the grid losses. Grid transmission loses 5 to 6% of the power in the US, making the grid 94-95% efficent.