Nuclear power is our best alternative. Hiroshima will have more negative impact here than in Japan. It can certainly be done properly but never to the satisfaction of the Eco Crazies. It is therefore a political question, not a scientific or engineering question. There are plenty of ways natural gas can be used in the interim.
Natural gas has lots of chemical industry uses as well. Having lots of it is pretty neat.
Thorium power is our best alternative and about a hundred years is probably what it will take to develop it at the pace we go.