Stop burning fossil fuels to generate electricity. Solar cells, hydropower, wind power, nuclear power. Solar cells are not yet practical or cost efficient. Will not work in high latitudes or cloudy areas where sunlight is not steady or intense. Hydropower is a regional solution.
Wind power is also a regional solution of limited capacity.
Also, there is only a limited supply of uranium for use in nuclear reactors. A possible solution is nuclear fusion. This is the process which powers the sun. The technological problems for practical nuclear fusion power are enormous. Because of the technological problems, the U.S. is lagging far behind the rest of the world in developing fusion power.