"Natural gas will replace coal as the leading fuel for generating electricity in the U.S. by 2025, when it will also become the world's No. 2 overall fuel source thanks to its abundance and a drive for cleaner-burning energy, according to the latest long-term outlook from Exxon Mobil Corp.
Natural gas will overtake coal as the second-largest fuel source overall, ranking behind oil and powering everything from electrical plants to home-heating systems. But Exxon said coal use will continue to grow through 2025 around the world, primarily in developing nations such as China and India and the African continent, because economic growth will be fastest in emerging nations."
MP: The chart above (source) illustrates one of the reasons that the use of natural gas will continue to grow. It has a significant cost-advantage over other forms of energy. Compared to natural gas, coal is 46% more expensive on an energy-equivalent basis, offshore wind is nearly four times more expensive, and some solar energy is almost five times more expensive.