Study: Fossil fuels like coal, natural gas and petroleum will continue to be a primary source of energy in the future even as new technologies are at hand to ensure they are environmentally safe, a US study has pointed out. "In less developed nations such as China and india, oil and coal often set the economic standard as a central-station electricity source, not biopower and intermittent alternatives such as energy from sunlight and naturally blowing wind,"a paper by Robert L Bradley, president of the Institute for Energy Research in Houston and an adjunct scholar of the Washington-based Cato Institute has said.