Solar cells, wind turbines and biofuels are poised to become major energy sources. (scientificamerican.com)
You don't need to predict what will be the next major energy source. (greedydwarf.blogspot.ru)
Against an overall increase in Chinese energy use of 2.2 per cent, coal was the only major energy source to see falling demand during 2014, with a 2.9 per cent drop. (carbonbrief.org)