 P. E. Hodgson, a senior research fellow emeritus in physics at Corpus Christi College, Oxford, expects the world energy use to double every fourteen years and the need to increase faster still, and he insisted in 2008 that the world oil production, a main resource of fossil fuel, was expected to peak in ten years and thereafter fall.The principle of supply and demand holds that as hydrocarbon supplies diminish, prices will rise.Therefore, higher prices will lead to increased alternative, renewable energy supplies as previously uneconomic sources become sufficiently economical to exploit.