More than 80% of the world-wide energy demand is currently supplied by the fossil fuels coal, oil or gas. It will be impossible to find alternative sources, which could replace fossil fuels in the short or medium term. The energy demand is simply too high.... Another issue is the non-renewable characteristic of fossil fuels: It took nature millions of years to generate these resources, however we will have used them up within the next decades. Alone the shrinking supply will not make it possible to continue as usual for a longer time... Hope it helps..