The oil reservoirs under the continents are fast running out. We are now searching deep in to the ocean bed for fuel oil. Coal, natural gas resources are also almost spent. With everyday advancement of technology, you are in need of more and more power sources and the storages are running out faster. Within next 50-100 years, most of the conventional fuel sources will be totally empty. Mankind is standing on the verge of a major energy crisis. Our existence of modern technology will be under serious threat if we don't find a solution now.