ABSTRACT
The world’s current energy system, based primarily on fossil fuels, does not correspond to the requirements of sustainability in many respects [1-2]. The expanding world population and the improving standards of living and demands for energy in developing countries is putting increasing pressure on diminishing fossil fuel resources and making them even more costly. Predictions based on extrapolation of the energy consumption show that the demand will soon exceed the supply. However, it is dif—cult to establish exactly how long the fossil fuels will last. New oil and gas —elds are being still discovered, and the methods for retrieving oil from known —elds are continuously improving although extraction energy costs would become higher than the actual energy yield due to the increased energy costs for research, deep drilling, as well as to lower quality and accessibility of the still available oil storages [3]. Vast reserves, like tar and gas hydrates, await novel technology to enable their economically and environmentally sound exploitation. Large coal reserves can also be exploited, for example, through gasi—cation and Fischer-Tropsch synthesis.
