Sustainable Energy Systems based on Renewable Energy Sources

A sustainable energy supply will need two bases. First, it must rest on renewable energies; second, it must use available resources efficiently. Solar energy, geothermal energy, wind power and hydropower are the earth's only real renewable energy sources and must be utilised in a way to provide enough energy to cover an ever increasing energy demand throughout the whole year.

Scientific studies have repeatedly documented the possibility of a full supply by renewable energies. Such studies were never disproved but considered utopian, although they relied on the status quo of the technologies already achieved and projected the introduction of these renewable energies on to total energy demands. This optimism can be justified by the experience of several technical revolutions. Modern technological history shows us many examples of technologies, which were underestimated at the outset but became a dominant mass product only a few decades later (e.g. Telephone, cars or computers). Each of them caused structural changes, transforming societies, creating new jobs and displacing earlier technologies and economic strategies. Technologies for the use of renewable energy are less complex than those of the aviation and space industry or the use of atomic energy.

A solar energy system that provides a reliable energy supply throughout the year includes the consistent use of local renewable energy sources, whether it is wind power along the coast or in windy regions, biomass in rural areas, photovoltaics in developed localities, the passive and active use of solar heat, solar thermal power plants in sunny regions and hydropower, wherever possible. A second feature of such an energy supply structure is the intelligent exchange of energy between these regions. This exchange can take place through the power grid or a gas network using solar generated hydrogen or by transporting biomass. A national or international network can serve to exchange energy or to store surpluses.

Different technologies using renewable energy sources and the potential of different regions with varying strengths and weaknesses will mutually replenish a functioning energy supply system throughout the year. This approach balances the fluctuations in energy provision that can occur with some renewable energy technologies (such as wind farms). If the wind stops blowing in one region, power is then initially supplied by other regional sources such as local biomass power plants or photovoltaic units. If this is not enough, plants in other regions deliver power. The following scenarios describe such full renewable energy systems and/or the extension of renewables for different regions.

Scenarios: World / Europe / Japan / Catalunya / Germany