The developed sustainability scenario for a sustainable energy use in Germany until 2050 represents an all-embracing basis for the discussion about the German energy future that has to fulfil ecological and economical criteria in equal measure.

The study showed that a reduction of CO2-emissions by 80 percent until 2050 versus 1990 is technically and economically feasible for Germany by increasing the energy efficiency and the further development of the renewable energies. Such a reduction can be realised without nuclear power and without a so far disputed carbon capture and storage. This kind of development towards a sustainable energy use contributes to an active protection against crises by introducing new technologies on the market and by reducing necessary energy imports compared to the trend scenario. Even if the modification need in all sectors is very high, the relevant stakeholders have not to cope with irresolvable problems. The study starts with the identification of today's sustainability deficits in the worldwide energy use:

• The global warming mainly resulting from extensive use/combustion of the fossil energy carriers carbon, oil and gas.
• The foreseeable scarcity and rising prices for oil and gas reserves due to the fact that the production maxiumum worldwide is expected in 20 years.
• Risks related to the use of nuclear power.
• The considerable gap existing in the energy use between industrialised and developing countries kept unchanged until now.

A simultaneous reduction of all existing sustainability deficits is only possible in combination with a massive efficiency strategy basing on the development of renewable energies. In order to achieve this aim in Germany, it is necessary to consistently pursue the existing drive of an increased renewable energy use; to profit from the upcoming replacement and modernisation need of the power plant fleet by significantly increasing the energy efficiency and the use of combined heat and power generation; and to establish energy saving - especially in the electricity sector - as a main focus in the energy policy. Moreover, the long-term infrastructure demands like the already increasing decentralisation of energy and heat supply and the future transition to e.g. hydrogen as an alternative fuel require an early preparation of necessary decisions as well as to take adequate and robust development lines. The study bases on alternative scenarios trying to explore for relevant stakeholders precise lines towards a sustainable energy use in Germany. This concerns the detailed analysis of possibilities offered by technologies (Alternative scenario "Fuel cell as all-rounder") as well of structure driven modification need (Alternative scenario "Combination is the key, intelligent combined heat supply").

The study "Long Term Scenarios for a Sustainable Energy Use in Germany" was published within the UBA series "Climate Change" in a long version (no. 01/02) and a short version (no. 02/02).