The physicist Werner Zittel has been analyzing the depletion of fossil fuels and the restructuring of energy supply structures both regionally and worldwide. He is a founding member of the Association for the Study of Peak Oil and Gas (ASPO), a member of the steering board of its German chapter as well as a member of the Energy Watch Group. He has been working for the Ludwig-Bölkow-Systemtechnik GmbH since 1989. Zittel is a co-author of the books "Ölwechsel" and "Aufbruch. Unser Energiesystem im Wandel."