My basic motivation has been, and still is, the compassion for social justice caused by a feeling that this is right. In addition, I fancied for myself not to become a mere private individual but to participate in developing and designing society. For these reasons, I became, in 1965, a member of the Social Democratic Party (SPD). I engaged in the students' revolution between 1967 and 1969 and became president of the student's parliament at the University of Heidelberg, then I was engaged in the young socialists' party, the youth organization of the SPD. In 1975/76, I was federal vice chairman of this organization.

Having finished my studies in political and social science, public law and economics in 1972, I worked as a scientist at the University of Stuttgart, and from 1976 to 1980 at the German Nuclear Research Centre. There I elaborated studies in the field of Nuclear Non-Proliferation.

In 1980, I became an elected member of the German Parliament.  In the 80ies, I focused politically mainly on disarmament and arms control. I became spokesman of the SPD group in the German Parliament and later chairman of the Parliament's committee on disarmament and arms control. In 1986, I published "The Liberation From The Bomb" - a book where I elaborated the urgent need and the strategy for a comprehensive global nuclear disarmament.

In the mid of the 80ies, when the call for a shut-down of nuclear reactors became popular, I supported this. But my question for the future was: "What is the non-fossil alternative to nuclear energy?" It seemed to me a narrowed view only to call for energy savings and energy efficiency. I started working on the solar alternative to nuclear and fossil energies. The huge majority of energy experts, including the experts in ecological issues, underestimated the real potential of Renewable Energies.

In 1988, I founded the European Association for Renewable Energies EUROSOLAR, a non-profit organization, and became its president in an honorary function. This organization has the goal to work for the full replacement of nuclear and fossil energies and defines it as the main challenge for the coming century. The work of EUROSOLAR focuses on

• the public campaign to create a public awareness: the cancellation of all nuclear and fossil energy supplies is possible;
• the development and dissemination of policy concepts from the local to the international levels to promote Renewable Energies;
• organizing democratic pressure in the public and within public institutions to implement promoting steps;
• organizing many conferences to multiply concepts in the fields of: solar architecture and urban planning, development of green power markets, financing Renewable Energies, training and education for Renewable Energies' issues, energy for Africa, and others.

Since 1988, EUROSOLAR organized more than 25 international conferences, among them the European Conference Solar Energy in Architecture and Urban Planning, with 800 participants; the Earth Conference on Biomass, with 600 participants; and the European Conference Renewable Energies for Regions and Cities, with 500 participants. Furthermore, EUROSOLAR organized several hundred workshops and was represented with speakers in more than 20 000 events on Renewable Energies.

EUROSOLAR gave the incentives for national initiatives for Renewable Energy Feed-in-Tariff-Laws, for the EU White Paper on Renewable Energies, for new research and development activities on Renewable Energies, for solar village and solar home concepts of the World Bank and other development banks, and for new legal frameworks for buildings using solar energy.

In the German Parliament, the German Renewable Energy Feed-in-Tariff-Law, the new Federal Building Law (prioritising Renewable Energies), the Tax-Free-Law for Biofuels and the 100,000 PV-Roofs-Programme are based on my initiatives.

Since 1988, I gave more than 200 public speeches at the national and the international level and I published several hundred articles.