Clemens has been working in the field of sustainability, waste management and renewable energy for more than fifteen years. His career took him from industrial companies, consulting companies, to independent consulting activities and international organisations. He spent four years at the ALIARSE foundation in Costa Rica, managing waste and renewable energy projects. Since 2013 he has been working for the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH and focuses on the use of biogas-technology in developing and emerging countries. In the area of renewable energy and energy efficiency GIZ is currently implementing more than 170 projects in more than 50 countries. Capacity development plays a crucial role in these projects.