He is an environmental engineer and studied Technical Environmental Protection (Technical University of Berlin) with 25 years of experience. Since 2006 he is full professor of Waste Management and Material Flow of the Faculty of Agricultural and Environmental Sciences of the University of Rostock, Germany. Since 2012 Prof. Nelles is also the Scientific Director of the German Biomass Research Center (DBFZ) in Leipzig.
His research activity is based on: fundamental and applied aspects of waste management with focus on technological, environmental and economic aspects to mechanical, biological and thermal treatment systems of waste and biomass in different recycling and recovery routes.
He is a member of national and international Advisory Boards of organisations, conferences and journals in the field of waste management and biomass utilisation. He is author of over 400 articles and chapters in books and journals since 1993.