1. RWTH Aachen University, Institute of Environmental Engineering, 52066 Aachen, Germany E-mail: beier@isa.rwth-aachen.de; cramer@isa.rwth-aachen.de; koester@isa.rwth-aachen.de; palmowski@isa.rwth-aachen.de; schroeder@isa.rwth-aachen.de; pinnekamp@isa.rwth-aachen.de
2. Pöyry GKW GmbH, Kruppstraße 82, 45145 Essen, Germany E-mail: christian.mauer@poyry.com