1. Industrial Ecology Program, Energy and Process Engineering; Norwegian University of Science and Technology; Høgskoleringen 5, E-1 7491 Trondheim Norway
2. Norwegian Forest and Landscape Institute; P.O. Box 115 1431 Ås Norway
3. Center for International Climate and Environmental Research - Oslo (CICERO); P.O. Box 1129 Blindern 0318 Oslo Norway