1 Biosystems Department, Risø National Laboratory for Sustainable Energy Technical University of Denmark-DTU, Building 330, P.O. Box 49, 4000, Roskilde, Denmark. mette.hedegaard.thomsen@risoe.dk.
2 Biosystems Department, Risø National Laboratory for Sustainable Energy Technical University of Denmark-DTU, Building 330, P.O. Box 49, 4000, Roskilde, Denmark.