1. Institute of Engineering Thermodynamics, Electrochemical Energy Technology, German Aerospace Center (DLR), Pfaffenwaldring 38-40, Stuttgart D-70569, Germany
2. Institute of Building Energetics, Thermotechnology and Energy Storage (IGTE), University of Stuttgart. Pfaffenwaldring 31, Stuttgart D-70569, Germany
3. Department of Chemistry, Centre for Materials Science and Nanotechnology (SMN), University of Oslo, Oslo NO-0315, Norway
4. Department of Mechanical Engineering, College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan
5. Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8569, Japan
6. SINTEF, Forskningsveien 1, Oslo NO-0373, Norway