Bent Sørensen is professor emeritus in physics at Roskilde University, Denmark). He has held academic positions at University of California in Berkeley, Yale University, The National Renewable Energy Laboratory in Golden (US), Kyoto University (Japan), University of Grenoble (France) and University of New South Wales (Australia) and served as advisor for the OECD, the Japanese and Australian governments, and various UN agencies, including as lead author the IPCC working group on climate change mitigation. He has published nearly 1000 scientific articles and many books, including two volumes on hydrogen and fuel cells. He served as chairman of the Danish Energy Agency's Solar Energy and Hydrogen Energy Committees, and received prizes such as the Australian-European Award for Eminent Scholars (1982) and the European Solar Prize (2002).Giuseppe Spazzafumo is associate professor at University of Cassino and Southern Lazio (Italy) and CEO at EnTraT srls. Author of more than 100 scientific papers mainly focused on hydrogen energy systems, fuel cell systems, and power to gas, Dr. Spazzafumo is also editor or co-author of four books. He has been invited as a plenary speaker to several international conferences and was a member of scientific committees at many international conferences. He was the scientific coordinator of some research activities financed by ENEA, ENEL, APAT, Italian Ministry of Research and obtained 4 Italian patents. He is a member of the Board of Directors and the Executive Vice President for Conferences of the International Association for hydrogen Energy.