Professor Emeritus at the Department of People and Technology, and a professor of physics at the Institute of Mathematics and Physics, both at Roskilde University, Denmark. He is also an independent consultant at Novator Advanced Technology Consulting. Bent Sørensen’s research is cross-disciplinary and has resulted in nearly a thousand scientific articles and some 40 books, including foundation work in economic theory (the scenario method, life-cycle analysis) and in energy research (renewable energy resources, technology and applications). Dr. Sørensen is one of the world’s leading specialists in renewable energy. He has five decades of experience in researching the field, and has published hundreds of monographs, articles in scientific journals, technical reports, and conference contributions. He has received several awards and has been knighted by Her Majesty Queen Margrethe of Denmark. He has worked at universities in Japan, France, Denmark, Australia and the United States (Berkeley and Yale), has been a consultant to governments and international organizations, a lead author in the IPCC climate assessment recipient of several international prizes and honors. Giuseppe Spazzafumo is an associate professor at the Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, Cassino, Italy. He obtained a degree in Mechanical Engineering and a PhD degree in Energy Systems at the University of Pisa, Pisa, Italy. His main research field is Hydrogen Energy Systems. He coauthored with Prof. Bent E. Sørensen in the third edition of Hydrogen and Fuel Cells. He is a member of the IAHE (International Association for Hydrogen Energy) Board of Directors since 1999 and President of the IAHE Hydrogen Energy Systems Division. He coordinates the HYPOTHESIS (HYdrogen POwer THeoretical and Engineering Solution International Symposium) series