Pierre Odru is an engineer at the Ecole Centrale de Lyon, France, and has retired from IFPEN. He worked in research and development in deep-sea oil production, gas transport with IFPEN and energy storage for the French National Research Agency. Elena Palomo Del Barrio is a professor at the University of Bordeaux, France, and Scientific Director of the Thermal Energy Storage Department at CIC energiGUNE in Spain. She is a world-renowned specialist in phase-change materials and has published over 100 articles in international journals.