Blay-Roger, R, Bach, W, Bobadilla, LF, Reina, TR, Odriozola, JA, Amils, R and Blay, V (2024) Natural hydrogen in the energy transition: Fundamentals, promise, and enigmas. Renewable and Sustainable Energy Reviews, 189. 113888. doi:10.1016/j.rser.2023.113888