Electrolyser-based energy management (EBM) offers a versatile means for optimising the process of harnessing energy supplies derived from variable and/or intermittent renewable resources, e.g. solar (photo-voltaic), wind, wave and tidal. In general, EBM systems consist of an electrolyser, water and gas (hydrogen and, optimally, oxygen) storage and management systems and a means of (re-) generating electricity, e.g. a fuel cell. Such systems achieve their management via energy conversion and storage, this operational principle being referred to as electricity supply-and-demand management (ESDM). Implementation of this principle offers significant advantages in the utilisation of variable and/or intermittent renewable resources, as it permits electricity generated during periods of high-availability/low-demand to be ＇＇time-shifted＇＇ for subsequent re-supply during periods of low-availability/high-demand. Furthermore, EBM systems have the important advantage over other ESDM systems that the stored form of energy is readily utilisable as a pollution-free gas supply for thermal end-uses. This reconversion route significantly enhances the overall energy-conversion efficiency. Electrolyser and fuel cells based upon proton-exchange membrane technologies are preferred because these afford considerable operational advantages over any alternatives. In this paper these advantages are expanded upon and preliminary data based on these ideas are presented.