An assessment of electrolyser portfolio for offshore hydrogen production considering its key properties – efficiency, ramp rate and capacity

Wind-electrolyser systems that produce green hydrogen – including hydrogen-generating offshore energy hubs – have received a lot of attention. The electrolyser capacity in such systems can be arranged in different configurations by varying the location setup of the electrolysers. The setup influences not only the dynamic performance of electrolysers but also the system economics. This paper analyses the differences in the dynamic performance of electrolysers in a centralised and decentralised setup from a technical and economic perspective, when the target is to produce as much renewable hydrogen as possible using today’s electrolyser technology. The economic effects of scaling for various wind turbines under different wind conditions are incorporated in the analysis. Differences in electrolyser efficiency, start-stop, ramping, operation range and scale are modelled, and the models are applied to a case study depicting an offshore energy hub. Using a representative wind profile of fluctuating conditions and considering identical electrolyser ramping and efficiency for the same turbine configuration, the analysis shows that the single electrolyser solution (centralised), where the electrolyser is sited at a substation, gives a better levelized cost of hydrogen than the alternative setup (decentralised) with multiple in-turbine electrolysers.