Minimizing renewable hydrogen costs at producer's terminal gate with alkaline electrolyser, proton exchange membrane, and their co-installment: A regional case study in China

China leads in deploying large-scale alkaline (ALK) and proton exchange membrane (PEM) electrolysers for renewable hydrogen production. However, they are often overbuilt to handle intermittent renewable electricity (RE), leading to frequent system shutdowns, wasted capacity, or extensive investment. In this work, we propose a co-optimization solution in which ALK and PEM are collocated alongside hybrid RE supply from solar and wind energies. Implementing such a strategy could achieve the lowest hydrogen costs at producer's terminal gate, with production levelized costs of hydrogen (PLCOHs) down to 5.05, 4.13, 3.89, and 5.97 USD per kg respectively in south, north, west, and east regions of China. The co-optimization strategy, harnessing the combined strengths of ALK and PEM systems, efficiently minimizes hydrogen production costs while also presenting opportunities for the integration of advanced technologies into existing facilities.