Optimal techno-enviro-economic analysis of a hybrid grid connected tidal-wind-hydrogen energy system

The study deals with the techno-enviro-economic aspects of hydrogen production using polymer electrolyte membrane electrolysers powered by a hybrid grid-connected tidal-wind energy system. System modelling is presented initially. The energy management strategies for hydrogen production are then analysed as rule-based approach and as optimised approach. An objective function to maximise the operating profit under optimal system operation is formulated considering the variable energy costs, capital and maintenance expenditure, and real system constraints. A comprehensive cost analysis of the system is obtained by comparing two different optimisation approaches based on fixed cost and levelised cost factors, respectively. Towards reaching this goal, the use of mixed integer genetic algorithm optimisation is investigated. The operation of electrolyser in terms of its different operating modes, namely stop, running, and stand-by is presented. The dynamic optimisation of an electrolyser capable of working at up to twice its nominal rating for a limited duration is also analysed in the study. The results of the optimisation approach are 41.5% and 47% higher than the rule-based approach in terms of the annualised profit and carbon emission savings, respectively. In addition, the recurrent switching of electrolyser unit operating modes is avoided with the optimisation approach, reducing the associated energy consumption of about 27.2 MWh annually. The proposed model can be used as a generic tool for hydrogen production analysis under different contexts and it is especially applicable in high green energy potential sites with constrained grid facilities.