A model-based parametric and optimal sizing of a battery/hydrogen storage of a real hybrid microgrid supplying a residential load: Towards island operation

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In this study the optimal sizing of a hybrid battery/hydrogen Energy Storage System “ESS” is assessed via a model-based parametric analysis in the context of a real hybrid renewable microgrid located in Huelva, Spain, supplying a realtime monitored residential load (3.5 kW; 5.6 MWh/year) in island mode. Four storage configurations (battery-only, H2-only, hybrid battery priority and hybrid H2 priority) are assessed under different Energy Management Strategies, analysing system performance parameters such as Loss of Load “LL” (kWh;%), Over Production “OP” (kWh;%), round-trip storage efficiency ηESS (%) and total storage cost (€) depending on the ESS sizing characteristics. A parallel approach to the storage optimal sizing via both multi-dimensional sensitivity analysis and PSO is carried out, in order to address both sub-optimal and optimal regions, respectively. Results show that a hybridised ESS capacity is beneficial from an energy security and efficiency point of view but can represent a substantial additional total cost (between 100 and 300 k€) to the hybrid energy system, especially for the H2 ESS which presents higher costs. Reaching 100% supply from renewables is challenging and introducing a LL threshold induces a substantial relaxation of the sizing and cost requirements. Increase in battery capacity is more beneficial for the LL abatement while increasing H2 capacity is more useful to absorb large quantities of excess energy. The optimal design via PSO technique is complemented to the parametric study.