Optimal design of stand-alone solutions based on RES + hydrogen storage feeding off-grid communities

Concerning off-grid areas, diesel engines still dominate the scene of local electricity generation, despite the related pollution concerns and high operating costs. There is thus a huge global potential, in remote areas, for exploiting local renewable energy sources (RES) in place of fossil generation. Energy storage systems become hence essential for off-grid communities to cope with the issue of RES intermittency, allowing them to rely on locally harvested RES. In this work, we analysed different typologies of off-grid renewable power systems, involving batteries and hydrogen as means to store energy, to find out which is the most cost-effective configuration in remote areas. Both Li-ion and lead-acid batteries were included in the analysis, and both alkaline and PEM electrolysis technologies were considered for the production of hydrogen. Starting from single cell electrochemical models, the performance curves of the electrolyser and fuel cell devices were derived for a more detailed techno-economic assessment. Lifetimes of batteries and H2-based components were also computed based on how the power-to-power (P2P) system operates along the reference year. The particle swarm optimization (PSO) algorithm was employed to find the component sizes that allow minimizing the levelized cost of energy (LCOE) while keeping the off-grid area energy autonomous. As a case study, the Ginostra village, on the island of Stromboli (North of Sicily, Southern Italy), was analysed since it is well representative of small insular locations in the Mediterranean area. The renewable P2P solution (0.51 €/kWh for the cheapest configuration) was found to be economically preferable than the current existing power system relying on diesel generators (0.86 €/kWh). Hydrogen, in particular, can prevent the oversizing of both battery and PV systems, thus reducing the final cost of electricity delivered by the P2P system. Moreover, unlike diesel generators, the RES-based configuration allows avoiding the production of local air pollutants and GHG emissions during its operation.