Techno-economic assessment of integrating hydrogen energy storage technology with hybrid photovoltaic/pumped storage hydropower energy system

Due to the intermittency of solar radiation, solar-driven energy systems need to be equipped with storage facilities to be sustainable. Using multiple storage facilities improves the reliability of an energy system. This study aims to assess the techno-economic influences of adding a hydrogen energy storage (HES) facility (composed of electrolyser, fuel cell, compressor and hydrogen tank) to a hybrid photovoltaic (PV)/pumped storage hydro-power (PSH) system. To this end, PV-PSH and PV-PSH-HES systems are separately designed for an off-grid coastal area in the south of Iran. The designed systems are then compared to figure out the influences of the added HES section. Although the HES unit is found to have a relatively small capacity compared to the PSH unit, it provides a variety of benefits. The HES unit consumes part of excess electricity to produce hydrogen and causes the excess electricity supply to be reduced by 15.3%. Furthermore, it helps producing electricity in summer time and, accordingly, allows the PV and PSH sections to be designed smaller. The turbine power, reservoir volume, and PV size of the PV-PSH-HES system are observed to be 9.8%, 2.3%, and 0.6% less than those of the PV-PSH system, respectively, that leads to a total cost reduction of 0.5%. The addition of the HES unit also results in a 5.4% increase in the exergy efficiency due to the reduced solar exergy input (as a result of a smaller PV size) and the added chemical exergy output as hydrogen. The cost analysis shows that for both PV-PSH and PV-PSH-HES systems, the highest cost is related to the PV section (about 53% of total cost) followed by the PSH section (about 45% of total cost). Also, the HES unit in the PV-PSH-HES system imposes the lowest cost (about 2% of total cost) due to its relatively small size.