This paper presents the life cycle impact (LCI) assessment of a solar photovoltaic (PV)/fuel cell/battery/electrolyzer/hydrogen storage hybrid energy system for powering a 19 m³/day seawater reverse osmosis desalination plant across four South African coastal locations: Alexandra Bay, Jeffery Bay, Paternoster, and Ramsgate. Following the IEA-PVPS Task 12 methodology extended to all hybrid system components, the LCI is evaluated in terms of the life cycle carbon emission rate (LCER), global warming potential (GWP), cumulative energy demand (CED), energy payback time (EPT), and net energy ratio (NER). A cradle-to-operation system boundary is adopted with a functional unit of 1 m³ of freshwater produced. The CED reported represents the single-installation embodied energy of all components, consistent with the IEA-PVPS attributional LCA convention. Using site-specific annual solar irradiation of 1,680 to 2,223 kWh/m²/yr, a GHG emission rate of 37.3 to 72.2 g CO₂-eq./kWh for monocrystalline silicon modules, and system lifetimes of 20 to 30 years, the total system CED ranges from 91,128 to 185,488 MJ-eq. The EPT values range from 2.04 to 3.89 years after proper unit conversion of CED from MJ-eq. to kWh-eq. (division by 3.6), and NER ranges from 5.15 to 14.69 across sites and lifetime scenarios. The battery bank and hydrogen storage subsystem each contribute approximately 22% and 22% of total lower CED respectively, representing a combined storage burden of 44% that exceeds the contribution of the PV array components at most sites. All hybrid configurations achieve lifecycle GWP reductions of 87.9 to 94.7% relative to a diesel generator baseline. These results show that although hydrogen integration offers long-duration storage, it has a lifecycle energy burden that is similar to that of the battery bank, showing that a critical trade-off of storage will need to be considered when designing hybrid renewable desalination systems alongside operational reliability.
Keywords
Life cycle impact assessment; solar PV; hydrogen storage; fuel cell; desalination; energy payback time; net energy ratio; cumulative energy demand; South Africa.