Photovoltaic power plants with hydraulic storage: Life-cycle assessment focusing on energy payback time and greenhouse-gas emissions- a case study in Spain

The present work sets out to evaluate the environmental profile of a Photovoltaic (PV) plant with hydraulic storage in Catalonia (Spain). Life Cycle Assessment (LCA) has been conducted. Eight configurations have been studied: the initial one and seven alternative options. The reference plant is of 150 kWp and has 385 mono-Si PV modules, 4.3 kWh/kWp/day specific PV power output and 150 m height difference between the high-level reservoir and the low-level one. The reference system has a storage capacity of 500 kWh and the turbine has 70% efficiency. The other configurations have different materials/components (pumps, pipes, etc.) comparing to the initial one. Regarding the reference system, global-warming-potential and cumulative-energy-demand results reveal that the PV panels are responsible for about 60-62% of the total impact. The storage system shows percentages which range from around 12 to 14%. Considering a lifespan of 25 years, the initial system offers 9.1 t CO2.eq/kWp lifetime avoided emissions and has life-cycle emissions which vary between about 67 and 76 g CO2. eq/kWh. Taking into account all the PV plants, energy-payback-time values range from 2 to 3 years (approximately). Considering all the scenarios, the life-cycle emissions range from around 66 to 81 g CO2.eq/kWh.