Life cycle assessment of offshore low-head pumped hydro storage and its comparison with other energy storage technologies

Abstract Purpose Europe aims to decarbonize its economy by 2050, which implies a significant deployment of renewables and energy storage technologies. Offshore low-head pumped hydro storage (O-PHS) is presented as an alternative solution for coastal countries with shallow seas and flat topography as a technology for grid-scale energy storage. Methods We conduct a Life Cycle Assessment (LCA) for the construction, operation, and maintenance stages of an O-PHS plant located in the North Sea, with a rated installed power of 2 GW and an average daily storage capacity of 8 GWh. We further compare O-PHS with conventional pumped hydro storage (C-PHS) in two inland European locations and lithium iron phosphate (LFP) batteries. Due to the location of the O-PHS plant, offshore wind electricity generation is assumed. Although the study focuses on climate change, the results for all 16 environmental impact categories of the European Product Environmental Footprint methodology are provided. Results and discussion We find that the O-PHS plant’s construction, maintenance, and operation emits around 33 gCO2eq/kWh. When comparing technologies, O-PHS greenhouse gas (GHG) emissions are slightly higher than C-PHS in the Alpine region and LFP batteries. In contrast, C-PHS results in the non-Alpine region are twice as high as the rest of the technology values. From these emissions, we see that the impacts related to electricity storage are roughly the same as those related to electricity generation. In other words, the use of O-PHS technology doubles the emissions from offshore wind farms. Although this may seem a high premium to pay, it becomes a relatively low value when comparing it to the GHG emissions from the electricity mix from surrounding countries like Germany or the Netherlands. On the other hand, the high demand for steel, copper, and magnets, together with efficiency losses, makes turbines a hotspot for the O-PHS plant in all environmental indicators. Conclusion This article urges engineers working in the O-PHS technology to focus on the turbines, increasing efficiency and considering circularity strategies during the design phase, including lifetime extension and recycling to reduce emissions across all impact categories.