Battery energy storage system (BESS) could be a major enabling technology for the successful integration of renewable energy, providing improved grid flexibility, but they are vulnerable from an environmental perspective because of their production, mining and end-of-life processes. The 100 MW / 129 MWh Interface Minety BESS in Wiltshire, UK is one of the largest lithium-ion BESS projects in Europe and this case study applies Life Cycle Assessment (LCA) methodologies (ISO 14040/14044) to look across its cradle-to-grave impacts based on data provided by Carvalho et al. (2021). The study shows that the initial life cycle climate impact of charging electric vehicles with this electricity is 24.2 g CO₂-eq per kWh delivered, where most of the climate impact comes from manufacturing and operational charging losses. Most importantly, the operational electricity mix affects the environmental impact: emissions decrease by more than 50% if the charging is done entirely with renewables. Longevity of batteries, as well as recycling and usage, are also significant factors in the sustainability outcomes. The main thing we learned from the Minety project is the importance of clear environmental reporting. It is suggested in this analysis that existing procurement approaches need to move beyond just operational efficiency to whole-life driven approaches, both for grid-scale storage solutions and for procurement by both policymakers and developers more broadly. Sustainability of BESS is not only dependent on battery chemistry, but also on charging patterns, decarbonization pathways of the grid, material recovery and BESS asset management.