Scalability of the Environmental Impacts of Pit Thermal Energy Storage: An Approach to Extrapolate the Global Warming Potential

Abstract

Pit Thermal Energy Storage (PTES) can enable seasonal load shifting, but reliable environmental indicators are lacking in early planning phases. The goal is to provide a reliable estimate of the global warming potential (GWP) without a complete life cycle assessment (LCA) for each variant. Our contribution comprises four elements: We create a transparent life cycle inventory and life cycle impact assessment (LCIA) for a referenced PTES, identify the GWP driver, derive simple geometric scalings, and provide directly usable GWP values over volume. Methodologically, we combine a prospective LCA with a geometry-based scaling of the impact driver. Two cover variants are balanced and prove to be practically equivalent. The LCIA results in a total of ≈ 5.24×105 kg CO2-eq, specifically ≈ 76 kg CO2-eq/MWh and ≈ 6.9 kg CO2-eq/m³. The drivers are the covering materials, PE foam and high-density polyethylene (HDPE), together accounting for ≈ 61%. For scaling, we use an additive multi-term model: area proportions ∝ V2/3, volume proportions ∝ V, with a small remainder remaining constant. Specific emissions decrease sublinearly, with a power fit yielding b ≈ −0.28. This results in clear priorities for planning: optimize coverage and select size specifically.