Decarbonized Electricity Systems: The Critical Impact of LCA Methodology on Climate and Toxicity Impacts

Life cycle assessment (LCA) studies show that electricity supply and consumption are often a dominant contributor to environmental impacts, yet these results are highly sensitive to the choice of inventory database and its embedded assumptions. This study examines how database structure and scenario flexibility shape electricity-related impacts by comparing three approaches for the 2022 Northeast Power Coordinating Council (NPCC) region in the USA: the Ecoinvent “market for electricity” dataset, the modular U.S. electricity model from the Sphera database, and a customized NPCC model built from Ecoinvent unit processes. Impacts were assessed with both ReCiPe 2016 and TRACI 2.1. While climate change and fossil resource depletion results were consistent across databases and impact assessment methods, toxicity-related categories diverged substantially, with substantially higher values from Ecoinvent inventories. These high toxicity values were directly linked to assumptions about the use of copper in grid infrastructure (66%), including incineration at its end of life (18%), a disposal technique that is not relevant to the NPCC area. A case study of residential heating electrification further highlighted that while heat pumps with a decarbonized grid consistently reduced climate impacts, conclusions for other categories varied depending on the database used. These findings underscore the importance of transparent electricity models and cross-database sensitivity analysis in prospective LCAs when evaluating the overall environmental and health benefits of a sustainable energy future (UN SDG 7, 13). Without such practices, non-climate results, particularly toxicity outcomes, risk reflecting database assumptions and artifacts rather than real technological and environmental differences.