Life Cycle Assessments on Battery Electric Vehicles and Electrolytic Hydrogen: The Need for Calculation Rules and Better Databases on Electricity

Abstract

LCAs of electric cars and electrolytic hydrogen production are governed by the consumption of electricity. Therefore, LCA benchmarking is prone to choices on electricity data. There are four issues: (1) leading Life Cycle Impact (LCI) databases suffer from inconvenient uncertainties and inaccuracies, (2) electricity mix in countries is rapidly changing, year after year, (3) the electricity mix is strongly fluctuating on an hourly and daily basis, which requires time-based allocation approaches, and (4) how to deal with nuclear power in benchmarking. This analysis shows that: (a) the differences of the GHG emissions of the country production mix in leading databases are rather high (30%), (b) in LCA, a distinction must be made between bundled and unbundled registered electricity certificates (RECs) and guarantees of origin (GOs); the residual mix should not be applied in LCA because of its huge inaccuracy, (c) time-based allocation rules for renewables are required to cope with periods of overproduction, (d) benchmarking of electricity is highly affected by the choice of midpoints and/or endpoint systems, and (e) there is an urgent need for a new LCI database, based on measured emission data, continuously kept up-to-date, transparent, and open access.