Allocation Procedures in Life Cycle Assessment of Negative Emission Technologies

Negative emission technologies (NETs) play a key role in the mitigation of climate change by removing CO2 from the atmosphere. In this study a comparative life cycle assessment (LCA) of three NETs – Pyrolysis Carbon Capture and Storage (PyCCS), Bioenergy Carbon Capture and Storage (BECCS), and Direct Air Carbon Capture and Storage (DACCS) – is conducted, using a common functional unit of 1 ton of CO2 captured and stored. To account for the co-production of electricity and/or heat in PyCCS and BECCS, different allocation procedures – mass-based, energy-based, and economic – are applied and their influence on the net carbon dioxide removal (CDRnet) potential is quantified. The results indicate that the investigated PyCCS system exhibits the lowest climate change impacts in this comparison, followed by DACCS and BECCS. The application of different allocation methods reveals substantial variability in impacts, underscoring the critical importance of transparent and standardized allocation procedures for accurately assessing the environmental performance of NETs.