Waste-to-energy and waste-to-hydrogen with CCS: Methodological assessment of pathways to carbon-negative waste treatment from an LCA perspective.

• BECCS technologies operated on waste feedstock present a negative carbon footprint. • Technology and market readiness levels quantify the risk for commercial exploitation. • Climate change impact is highly dependent on the choice of functional unit. • WtH 2 has higher emissions than WtE with CCS, but these are offset by higher credits. • Temporal and geographical aspects can change the ranking order of different technologies. A growing global population and rising living standards are producing ever greater quantities of waste, while at the same time driving ever-larger demand for energy, especially electricity, or new emerging markets, such as hydrogen in more industrialised countries. A key solution to these challenges of waste disposal, rising energy and hydrogen demand is BECCS (Bioenergy with Carbon Capture and Storage); the generation of bioenergy – in the form of electricity (WtE) or hydrogen (WtH 2), as well as heat – from the thermochemical processing of waste. The addition of carbon capture and storage (CCS) to WtE or WtH 2 has the potential to make waste a zero or even negative emissions energy source, thus contributing to the removal of greenhouse gases from the atmosphere. This work undertakes a pre-screening of different BECCS configurations based on state of the art technologies and then performed an assessment of representative cases in UK for WtE and WtH 2 , necessary to understand if novel waste thermal treatment processes may become potential alternatives or improvements to current WtE plants when retrofitted with CCS. A systematic and comprehensive examination of different key Life Cycle Assessment methodological aspects reveals the importance of the functional unit and allocation approach in determining the preferred pathway in a specific context. [ABSTRACT FROM AUTHOR]