Life Cycle Assessment of hydrogen production from waste

As the global population and standards of living continue to rise, so do waste generation and energy demand, creating an urgent need for sustainable energy solutions. Hydrogen is emerging as a key component of the transition away from fossil fuels, especially for sectors and activities where direct electrification appears unfeasible. As an alternative to the widely studied green and blue hydrogen production technologies, this dissertation explores hydrogen production from non-recyclable mixed plastic waste (Waste-to-H2 concept) as an innovative approach that combines waste management with renewable energy production. In particular, the objective of the work, bridging recent studies and research on the Waste-to-H2 concept, is to discuss the full environmental implications of hydrogen production from waste and present a life cycle assessment (LCA) of such process, applied to mixed plastic waste (MPW). A process scheme for the Waste-to-H2 concept, based on advanced gasification of MPW coupled with carbon capture and storage (CCS), is identified and the related mass and energy balances are estimated. Inputs and outputs are compared with those from MPW incineration with CCS for electricity and heat generation. Eventually, the life cycle inventory of the Waste-to-H2 process is reconstructed, complementing data from relevant literature and databases, in order to track the emissions of greenhouse gases alongside the entire supply chain of the process. The results allow estimating a carbon intensity of hydrogen production via waste gasification. A comparison with the carbon intensity of established green and blue hydrogen technologies is performed. The findings indicate that Waste-to-H2 offers significant environmental advantages by transforming waste into hydrogen, while minimizing greenhouse gas emissions through CCS. However, energy-intensive steps like gasification and syngas purification are identified as critical areas for future efficiency improvements.