This work focuses on different processes for the production of H2 from biomass and/or waste. It is divided into three parts: bio-fuels and hydrogen from biomass gasification; overview of technologies for H2 production from waste; case study analysis of an electrolyzer in an incineration plant (Waste-to-Energy – WTE).
Without adequate supporting legislation, biomass conversion processes based on gasification are hardly competitive from an economical perspective, but the analysis conducted has highlighted how they can work as a versatile system with the potential to increase the renewable energy system resilience. The following points are highlighted:
– The “biomass-to-X1” systems are suitable for integration with electrolyzers in “power & biomass-to-X2” systems, capable of increasing the exploitation of biogenic carbon (up to carbon efficiency values above 90%) and the production of biomethane, bio-methanol, or other bio-fuels during hours with abundant renewable electricity.
– “Biomass-to-X” systems are flexible in terms of management, as they can co-produce hydrogen, electricity, or a carbon-based product, following market demand and contributing to the provision of ancillary services, which increases the value of this solution for the electricity system
– Biomass-to-X systems generate excess biogenic CO2 that can be permanently sequestered with carbon capture and storage (CCS) systems, thus achieving net negative GHG emissions. Integration with CCS infrastructure is considered the preferred solution for biohydrogen production plants.
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From the analysis of the various technologies at different development stages which exploit waste to obtain hydrogen or biofuels, two essentially emerge as the main ones: those based on pyrolysis/gasification, and those adopting a plasma treatment, with uncertain results from the point of view of economic feasibility (these are extremely energy-intensive processes).
As for the study of the integration of an electrolyser in a waste incineration plant, reference was made to the SILEA waste-to-energy plant in Valmadrera (LC) on which a technical-economic feasibility analysis was conducted. The economic assessment shows how, in the hypothesis of a cost of energy taken from the grid equal to 120 €/MWh and an opportunity cost of energy taken from the waste-to-energy plant equal to 57.5 €/MWh, the alkaline system is more economically advantageous than the high-temperature SOEC electrolyzer. In the mid-term case (considering the economic prospects of the technologies in the medium term), the advantage of the alkaline system is diminishing, and the two low- and high-temperature technologies are economically equivalent.