Environmental assessment of gasification and green hydrogen potential role in waste management decarbonization

Achieving sustainability involves implementing a circular economy model and decarbonizing the waste management sector. The development of innovative technologies that enable the reduction of emissions and resource recovery is one of the sector's greatest challenges. From this perspective, the waste-to-methanol (WtM) process represents a viable prospect, the potential environmental impacts of which have never been studied from a life-cycle perspective. A cradle-to-grave LCA analysis was conducted, studying WtM technology and its potential implementation of green hydrogen (WtM-GH) in the process, through a comparison with traditional waste-to-energy (WtE).

The results showed that WtM-GH performs best for global impacts, with a global warming potential of 3.52·10⁷ kgCO_2eq instead of 1,04·10⁸ kgCO_2eq proper of the WtE. Positive effects take place also for the fossil resource scarcity. Looking for non-toxic regional/local impacts WtE represents the best scenario, with the best performance on water consumption (7.96·10⁷ m³) and ionising radiation (2.82·10⁷ kBq Co-60_eq). Cumulative impact results, obtained through the normalization, found that WtM is the best scenario, thanks to the less toxic impact compared to the other two, especially for freshwater ecotoxicity (5.26·10⁶ kg 1,4-DCB) and marine ecotoxicity (6.73·10⁶ kg 1,4-DCB).

WtM-GH allows the production of 1366 kg of methanol per ton of Refuse Derived Fuel, thanks to the conversion of the entire CO₂ contained in the waste, enhancing the value of by-products and carbon credits on the market and making the process more economically sustainable.