Environmental Sustainability Assessment of Hydrogen from Waste Polymers

The rising demand for single-use polymers calls for alternative waste treatment pathways to ensure a circular economy. Here, we explore hydrogen production from waste polymer gasification (wPG) to reduce the environmental impacts of plastic incineration and landfilling while generating a valuable product. We assess the carbon footprint of 13 H₂ production routes and their environmental sustainability relative to the planetary boundaries (PBs) defined for seven Earth-system processes, covering H₂ from waste polymers (wP; polyethylene, polypropylene, and polystyrene), and a set of benchmark technologies including H₂ from natural gas, biomass, and water splitting. Our results show that wPG coupled with carbon capture and storage (CCS) could reduce the climate change impact of fossil-based and most electrolytic routes. Moreover, due to the high price of wP, wPG would be more expensive than its fossil- and biomass-based analogs but cheaper than the electrolytic routes. The absolute environmental sustainability assessment (AESA) revealed that all pathways would transgress at least one downscaled PB, yet a portfolio was identified where the current global H₂ demand could be met without transgressing any of the studied PBs, which indicates that H₂ from plastics could play a role until chemical recycling technologies reach a sufficient maturity level.