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.

Automated summary

The increasing demand for single-use polymers requires the exploration of alternative waste treatment methods to achieve a circular economy. This study investigates the production of hydrogen from waste polymer gasification (wPG) as a means to reduce the environmental impact of plastic incineration and landfilling while generating valuable products. The carbon footprint and environmental sustainability of various H2 production routes, including wPG, natural gas, biomass, and water splitting, are assessed in relation to planetary boundaries. Results suggest that wPG combined with carbon capture and storage can effectively reduce the climate change impact compared to fossil-based and electrolytic routes. While the cost of wPG might be higher than fossil and biomass-based alternatives, it remains cheaper than electrolytic routes. Furthermore, a combination of pathways can meet the current global H2 demand without exceeding the studied planetary boundaries, indicating the potential role of H2 from plastics until chemical recycling technologies mature.