Sustainable ammonia production from plastic waste gasification integrated with partial oxidation: Technoeconomic assessment

Plastic waste has become a pressing global environmental issue as production and disposal rates surge worldwide. Most plastics are non-biodegradable and accumulate in landfills and the natural environment, posing severe ecological risks. Meanwhile, energy demand continues to escalate rapidly due to population and economic growth. Dependence on fossil fuels exacerbates climate change through emissions of greenhouse gases. There is urgency to find sustainable solutions to both the plastic waste crisis and clean energy needs. Ammonia has great potential as a carbon-free fuel and hydrogen carrier to facilitate renewable energy storage and distribution in a low-carbon economy. However, current ammonia is predominantly manufactured through natural gas reforming, which is carbon intensive. This study proposes an integrated process design to produce ammonia via plastic waste gasification coupled with partial oxidation for clean hydrogen generation. The concept offers a circular solution by thermally recycling plastic materials into a useful chemical commodity while achieving carbon neutrality. Aspen Plus process modeling is employed to simulate three integrated plastic gasification and hydrogen production designs. Key results show the configuration coupling plastic waste gasification with natural gas partial oxidation (Case 3) achieves the highest cold gas efficiency, and process efficiency of 49% and 45.5% respectively, greater than the other designs. Case 3 also exhibits the lowest levelized ammonia production cost of $0.310/kg and is the only design found to be economically viable through cash flow analysis. The integrated plastic-ammonia process demonstrates promising potential to address mounting plastic pollution and energy transition challenges through chemical upcycling in a sustainable manner.