Techno-economic analysis of sustainable methanol and ammonia production by chemical looping hydrogen generation from waste plastic

In this work, a techno-economic analysis on a novel plant configuration achieving the combined production of ammonia and methanol through chemical looping has been carried out. The innovative process presents advantages in terms of reduced dependency on market price fluctuations, thanks to the combined production of two chemicals, and optimal utilization of the chemical looping gases. The chemical looping plant is fed with recycled high density polyethylene to enhance the carbon circularity of the process. In this case, part of the captured CO2 is employed for methanol production along with hydrogen from chemical looping, while hydrogen from electrolysis is used for ammonia production by reaction with nitrogen from the air reactor. Renewable electric energy supply ensures a carbon free power to fuel conversion. Several sensitivity analyses were carried out to assess the optimum process parameters combination, i.e. fuel flow rate, steam flow rate, oxygen carrier inlet temperature. The final production rate is divided between 174 kg/h of methanol and 910 kg/h of ammonia. An economic analysis was then carried out. A capital cost of 27 M€ and an operating cost of 3 M€/y were computed. Sensitivity analyses on the impact of the electricity input cost, the electrolytic oxygen selling price, the electrolyser capital cost and the internal rate of return were carried out. The electricity demand was discovered to impact for the 68% of the total operating costs. For an electricity cost of 0.03 €/kWh, oxygen selling price of 0.07 €/kgO2 and internal rate of return of 8%, a final products cost of 0.76 €/kg was then determined. The process achieves specific CO2 emissions of 0.017 kgCO2/kgprd, which is significantly lower than the traditional processes (0.24 kgCO2/kgCH3OH and 1.66 kgCO2/kgNH3), and an energy intensity of 36 GJ/tprd. The final selling price of the products is still not competitive with the traditional processes but is comparable with ammonia production from electrolysis and air separation and methanol production from electrolysis and direct air capture.