Conceptual design of a green ammonia production process: cost and safety assessment

Ammonia production accounts for about 2% of global CO2 emissions, and there is a strong industrial interest in deploying alternative sustainable routes. The scope of the Thesis is the conceptual design of an inherently safer and more environmentally sustainable process for ammonia production. Low carbon emissions are achieved by considering the electrification of the Haber-Bosch process and the substitution of fossil-based feedstocks with water and air. Process safety issues are tackled since the beginning of the conceptual design according to the principles of inherently safe design, thus allowing for the selection of safer solutions while driving the arrangement of the process operations. A reduced plant capacity (100 ton/day) is considered. Specification on ammonia purity is set at 99.9%w. The final design is also evaluated in terms of its economic performance, considering different scenarios based on different electricity prices. The economic assessment highlights the high production costs, primarily due to the high electrical demand and capital costs necessary to retrieve the hydrogen-nitrogen mixture. The best-case scenario, with an electricity price fixed at 0.08 €/kWh, leads to an ammonia selling price of 2.30 €/kgNH3, nearly five-fold the current market value (0.47 €/kgNH3).