Advancement in neutral and negative emissions production of ammonia from carbonaceous sources: A review
Yongxing Zhang, Jafar Zanganeh, Behdad Moghtaderi
Abstract
The demand for sustainable ammonia has been increasing substantially since ammonia has been recognised as a promising energy carrier over hydrogen. The carbon-neutral and/or negative ammonia production via carbonaceous feedstocks could be achieved by efficient system design, such as integrating advanced carbon-to-hydrogen technologies and integrating chemical looping with Harber-Bosch process (ICLHB). This review is to provide an overview on technologies towards net-zero emissions and theoretical BAT energy performance for ammonia production via carbonaceous feedstocks (coal, methane, and biomass) through thermochemical methods, which is the most carbon- and energy-intensive pathways. It highlighted that the viable path to achieving carbon-neutral ammonia production via carbonaceous feedstocks requires a multi-faceted approach. Coal-based ammonia production, the most carbon-intensive method, relies on coal gasification to produce synthesis gas, resulting in high CO₂ emissions and energy consumption. The integration of co-gasification with biomass results in negative emissions of −0.656 t CO 2 /t NH 3 , making the coal to ammonia process a carbon-negative industrial method. ICLHB represents the most promising pathway to synthesis clean ammonia from coal. Methane-based production, currently the most widely used method, offers higher energy efficiency and lower CO₂ emissions compared to coal. Gas switching reforming (GSR) and membrane assisted autothermal reforming (MA-ATR) exhibit superior performance and are the most promising approaches for clean ammonia production via natural gas. Biomass-based ammonia production presents a potentially carbon-neutral alternative, contingent on sustainable feedstock sourcing and efficient gasification technologies. Techno-economic analysis indicates that biomass fed ICLHB could be the best option for clean ammonia from biomass. The selection of technology for biomass-to-ammonia production must consider the influence of feedstock variability. Different feedstocks exhibit varying characteristics that can impact the overall process efficiency and economic viability. In this context, the implementation of a carbon tax is essential, as it incentivizes the transition to carbon-neutral and economically sustainable ammonia production pathways across diverse feedstock types. • Co-gasification with biomass makes the CtA a carbon-negative process. • GSR and MA-ATR are the most sustainable approaches for MtA. • ICLHB could be the best option for clean ammonia from biomass. • Sustainable ammonia via carbonaceous feedstocks requires a multi-faceted approach.