Eco-friendly ironmaking by biomass CO2 gasification: Process simulations for ecological and economic evaluation of CO2 recycling in direct reduction ironmaking

• Biomass CO 2 gasification can supply reducing gas for direct reduction ironmaking. • Energy demand is 10.8–14.9 GJ/t CDRI at 38–55 % energy efficiency of ironmaking. • Net-negative CO 2 emissions are possible using biogenic carbon capture and storage. • The cost of producing 1 ton of CDRI by CO 2 gasification is calculated at 346–545 €. • Higher CO 2 conversion in the gasifier increases process efficiency and profit. This study describes a new process where the reducing gas for direct reduction ironmaking (DRI) is produced from renewable feedstocks by biomass gasification with CO 2 as the gasifying agent. The process recycles CO 2 from the DRI process as a reactant to the gasifier and converts it in reactions with biomass to CO. This study includes process simulations of six novel biomass CO 2 gasification-direct reduction ironmaking (BCG-DRI) routes and two simulations using established natural gas reforming technology (NGR-DRI). The BCG-DRI routes produce reducing gas with higher reduction potential (13–28) and lower H 2 :CO ratio (0.5–0.7) compared to NGR-DRI (9 and 1.8). Energy efficiency of ironmaking is higher for the NGR-DRI configurations (59 % versus 38–55 %). All BCG-DRI routes show significantly lower CO 2 -equivalent emissions, reaching net-negative emissions up to −1,190 kg CO2e /t CDRI . At current wood and natural gas prices in Austria, the levelized cost of production (LCOP) is lower for the BCG-DRI routes (down to 346 €/t CDRI ) compared to 417 €/t CDRI for the NGR-DRI process without carbon capture. The main reasons for this LCOP difference are cost savings for CO 2 emission allowances and price advantages for biomass versus natural gas. A new plant should strive to reach a high conversion of CO 2 in the gasifier, as this brings advantages in key areas like process efficiency and production costs. The combination of economic and ecological advantages identified for biomass CO 2 gasification is crucial because it can help the industry to defossilize while remaining competitive.