This paper explores the potential of achieving negative emissions in steelmaking by introducing bioenergy with carbon capture and storage (BECCS) in multiple steelmaking routes, including blast furnace and HIsarna smelt reduction, and Midrex and ULCORED direct reduction. Process modelling and life cycle assessment were used to estimate CO₂ balances for 45 cases.

Without bioenergy or CCS, the estimated life cycle CO₂ emissions for steelmaking were 1.3–2.4 t CO₂/t steel. In our model, aggressive BECCS deployment decreased net CO₂ to the order of −0.5 t to 0.1 t CO₂/t steel. CCS showed a larger mitigation potential than bioenergy, but combined deployment was most effective.

As BECCS use increased, CO₂ from background supply chains became more relevant. In the high BECCS cases, if decarbonized electricity is assumed, net CO₂ estimates decreased by 400−600 kg CO₂/t steel. Conversely, at 700 g CO₂/kWh, all cases appeared to be net CO₂-positive. Accounting for the “carbon debt” of biomass, beyond biomass supply chain emissions, increased net CO₂ estimates by approximately 300 kg CO₂eq/t steel.

We conclude that CO₂-negative steel is possible, but will require significant interventions throughout the production chain, including sustainable biomass cultivation; efficient steel production; CO₂ capture throughout steel and bioenergy production; permanent storage of captured CO₂; and rigorous monitoring.

本文探讨了通过在包括炼铁厂和HIsarna冶炼以及Midrex和ULCORED直接还原在内的多种炼钢路线中将生物能源与碳捕集与封存（BECCS）引入炼钢中实现负排放的潜力。使用过程建模和生命周期评估来估计45例患者的CO ₂平衡。

如果不使用生物能源或CCS，则炼钢的生命周期估计CO ₂排放量为1.3–2.4 t CO ₂ / t钢。在我们的模型中，积极的BECCS部署将净CO ₂降低至-0.5 t至0.1 t CO ₂ / t钢的数量级。CCS显示出比生物能源更大的减缓潜力，但联合部署最为有效。

随着BECCS使用的增加，来自背景供应链的CO ₂变得越来越重要。在高BECCS情况下，如果假设采用脱碳电力，则净CO ₂估算值将减少400-600 kg CO ₂ / t钢。相反，在700 g CO ₂ / kWh下，所有情况似乎都是净CO ₂阳性。考虑到生物质的“碳债务”，不包括生物质供应链排放，使净CO ₂估算值增加了约300 kg CO ₂ eq / t钢。

我们的结论是，CO ₂负极钢是可能的，但是将需要在整个生产链中进行重大干预，包括可持续的生物量种植；高效的钢铁生产；钢铁和生物能源生产中的CO ₂捕集；永久储存捕获的CO ₂ ; 并进行严格的监控。