INITIATE: One project, different routes to decarbonise steel [Promoted content]

The INITIATE project proposes an innovative process to produce urea from residual gases of steel making and demonstrates the importance of industrial symbiosis between different industrial sectors (steel sector, chemical sector, agriculture).

By Nicola Zecca and Giampaolo Manzolini from Politecnico di Milano.

Introduction 

Steelmaking is a major emitter of industrial greenhouse gases and is considered a hard-to-abate sector, as the current potential for the use of renewable feedstocks and energy is limited. The EU-funded project INITIATE proposes a novel symbiotic process from steel residual gases to tackle this issue. It utilises two types of residual steel gases, the Blast Furnace Gas (BFG) and the Basic Oxygen Furnace Gas (BOFG) which collectively represent approx. 80% of the emissions of steel made through the Blast Furnace route.  

UREA production 

The basic configuration of the symbiotic system consists of processing the gaseous components of the Blast Furnace Gas and the Basic Oxygen Furnace Gas, namely hydrogen (H₂), nitrogen (N₂), carbon monoxide (CO) and carbon dioxide (CO₂) within the same process. The CO present in the residual gases is converted to CO₂ and separated from the mix, leaving a hydrogen-nitrogen mixture in proportions favourable to synthesising ammonia. The produced ammonia is then combined with part of the separated CO₂ to produce urea. Urea is widely used as a source of nitrogen in fertilisers and animal feed as well as an important raw material for the manufacture of plastics and the chemical industry (i.e. drugs to treat skin conditions, cleaning products, glues).  

This symbiotic system reduces CO₂ emissions compared to the traditional, separate production of steel and urea, assuming that the excess CO₂ is stored geologically or in products. The utilisation of renewable electricity in the process reduces the carbon footprint through the substitution of fossil fuels.  

This concept will be demonstrated at the facility that is being built in Luleå, Northen Sweden, at the Swerim site with a production of 5 tonnes per day. 

Besides urea production, INITIATE will also explore additional symbiotic pathways for the utilisation of the residual gases, for example for the production of methanol, the production of construction materials through CO₂ mineralisation, the generation of low-carbon dispatchable power via ammonia or the development of hybrid steel making processes. 

Carbon Capture and Utilisation (CCU) 

Using the captured CO₂ for the production of every day, carbon-containing molecules will help transition into more sustainable production routes.  

Methanol is a versatile platform molecule that can be used as a chemical and as a fuel in the maritime sector. In the case of methanol production, the symbiotic process is similar to the one described for the urea case, but for an additional step. The hydrogen-nitrogen mixture has to be further purified to obtain pure hydrogen. The hydrogen is then used with part of CO₂ separated to synthesise methanol. Results indicate an emissions reduction of up to 49% compared to conventionally produced methanol can be achieved. 

CO₂ can also be bound permanently, through the process of mineralisation as an alternative to underground storage. Specifically, two mineralisation approaches are considered, namely with olivine and with Basic Oxygen Furnace slag – a major waste product generated during the steelmaking process. It is found that both these approaches reach similar emission reductions compared to underground pressurised CO₂ storage as a reference case. Basic Oxygen Furnace slag mineralisation appears to be the best-performing case even if mineralisation with olivine shows similar results. Future studies are recommended to evaluate the economic performance of mineralisation, especially considering different transport distances to reach underground storage. Mineralisation is expected to have less stringent requirements, thereby reducing purification costs and energy penalties with respect to the pressurised underground storage. 

Power generation via ammonia 

The ammonia produced starting from the hydrogen-nitrogen mixture, is used as fuel in an ammonia gas turbine that allows to generate power without emitting CO₂. Results indicate that a reduction of CO₂ emissions in the range of 63% can be achieved through this process compared to the separate production of steel and ammonia while allowing a dispatchable form of power generation.  

An element to be considered in those alternative pathways is the replacement of the displaced electricity from steel gases within the steel plant. The use of low carbon power, instead of electricity sourced from natural gas, is found to effectively reduce the emissions of the symbiotic systems achieving a reduction of emissions of ~80%. These improvements are also expected to further grow when process heating is also decoupled from fossil resources. 

Hybrid steelmaking system 

The INITIATE hybrid steelmaking concept consists of using a hydrogen-rich stream from the residual gases as fuel in the reformer of a direct reduction (DR) steelmaking process allowing the production of an additional quantity of steel with CO₂ emissions close to 0. The results indicate that steelmaking can be effectively decarbonised by integrating Blast Furnace and direct reduction steelmaking plants via the INITIATE technology. The results show a decrease of CO₂ emissions equal to 71% with respect to a conventional steel plant. When carbon-neutral electricity is used the emissions can be further reduced. 

The INITIATE project therefore will advance the implementation of circular economy and industrial symbiosis by re-using residual steel gases as a resource for the cross-sectorial, more efficient and sustainable manufacture of a second product such as urea or methanol, at a significantly reduced carbon footprint. 

The INITIATE project has received funding from the European Union’s Horizon 2020 research and innovation programme, under grant agreement No 958318.