Solutions for producing greener steel

The Green Industry Act was passed on 11^th Octo­ber 2023. Its main aim is to decar­bon­ise exist­ing indus­tries. The stakes are high: in France, industry accoun­ted for 18.1% of green­house gas (GHG) emis­sions in 2022¹. The iron and steel industry is one of the biggest sec­tors to be decar­bon­ised. In France, it is the 4^th largest indus­tri­al sec­tor in terms of GHG emis­sions (20% of indus­tri­al GHG emis­sions, or 4% of the country’s total emis­sions). But on a glob­al scale, the sec­tor is in first place: around 2.8 bil­lion tonnes of CO₂ are emit­ted every year in steel pro­duc­tion, or 7% of glob­al GHG emis­sions². Yet demand is soar­ing. Steel and iron are essen­tial for con­struc­tion, mobil­ity, and the pro­duc­tion of renew­able energy – a wind tur­bine is made up of more than two-thirds steel! Accord­ing to pro­jec­tions by the Inter­na­tion­al Energy Agency (IEA), glob­al demand could increase by more than a third by 2050³.

Steel­mak­ing requires large quant­it­ies of energy: for example, melt­ing reaches 1,500°C in the blast fur­nace. Yet in 2019, three quar­ters of the energy con­sumed by the sec­tor was sup­plied by coal. To date, recyc­ling with­in the elec­tri­city sec­tor is the most car­bon-free option. It requires only one eighth of the energy of steel pro­duced from ore, and mainly in the form of elec­tri­city rather than coal. “We need to increase the recycled pro­por­tion, but this sec­tor is lim­ited by resources: a large pro­por­tion of steel, for example, is immob­il­ised for dec­ades in build­ings,” explains Fabrice Patisson.

In the short term, the cir­cu­lar eco­nomy is the most prom­ising driver. Tech­no­lo­gic­al innov­a­tions for decar­bon­isa­tion are based on renew­ing the pro­duc­tion fleet, which has an aver­age age of 13 years world­wide, or less than a third of its tra­di­tion­al lifespan. In its for­ward-look­ing scen­ario aim­ing for a 50% reduc­tion in the sector’s emis­sions by 2050, the IEA points out that 40% of the cumu­lat­ive reduc­tions in GHG emis­sions between 2020 and 2050 are based on the cir­cu­lar eco­nomy. Simply put, this is the lever for energy sobri­ety: by redu­cing demand, emis­sions are reduced. This mainly involves extend­ing the lifespan of build­ings, but also improv­ing man­u­fac­tur­ing effi­ciency, redu­cing the use of cars and mak­ing them light­er, improv­ing build­ing design and reusing steel.

At the same time, a num­ber of oth­er solu­tions are avail­able. It is impossible to meet rising demand without pro­du­cing primary steel. One of the major levers for decar­bon­ising pro­duc­tion? Mov­ing away from coal. The steel industry’s high GHG emis­sions are mainly due to the form­a­tion of CO₂ in blast fur­naces through chem­ic­al reac­tions, and the high tem­per­at­ures required. “Green” iron would be pro­duced by the dir­ect reduc­tion of iron ore using elec­tri­city or green hydro­gen (H₂), instead of coke. It can then be integ­rated into the usu­al elec­tri­city chain and trans­formed into steel in an elec­tric arc fur­nace. This tech­no­logy is known as “dir­ect car­bon avoid­ance”. “To date, the dir­ect reduc­tion pro­cess is well known and wide­spread – it accounts for around 7% of the world’s steel – but it relies on the use of syn­gas (a syn­thet­ic gas derived from nat­ur­al gas), which con­tains around 60% H₂,” explains Fabrice Patis­son. “The biggest chal­lenge is to go to 100% H₂ on an indus­tri­al scale.”

The hydro­gen route is the most advanced: of the 60 steel decar­bon­isa­tion pro­jects iden­ti­fied in Europe in Novem­ber 2022, 42 are based on the use of hydro­gen⁵. In Sweden, the Hybrit pilot pro­ject has been pro­du­cing the world’s first tonnes of steel using this pro­cess since 2021. It could reduce CO₂ emis­sions by 85%⁶. “From now on, the devel­op­ment of the sec­tor depends on the will­ing­ness and capa­city of steel­makers to invest,” says Fabrice Patis­son. As for elec­tri­city require­ments – if hydro­gen is pro­duced by elec­tro­lys­is of water, they would amount to 370 TWh to decar­bon­ise all the EU’s primary steel pro­duc­tion⁷, or 14% of cur­rent total elec­tri­city pro­duc­tion⁸.

There is anoth­er tech­no­lo­gic­al route – one that is com­ple­ment­ary to the car­bon avoid­ance route – and that is the “intel­li­gent use of car­bon”. This involves optim­ising exist­ing pro­duc­tion pro­cesses. Even if the industry has mastered blast fur­naces, there is still room for improve­ment. It has been shown, for example, that more than half of the energy pur­chased by steel­makers is lost dur­ing the pro­cess⁹. Using the best avail­able tech­no­lo­gies and optim­ising pro­cesses could make it pos­sible to reduce the sector’s cumu­lat­ive glob­al emis­sions by 21% between 2020 and 2050, accord­ing to the IEA’s for­ward-look­ing scen­ario, which aims to reduce the sector’s emis­sions by 50% by 20503. This involves deploy­ing heat recov­ery sys­tems, improv­ing coke qual­ity, par­tially repla­cing coal with nat­ur­al gas or bioen­ergy, and imple­ment­ing pre­dict­ive main­ten­ance tools.

Car­bon cap­ture and stor­age is an effect­ive option in the short term, before clean tech­no­lo­gies – such as hydro­gen – are deployed

Intel­li­gent use of car­bon also involves its recov­ery. As in many indus­tri­al sec­tors, the cap­ture and recov­ery or stor­age of CO₂ is seen as essen­tial if we are to make a suc­cess of the trans­ition by 2050. Accord­ing to the IEA, this could make it pos­sible to cap­ture 6% of the emis­sions gen­er­ated between 2020 and 2050, with the cap­ture rate rising to 25% per year by 2050. Only one com­mer­cial CO₂ stor­age unit cur­rently exists in the world, in the United Arab Emir­ates. A few recov­ery pro­jects are cur­rently under devel­op­ment. “CO₂ cap­ture is easi­er in the steel industry than in oth­ers,” adds Fabrice Patis­son. “Cap­ture and stor­age is an effect­ive option in the short term, before clean tech­no­lo­gies – such as hydro­gen – are deployed.”

Finally, the EU and France are com­mit­ted to a policy of relo­cat­ing indus­tri­al activ­ity. Gone are the emis­sions asso­ci­ated with trans­port­ing products. France’s energy mix, with its rel­at­ively low car­bon foot­print, is also an advant­age in terms of GHG emis­sions. One of the aven­ues being explored is the devel­op­ment of clusters of activ­ity based on an indus­tri­al eco­logy approach. “The aim of this approach is to design activ­ity clusters, like eco­parks, that optim­ise the exchange of flows between dif­fer­ent man­u­fac­tur­ers,” explains Mari­anne Boix. “By pool­ing ser­vices, the sup­ply chain, energy and raw mater­i­als, envir­on­ment­al impacts and costs are min­im­ised.” GHG emis­sions can be cut by up to 75% com­pared with the same plant without cooper­a­tion¹⁰. The ArcelorMit­tal site in Dunkirk is a case in point: the slag – a by-product of the blast fur­naces – is recycled as a build­ing mater­i­al, and the waste heat is fed into Dunkirk’s muni­cip­al heat­ing net­work¹¹. Two new EPR nuc­le­ar react­ors are due to be built there, as well as a green hydro­gen pro­duc­tion unit… which will be able to sup­ply ArcelorMittal’s future dir­ect hydro­gen ore reduc­tion unit¹². Mari­anne Boix con­cludes: “Integ­rat­ing the hydro­gen vec­tor into eco­parks makes the pro­cess prof­it­able, both eco­nom­ic­ally and envir­on­ment­ally. It’s a very inter­est­ing oppor­tun­ity in this context.”

Anaïs Marechal