Steel industry's enviromental footprint
With most of the steel industry’s environmental impact coming from the steelmaking process, Khai Trung Le looks at the efforts in the USA and Europe to mitigate this damage.
The environmental qualities of steel are well known and well reported – steel is the most recycled material in the world, with, according to the Steel Research Institute, more than 60 million tonnes recycled in 2015 in the USA alone – and it is an integral part of the circular economy. But with the vast majority of the sector's environmental impact being produced through the steelmaking process – around two tonnes of CO2 for each approximate tonne of steel – steelmakers have long explored methodologies to decrease this impact. In this light, perhaps it is this comment from Professor Sridhar Seetharaman, Warwick Manufacturing Group, University of Warwick, that warrant the most attention.
‘Companies aim to comply with the least denominations. They’re not going to do anything beyond that, but that’s the same with any industry. They’re not in the business of helping the environment, they’re there to make steel in the most cost-efficient way. Ultimately, it’s an industry that burns fossil fuels to make iron. There is mitigation, but you could argue that there is no steel industry that can be good for the environment.’
So, with a plethora of sustainable steel organisations endeavouring to make steelmaking green, how valid is his cynicism?
Ultra-Low CO2 Steelmaking (ULCOS), a consortium of 48 European steel companies and manufacturers, is the largest collection of steel industry companies working towards developing sustainable steelmaking processes, and has highlighted four technologies that look to reduce the environmental impact of blast furnaces – Top Gas Recycling, HIsarna, ULCORED and ULCOWIN. ULCOS European Coordinator Jean-Pierre Birat commented, ‘They are all climbing up the technology readiness level. Top Gas would be near to 7 [out of 10], HIsarna at 6, and ULCORED and ULCOWIN are still experimental work, so around 2 and 3, respectively.’ Top Gas and HIsarna are awaiting opportunities for testing in a pilot plant and, while ULCOS and steel industry commentators had previously predicted these technologies would become commercially viable by 2015, considerable and continued delays have put the future of the ULCOS technologies into jeopardy.
‘Those predictions, made around 2010, were much too early. Things have slowed down a lot with the economic crisis. There were plans to build large demonstrators that have since been put on hold, pushing any deadline by at least five years, if not more,’ said Birat. The continuation of the ULCOS technologies is said to be dependant the stabilising of global economy. ‘Until this changes, nothing will happen – at least in Europe.’
The cancelled Florange Top Gas CCS (carbon capture and storage) plant remains one of ULCOS’ highest-profile missteps. Steel manufacturer ArcelorMittal originally sponsored the plan to retrofit the idle Florange steelworks in Lorraine, France with post-combustion CO2 capture capability. However, the project was withdrawn from the European Commission’s NER300 scheme in 2012, despite being expected to meet financial criteria for funding. ArcelorMittal denied abandoning the scheme in December 2012, at the time reiterating the company’s long-term commitment, although there have been no updates on the project since. A refreshed start date of 2016 was found on the MIT CCS Project Database, but has been refuted by ULCOS. ‘I don’t know anything about that,’ Birat confirmed.
Despite this and the commercial stagnation of ULCOS technologies, Valentina Colla, Technical Research Manager at Scuola Superiore Sant’Anna and co-author of ESTEP paper Sustainable Steel Production for the 2030s with Birat, defends their efforts, stressing the significant obstacles already overcome. ‘It is not simply an incremental increase. These are entirely new ways to produce steel, and adopting them implies a huge investment, as well as rethinking the entire process. And as new methodologies that need further investment to consolidate the outcomes, that investment, both time and money, is not easy to find in these times.’
Seetharaman was also keen to celebrate the achievements of the consortium. ‘I don’t think there is another umbrella organisation in the world like ULCOS, and for that ULCOS is commendable. And they have done a lot of work in terms of containment. It’s never seen as breakthrough technology but it is, in engineering terms.’ However, with the ULCOS companies heavily invested in blast furnace technology, Seetharaman believes they will never commit to Electric Arc Furnace (EAF), which he sees as one of the more effective technologies in recent commercial use and is seeing considerable pickup in the USA.
EAF is charged with ‘cold’ material, normally steel scrap. With the furnace filled with scrap, a lid containing electrodes is lowered inside, where an electric current is passed through the electrodes to form an arc. The heat generated from the arc melts the scrap, and a standard EAF can make 150 tonnes in each melt, which takes around 90 minutes.
‘In the USA, it started out as minimals. Small, low-capital intensive mills using scrap and selling back to low-end markets,’ said Seetharaman, and throughout the last four decades, the largest steel manufacturers in the USA including U.S. Steel, have committed to EAF, with the company announcing the replacement of a number of existing blast furnaces – with the most recent being Fairfield Works, Alabama.
USA-based Nucor has long adopted EAF with its ‘mini mill’ steel production process, and now celebrates an output of 29 million tonnes (Mt), over U.S. Steel’s 19Mt, to become the country’s largest steel producer. While scrap prices are high at the time of publication, Seetharaman expects the same surplus of steel products exiting China that currently threatens much of the UK’s steel industry will mean EAF remains en vogue.
European steelmakers have yet to show the same dedication to EAF and, although acknowledging the significant investment required, Seetharaman has criticised ULCOS’ hesitance to either adapt to EAF or press ahead with its promoted technologies. ‘It’s partly a lack of leadership and partly a fear of what might happen. They would rather slowly bleed to death than take the bull by the horns.’
Birat does not dispute this, noting, ‘It’s true that the steel industry is conservative, in general. Supporting sustainable steel requires an extremely high investment over a long-term deal. Frankly, at the present time, implementing this technology is still an uncertainty – nobody is certain about who should pay for it. I hope this changes soon – you can experiment as much as you want, but there is no business model for the implementation of our technology yet. There is a real need to find that business model.’
However, Colla challenged the claims of a reserved industry. ‘The steel making industry is prone to innovation. There is innovation in the processes but due to difficulties and huge costs, it can sometimes be slow. This doesn’t mean it isn’t progressing. Considerable efforts are being made, particularly in sustainability. There are efforts, perhaps not widely known, and it might be easier for researchers to get better visibility working on other topics, but just because it’s not fashionable, it doesn’t mean there is no technological content.’
The CO2 price
On 30 September 2015, worldsteel issued a statement on the UN Sustainable Development Goals, a reaffirmation of its ‘commitment to shaping a better future for our planet’ with a 27-page document outlining upcoming events, online materials and infographics on the value of steel as a sustainable material, but lacking solid information on changes to the steelmaking process.
Moreover, the question of the environmental impact of steelmaking has been described as ‘politically charged‘ by Birat, who said, ‘When you produce electricity, you take coal and burn it, taking heat from the combustion. It’s an extremely wasteful process, taking something that has a very high level of energy and transforming it into the lowest possible level of energy, with a lot of CO2, but this is a cost that we seem willing to pay.
‘Right now, if you want to make one tonne of steel, you have to make two tonnes of CO2. There’s no arguing around that. There are many ways being explored on how we can reduce it, being as clever as our engineers are. But at the end of the day, that CO2 is the price. The issue is whether we are willing to pay that cost.’
The copious and rightly celebrated work to combat the environmental effects of steelmaking should be acknowledged, but until that price is determined – the carbon footprint of steel – Professor Seetharaman’s cynicism may be justified.
Top Gas Recycling
The separation of off-gasses allows useful components to be recycled back into the furnace and used as a reducing agent. This reduces the amount of coke needed, and enables the injection of oxygen into the furnace instead of preheated air, removing nitrogen from the gas and facilitating CCS.
A technology based on bath-smelting, HIsarna combines coal preheating and partial pyrolysis in a reactor, a melting cyclone for ore melting and a smelter vessel for final ore reduction and iron production. This requires significantly less coal usage and reduces CO2 emissions.
An electric arc process, direct-reduced iron is produced from direct reduction of iron ore by a reducing gas produced from natural gas. The reduced iron is in solid state and for melting, electric energy is required. This is carried out in an Electric Arc Furnace.
Electrolysis of iron ore is the least developed process route currently being studied in ULCOS. This process would allow the transformation of iron ore into metal and gaseous oxygen using only electric energy.
*Technology descriptions from www.ulcos.org