5 Groundbreaking Methods To Decarbonize Steel

November 30, 2022
- Consumer Products
- Life Sciences

Modern economies and technologies are heavily reliant on steel as a construction material. Given its centrality to our lifestyle, it is no surprise that the iron and steel demand has increased more than threefold since 1970. A direct consequence of this dependence is the environmental impact of producing it. The iron & steel industry accounts for 8 percent of global carbon dioxide emissions and is thus one of the major pollutants. This necessitates developing and implementing technologies that can help in the decarbonization of steel plants.

Challenges to Steel Decarbonization

The steel industry entails heavy infrastructure and massive investment in setting up production plants. Assets such as the blast furnace once created last for 20-40 years. This makes it problematic to introduce changes in the manufacturing process or shift the factories. Almost 60% of steel units use the high-carbon BF-BOF method which requires copious amounts of heat for the smelting process, that accounts for the high levels of CO2 emissions. As a result, the financial barriers to steel decarbonization are one of the major constraints to reform in the sector.

Factors Driving The Decarbonization Initiatives

The demand for green steel is shaping the manufacturer’s response and escalating changes, despite the constraints. This demand comes from:

Customers asking for carbon-friendly steel products. For example, BMW invested in US clean steel startup Boston Metal to make their industrial portfolio eco-friendly.
Governments globally are tightening carbon emission requirements. Important climate pacts like the Paris Agreement, European Green Deal etc. are a case in point.
Increasing awareness about sustainability. The looming threat of climate change is making everyone rethink their choices. Investors are now more interested in putting their money into technologies of the future that involve sustainable innovations.

Ways To Decarbonise Steel Plants

Replacing Coke in the Furnace
Coke is the primary agent used to produce heat and reduce iron ore. And this process is where the maximum emissions come from. To curb this, lesser polluting alternatives to coke, like biomass-based, olefin coke, and hydrogen-based blast furnace reduction are being considered.
Using Renewable Energy Source For Furnaces
Electric arc furnaces have so far produced favourable results in controlling carbon emissions. Instead of coal-based electricity, green sources such as wind, tidal, solar etc. can be used to further reduce CO2. Another change can be making the feed carbon-neutral by reducing iron in its solid-state using hydrogen.
Replacing Graphite Electrodes
Graphite electrodes are used in electric arc furnaces to act as conductors for the electric current used to melt the iron. These electrodes have a high thermal conductivity but are consumed in the process, thereby contributing to pollution. Replacing graphite with inert metallic electrodes can instead be used for the melting process.
Carbon Capture
There is an opportunity to capture the carbon released during the metal-reducing step before it reacts with oxygen to produce carbon dioxide. The captured carbon can act as a raw material for various processes. For example, it can be sent to bio-reactors for fermentation to produce bioethanol.

Considerations for Integrating Sustainable Methods

There are certain parameters to consider before committing to a technology that promises to reduce carbon emissions. Like, the readiness of the tech for full scale commercialization, ease of integration with existing infrastructure, and the feasibility of raw material sourcing. Other than these aspects, the decision will also be influenced by the extent to which the new measures will be effective in reducing emissions compared to those already in place. If the difference does not justify the cost, then the whole exercise may be futile.

New Innovations in the Market

Since the industry is extremely energy intensive, innovating efficient and energy-saving methods is becoming a top priority. Some of the breakthroughs in the same are:

Molten Oxide Electrolysis by Boston Metal
In the traditional steel making process, iron ore is refined and then reduced in a blast furnace using coal. But Boston Metal’s new invention involves dissolving the iron oxides in a mixture of molten oxides like silica, magnesia etc. before heating it by electric current. This produces a clean, high purity liquid metal that can directly be sent to ladle metallurgy, thus eliminating the need for coal.
Direct Reduction by Midrex
Midrex’s direct reduction method, referred to as Midrex H2, is considered a trail-blazing technology that can dramatically reduce CO2 emissions. Per CEO Stephen Montague, it promises 100% hydrogen from day one to produce over 2 million mt of DRI with up to 95% reduction in CO2. The idea is to use green hydrogen to reduce the iron ore to DRI, which can later be sent to an electric furnace for steelmaking. Green hydrogen is produced by the electrolysis process which uses electricity to break water into hydrogen and oxygen.
Electrowinning by ΣIDERWIN
This novel method entails combining steel making with an electrochemical process to offer a CO2 free steel production process. It will use an electrolytic method that uses renewable energy sources to transform iron oxides into a steel plate. Led by ArcelorMittal, it promises an 87% reduction of the direct CO2 emissions and a 31% reduction of the direct energy use. It is also capable of producing steel from by-products rich in iron oxides from non-ferrous metallurgy residues.
HYBRIT by SSAB, LKAB and Vattenfall
With the potential to reduce Sweden’s total carbon dioxide emissions by at least ten percent, the Hydrogen Breakthrough Ironmaking Technology (HYBRIT) aims to create a fossil-free value chain from mine to steel using fossil-free electricity and hydrogen. The conventional blast furnace process for coal reduction will be replaced by a direct reduction method using fossil-free hydrogen gas. The by-product in this case would be water, instead of CO2.

Conclusion

The roadmap to achieve decarbonization of the iron & steel industry will consist of innovative thinking and the willingness to incorporate the new tech. Leviathans like the iron & steel industry cannot be upgraded overnight. There is considerable planning involved to cater to the long-term goals and infrastructure. Therefore, the time to think is now so that these changes may be implemented in the near future.

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