The steel industry is considered to be one of the dirtiest industries and accounts for more than 7% of worldwide carbon emissions. To reduce the environmental impact of greenhouse gas emissions, industry experts are now turning towards a sustainable steel-making process that has the potential to bring the global CO₂ emissions close to zero. Green steel is one such endeavor to produce steel to have the lowest possible carbon footprint during production. It is believed the green steel production process reduces the CO₂ emissions by 95% as compared to the traditional steel-making process. in this article, we will explore more about Green Steel and its production. Let’s start with the definition of green steel.
What is Green Steel?
Green steel is environmentally friendly steel produced by reducing its carbon footprint as compared to the conventional steel-making process. The reduction in this footprint is obtained through the implementation of non-coal-based alternative technologies. In most cases, green steel production utilizes green hydrogen instead of coal and electricity generated from fossil-free sources.
Green Steel Production
Green steel making involves hydrogen-based direct reduction of iron ore. The first step of the chemical green steel-making process is reducing the solid iron ore using hydrogen. It generates an intermediate product known as ‘sponge iron.’ Then, this sponge iron is fed into an electric arc furnace where the sponge iron is melted to produce the steel. In a greenfield steel plant, most of the processes involved in green steel production are fully integrated, digitized, and automated.
The green steel production process (Refer to Fig. 1) consists of the following steps:
- Decomposing water into hydrogen and oxygen by electrolysis.
- Exposing iron ore to the hydrogen inside a reactor to generate direct reduced iron which is then transported to the electric arc furnace while the DRI is in a hot state.
- The electric arc furnace heats the DRI and steel scrap to generate a homogeneous liquid steel melt. The melt is then transferred to a laddle furnace and degasser where alloying additions are done to get desired properties.
- In the next step liquid steel is converted into solid green steel products using continuous casting and rolling process.
- In the final step, depending on the customer requirement, downstream finishing is done using various treatment processes like cold working, galvanization, heat treatment, etc.
Challenges with Green Steel
Decarbonizing the whole steel industry is a big hurdle while dealing with climate change. Conventional steelmaking produces around 7% of global greenhouse gas emissions, which is approximately equivalent to the annual emissions of all the cars on the world’s roads. Again, steel is required to make cars, so the impact is overlapping. This is the reason when it comes to climate change, steel is such a big deal.
Estimates show that 1 ton of steel production using the traditional methods roughly releases 2 tons of CO2 into the atmosphere and the world uses more than 2 billion tons of steel each year. Over half of the total emissions is from the blast furnace, where the iron ore is converted to pig iron.
Reducing this carbon emission in an economical way is still very challenging and various process improvements are still required. In the coming years, there will be an increased push from environmentalists to go for green steel production. Various research and development works are still ongoing and in near future, green steel production on a massive scale will become a reality.
Many countries are trying to commercialize large-scale green steel production and Sweden is currently leading the world.
This is an interesting article on an emerging technology. Is there any information that can be added to what the costs involved are relative to the more common methods making steel?
Must scrap metal be added? Is the quality of the finished product dependant on the quality of the scrap metal?