What is biochar and how can it aid sustainable steel production?

India’s steel sector accounts for about 12% of India’s carbon dioxide (CO2) emissions.

In March, the government established a task force to explore the prospects and challenges of using biochar in steel production, partially replacing traditional raw materials such as coke and coal amid aims to reduce carbon emissions associated with the steel industry.

The steel sector accounts for about 12 percent of India's carbon dioxide (CO2) emissions, with an emission intensity of 2.55 tonnes of CO2/tonne of crude steel (tCO2/tcs) compared with the global average emission intensity of 1.85 tCO2/tcs, according Institute for Energy Economics and Financial Analysis (IEEFA).

So far, 13 task forces have been established to concentrate on different facets of more eco-friendly steel production, touching upon aspects such as raw materials, technology, and policy frameworks.

The 14th one was formed last month to look at the use of biochar in steelmaking. But what is biochar and how can it help reduce emissions? MC explains.

What is biochar?

When plants convert CO2 through photosynthesis, the carbon gets stored in their biomass. Burning this biomass in a high-temperature, low-oxygen environment (pyrolysis) creates a solid carbon substance called biochar. It is mainly produced from the waste materials of biomass including crop residues such as food and forest waste, field and processing residues, and animal manure.

What is the role of biochar in carbon emissions? 

For biochar to truly aid in carbon reduction, it must be produced from waste or sustainably grown biomass. This requires a thorough analysis of the entire process, from biomass harvesting to biochar production and application, to ensure a minimal carbon footprint.

Biochar reduces carbon emissions through long-term carbon storage. When biomass is converted into biochar, the carbon that plants absorb from the atmosphere during photosynthesis is locked into a stable form, preventing it from re-entering the carbon cycle as CO2. In fact, biochar application to soil can reduce emissions of methane (CH4) and nitrous oxide (N2O), potent greenhouse gases.

How will the steel sector benefit from the use of biochar? 

As of now, fossil-based fuels are consumed largely for heat generation and as reducing agents in steel production, processes that lead to huge global CO2 emissions. "Biochar has significant potential for reduction of emissions in blast furnace ironmaking as well as in rotary kilns for production of DRI (direct reduced iron)without any change in equipment or design," a steel ministry official told BigMint, an online platform providing data and analyses on the industry.

Biochar can be blended with coke used in blast furnaces and can also be added to iron ore pellets, which are then fed into the blast furnace. In electric arc furnaces, which use scrap steel as the primary feedstock, biochar can serve as a reductant during the steelmaking process.

What are the barriers to biochar adoption?

The primary obstacle in substituting a portion of thermal coal with biomass in DRI production is evidently cost. Thermal coal is more economically viable, benefiting from established global supply chains. The expenses associated with producing, processing and transporting biochar, as well as the significant thermal energy demand during pyrolysis, further contribute to the overall cost.

Robust supply chains exist to move large amounts of raw materials (such as coal, iron ore, lime, scrap) required in modern steelmaking. Similar supply chains must be developed to harvest biomass at volume, convert and process it to char, and to deliver it reliably to steel manufacturing facilities, according to a research report from World Steel Association.