How are steel majors trialling biochar as a key decarbonisation lever? BigMint explores

• Ministry of Steel projects biochar demand to reach over 30 mnt
  
  
• SAIL engaged in extensive R&D on biochar use in iron and steelmaking
  
  
• Blending target may be introduced in steel sector much like power sector
  
  

Morning Brief: The Ministry of Steel has constituted 14 Taskforces to delineate a 'green steel' roadmap for the Indian iron and steel industry. The 14th Taskforce was set up later, which was tasked with investigating the use of biomass derivatives in steelmaking with the aim to reduce carbon footprint.

Biomass, as a renewable material derived from plants, holds promise for reducing emissions in steel production. Biochar is produced from biomass using different processes and has comparable metallurgical properties to coke. Biochar is a sustainable alternative for decarbonising the steel industry and can potentially reduce the industry's environmental impact, the Ministry notes in its latest report.

Biochar is a carbonaceous solid fuel, prepared from biomass which can be a substitute for coal. Carbon content of raw biomass typically ranges from 10-25% with higher VM content. Pre-treatment is necessary to obtain bio-substitutes as a partial replacement for fossil fuels in metallurgical processes.

Trials & results

Overcoming all technical challenges, industrial trial of biochar injection with PCI was carried out during August 2024 at BF-1 of Rourkela Steel Plant (RSP) of SAIL. Charcoal and/or torrefied biomaterials may be injected into the BF through tuyeres, either separately or mixed with pulverised coal, using the existing pneumatic conveying system.

The Research and Development Centre for Iron and Steel (RDCIS) under SAIL has interacted with suppliers, vendors, manufacturers for study of various types of biochar for their suitability in the steel industry. RDCIS has collected various types of biochar samples and analysed at RDCIS Ranchi to study their suitability as partial replacement of PCI coal. Bamboo and babul-based biochar was found to be a suitable replacement of PCI coal.

Besides SAIL, Tata Steel has set a target of becoming net zero by 2045. Biochar has been identified as an alternate fuel to replace fossil fuels for Carbon Direct Avoidance (CDA) in the short- and medium-term. Biochar injection in blast furnace has been envisaged to replace 10% of PCI.

Again, severely torrefied biomass has been trialled to partially replace coke breeze/anthracite for heating in iron ore sintering process. RDCIS has collected various biochar samples and analysed them for 10-15% replacement of coke breeze with biochar, which has been tested successfully. Industrial trials are being explored as part replacement with coke breeze.

Biocoke is a coke in which part of the coal in the coal blend is replaced by biomass (biomass can be used in its original state or after torrefication) and obtained at a temperature of 1,100 degree C like conventional coke. Biochar/biomass should have low ash, high carbon, less moisture and other coking properties like rheological properties for its use in coke-making. Testing in pilot coke oven with part replacement of indigenous coking coal is being carried out by RDCIS, SAIL.

Emissions reduction potential

Biochar can be used in BF-BOF and the EAF route. The biomass-derived materials are being produced renewably, i.e., the CO2 emitted through their use is balanced by CO2 captured from the atmosphere for its growth.

There is a total replacement and emission reduction potential of 0.7 - 1.29 tCO2 /tcs for the integrated route and 0.029 - 0.057 t-CO2 /tcs for the EAF route. This analysis indicates that the largest potential gains are within the integrated route, where BF pulverised fuel injection has the greatest impact and is a crucial area for further R&D, the MoS has observed in its latest report on 'Greening the Steel Sector In India'.

Demand trajectory

The government has acknowledged that biomass is a dispersed resource. Lack of mechanisation in the farm residue management process, storage infrastructure, high cost of transportation, and absence of market mechanisms make it economically unavailable to collect and process it into biochar. Additionally, there are inadequate players in the ecosystem and constraints include the availability of scientific data.

However, the MoS predicts that the demand for biochar in different processes in the iron and steel industry in the immediate and long term will be around 32.5 million tonnes (mnt) per annum.

On the other hand, research by RDCIS shows that by 2030-31 (given a set of assumptions) projected demand for biochar is expected to reach a level of nearly 37 mnt per annum.

The MoS-appointed 14th Taskforce has suggested that the iron and steel sector may be encouraged to use biochar from farm waste, bamboo, and agri-residues. The MoS could develop a policy framework for mandating a certain percentage blend of biochar along with coal after assessing the techno-economic feasibility and safety aspects. A graded biochar blending mandate can be introduced for steel players with offtake agreements for 10 years, with higher mandates depending on technology maturity and cost economics stabilisation.