Bioenergy in Steelmaking

Bioenergy is defined as the energy generated from Biomass. Bioenergy accounts for about 55% of all renewable energy, that is, roughly one-tenth of the world’s primary energy supply. Biomass is renewable organic material that comes from plants and animals, containing stored chemical energy from the sun. Plants produce biomass through photosynthesis. Bioenergy may derived by using biomass as solid fuels and burning directly for heat, by converting to liquid biofuels like ethanol and biodiesel, or as biogas. In order to meet global zero emission commitments, there has been a rapid increase in the use of bioenergy to displace fossil fuels. Iron and Steel industry is also following the path. Sources of bioenergy includes:

• Wood and wood processing wastes firewood, wood pellets and wood chips, lumber and furniture mill sawdust and waste, and black liquor from pulp and paper mills
• Agricultural crops and waste materials - corn, soybeans, sugarcane, switchgrass, woody plants algae, and crop and food processing residues
• Biogenic materials in municipal solid waste - paper, cotton and wool products, and food, yard and wood wastes
• Animal manure and human sewage
• Landfill gas
• Biofuels made from biogenic alcohol

Applications of Bioenergy in Steelmaking

Metallurgical coke production

Metallurgical coke is produced from coking coals by carbonization at high temperature (1000–1100 °C) in the absence of air. Under strict quality requirements set for coke, bio-coke can also be produced with part of the coking coal replaced by some sort of biomass.

For reduction

Various biomass-derived fuels have demonstrated promise as substitutes for fossil-based reducing agents in integrated steel production. Solid biofuels, such as torrefied biomass and charcoal, offer potential replacements for coke breeze in sintering, coking coal in coke production, as well as for coke breeze/coal in agglomerates and pulverized coal in blast furnace (BF) injection. The most conventional use of biomass within the BF-BOF steelmaking route is in the form of charcoal, which requires upgrading through pyrolysis process. This is done primarily in Brazil. The Torero partnership project has been evaluating the utilization of biocoal (torrefied waste wood) as a partial replacement for coal at ArcelorMittal's facility in Ghent, Belgium. Project construction commenced in 2018, with reactor #1 slated to commence production in 2022 followed by reactor #2 in 2024. Each of these reactors is projected to yield an annual output of 40,000 tonnes of biocoal. Additionally, gaseous fuels like Bio-H₂ and Bio-SNG could be introduced into the BF or utilized in reheating furnaces (Bio-SNG) to supplement liquefied petroleum gas (LPG).

Challenges

Rising demand for bioenergy feedstock is sparking conflicts due to competing land use demands. The primary concern revolves around the competition for arable lands needed for food and fiber cultivation. Moreover, the production and utilization of biomass feedstock, including agricultural and forest residues for energy, pose potential environmental challenges such as soil disruption, nutrient depletion, and compromised water quality.

Opportunities

Biomass can easily be cultivated sustainably by steel companies, or acquired from third party growers. A number of stewardship initiatives like Forest Stewardship Council and Sustainable Biomass Program supports users of biomass. Regional schemes include the European Programme for the Endorsement of Forest Certification, the American Sustainable Forestry Initiative and the Brazilian CERFLOR programme.