Life Cycle Based Climate Emissions of Charcoal Conditioning Routes for the Use in the Ferro-Alloy Production

Abstract

Renewable reductants are intended to significantly reduce CO2 emissions from ferro-alloy production, e.g., by up to 80% in 2050 in Norway. However, charcoals provide inferior properties compared to fossil fuel-based reductants, which can hamper large replacement ratios. Therefore, conditioning routes from coal beneficiation was investigated to improve the inferior properties of charcoal, such as mechanical strength, volatile matter, CO2 reactivity and mineral matter content. To evaluate the global warming potential of renewable reductants, the CO2 emissions of upgraded charcoal were estimated by using a simplified life cycle assessment, focusing on the additional emissions by the energy demand, required chemicals and mass loss for each process stage. The combination of ash removal, briquetting and high-temperature treatment can provide a renewable coke with superior properties compared to charcoal, but concomitantly decrease the available biomass potential by up to 40%, increasing the CO2-based global warming potential of industrial produced charcoal to ≈500 kg CO2-eq. t−1 FC. Based on our assumptions, CO2 emissions from fossil fuel-based reductants can be reduced by up to 85%. A key to minimizing energy or material losses is to combine the pyrolysis and post-treatment processes of renewable reductants to upgrade industrial charcoal on-site at the metallurgical plant. Briquetting showed the largest additional global warming potential from the investigated process routes, whereas the high temperature treatment requires a renewable energy source to be sustainable.

Life Cycle Assessments in Renewable Energy: Solar and Wind Perspectives

“…The study by Surup et al [87] indicated that LCA can reduce global warming by 5 % to 10 %. This implies the need to reduce the global warming potential of carbon reducers by 80 to 90 % compared to metallurgical Coke.…”

Substitution of Fossil Coal with Hydrochar from Agricultural Waste in the Electric Arc Furnace Steel Industry: A Comprehensive Life Cycle Analysis

“…The objective of this work was to compare the environmental performance of fossilbased and renewable injecting materials employed as carbon sources in the EAF steelmaking process. To the best of the authors' knowledge, despite many studies on the environmental impact of steel production [13][14][15], there is a lack of life cycle assessment studies on the use of hydrochar in the EAF steelmaking process based on an industrial scale [16][17][18]. This work was aimed at providing insights into the potential application of bio-based carbon material in the steelmaking process in order to reduce its overall environmental impact.…”

“…Life cycle assessment (LCA) is a standardized framework for assessing the environmental impacts of a product or process at every stage of its life cycle, from manufacture to disposal. Despite the several studies dealing with the environmental impact of steel production [13][14][15], there is a lack of LCA studies on the use of biocarbon in the EAF steelmaking process [16][17][18]. This study aimed to provide a comprehensive assessment of the environmental impacts of steel produced using electric arc furnaces that employ pulverized hydrochar as charged and injected material as a substitute for fossil coal.…”