Decarbonisation Pathways for the Finishing Line in a Steel Plant and Their Implications for Heat Recovery Measures

Steel production is one of the biggest emitters of greenhouse gas in the industrial sector with about 8% of total global CO2 emissions. Although the majority of emissions can be attributed to primary steel production, there is also potential for reducing CO2 emissions in downstream steel processing. Large industrial furnaces, which are necessary for heating steel, are currently primarily fired with natural gas and by-product gases from primary steel production, offering great potential for heat recovery measures from exhaust gases. However, switching to alternative climate-neutral fuels could change this potential and thus jeopardize the economic viability of heat recovery measures. In the present work, it was therefore examined to what extent a change in energy sources in industrial furnaces affects the potential use of heat recovery in steel processing. For this purpose, an optimization model was used that takes into account heat recovery by means of direct heat transfer, heat pumps and heat distribution systems. Potential future changes in energy supply for industrial furnaces were examined using different storylines. Two different energy price scenarios were also considered to address uncertain developments in energy markets. The results show that heat recovery is a cost-effective and definitely recommendable measure. Switching to alternative fuels has little impact on the use of heat recovery. Electrification and thus the elimination of flue gas, on the other hand, greatly reduces the potential for heat recovery.