Abstract
Abstract Steelmaking is responsible for around 7% of the global emissions of carbon dioxide and new steelmaking processes are necessary to reach international climate targets. As a response to this, steelmaking processes based on the direct reduction of iron ore by hydrogen produced via water electrolysis powered by renewable electricity have been suggested. Here we present a novel variant of hydrogen-based steelmaking incorporating methanol as a hydrogen and carbon carrier together with high-temperature co-electrolysis of water and carbon dioxide and biomass oxy-fuel combustion. The energy and mass balances of the process are analyzed. It is found that this methanol-based direct reduction process may potentially offer a number of process-related advantages over a process based on pure hydrogen, featuring several process integration options. Notably, the electricity and total energy use of the steelmaking process could be reduced by up to 25% and 8% compared to a reference pure-hydrogen process, respectively. The amount of high-temperature (>200 °C) heat that must be supplied to the process could also be reduced by up to approximately 34%, although the demand for medium-temperature heat is substantially increased. Furthermore, the suggested process could allow for the production of high-quality direct reduced iron with appropriate carburization to alleviate downstream processing in an electric arc furnace, which is not the case for a process based on pure hydrogen.
Highlights
Iron ore-based steelmaking is currently responsible for around 7% of global carbon dioxide (CO2) emissions [1]
An important aspect of the suggested CH3OH-based DR process is the carbon mass balance: the amount of CO2 delivered by the oxy-fuel combustion process and separated out from the top gas must be sufficient for the operation of the high-temperature electrolyzer
The net CO2 emissions from the process should be significantly lower compared to the conventional blast furnace-basic oxygen furnace (BF-BOF) steelmaking process under the condition that the consumed electricity is predominately generated from fossil-free sources
Summary
Iron ore-based steelmaking is currently responsible for around 7% of global carbon dioxide (CO2) emissions [1]. Reducing these emissions to meet climate targets is challenging as the currently dominating form of steelmaking, the blast furnace-basic oxygen furnace (BF-BOF) process, is dependent on coal as a reductant and fuel [2,3,4]. There are two options for reducing CO2 emissions from steelmaking: to keep the BF-BOF process and implement carbon capture and storage (CCS) technology, or to seek new low-emissions processes [5]. One of the alternative processes currently considered promising is the production of direct reduced iron (DRI) via hydrogen (H2) direct reduction (H-DR) [6]. The goal of the HYBRIT project is to achieve full-scale implementation of H-DR by 2035 [1]
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