Environmental Analysis of Methanol Production from Steel-Making Offgas

Linz-Donawitz gas is currently used as a heat source for the steel-making process by combustion, which is a conventional pathway. In a resource-efficient and environment-friendly point of view, methanol can be produced from Linz-Donawitz gas with balancing hydrogen due to its high carbon monoxide contents. This study designs a large-scale process for the catalytic conversion of Linz-Donawitz gas to methanol based on the validated kinetic studies and performs a lifecycle assessment of the proposed process. A lifecycle assessment of the methanol production from Linz-Donawitz gas, a new pathway, is conducted by defining the “cradle-to-gate” system boundary and are compared with those of the conventional pathway based on the ReCiPe 2016 Midpoint level methodology. Consequently, the lifecycle assessment results show that three ones among eighteen environmental impact results, global warming, fossil resource scarcity, and water consumption, of the new Linz-Donawitz gas pathway are lower than those of the conventional pathway by 86.9%, 88.8%, and 75.5%, respectively. They are dominated by the displacement effect of the heat generation of Linz-Donawitz gas by the primary sources. Using wood chips as a primary source could reduce especially global warming, fossil resource scarcity, and water consumption than using hard coal or natural gas by 29.8–58.9%, 32.5–49.1%, and 50.0–91.7%, leading to an environmental-friendly Linz-Donawitz gas process.