Manufacturing methanol from carbon dioxide and hydrogen contained in the residual gases of steel production. This is the aim of the FReSMe (From Residual Steel gases to Methanol) project, funded by the Horizon 2020 research and innovation programme, concluded after four years of work.
The researchers estimate that with the FReSMe system, carbon dioxide emissions in Italian steel plants could be reduced by 61% compared to the current situation, which is much higher than with conventional CO2 capture technologies.
The process implemented by FReSMe is based on the SEWGS (Sorption Enhanced Water-Gas Shift) system which, starting from steel mill gases, produces two streams rich in carbon dioxide and hydrogen. The resulting hydrogen is partly used in the steelworks itself as a fuel, partly used to produce energy and partly transformed into methanol. The retained carbon dioxide is partially used for methanol production, while the excess is stored underground. Lastly, an electrolyser has been integrated into the system to increase methanol production.
The role of the Politecnico di Milano was to identify the ideal plant configuration, given the multiple possibilities of using hydrogen (use in steelworks, production of energy or methanol) through a detailed technical-economic analysis of the entire system. The aim of this analysis was to optimise the plant from an energy, environmental and economic point of view.
More specifically, various plant configurations were analysed, characterised by different volumes of methanol produced and different solutions for recovering the heat available in the process, as well as different quantities of hydrogen produced by the electrolyser. The results showed that the process can significantly reduce carbon dioxide emissions related to the steel production process.
During the project, we also carried out a technical-economic analysis aimed at optimising the FReSMe process in terms of methanol production volume and plant configuration, considering four methanol production capacities (300, 600, 900 and 1200 t/day)
says Professor Giampaolo Manzolini, the Politecnico di Milano’s contact person for the project.
The results showed that the optimal configuration with a carbon tax of less than €60/tonne and a methanol selling price in the range of €350-450/tonne, is characterised by a production of 600 tonnes/day: thus, using half of the steel mill gas to produce methanol and half to meet the needs of the steel mill itself. In general, the avoided CO2 cost is less than 20 €/tCO2, which is economically competitive, and the FReSMe system in this configuration allows a 61% reduction in carbon dioxide emissions, which is much higher than what could be achieved with conventional CO2 capture technologies (e.g. with amines it is about 17%).
