Evaluating the potential of synthetic natural gas production from cement plant off-gas in Austria: A sectoral comparison with biogenic CO2

This study investigates the potential of CO 2 methanation with hydrogen in a PtG process, using unavoidable emissions from an Austrian cement plant as a representative industrial CO 2 point source. The objective is to analyze the performance of such a PtG plant through techno-economic analysis (TEA) and carbon footprint evaluation, while also providing a quantitative comparison with biogenic CO 2 methanation of biogas. The reference scenario is based on hard to abate process emissions of 750,000 t CO2 a −1 from cement production. Aspen Plus simulations show an annual, possible synthetic natural gas (SNG) output of 3.8 TWh. This equals nearly twice Austria’s current total biogas production (2 TWh a −1) and about 35% of the maximum biomethane potential projected for 2040. Results indicate high carbon efficiency (85%), moderate global efficiency (53%) and high specific energy demand (25.9 kWh kg CH4 −1), driven mainly by hydrogen requirements. The net production cost (NPC) is calculated with 0.41 EUR kWh CH4 −1, with electricity price identified as the main cost driver. The carbon footprint analysis highlights the crucial role of the electricity source. Assuming Austria’s current electricity mix, SNG production results in more than 2.5 times the CO 2 emission compared to direct release of CO 2 from cement production. In contrast, using 100% renewable electricity reduces the footprint by more than 80%. Overall, large-scale CO 2 methanation at industrial point sources could supply SNG volumes comparable to a significant share of Austria’s total gas demand, offering a transitional option to enhance energy security until fully renewable CO 2 sources such as DAC become viable.