Comparison and techno-economic evaluation of process routes for lower olefin production via Fischer–Tropsch and methanol synthesis

This paper describes the simulation and techno-economic evaluation of a carbon dioxide capture and utilization unit integrated in a cement plant with a capacity of 10,000 tons of CO ₂ per year. The aim is to utilize CO ₂ along with hydrogen to produce lower olefins (C ₂–C ₄), the feedstock for polyolefin production. In a first step, three process routes, namely a Fischer–Tropsch synthesis with steam cracker, a methanol synthesis with rWGS syngas production and a methanol synthesis with direct hydrogenation of CO ₂, latter two followed by a methanol-to-propylene unit, are simulated in ASPEN Plus V12.1®. Furthermore, the effect of a high- and a low-temperature electrolysis on key performance indicators are also considered in the evaluation. Additionally, an estimation of investment, operating and specific net production costs (NPC _PR) of the different process routes is made. The evaluation is based on the comparison of calculated global efficiencies, specific energy consumption (SEC), NPC _Pr and yields of the lower olefine products (C ₂–C ₄). The power-to-lower olefin plant, consisting of an amine scrubber unit, a PEM electrolysis and a Fischer–Tropsch synthesis with downstream steam cracker proves to be the most efficient process route for polyolefin production, resulting in a global efficiency of 38.2 %, an SEC of 34.4 kWh/kg and an NPC _Pr of 14.92 EUR/kg of lower olefine product.