The economic and CO2 reduction benefits of a coal-to-olefins plant using a CO2-ECBM process and fuel substitution

Abstract

Taking advantage of coalbed methane as a substitute for coal fuel can facilitate CO₂ reduction in addition to CO₂ sequestration. Here, the CO₂ reduction potential and economic impact of CO₂ recovery of methane from a coalbed were evaluated at a CTO plant in the Inner Mongolia Autonomous Region of China. Emission reductions and capital, annual, and methane costs were analyzed basing on engineering data, empirical formulas, and assumptions. Cost analysis included the influence of a potential carbon tax. In addition, a sensitivity analysis was conducted on the annual gross profit to parameters, including carbon tax, CO₂ capture rate (CCR), pipeline distance, capital recovery factor, CO₂ injection rate, operation and maintenance (O&M) percentage, coal depth, and methane price. Results showed that an optimal CO₂ capture rate is about 80%, taking into consideration total capital, annual, and methane costs. At this optimum CCR, the methane price was calculated as $0.12 Nm⁻³ and a total capital cost of $323.14 M, which also results in a 58% reduction in CO₂ emissions. Reductions from CO₂ sequestration and fuel substitution respectively account for 66% and 34% of the total emissions reductions. The carbon tax impact analysis suggests a carbon tax greater than $20 per tCO₂ will maintain a profitable system with a range in CCR of 70–80%. The sensitivity analysis demonstrates that carbon tax, CCR, and pipeline distance have the greatest effects on annual gross profit.