Techno-economic evaluation of hybrid systems of pressure swing adsorption and membrane processes for coalbed methane separation

The purpose of this conceptual design study is to evaluate coalbed methane (CBM) separation systems from an economic perspective. To achieve this goal, we propose several system configurations by combining membrane and pressure swing adsorption technologies with recycling. We then perform rigorous process simulations of the proposed CBM separation systems to meet the design specifications (CH₄ purity of product stream: 97%, CH₄ recovery rate: >90%) from a feed gas (CH₄: 90% and CO₂: 10%). We compare the systems using various technical and economic metrics, including methane recovery, process energy efficiency, and methane production cost. The top-performing system produces methane at a cost of 0.37 $/kg of CH₄ (6.9 $/MMBTU), which can be further improved up to 0.27 $/kg of CH₄ by applying promising scenarios.