Abstract: A modular plant has the characteristics of small scale, mobility, and flexible production, which is a promising way for stranded coalbed methane (CBM). However, the variable composition of CBM brings uncertainties to the process performances. Based on five typical CBM compositions, simulation models of CBM liquefaction process and CBM to methanol process are established. The supplementary of CO₂ is also considered to adjust to the hydrogen to carbon ratio suitable for methanol synthesis. The mass balance, energy consumption, and economic analysis are then carried out to explore the effects of each key component on the CBM liquefaction process and CBM to methanol process. The results of mass balance and energy consumption analysis show that CO₂ in CBM can improve the hydrogen to carbon ratio of syngas in the CBM to methanol process, but it increases the energy consumption of decarbonization in the CBM liquefaction process; The presence of nitrogen makes methane more difficult to be liquefied, and it also increases the recycling syngas and the associated energy consumption in the CBM to methanol process. Nitrogen is an unfavorable factor for CBM processing. The economic analysis shows that liquefaction of high-purity CBM can obtain a higher net present value. The CBM containing carbon dioxide is more suitable for methanol production, and the methanol production process is preferred for a wider range of CBM compositions. The high nitrogen content makes the two processing methods lose economic attraction.