Upgrading Biogas from Small Agricultural Sources into Biomethane by Membrane Separation

Area of Science:

• Chemical Engineering
• Materials Science
• Environmental Science

Background:

• Poland's agricultural sector has significant biogas potential, but low-capacity, dispersed plants limit its use.
• Upgrading biogas to biomethane is crucial for meeting grid gas quality standards.
• Membrane processes offer a viable solution for biogas upgrading.

Purpose of the Study:

• To investigate the feasibility of using membrane technology for upgrading biogas to biomethane meeting Polish grid gas standards.
• To compare the performance of polyimide and polysulfone membranes for this application.
• To assess methane recovery, purity, and energy efficiency of the membrane process.

Main Methods:

• A case study of an agricultural biogas plant in southern Poland was used.
• Biogas upgrading was simulated using modified polysulfone (Air Products PRISM PA1020) and polyimide (UBE UMS-A5) membranes.
• Key performance indicators such as methane recovery, purity, and energy efficiency were theoretically evaluated.

Main Results:

• Biomethane with over 96% CH4 purity was theoretically achievable using both membrane types.
• Methane recovery was higher with polyimide membranes (up to 87.5%) compared to polysulfone (up to 71.6%).
• Polyimide membranes exhibited significantly higher productivity (up to 38.3 kWth m-2) than polysulfone membranes (up to 3.13 kWth m-2).

Conclusions:

• Membrane technology, particularly using polyimide membranes, is a viable option for upgrading agricultural biogas to grid-quality biomethane in Poland.
• Polyimide membranes offer superior performance in terms of methane recovery and productivity.
• The energetic efficiency of both membrane types is comparable, suggesting cost-effectiveness for biomethane production.