Enhanced Membranes for Sweetening of Manure based BioGas

Every year over 1 billion tons of fresh animal manure is produced in US and it raises pollution concerns. "Anaerobic digestion" is an environmental friendly and energy efficient way to dispose animal manure. Animal manure is converted to biogas and digestate through this process. The animal manure digestate has a much less pollution potential than untreated animal manure and can be used as a chemical fertilizer replacement. Biogas is a mixture of 60% methane, 40% carbon dioxide and trace amounts of other contaminant gasses. After non-methane component removal, biogas is chemically identical to natural gas. Biogas cannot be injected into the natural gas grid directly because pipeline natural gas requires less than 2% carbon dioxide (CO2). Currently there is no low cost and reliable method to remove such a high percentage of CO2 from biogas, especially for small farm-run anaerobic digesters. The most common use of biogas is to burn it directly and use its energy to generate electricity through microturbines, which limits the economic value of biogas.Compact Membrane Systems is proposing a membrane separation technology which can efficiently remove CO2 from biogas. The proposed fluorinated polymer membrane exhibits preliminary data showing very high CO2 permeation and good CO2/methane selectivity. Parallel data shows that the CMS fluorinated membrane has excellent sulfur (e.g. H2S) resistance and excellent hydrocarbon fouling resistance. Preliminary economic analysis suggest improvements in the economics of carbon dioxide removal of at least 30% compared to water scrubbing or other membrane separation processes. The CMS membrane separation system is a perfect fit for small size biogas upgrading requirements. With this carbon dioxide removal technology, farmers can sell the upgraded biogas directly through the natural gas grid as a renewable natural gas and the economics of anaerobic digestion will be greatly improved.