Abstract: A thermodynamic method and system is described and claimed for treating wellhead gas to recover valuable liquefiable hydrocarbon components from such gas and for utilizing the resulting dry gas as a fuel for an internal combustion engine driving a generator for the co-generation of electric power. In accordance with the invention, raw wellhead gas as a by-product of gas and oil field operations is compressed and cooled to condense the ethane and higher molecular weight hydrocarbon components of the gas and the condensed components are removed as liquefied hydrocarbon product. The remaining non-condensible methane and lower molecular weight components of the gas are used as fuel in an internal combustion engine driving a generator.

Abstract: A thermodynamic method and system is described and claimed for up-grading the quality of digester methane gas by removing substantially all of the non-combustible carbon dioxide gas from the digester gas in a scrubbing system operated by the waste heat of an internal combustion engine utilizing the up-graded methane gas as its fuel source and driving a generator to produce electric power. In accordance with the invention, raw digester gas is compressed and blended with relatively cold water (absorbent). The compressed gas-water mixture is scrubbed in a contact tower with the result that an absorbent-condensed gas stream (primarily water and condensed carbon dioxide) is formed. The absorbent-condensed gas stream is removed from the tower, heated and expanded to release the carbon dioxide component of the stream as product CO.sub.2 gas.