A Biogas-Tolerant Engine-Generator for Advanced Agricultural Waste Management Systems

Anaerobic digesters are capable of producing methane-rich biogas from animal manure and also offer the advantages of controlling odors, reducing pathogens, and minimizing the environmental impact of the waste. The biogas produced from anaerobic digesters is a renewable, distributed source of energy that can be used to generate electricity to offset power consumption on farms. Unfortunately, biogas is a sour gas that is rich in hydrogen sulfide (H2S), a highly corrosive gas that quickly embrittles the cast iron and steel used for many engine components. As a result, conventional engines fail after several months of exposure to the high levels of H2S in biogas. No small (<100 kWe) generators are currently available that can use this fuel without pretreatment to remove the H2S--a process that adds complexity, cost, consumables, and maintenance. As a result, many smaller biodigester installations simply flare the biogas rather than extracting any useful work from the fuel. The objective of this project is to develop an inexpensive, low-maintenance, high-efficiency, biogas-tolerant engine that does not require preconditioning of the biogas to remove H2S.