Pipeline-Quality Methane from Anaeronbic Digestion Streams

Large farms and feedlot operations produce large quantities of manure in a small area. Anaerobic digester units capable of producing pipeline quality methane installed at each farm or dairy could be instrumental in eliminating the difficulties associated with the transport of manure off site. If consumed properly, use of manure-derived fuels can also protect against environmental problems such as groundwater leaching and greenhouse gas emissions (methane emissions) associated with land filling of the farm wastes. The use of anaerobic digester gas reduces the amount of methane emitted into the atmosphere and provides a new and untapped resource of energy. TDA Research, Inc (TDA) is developing a vacuum swing adsorption (VSA) based system for upgrading the biogas produced from farm wastes to pipeline specifications. TDA's system uses a novel low cost, high capacity CO2 adsorbent to convert the biogas to pipeline quality methane. The vacuum swing adsorption process results in a low methane loss, more than 95% of the methane entering the separation unit is sent to the pipeline and the unit has very low capital and operating costs. Results: In Phase I TDA successfully demonstrated the feasibility of TDA's VSA system to produce pipeline quality methane from biogas in bench-scale experiments and showed its economic viability through process simulations and engineering analysis. In Phase II TDA will build and test a sub-scale prototype unit and scale up production of the sorbent. As part of Phase II TDA will carry out a field demonstration in actual biogas derived from wastes. TDA has partnered with CDM (Seattle, WA) to carry out a field demonstration of our technology in combination with the pilot-scale ADG system that they will be building and operating at Air Force Academy in Colorado Springs, CO to run on food wastes. The installation and operation of the ADG system is funded by the DoD and will be available at no-cost to the EPA. Potential Commercial Applications: This technology will enable animal and dairy farms to solve a major waste "manure" handling problem. This will also provide a cheaper way to upgrade the biogas to a high-value fuel, pipeline methane that can be exported from the farm. It will also find use in waste water treatment, food processing industry or any other facilities that use anaerobic digestion and want to sell pipeline quality natural gas instead of burning the gas on-site.