This SBIR Phase I project will develop a new technology to remove carbon dioxide from biogas. The innovation lies in using a bed material of zeolite-activated carbon to adsorb carbon dioxide. Biogas is a combustible mixture of methane and carbon dioxide (CO2). Raw biogas (60-70% methane) can be used as a low-grade fuel for low value on-site power generation. Commercial projects to upgrade biogas to pipeline quality natural gas, so-called ?Waste to Energy? processes, target much higher value for the methane.
The broader/commercial impact of the project will be in generating an alternative source of energy, which in turn will reduce greenhouse gas emissions.
This Small Business Innovation Research Phase I project was aimed at a significant reduction in the purification cost of biogas produced from anaerobic digestion of dairy and food waste. The project demonstrated the feasibility of InnoSepraâ€™s novel adsorption process for cost effective purification of raw biogas to produce pipeline quality natural gas through extensive lab and field testing, process modeling and simulation, and a detailed engineering scale up study. Laboratory and field tests indicated that the raw biogas containing about 60% methane can be upgraded to a natural gas stream containing >99% methane with a methane recovery of 95-98%. Lab testing also indicated that the methane-depleted gas from the purification unit can be used to provide some of the energy required for the process and to provide the heating requirements for the digester. Field tests at a dairy farm indicated that the process can successfully handle the contaminants in the raw biogas namely high moisture levels (saturated with moisture) and high H2S levels (up to 2,000 ppm). Process economic evaluation based on the experimental data, process modeling, and scale up studies indicates that the InnoSepra process has a 40-66% lower capital requirements compared to the competition (membranes, amine based absorption, and pressure-swing adsorption) and results in more than 60% reduction in the cost of producing the pipeline quality natural gas. Significantly lower biogas purification costs can effectively address more than $400 MM/yr biogas market (up to 2 million tons/year of methane) in the United States with potential for CO2 equivalent emission reductions of up to 50 millions tons per year.