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BIOMETHANE FOR TRANSPORTATION
Impact/Purpose:
The purpose of this action is to request approval of a new grant assistance agreement between Western Washington University and the U.S. Environmental Protection Agency (EPA). The proposed project was submitted to the EPA in response to the 2005 solicitation for RFA 2005-P3-Z3 for the 3rd Annual P3 Award: A National Student Design Competition for Sustainability Focusing on People, Prosperity, and the Planet.
With increasing dependence on foreign oil, escalating energy prices, and persistent air and water pollution associated with energy production, there is an opportunity to develop cleaner, renewable energy sources to meet demand. To begin to address this challenge, this project aims to develop a small scale bio-methane fuel production and purification test bed, which will process biogas retrieved from local dairy farms. The resulting fuel will be tested for the amount of carbon dioxide and hydrogen sulfide removed and then used in a high-efficiency hybrid natural-gas powered engine. This renewable, clean energy technology will also contribute to resolving the challenge to dairy waste and the associated environmental burden in watersheds surrounding agricultural lands. This technology can lead to an increased use of alternative energy sources thereby reducing the air emissions associated with traditional energy production. This will mitigate environmental and human health effects currently associated with meeting energy demand.
Description:
During phase I of this project we designed and built two different small-scale biogas refineries. The first design used a caustic absorption system. Our initial results showed an increase in CH4 (methane) content from 60.50 Mol% in the raw biogas to 93.62 Mol% in the scrubbed gas. We achieved a reduction in CO2 (carbon dioxide) from 36.03 Mol% in the raw biogas to 2.05 Mol% in the scrubbed gas. Lastly, we achieved a reduction in H2S (hydrogen sulfide) from 0.34% Mol% to a value too low to be picked up by the gas chromatograph. Subsequent dräger tube tests showed levels of ~850ppm to ~900ppm.
Our second design is an amine absorption system. The best initial sample showed a composition of 94.88 Mol% CH4 (methane), 0ppm H2S (hydrogen sulfide), 0ppm CO2 (carbon dioxide) and 4.25 Mol% nitrogen. Nitrogen was our purging gas and proved to be problematic in some of the other samples accounting for 53.22 Mol % in one particular sample. This was due largely to operating error and was most likely caused by not completely venting the nitrogen used for purging the system from the drying tower before taking samples. However, all samples taken registered 0ppm H2S (hydrogen sulfide) and all but one registered less then 2% CO2 (carbon dioxide). Therefore the second design was considered as success. The amount of CO2 and H2S scrubbed by the second design showed an improvement over the first design and were well below are initial goal.