Friday, March 11, 2011

Examining the benefits of using bio-CNG in urban bus operations

Studies showed that exhaust emissions with bio-CNG are much fewer than other kinds of fuel in 2008. In 2004, the Irish government planned to release big amounts of bio-CNG to inspire the first growth of a biofuel marketplace and disturbed the production of pure plant oil, biodiesel and bioethanol in permitted pilot tasks. Many other studies have explored the benefits of bio-CNG, and also completed a work that expressed the local air pollution benefits in monetary terms from hydrogen fuel cell buses, CNG buses and Euro V diesel buses. “These studies presented a quantitative assessment of the local environmental benefits of using each type of bus along a central bus route in Gothenburg.” In order to compute the quantity of emissions produced by the fleet examined, it was necessary to obtain the necessary input data for the COPERT model. Consequently, the results of the estimated emissions from each of the four models estimated over a one year period. Overall the alternative bus fleets formed shows a considerable saving in terms of emissions. A comparison between the three alternatives examined demonstrates that the bus fleet operated using bio-CNG would result in the largest decrease in overall emissions. As for COPERT modeling, the modeled emissions of CO2 for the original fleet was compared to the actual CO2 emitted from the 2008 fleet. This was found using the range of 1400–1450 g of CO2 per kilometer. The margins of error for the COPERT figures compared to the actual were found to be 0.45%, −1.31% and −3.01% for the values of 1400 g/km, 1425 g/km, and 1450 g/km. The sensitivity analysis for the production of the bio-CNG for the bus fleet examined was based on two separate methods, CNG and diesel calculations. The CNG calculation had one variable, the fuel’s energy density, while the diesel calculation had two, the quantity of diesel used and its energy density. In conclusion, the outcome shows a major decline in all contaminants from the use of CNG EEV buses compared to the 2008 fleet for Euro II, III and IV buses. There was a minimum reduction of 70% in emissions of all air pollutants, and a 100% reduction in SO2 and heavy metal emissions due to the fuel used. There was a decrease of 63% in the emission of greenhouse gases when bio-CNG was used instead of CNG. People, in general, should keep this reduction as to pollution coming out of CO2 that contaminates clean air so we have a clean environment and healthy people.

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