Nitrous oxide emissions from gasohol, ethanol and CNG light duty vehicles

Abstract

A sample of 21 light duty vehicles powered by Otto cycle engines were tested on a chassis dynamometer to measure the exhaust emissions of nitrous oxide (N 2 O). The tests were performed at the Vehicle Emission Laboratory of CETESB (Environmental Company of the State of Sao Paulo) using the US-FTP-75 (Federal Test Procedure) driving cycle. The sample tested included passenger cars running on three types of fuels used in Brazil: gasohol, ethanol and CNG. The measurement of N 2 O was made using two methods: Non Dispersive InfraRed (NDIR) analyzer and Fourier Transform InfraRed spectroscopy (FTIR). Measurements of regulated pollutants were also made in order to establish correlations between N 2 O and NO x . The average N 2 O emission factors obtained by the NDIR method was 78±41 mg.km −1 for vehicles running with gasohol, 73±45 mg.km −1 for ethanol vehicles and 171±69 mg.km −1 for CNG vehicles. Seventeen results using the FTIR method were also obtained. For gasohol vehicles the results showed a good agreement between the two methods, with an average emission factor of 68±41 mg.km −1 . The FTIR measurement results of N 2 O for ethanol and CNG vehicles were much lower than those obtained by the NDIR method. The emission factors were 17±10 mg.km −1 and 33±17 mg.km −1 , respectively, possibly because of the interference of water vapor (present at a higher concentration in the exhaust gases of these vehicles) on measurements by the NDIR method.

An overview of emissions of reactive nitrogen compounds from modern light duty vehicles featuring SI engines

“…A range of chemical reactions which form NH 3 and N 2 O are suspected to occur within a TWC under certain conditions. (See [2,7,11,12] and references therein for reviews of these processes and reactions. )…”

“…Other studies have also assessed the impact of usage of alternative fuels on RNC formation (e.g. [7,8,12,15]) -and a very large number of studies have reported NO x emissions from vehicles running various fuel types. A 2012 study [7] examined the impact of LPG and CNG on NH 3 emissions, finding no real change for LPG but a substantial reduction for CNG (compared to standard petrol).…”

“…Abundant discussions of the impact of vehicle duty cycle, temperature etc on emissions of NO x are to be found in the literature. For discussion relating to correlations with emissions of N 2 O see [11,12,16] for the case of NH 3 see [2,5,6,8,17].…”

Cold Start with Ethanol-Blend Fuels and Influences on Non-Legislated Emissions of a GDI Flex Fuel Vehicle

“…Nitrous oxide (N 2 O) was focused by the U.S. EPA as a greenhouse gas of a very high potential [28][29] and has started to be investigated by some researchers [25][26][30][31].…”

Planejamento e sustentabilidade: uma proposta de procedimentos com base na avaliação de sustentabilidade e sua aplicação para o caso do etanol de cana-de-açúcar no Plano Decenal de Expansão de Energia

“…Todavia, em contraste com as emissões da planta industrial, há ganhos na qualidade do ar em centros urbanos com a substituição da gasolina por etanol (ABRANTES et al, 2009;BORSARI;ASSUNÇÃO, 2011;SZWARC, 2010).…”