Evaluation of the Impacts of Biodiesel and Second Generation Biofuels on NO_x Emissions for CARB Diesel Fuels

Abstract

The impact of biodiesel and second generation biofuels on nitrogen oxides (NO(x)) emissions from heavy-duty engines was investigated using a California Air Resources Board (CARB) certified diesel fuel. Two heavy-duty engines, a 2006 engine with no exhaust aftertreatment, and a 2007 engine with a diesel particle filter (DPF), were tested on an engine dynamometer over four different test cycles. Emissions from soy- and animal-based biodiesels, a hydrotreated renewable diesel, and a gas to liquid (GTL) fuel were evaluated at blend levels from 5 to 100%. NO(x) emissions consistently increased with increasing biodiesel blend level, while increasing renewable diesel and GTL blends showed NO(x) emissions reductions with blend level. NO(x) increases ranged from 1.5% to 6.9% for B20, 6.4% to 18.2% for B50, and 14.1% to 47.1% for B100. The soy-biodiesel showed higher NO(x) emissions increases compared to the animal-biodiesel. NO(x) emissions neutrality with the CARB diesel was achieved by blending GTL or renewable diesel fuels with various levels of biodiesel or by using di-tert-butyl peroxide (DTBP). It appears that the impact of biodiesel on NO(x) emissions might be a more important consideration when blended with CARB diesel or similar fuels, and that some form of NO(x) mitigation might be needed for biodiesel blends with such fuels.

Impact of biodiesel and renewable diesel on emissions of regulated pollutants and greenhouse gases on a 2000 heavy duty diesel truck

“…For example, Soy B50 and An B50 show NO x increases of approximately 10% and 5%, respectively, for the UDDS cycle. This increasing effect of biodiesels on NO x emissions is consistent with previous studies (Karavalakis et al, 2009;Cheung et al, 2009;Hajbabaei et al, 2012). The degree of unsaturation and Cetane number of biodiesel are reported to be associated with NO x emissions (Knothe, 2005;Pham et al, 2013).…”

“…A number of studies have suggested that biodiesel can lead to higher NO x emissions (Karavalakis et al, 2009;Cheung et al, 2009;Durbin et al, 2011;Hajbabaei et al, 2012). The potential for increase in NO x emissions has been recognized as a major concern to the application of biodiesel.…”

“…Unlike the yellow transesterified biodiesel, the product is a clear and colorless hydrocarbon fuel, with a good Cetane number and better combustion properties than even petroleumbased diesel. Engine dynamometer emissions testing using 100% NExBTL renewable diesel reported reducing NO x emissions by 5e18% and PM by 5e28% compared to CARB-certified ULSD (Hajbabaei et al, 2012). Most of the studies on vehicle emissions have been generally focused on biodiesel impact using an engine dynamometer (McGill et al, 2003;Fang et al, 2008;Hajbabaei et al, 2012).…”

“…Engine dynamometer emissions testing using 100% NExBTL renewable diesel reported reducing NO x emissions by 5e18% and PM by 5e28% compared to CARB-certified ULSD (Hajbabaei et al, 2012). Most of the studies on vehicle emissions have been generally focused on biodiesel impact using an engine dynamometer (McGill et al, 2003;Fang et al, 2008;Hajbabaei et al, 2012). However, little investigation has been done examining whole vehicles on Chassis Dynamometer on the effect of blend levels of renewable diesel fuels on regulated emissions, global warming gases, and chemical composition of particulate matter in terms of a chassis dynamometer.…”

Effects of FAME biodiesel and HVORD on emissions from an older-technology diesel engine

“…The results of direct comparison of the effects of FAME biodiesels, HVORD and petroleum diesel on emissions from turbocharged, electronically controlled engines are available from the literature (Hajbabaei et al, 2012; Westphal et al, 2013; Kim et al, 2014), but the equivalent information for mechanically controlled, naturally aspirated engines is not readily available. This information is critical to underground mining operators that still have large fleets of light- and medium-duty vehicles powered by those engines.…”