![]() Their energy content may be considered doubled in the target of reaching a 14% renewable energy share within the final consumption of energy in the transport sector by 2030. The Renewable Energy Directive II 2018/2001/EC promotes biofuels and biogas produced from used cooking oil for transport. RME is produced from vegetable oil by transesterification which currently provides the highest conversion efficiency at the lowest cost. The real impact on emissions of biodiesel compared to diesel is thus quantified as opposed to the homologation engine dynamometer emission measurements. The innovative scientific contribution of this paper is to perform on-road emission measurements with a portable emission measurement system (PEMS) following representative conditions of urban bus driving. This paper addresses these shortcomings by post-processing raw emission measurements with correction factors that take into account the ambient weather conditions. compared emission measurements on a 18m bus fueled with pure diesel and B100 RME during standardised on-road test cycle (SORT) but did not include measurement uncertainties. also noticed a lack of statistical analysis of the emission measurements. More specifically, a clear need for careful and complete experimental designs is identified taking into account covariate factors such as ambient conditions. highlighted the lack of reliable emissions measurements of urban buses fueled with biodiesel blends under real-world operating conditions in the literature. Moreover, it only considered emissions measurements performed on engine dynamometers following the composite FTP, hot-start FTP and European emission test for type approval of HD engines (UN/ECE R49). However, this database did not contain any engine equipped with exhaust gas recirculation (EGR), NOx adsorbers or PM traps. The average emission impacts of biodiesel (B30) for heavy-duty highway engines indicated an increase in NOx emissions of ∼5% and a decrease in PM, CO and HC emissions of ∼18%, ∼18% and ∼29%, respectively. They did not observe a significant difference in exhaust CO 2 emissions between biodiesel and conventional diesel. This highlights the importance to study the emissions impacts of biodiesel on heavy-duty buses specifically. A comparison with emissions impacts collected from non-road engines and light-duty vehicles did not allow for concluding that different engine groups respond in the same way as heavy-duty engines do. They concluded that the emissions impacts of biodiesel did not differ by engine model year. Environmental Protection Agency conducted an extensive review on the effects of biodiesel blended fuels (soybean, rapeseed or animal biodiesel) on emissions of pollutants of heavy-duty highway engines of 1997 and earlier. Similar conclusions were drawn for the easy urban on-road bus emission measurements with smaller differences between B7 and B30 RME and UCOME. A measurement uncertainty analysis showed that the CO emissions were less reliable. The heavy urban on-road measurements indicated increased NOx emissions (24–26%), decreased PN emissions (43–45%) and slightly decreasing CO emissions for B30 RME and UCOME compared to B7. The bus followed the SORT which is representative of urban bus driving. ![]() The tests were carried out on a standard city bus belonging to the Euro V EEV emission standard that was equipped with a portable emission measurement system measuring NO, NO 2, PN, CO and CO 2 at the tailpipe. ![]() The aim of this paper is to compare on-road tailpipe emissions of a diesel bus when increasing the biodiesel concentration in the fuel. Captive fleets such as public transport buses could benefit from these GHG reductions by increasing the biodiesel content of their fuel because they have a consequent yearly fuel consumption. Pure rapeseed methyl ester (RME)and used cooking oil methyl ester (UCOME) are characterised by well-to-tank greenhouse gas (GHG) reductions of 54% and 88% compared to pure B0 petrodiesel, respectively. Increasing the biodiesel content of diesel fuels is encouraged because of its reduced carbon footprint. ![]()
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