In an effort to reduce CO2 emissions, governments are increasingly mandating the use of various levels of biofuels. While this is strongly supported in principle within the energy and transportation industries, the impact of these mandates on the transport stock’s CO2 emissions and overall operating efficiency has yet to be fully explored. This paper provides information on studies to assess biodiesel influences and effects on engine performance, driveability, emissions and fuel consumption on state-of-the-art Euro IV compliant Toyota Avensis D4-D vehicles with DPNR aftertreatment systems.
Two fuel matrices (Phases 1 & 2) were designed to look at the impact of fuel composition on vehicle operation using a wide range of critical parameters such as cetane number, density, distillation and biofuel (FAME) level and type, which can be found within the current global range of Diesel fuel qualities.
Vehicle test results from Phase 1 indicated a surprisingly large impact of CN on fuel consumption in addition to an expected effect of fuel calorific value. The CN effect was not so apparent in Phase 2 where fuels were of a much narrower cetane range. Compared to base fuels, FAME biofuel blends, at levels of B30 and below, typically showed reductions in HC emissions, a negligible impact or reductions in CO emissions and a negligible impact or increase in NOx emissions. B100 RME gave amongst the highest overall CO and CO2 emissions. At equivalent blend level of B20, RME tended to give amongst the highest HC, CO and NOx emissions compared to JME or CME.
The higher cetane premium fuels tested in this study (CN > 60), gave the lowest overall fuel consumption, HC and CO emissions. Hydrogenated vegetable oil (HVO) component offered further emissions advantages when blended at B5 level into a high cetane fuel, as well as giving significant emissions benefits at B20 level over standard European EN590 Diesel.
