Emission consequences of introducing bio ethanol as a fuel for gasoline cars

This article describes the direct vehicle emission impact of the future use of bio ethanol as a fuel for gasoline cars in Denmark arising from the vehicle specific fuel consumption and emission differences between neat gasoline (E0) and E5/E85 gasoline-ethanol fuel blends derived from emission tests using primarily the European NEDC and ARTEMIS driving cycles. The E0-E5 test vehicles (nine cars) represent today’s gasoline car traffic well where most of the driving is being made with cars certified as Euro 3+. The FFV test cars (25 cars) are all certified according to the Euro 4 emission standard introduced in Europe from the mid-2000s. This matches well with the propagation of the FFV technology in Europe.For vehicles using E5 rather than E0, the average fuel consumption and emission differences are small. For CO, VOC and NOx the derived average differences are 0.5%, −5% and 7%, respectively. For FFVs using E85 rather than E5, the emission differences become even smaller for VOC and NOx, but greater for CO. The derived average emission differences are in this case 18%, −1% and 5% for CO, VOC and NOx, respectively. In both comparative cases there is a large variation in the emission difference values calculated for the individual cars. The large standard deviations introduce some uncertainties in the final averages computed for each emission component.The vehicle based emissions are made up for two fossil fuel baseline scenarios (FS), characterised by high and low traffic growth rates. For each FS, two biofuel scenarios (BS1, BS2) are presented. BS1 reaches the Danish policy targets (10% biofuel share in 2020). BS2 is more ambitious (25% in 2030). By definition the biofuel part of the combusted fuel is CO2 neutral and the maximum CO2 emission difference between FS and BS2 becomes 27% in 2030. As predicted by the vehicle specific emission differences the calculated emission impacts of using bio ethanol are small for NOx, VOC and CO. Instead, for FS, BS1 and BS2 large emission reductions are due to the gradually cleaner new sold gasoline cars and the decline in total mileage until the mid-2010s.

► Emission impacts of using bio ethanol as a fuel for gasoline cars.
► Bio ethanol scenarios; 10% in 2020 and a more ambitious case (25% in 2030).
►  The maximum CO2 difference becomes 27% in 2030 for fossil vs. ambitious case.
► Bio ethanol impact is small for NOx, VOC and CO, as predicted from literature review.
► The literature based bio ethanol emission differences are suited for European models.