High-volume ethanol fuel composition optimized for cold driving conditions

VTT (Technical Research Centre of Finland) has together with the Finnish energy company St1 tested different high-volume ethanol fuel (E85) samples in order to find the optimum composition for this fuel to perform satisfactorily in low ambient temperature driving conditions encountered in Finland quite frequently during the winter season. Altogether six different fuel compositions were evaluated, with 70 to 85 % of anhydrous bioethanol, and various different mixes of regular petrol components and some specific species like ETBE, butane, etc. As a reference, new Euro-quality 95 RON petrol with 10% ethanol was used. Volatility of each sample was adjusted according to test temperatures to match summer or winter condition and to ensure effortless start-up. Test results showed that the composition of the fuel had marked influence on emissions. The lower the test temperature was, the more distinctive were the differences. Already at -7°C with "straight" E85 mixture composed of ethanol and petrol, the unburned hydrocarbon emissions were very high. On the other hand the more "engineered" fuels performed much better, and allowed starting as low as at -20 to -25 °C. Cold start and driving was possible at equal level of unburned hydrocarbons and other unwanted emission species (such as aldehydes) at an ambient temperature about 10 °C lower compared to "straight" E85 fuel.