Technical view on biofuels for transportation: Focus on ethanol end-use aspects

Päivi Aakko, Nils-Olof Nylund

Research output: Book/ReportReport


Finland has proposed a joint project with Japan, USA and Sweden on ethanol as fuel for transportation. This review is targeted to benefit this possible new project, and also to collect information on ethanol for national discussions on liquid biofuels in Finland. The European Union has given target values for the use of both biofuels and alternative fuels in the transport sector. Reactions from Member States are expected on these indicative targets. The most potential short-term options for liquid biofuels are biodiesel and ethanol. Biodiesel is mainly used as a blending component in diesel, but some engines are approved for operation also on neat biodiesel. Even operation on neat biodiesel requires no or only minor engine modifications. Ethanol can be used as a component in gasoline, and is sometimes also added to diesel. At high concentrations ethanol requires special engine technology. Today some synthetic fuel components are made from coal and natural gas. The amounts of biofuels and also the range of products could be increased if synthetic fuels were produced from biomass. When considering the production potential of liquid biofuels in Finland, it is clear that all possible feedstocks and fuel options should be taken into account. Agriculture based biofuels from set-aside lands could, using current production technology, cover less than 2% of the consumption of transportation fuels in Finland. Wood-based and wastebased fuels would offer a significant reserve of raw material for liquid biofuels, if costeffective production processes existed (limitations by competitive use). Alcohols are liquid fuels, which mean good energy density, easy re-fuelling and storage. Basically the same kind of distribution system as for conventional fuels can be used. However, in the case of gasoline/ethanol blends the distribution system needs special attention to avoid problems caused by water, as blends are very sensitive to moisture. Fuel properties of ethanol are in many respects similar to gasoline. Ethanol up to some 10% can be blended with gasoline and used without modifications in ordinary sparkignition engines. There is not much experience on the concentrations exceeding 10% with normal cars. The cars running on high-concentration blends (25%) in Brazil are, if not modified, at least recalibrated. Special cars, Fuel Flexible Vehicles (FFV), have been developed for high concentration alcohol blends (up to 85%, the balance being gasoline). Gasoline improves the coldstartability, which is poor for ethanol due to low vapor pressure and high heat of evaporation. Gasoline also improves safety as the flame becomes visible. The reduction in emissions depends on how well the engine and the emission control system are designed and "tuned" for ethanol, but there should be a potential for emission reductions substituting gasoline for high-concentration ethanol blends. Also heavy-duty diesel engines can use ethanol with certain limitations. The properties of ethanol are similar to gasoline, thus engine modifications (e.g. glow-plugs or pilot injection) or additives in fuel are needed, if ethanol is to be used in compression ignition engines. One option to use ethanol in diesel engines is a low concentration ethanol/diesel blend (or emulsion). The main concerns with this E-diesel are the safety issues and the general suitability for diesel engines (low cetane, low lubricity, stability). Biodiesel is suitable for current diesel engines, nontoxic and biodegradable, and thus an excellent fuel for use in sensitive environments. As a consequence, biodiesel is used e.g. in forest harvesting machinery. Many manufacturers, especially for non-road engines, allow the use of biodiesel within normal warranty conditions. Many reviews have been conducted to assess reasonable policies for the introduction of biofuels. One of the reviews, published by Concawe, gave a critical view on the appropriateness of the EU targets for biofuels in transportation. Some other studies have given optimistic views on the production potentials of liquid biofuels. It remains to be seen how the targets can be met, and if met, at what costs.
Original languageEnglish
PublisherVTT Technical Research Centre of Finland
Commissioning bodyFinnish Funding Agency for Innovation (Tekes)
Number of pages71
Publication statusPublished - 6 May 2004
MoE publication typeD4 Published development or research report or study

Publication series

SeriesVTT Processes. Project Report


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