Extending the role of alcohols as transport fuels using iso-stoichiometric ternary blends of gasoline, ethanol and methanol

Ethanol has become widely used in low concentration blends with gasoline in many parts of the world and has more limited use in high concentration blends. In the long term the supply of biomass for transport fuels will be severely limited, perhaps to as little as 20% of transport energy demand. The inability to satisfy the total transport demand means that biofuels are in danger of being regarded as a technological and strategic dead end. Methanol can be made from a wide variety of fossil and biomass feed stocks and can also be synthesized by reducing carbon dioxide and water using renewable energy. Methanol therefore has the potential to extend significantly the availability of alcohols for transport fuel. Ternary blends of gasoline, ethanol, and methanol (GEM) are proposed which can be formulated to have identical stoichiometric air-fuel ratios to any binary blend of gasoline and ethanol. The present work examines the properties of GEM ternary blends which are iso-stoichiometric with E85 and reports initial test results where the blends have been used as drop-in fuels for E85-gasoline flex-fuel vehicles. Provision of such fuels extends the ability of ethanol to displace gasoline from the transport fuel sector, increasing security of supply and, if the methanol feedstock is renewable, reducing the climatic impact of the transport sector. The increased gasoline displacement which can be achieved using the approach is discussed, together with the potential of the blends to decrease the operating costs of flex-fuel vehicles to lower than that which can be achieved when operating them on gasoline. (C) 2012 Elsevier Ltd. All rights reserved.