GEM Ternary Blends: Testing Iso-Stoichiometric Mixtures of Gasoline, Ethanol and Methanol in a Production Flex-Fuel Vehicle Fitted with a Physical Alcohol Sensor 2012-01-1279

The paper presents vehicle-based test work using tri-component, or ternary, blends of gasoline, ethanol and methanol for which the stoichiometric air-fuel ratio (AFR) was controlled to be 9.7:1. This is the same as that of conventional "E85" alcohol-based fuel. Such ternary blends are termed "GEM" after the first initial of the three components. The present work was a continuation of an earlier successful project which established that the blends were effectively invisible to a car using a virtual alcohol sensor. The vehicle used here employed the other major technology in flex-fuel vehicles to determine the proportion of alcohol fuel in the tank, a physical alcohol sensor.

Another aspect of the present work included the desire to investigate ternary blend replacements for E85 having low ethanol concentrations. Evidence from the previous work suggested that under specific conditions, ethanol was required in some amount to act as a cosolvent for the gasoline and methanol in the blend. The present paper discusses the position of the phase separation boundary with respect to the concentration of the individual components, and determines new blends for test which are closer to this boundary. These and other ternary blends were first tested on the road and in a cold chamber, where cold startability was gauged at -20°C. All of the ternary blends were found to start well except that corresponding to E85, which would not start at all at this low temperature using this summer grade fuel.

Of the fuel blends tested in the first phase, four were selected for more-controlled investigation in an emissions laboratory. Each was tested twice on the NEDC cycle under cold and hot conditions. In addition, gasoline baseline tests (using the same procedure) were conducted at the start and end of the ternary blend tests. The ternary blends were invisible to the vehicle, with no malfunction indicator light activity at all.

An estimate of the cost of one of the blends (containing 10% by volume ethanol), based on current individual costs of the individual components, is made to be 10.1% cheaper than gasoline, on an energy basis. Finally, there is a discussion of how renewable methanol can be introduced, aided by the ability of the existing flex-fuel vehicle fleet to accept these fuel blends, and also of a means of manufacturing such fully sustainable methanol by a coupling of the electricity and gas grids to enable massive storage of renewable energy.