Methanol Fuel Blending

China M15 June 2013Methanol has a number of physical properties that make it an ideal transportation fuel.  For refiners, the use of methanol allows for the expansion of gasoline supply over a greater number of vehicles, and the upgrading of regular gasoline to high premium grades by increasing octane.  For automakers, methanol contains oxygen for cleaner fuel combustion, a lower boiling temperature for better fuel vaporization, and a higher blending octane for smoother burning with reduced “knock.”  This last point has become a critical issue for the automotive industry, which is increasingly recognizing the benefit of using more alcohol – both ethanol and methanol have 109 Research Octane Number (RON) – to boost octane and facilitate higher engine efficiencies to facilitate compliance with CAFE fuel economy goals.

As wikipedia.org notes: “The higher the octane number, the more compression the fuel can withstand before detonating. In broad terms, fuels with a higher octane rating are used in high-compression engines that generally have higher performance.”  In the United States, as automotive technology advanced from 1900 to 1960, the transportation fuel pool steadily increased its octane rating.  This steady climb in octane ended in the 1960s, with regular gasoline peaking at 87 RON.  In other parts of the world, gasoline blends are marketed at 92-98 RON.  With 86% of the U.S. fuel pool made up of 87 RON regular gasoline (even 85 RON in mountainous areas of the country), automakers have had to design cars that operate on this lowest common denominator fuel.

Recently, automakers like Ford and Mercedes have been calling for the introduction of “high octane” fuels, with octane ratings of 100-102.  Increasing octane allows for the use of higher compression ratio engines, greater turbocharging, more direct fuel injection, and even engine downsizing.  For automakers to achieve the new 2025 CAFE fuel economy standard of 54.5 mpg for cars and light-duty trucks, more octane not only makes the job easier for the car manufacturer, but it would also significantly reduce the sticker price shock to the consumer.  These automakers have proposed the introduction of a mid-level ethanol fuel blend of 20-30 percent ethanol in gasoline to provide a 102 RON gasoline.  As Lotus has demonstrated, since ethanol and methanol can be readily mixed, a blend of 10% ethanol – the U.S. base gasoline – with an additional 10% methanol is attainable.  Methanol can provide all the octane needed for a mid-level alcohol fuel, but at a third of the cost.