Forces that accelerated the move to E10 in Maine, according to the Maine DEP, include:

• MtBE Ban. Methyl Tertiary Butyl Ether (MtBE) was added to conventional gasoline to enhance combustion and octane levels and to meet the federal Clean Air Act mandate requiring 2% oxygen in Reformulated Gasoline (RFG). The Maine Legislature banned MtBE as a gasoline additive in the state after 1 January 2007. With the MtBE ban in Maine and other states ethanol has been blended with gasoline in place of MtBE. However, Maine has no requirement to blend gasoline with any oxygenate such as ethanol. (Maine withdrew from the Reformulated Gasoline (RFG) program in 1999.)

  The US Energy Policy Act of 2005 (EPACT 2005) removed the federal Clean Air Act mandate requiring 2% oxygen in RFG as of 5 May 2006. MtBE was the refiners’ primary fuel oxygenate to comply with the RFG oxygen requirement. Although EPACT 2005 did not ban the use of MtBE, the elimination of the federal oxygenate requirement led to a rapid phase-out of MtBE and a significant increase in the use of ethanol. While RFG can be produced without oxygenates, the industry uses ethanol to provide performance (octane enhancement), help achieve the lower air toxics requirements of RFG, and to make up the lost volume from MtBE.

• Maine provides tax incentives for the manufacturing and distributing of biofuels.

• Refiners and distributors are choosing to blend gasoline with ethanol due to a federal tax incentive (VEETC, earlier post) which, in the case of E-10 is $0.051/gallon, which has created an industry incentive to use higher volumes of ethanol.

• Energy Independence and Security Act 2007. The Renewable Fuel Standard in the Energy Independence and Security Act mandates an increase in the amount of renewable fuels nationally to 9 billion gallons to be blended in the fuel supply in 2008 increasing to 36 billion gallons in 2022. Maine itself has no renewable fuel standard requirement.

Phase separation in a fuel tank. Click to enlarge. Source: Cim-Tek

With the increasing prevalence of E10, retailers are being forced to take measures to adapt their pumps, tanks and daily maintenance procedures for ethanol blend use. One of the biggest issues they face is preventing water contamination of the tank, which will induce phase separation. As little as 18 gallons of water in a 6,000-gallon tank can induce phase separation.

Depending upon condition, between 40-80% of the ethanol will be drawn away from the gasoline by the water, forming two discrete layers in the tank. The top will be a gasoline that is lower in octane, and perhaps out of specification; the bottom will be a mixture of water and ethanol that will not burn.

Resources

• Guidelines for Conversion of Retail Service Station Tanks from Gasoline to Ethanol - Blended Gasoline (Cim-Tek)