Just before the required deadline of June 1, 2015, the EPA issued proposed percentage standards of renewable fuels for the years 2014 through 2016. The annual volumes associated with the percentage standards are substantially below the volumes established by Congress in the Energy Independence and Security Act (EISA) of 2007. The Renewable Fuel Standard (RFS) program has the following four categories of renewable fuels:
(US DOE – Energy Efficiency and Renewable Energy Alternative Fuels Data Center)
- Conventional Biofuel: Any fuel derived from starch feedstocks (e.g. corn and grain sorghum).
- Advanced Biofuel: Any fuel derived from cellulosic or advanced feedstocks. Within this category are the following sub-categories:
- Biomass-Based Diesel: Diesel fuel substitutes made from renewable feedstocks, including biodiesel and nonester renewable diesel.
- Cellulosic Biofuel: Any fuel derived from cellulose, hemicellulose or lignin.
The following figure (www.afdc.energy.gov/laws/RFS.html) shows the volume requirements of the different biofuel categories as established in the 2007 EISA:
The following table compares the proposed revisions with the original volumes in billions of gallons:
The EPA used its authority under the Clean Air Act to reduce the volumes from their statutory requirements considering several factors:
- availability of qualifying renewable fuels;
- supply constraints to consuming vehicles; and,
- market conditions relating to production, infrastructure and relative pricing.
In 2014, the US biofuel ethanol industry produced 14.3 billion gallons. A small portion was exported to other countries, mostly Canada, the remainder was blended into gasoline, mostly at the 10 percent level (E10), the most common blend concentration for ethanol. In the same 2014 year the total US gasoline consumption was 136.78 billion gallons. It takes no genius in math to see that the amount of ethanol blended into gasoline was close to 10 percent; known in some circles as the “blend wall,” since 10 percent was the original maximum set by the Clean Air Act.
EIA projections indicate US gasoline consumption as relatively flat and then declining over the next several years. So how will even the revised modest growth projections for renewable fuels be achieved if ethanol concentration is limited to 10 percent? Let alone the ambitious projection of 36 billion gallons of renewable fuels by 2022 as established in the 2007 EISA.
There are two other possibilities presently available: E85 and E15, referring to the amount of ethanol blended with gasoline. Neither at present are significant sources for biofuel ethanol. E85 first of all requires specific pumps and can only be used in flexible fuel vehicles; i.e. those whose engines can run on any mixture of ethanol and gasoline from zero percent to 85 percent. There are only a limited number of such vehicles available and not many gasoline stations with special E85 pumps.
E15 is another story. In 2011 the EPA approved the use of this higher ethanol blend in conventional light-duty cars and trucks in model year 2001 and newer. However several concerns have limited the application of this higher blend. These include additional federal and state regulations, misfueling liability, and inability to meet EPA’s vapor pressure specification for E15 during the summer. (“E15 and Infrastructure,” a May 2015 National Renewable Energy Laboratory (NREL) report).
Ethanol gasoline blends in the 10 to 15 vol. percent range increase the vapor pressure of the resultant mixture by about 1 pound per square inch (psi). During the summer months from June 1 to September 15, EPA regulates gasoline vapor pressure to reduce evaporative emissions. E10 was granted a 1 psi waiver from these regulations in 1992. However this waiver does not apply to gasoline with ethanol concentrations higher that 10 vol. percent. In order to use the higher ethanol concentrations, refiners would have to produce a gasoline blend stock with a lower vapor pressure; adding additional costs to refinery operations. This is another inhibiting factor in being able to break through the “blend wall” of 10 percent.
As with all proposed new regulations, EPA allows for comments and any new data to be presented by interested parties before the regulations become effective; currently scheduled for November 30, 2015. It will be interesting to follow and see what, if any changes, are implemented during this time frame.