P-series fuels

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P-Series fuels are a family of renewable, non-petroleum, liquid fuels that can substitute for gasoline. It is a mixture of ethanol, methyltetrahydrofuran (MeTHF), "pentanes-plus", and butane. The formulas can be adjusted for cold weather and for 'premium' blends. Approximately 35% of the blend is or can be created from waste products of other industrial processes. It was originally developed by brothers Scott and Doug Dunlop, the co - founders of the Pure Energy Corporation and optimized by Dr. Stephen F. Paul of Princeton University. It was patented in 1997 (US 5,697,987) by Dr. Paul and assigned to Princeton University. Simultaneously, the Pure Energy Corporation was granted an exclusive license to commercialize P-Series fuels. Responding to a petition submitted by the Pure Energy Corporation, the DOE proposed in 1998 that P-Series be recognized as an alternative fuel in accordance with the Energy Policy Act of 1992 (see the Federal Register/Vol. 63, No. 144/Tuesday, July 28, 1998/Proposed Rules, page 40202.) The final rule designating P-Series as an EPACT alternative fuel was published in the following year, (see the Federal Register/Vol. 64, No. 94/Monday, May 17, 1999/Rules and Regulations, page 26822.)

In addition to the patent, the other publication detailing the P-Series fuels was Dr. Paul's 1998 paper entitled: An Optimized Alternative Motor Fuel Formulation: Natural Gas Liquids Ethanol And A Biomass-Derived Ether, which appeared in the Proceedings of the American Chemical Society Division of Fuel Chemistry, Fuels for the Year 2000 and Beyond, 216th ACS National Meeting & Exposition, August 23–27, Boston, 1998 43(3), p. 373-377.


A multi-component, liquid, non-petroleum, alternative motor fuel for spark ignition engines has been developed. The fuel is composed of approximately equal volumes of (1 )medium-molecular weight alkanes, isoalkanes, and cycloalkanes (C5 - C8) which are extracted in the course of coalbed gas or natural gas production and/or processing, (2) anhydrous fermentation ethanol, and (3) 2-methylTHF, a biomass-derived heterocyclic ether. The ether serves as a co-solvent that reduces the volatility of the ethanol/hydrocarbon blend. The formulation can be adjusted to vary the fuel characteristics over a range to formulate winter/summer and regular/premium grades:87-94octane; 0.74-0.78 specific gravity; and 6.5 - 13.5 psi Reid vapor pressure. P-Series fuels contain little or no sulfur, phosphorus, aromatics, olefins, or high-boiling-point hydrocarbons, but does contain 11 - 19% oxygen (by weight), with a corresponding reduction in heat content (100,000 - 106,000 BTU/gal). This fuel has been tested in unmodified 1996 and 1997 Ford Taurus ethanol-Flexible Fuel Vehicles. They vehicles come equipped with a fuel sensor that automatically adjust the air/fuel ratio to optimize running on a particular fuel. Emissions testing (USEPA's FTP protocol) show the following differences in the tailpipe exhaust characteristics (compared to conventional gasoline): 40 - 50% less unburned hydrocarbons, 20% less CO, no significant change in NOx, 4% less COz, 40% less ozone-forming potential, and 2 - 3 times less toxicity.

Most flexible fuel vehicles capable of running on E85 should also be able to handle P-Series fuel.

The projected retail price will be about 10% less than gasoline. As of June 2012 it is not available to the general public.

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