Freightliner will certify CleanFUEL’s 8L propane fuel injection system to run on the Thomas Built Type C school bus and Freightliner straight truck chassis. This partnership expands use of GM’s 8L long-block engine, originally intended for industrial and marine markets, to new on-highway applications of up to 33,000 lb GVW (gross vehicle weight). Conversion kits also will be available to switch medium-duty gasoline vehicles to run on propane.

The Propane Education and Research Council (PERC) approved a $3.9 million grant to support the project’s development. CleanFUEL, FCCC, GM and Powertrain Integration will co-fund the project and release a generator version of the engine for the agriculture market, where propane equipment currently supports 865,000 US farms (e.g. irrigation pumps, grain dryers, standby generators, etc.).

Since the discontinuance of the GM 8.1 liter engine there have been limited options for medium-duty propane engines. Demand for medium-duty propane engines still persists. From a fleet standpoint, we see immense potential for this new 8L platform to stimulate additional interest and adoption in the market for propane-powered vehicles.

—Tucker Perkins, President and COO, CleanFUEL USA

LPI is a direct replacement of the OEM gasoline injection system. CleanFUEL’s LPI system utilizes Icom JTG technology, and is a fully integrated, dedicated engine system. The company currently has an LPI solution for the GM 8.1L medium-duty engine, as well as a 6.0L GM engine. The LPI system to be applied in the 8.0L engine is essentially a second-generation system incorporating some changes in materials, Perkins said.

Perkins suggests that the partnership with Freightliner may expand to move into step chassis and some of the other products that it sells, such as in the trolley market or RV chassis. Perkins said that CleanFUEL is also talking with Freightliner about moving into port tractors and possibly hybrid technology.

We have been thrilled with the performance of liquid injection in general—such good performance characteristics, gas mileage, emissions, service and warranty—that’s the wave of the future for OEM programs.

—Tucker Perkins

Propane. Liquefied petroleum gas (LPG), also known as propane or autogas, can be used to replace gasoline and diesel. LPG is the fourth most common vehicle fuel in the US behind gasoline, diesel, and natural gas; it powers more than 14 million vehicles around the world, according to CleanFUEL. (PERC identifies more than 13 million vehicles worldwide in 2007 as propane-fueled.) Propane is a cleaner burning fossil fuel, yielding 87% less hydrocarbons and 50% fewer toxins than gasoline, and is more economical compared to petroleum-based options, roughly 40 to 50% less than gasoline/diesel per gallon, although less attractive on a cost per energy equivalent basis due to its lower energy content.

PERC estimates that operating costs of a propane fleet typically range from 5 to 30% less than a gasoline-powered fleet, when capital costs (vehicle and infrastructure) and operation and maintenance costs are all taken into consideration. Of all available alternative fuels, propane offers the best mix of vehicle driving range, durability and performance, PERC claims. Propane is also an approved alternative fuel under the Energy Policy Act of 1992 and qualifies for several alternative fuel vehicle tax incentives.

According to a report to Congress by the US Department of Transportation earlier this year—Transportation’s Role in Reducing US Greenhouse Gas Emissions—for the current industry average LPG supply (60% produced from natural gas, 40% from crude oil), GREET 1.8b estimates GHG reductions of 17% for LPG vehicles compared to gasoline vehicles. As with natural gas vehicles, GHG levels associated with LPG are roughly comparable to those from diesel vehicles, the report notes.

Renewable propane. In addition to being an alternative fuel, Perkins noted, propane may also be able to be produced as a renewable fuel. Researchers at MIT had earlier demonstrated the ability to make biopropane (LPG from corn or sugarcane) using a supercritical water process, and created a startup (C3 BioEnergy) in 2007 that attempted to commercialize the technology.

In February of this year, the Gas Technology Institute (GTI) prepared a report for PERC analyzing the viability of the concept of synthetic and/or bio-LPG.

...the Propane Education and Research Council (PERC) is interested in developing key R&D and business strategies for the commercial production of bio-propane (e.g., propane derived from biomass feed stocks) and synthetic propane (e.g., propane derived from non-petroleum fossil fuels : natural gas, coal or petroleum coke) based on technical and economic analyses of various promising technologies.

PERC is also interested in evaluating the potential of bio/synthetic DME (Dimethyl Ether; currently used commercially as a high-grade aerosol propellant), as a LPG supplement. Stored and transported like propane, DME is currently attracting worldwide attention as a supplement or alternative for LPG as well as for diesel and LNG applications.

—“Expert Analysis of the Concept of Synthetic and/or Bio-LPG”

For the near term for synthetic LPG, the report notes, the ExxonMobil MTG (Methanol-to-Gasoline) technology is a key commercially proven technology to produce LPG as a byproduct of gasoline production. The process uses synthesis gas produced from natural gas (NG), coal or petroleum coke. Haldor Topsøe (HTAS) is developing a competing process (the TIGAS - Topsøe Integrated Gasoline Synthesis - process, demonstrated at a scale of 5 bbl/day) to utilize NG, coal or biomass for the production of gasoline with LPG as a byproduct.

The report notes that there are four primary emerging technologies for LPG synthesis of interest:

• Virent’s BioForming process, currently being developed for the production of gasoline and diesel from biomass; the process was initially developed to primarily produce bio-propane.

• The Japan Gas Synthesis Co. Ltd. (JGS) process, proven at bench-scale level, for the direct synthesis of LPG (with very high selectivity) from synthesis gas produced from natural gas, coal and biomass.

• The University of Kitakyushu process for the conversion of DME to LPG using hydrogen. This provides a pathway for LPG production if low-cost DME is available in specific locations, and the demand for LPG is relatively high. This concept, if commercialized, would avoid a key problem for large-scale utilization of DME which, typically, cannot be used in existing LPG infrastructures (e.g., pipelines) with relatively high DME/LPG ratios primarily due to material compatibility issues related to seals, gaskets etc., the report noted. For plants where DME would be produced from biomass (or coal/NG), a part of the required H₂ for conversion of DME to LPG would be derived from the gasification (or NG-reforming) sections.

• The GTI IH² process in which LPG would be produced as a by-product with gasoline plus diesel.

There is so much talk in Washington about renewable fuel, that although there are hundreds of years of propane supply, we want to be able to position as a renewable fuel. We can take woodwaste and some switchgrasses and make propane. We’re 100 percent sure that it will work.

—Tucker Perkins

Resources

• Transportation’s Role in Reducing US Greenhouse Gas Emissions (USDOT, April 2010)

• Expert Analysis of the Concept of Synthetic and/or Bio-LPG (GTI project number 20847)