Over the past 50 years Shell Oil has been quite active in technology to liquefy natural gas for import/export, and now, with North American shippers looking for relief from high diesel fuel costs, the company is seriously exploring infrastructure projects to put LNG in the trucker's tank.
Currently, under the leadership of James Burns, general manager for LNG for Transport, Shell has been developing technology, relationships and logistics for a Green Corridor from Edmonton to Calgary that would make the necessary fueling stations available for over the road truckers driving LNG-powered diesels. That project has quietly taken shape, fueled by a small LNG plant near Jumping Pound and the cooperation of a number of Flying J stations along the way.
Burns says the corridor is an example of what can be done in areas with plentiful natural gas supplies. It's also the first fruits of what Shell hopes might include others, possibly in the Boston-NYC-Washington corridor near the Marcellus Shale Formation, or in South Texas near the Eagleford formation. In fact, he says those areas are being developed and LNG fueling is a real possibility in both areas in the near future.
While a number of proponents of natural gas for transport fuel are concentrating on compressed natural gas (CNG), Shell has cast its lot with LNG, which requires no high-pressure tanks and compressors, and provides better energy density in "diesel equivalent"( DE) amounts of fuel required for long-distance travel.
Burns says on a DE basis, LNG costs about 70% of diesel fuel's price, although he notes an LNG truck is likely to cost 50% or more than a traditional diesel upfront. "When you consider LNG is non-corrosive and creates very few engine deposits, and it's a low-carbon emission fuel, we think there's room for it regardless of the higher cost of the equipment to burn it."
LNG is natural gas (methane) super cooled to -260 F, and is stored in insulated, non-pressurized tanks. The cooling process reduces the volume of the energy-rich fuel to 1/600th of its gaseous state. Compressed Natural Gas, however, requires high-pressure-capable fuel tanks and compressors capable of squeezing the gas into the tanks at 3,500 psi. A comparison of the two is about 28 gallons of LNG to travel 100 miles in a tractor-trailer rig, or 58 gallons of CNG to go the same distance.
"That's a lot of difference in fuel storage space that has to be designed into the truck," Burns explains. "Remember, to travel that same distance would require only about 15 gallons of diesel fuel."
Still, even with the storage challenges, Shell is working with OEMs and engine manufacturers to see that LNG trucks are available in Green Corridors to "put them on the map" and demonstrate their usefulness. Overall, the carbon emissions from LNG (from well head to truck wheel) are about 80% of that of a traditional diesel-powered rig.
"LNG is the fuel of the future, and it is here now," Burns adds. "Gas is becoming more plentiful, the demand for low-carbon-emission fuels is great, and the infrastructure to produce and use LNG is not nearly as complicated as that required for CNG."