The low cost of natural gas and the high cost of petroleum products like diesel and gasoline have produced a lot of interest in natural gas as a transportation fuel. It is an idea that’s been around for a while and works fine in practice. Most of the interest and effort has gone into using compressed natural gas (CNG). UPS recently announced it was adding 48 trucks to its fleet of 18-wheelers that will run on liquefied natural gas (LNG).

LNG is attractive relative to CNG because the higher energy densities allow a truck to go farther on a full tank of fuel. (Still, LNG has substantially lower energy density than diesel, so fuel tanks will be larger or range will be reduced.)

T. Boone Picken’s energy plan is heavy into natural gas for transportation, and his private investments reflect his interest. His company Clean Energy claims to be the “leading provider of natural gas fuel for transportation in North America.” Not surprisingly, Clean Energy is involved in the UPS LNG effort.

The New York Times Green blog reports “U.P.S. Finds a Substitute for Diesel: Natural Gas, at 260 Degrees Below Zero“:

The final frontier for alternative motor fuels, powering big tractor-trailers, has been crossed.

The alternative is natural gas, but not in the now-familiar form of compressed gas. Instead, a growing number of the biggest trucks are running on liquefied natural gas. Burdened by diesel prices that topped out at over $5 a gallon in 2008 and mindful of the sustained collapse of natural gas prices, trucking companies are expressing new interest in liquefied natural gas for their thirstiest trucks, the over-the-road 18-wheelers.

“It’s the only long-term viable option to diesel,’’ said Michael G. Britt Sr., director of maintenance and engineering at United Parcel Service, which is about to add 48 L.N.G. trucks and would like to deploy many more, if the fueling infrastructure is in place and if truck production volume rises enough to bring down costs. Many other companies are running test fleets….

U.P.S. received $5.5 million for the project from the state of California that was allocated by the federal Energy Department. The company used $4 million to pay for the extra cost of the trucks and funneled $1.5 million to Clean Energy of Seal Beach, Calif., to build a fueling station.

I’m not so ready to declare that “the final frontier for alternative motor fuels … has been crossed,” since the “crossing” was subsidized to the tune of $5.5 million.

The technology doesn’t seem to be new, just the use of LNG in this particular application. Are we – the subsidizing taxpayers – learning anything useful from the project? Will any data collected be publicly available? I’m all in favor of experiments and innovation, but if public monies are supporting the work, then the results should be made available for public review.