As a vehicle fuel, natural gas holds considerable promise but faces a number of challenges.
Overcoming those challenges is the goal of recent funding granted by the U.S. Department of Energy for a handful of research projects.
Among them are the challenges of incorporating high-pressure natural gas storage tanks into vehicle designs.
While pickup-truck adaptions customarily put the cylindrical tanks in the front of the bed, or perhaps under the bed between the frame rails, the challenges are much tougher for passenger cars.
The 2013 Honda Civic Natural Gas, for instance--the only passenger vehicle currently sold that runs on natural gas--loses about two thirds of its trunk volume to accommodate the natural gas tank--because there's no other space in the car large enough to accommodate it.
A research project at Ford, funded by the Advanced Research Projects Agency--Energy (ARPA-E), will look at materials that would allow the natural gas to be adsorbed in a tank that could thus carry more energy at lower pressures.
The goal there would be to provide natural-gas vehicles with equivalent range to any other passenger car. Today, the Honda Civic Natural Gas provides a range of 150 to 180 miles in real-world use, versus twice that in any gasoline Civic model.
Overall, ARPA-E plans to award up to $30 million in grants for research on making natural-gas vehicles more practical.
Another project from the DOE’s Pacific Northwest National Laboratory, in Richland, Washington, proposes developing a ball-shaped tank made of less expensive materials that would nonetheless increase the storage efficiency by 90 percent over current tanks.
2010 Honda Civic GX natural-gas vehicle, Los Angeles, November 2010
Finally, home refueling for natural gas--long seen as the Holy Grail for adoption of natural-gas passenger vehicles--will be addressed under a project initiated by General Electric.
Their research involves a home refueling station that would chill natural gas drawn from a home's gas line, making it easier to remove the water it contains, which cannot be part of the fuel when it enters the car's engine.
Home refueling stations will remain necessary because the low pressure of household gas supply lines isn't nearly sufficient to fill a car's high-pressure tank.
That requires a compressor that runs for several hours, typically overnight.
The various challenges and approaches to solving these problems were, according to John Gartner of Navigant Research, a frequent topic of discussion at the most recent ARPA-E Summit meeting.
That gathering was held late in February in Washington, D.C.