Are natural gas vehicles ready for their next act? With new supplies of gas predicted to keep the United States awash in cheap fuel for the next few decades, teams of researchers at both academic labs and startup companies are banking that natural gas could -- this time -- really be the fuel of the future.
They are working to overcome some of the obstacles that have limited natural gas cars to a small portion of the U.S. fleet, mostly buses and fleet vehicles. These problems include the refueling technology, safety, and getting compressed natural gas (CNG) cars the same driving range as regular gasoline powered ones.
Right now, natural gas is cheaper than either petroleum gas or biofuels. And the good thing is that, with a few modifications, natural gas can run in standard internal combustion engines. The big obstacle is getting the gas compressed so it lasts a while in a car’s on-board fuel tank. There are only 600 natural gas filling stations across the United States.
A team at Oregon State University is hoping to make it easier to fill up with the same utility gas pipe used to heat homes. They are turning an existing diesel pickup truck into a vehicle that can compress its own natural gas with one of its six cylinders.
"When it's at home, you hook up the natural gas to the vehicle, put it into compression mode, and five of the cylinders will combust normally with natural gas, the sixth acts a compressor," said Chris Hagen, associate professor at OSU-Cascades in Bend, Ore. "You're looking at 90 minutes fill time, relative to eight hours it took before."
Hagen received a $700,000 grant from the Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E) along with collaborators at Colorado State University and the Fort Collins-based engineering firm Czero.
Hagen is taking an existing engine and adding additional valves and small tanks to handle the increased pressures of compression of natural gas. He needs to compress the gas from the 1 bar (atmosphere) that is standard from a home utility line to 250 bars needed for the fuel tanks. The advantage is that the engine creates its own fuel and extends the driving range of the vehicle.
"Your compressor rides with you," Hagen told Discovery News. "You can go on long trips and fill at other people's houses."
Hagen said he the goal is to design modifications that cost only $400 to existing engines, much cheaper than existing compressor stations. With the average American spending over $2,000 per year on gas, switching to natural gas vehicles could save drivers $1000 per year, according to the DOE.
In a separate project, a research team at General Electric is developing an at-home compressor that will remove water from natural gas -- a problem for engines -- by chilling it to -58 degrees Fahrenheit (-50 C) so the water condenses as ice and is taken out. The chiller system will allow people to fill their cars at home in less than an hour, rather than the current 8-hour refill.
And yet another group, this one based out of Texas A&M, is building new kinds of composite materials that fit into compressed natural gas tanks that will allow them to hold more fuel by special chemical techniques that will hold fuel without compressing it.
"You make a very porous material and the methane in the gas will stick to it," said Joe Zhou, professor of chemistry at Texas A&M. "You don't need to go to high pressure."
Texas oilman T. Boone Pickens said that Wal-Mart and FedEx will soon start using natural gas in long-distance truck routes. As owner of numerous gas wells, Pickens is bullish on the U.S. transportation fleet switching from foreign to domestic fuel sources. Pickens himself drives a modified Honda Civic that runs on natural gas from his home in Dallas.
"It all is going to happen because of the differential in the price of fuel," between oil and natural gas, Pickens said. "It's happening right now."