For decades, engineers have tried to find safe, reliable, and affordable ways to use natural gas to fuel automobiles. But due to a combination of infrastructure challenges inherent with natural gas, a dearth of natural gas fueling stations, and the relatively low cost of gasoline, the economics and logistics have never penciled out very well. In fact, just two percent of the natural gas consumed is currently used for transportation, and more than that is lost during production and piping the fuel.
New advances in horizontal drilling techniques and hydraulic fracturing have caused the price of natural gas to fall as supply has swollen, and researchers at Oregon State University are working on innovative ways to power automobiles with natural gas.
Chris Hagen, assistant professor in the Energy Systems Engineering Program at the OSU-Cascades campus in Bend, Ore., heads one of only 13 research projects nationwide that have been awarded significant funding from the U.S. Dept. of Energy’s Advanced Research Projects Agency–Energy (ARPA–E) to fast-track research that will lead to more natural gas-fueled vehicles. The funding is part of ARPA–E’s Methane Opportunities for Vehicular Energy (MOVE) program.
Hagen, who previously worked for Chevron and taught at Colorado State University before coming to OSU-Cascades in 2012, spoke at a recent Science Pub Corvallis about his research project, which has garnered more than $1 million in funding from ARPA–E so far.
“Natural gas vehicles have been available for a while, and converting an engine to natural gas is quite straightforward,” Hagen said. “But infrastructure is the challenge. The question is: how can we efficiently fuel vehicles with natural gas in a safe way?”
Hagen’s group includes an Oregon State spinout company called Onboard Dynamics, Inc., where he serves as chief technical officer. He and his team of students have innovated a way to adapt a traditional internal combustion engine so that it also functions as a mobile natural gas compressor. The engine would allow drivers to refuel anywhere a natural gas tap is available.
“Infrastructure is the issue we’re trying to attack,” said Hagen. “Natural gas is cheap, but how are you going to get that fuel into vehicles when there are only 600 natural gas filling stations in United States — compared to something like 150,000 gas stations? Well, there are tens of millions of homes plumbed with natural gas. The nice thing about this dual-mode engine is that the compressor travels with you, so if you have a tap at your house, and I have one at mine, we can fuel up at either location.”
The team has converted a Cummins diesel engine by adding two extra valves on one cylinder that can be toggled on or off to make that piston function as an onboard compressor.
“In a nutshell, we’re taking an internal combustion engine and making it into a dual-function engine,” Hagen said. “The whole idea is that we wanted to take advantage of what’s already under the hood, which looks a lot like a compressor, and use that to compress natural gas.”
The current state-of-the art natural gas fueling technology for residential use is a compressor system installed in a garage that runs all night to refuel a vehicle’s tank, Hagen said. But the system costs up to $5,000 to install, and there have been some mechanical issues.
The onboard compression technology Hagen’s team is developing has a flow rate ten times greater than existing systems, an operating lifetime that is three times longer, and adds only $1,000 to the price of the engine.
“Given that the stored energy per mass unit in natural gas is higher than gasoline and the fact natural gas prices have fallen, powering cars by natural gas makes sense,” Hagen said.
Hagen was quick to point out the “good, bad, and ugly” of using natural gas for automotive fuel. The “good” is that natural gas has more energy per unit mass, so it produces less CO2 when burned. The “bad” is that horizontal drilling and hydraulic fracturing (commonly called fracking), is controversial. And the “ugly” is that during the production of natural gas, things can go wrong, and there are concerns about groundwater contamination from the chemicals used in fracking.
Still, Hagen believes that as the industry matures, more controls will be put in place, and as other technologies like the one he is developing come online, the production process will become safer and powering cars with natural gas will be the wave of the future.
— Gregg Kleiner