Corn for clean air

The city of Kansas City owns more than 200 cars and trucks that run on natural gas, a cleaner and less expensive fuel compared to liquid gasoline. But a couple of flaws in the technology have caused private consumers to steer clear — until now.

MU physics professor Peter Pfeifer, working with the Midwest Research Institute, recently discovered a way to improve the process by using corn briquettes.

Pfeifer designed and installed a new natural gas tank that holds the fuel at a lower pressure — 500 psi versus 3,600 psi — because it is filled with corn briquettes that absorb natural gas like a sponge.

Pfeifer and the institute hopes the new gas tank will overcome consumer objections to natural gas powered vehicles.

Phil Buckley, who manages the Midwest Research Institute’s role in the project, said Tuesday he analyzed one of Kansas City’s Ford F-150 pickup truck’s performance and determined that it got almost 15 miles per gas gallon equivalent.

The truck gets an estimated 15 to 17 miles per gallon on liquid gas, Buckley said. The gas gallon equivalent is determined by a ratio of 14,000 Btu of natural gas to one gallon of regular gas and both produce the same amount of thermal energy.

“I’m proud to say that we haven’t had any problems with the system,” Pfeifer said.

But the old natural gas cars had a number of problems.

“There are three problems with natural gas,” said Sam Swearngin, the superintendent of Kansas City’s Central Fleet Division. “One, the cost to compress it. Two, the tank uses trunk space. And three, the cost of the car itself.”

Swearngin said the tanks in natural gas powered vehicles are currently stored in a car’s trunk or in the bed of a pickup. This makes the vehicles unpopular with consumers who would like to use their trunks or truck beds for other purposes.

He said another problem is that in order to hold enough gas to power a car or truck for a few hundred miles, the natural gas needs to be pressurized to 3,600 pounds per square inch which requires expensive and high-maintenance compressors to either pressurize the gas when it is put into a gas station storage tank or as it is injected into a vehicle’s tank. Homeowners can purchase a small compressor that runs off the interstate natural gas lines, but they take all night to fill the car.

Tom May, the director of marketing at MFA Oil, said supplying natural gas to consumers using the compressors is too expense to make it a viable option for his company.

Pfeifer said the new tanks can hold an equal amount of natural gas as the older tanks, but at a much lower pressure, cutting out the need for expensive compressors.

He said the research team set 500 psi as the target pressure for a reason — to solve one of the problems with current natural gas vehicles that is an obstacle to commercial viability. Interstate natural gas lines run at 500 psi and currently feed natural gas to many homes and commercial buildings across America. The lines can be hooked up directly to a tank filled with the corn briquettes, bypassing the need for a compressor and the need to store the natural gas on site. The design will do away with the compressors, making it cheaper for fill stations to offer natural gas at the pump, Sweargnin said.

The old natural gas tanks also cost more than liquid gas tanks, making natural gas vehicles, or NGVs, more expensive. A Honda Civic NGV costs about $5,500 more than the non-NGV model. Kansas City pays as much as $6,000 more for some of the NGVs in its fleet, Swearngin said.

The corn-filled tank should only cost about $1,000 to make, Pfeifer said.

He said automobile manufactures have been reluctant to invest in the older natural gas models, but he said manufacturers have expressed interest in the corn briquette-filled tanks. He declined to name the interested parties, because he said negotiations are still under way.

“There are domestic as well as foreign companies that we are working with,” Pfeifer said.

The average cost of natural gas across the country is 94 cents less than an equivalent amount of liquid gasoline, according to the Department of Energy’s Web site. The Energy Information Administration, a branch of the Department of Energy, said most natural gas used in the U.S. is produced in the United States or Canada from gas fields or from renewable sources such as landfills.