MU team brews its own, cheaper gas

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MU team brews its own, cheaper gas
By Eric Hand
ST. LOUIS POST-DISPATCH
Sunday, May. 21 2006

Peter Pfeifer wants to turn corncobs into the natural gas fuel tank of the
future.

Pfeifer, a physicist at the University of Missouri at Columbia, bakes the cobs
into a charred carbon that can hold 163 times its own volume of natural gas,
much like a sponge holds water.

Early next month, engineers in Kansas City will test the carbon tank in a
natural gas-powered pickup. If it works, it will show automakers a way past the
alternative fuel's biggest problem: It's hard to pack enough natural gas for
long trips in the bulky high-pressure tanks currently used. Low-pressure carbon
tanks could store natural gas in the unused nooks of a car.

With gasoline prices pushing $3 a gallon, alternative fuels are jostling for
attention. Natural gas - clean, cheap, plentiful and domestically produced - is
in the race. The story of Pfeifer's corncob carbon tanks shows how ideas that
didn't make economic sense a decade ago now have traction.

"If this pans out, it could be revolutionary," said Sam Swearngin, the fleet
manager for the city of Kansas City's 218 natural gas vehicles. "It could
change the face of natural gas vehicles."

A cheaper gas

Last week, Swearngin pulled his Ford F-150 pickup alongside a filling station
pump a few hundred yards from the spot by the Missouri River where Kansas City
draws its water.

He snapped a yellow collar over the pickup's fuel injector, spun a valve and
pushed a green start button. Instead of the glug of gasoline, out came the
high-pressure hiss of natural gas. It poured in at 3,600 pounds per square inch.

In three minutes, he had filled his tank with the equivalent of eight gallons
of gasoline - at only $1.40 per gallon.

"For the American public, it comes down to brass tacks: Is it cheaper? We may
be getting there," he said.

Surging demand has kept ethanol and biodiesel prices as high as gasoline. At
the moment, natural gas is the cheapest of them all. It burns far cleaner than
gasoline.

There are geopolitical reasons for supporting natural gas, too. The United
States produces 85 percent of the natural gas it burns, with Canada piping in
most of the remainder. Domestic reserves can meet decades of demand.

And natural gas is potentially renewable: Engineers could harvest natural gas
from decomposing trash in bioreactor landfills.

The problem for natural gas vehicles is storage. It takes 123 cubic feet of
natural gas to match the energy of one gallon of gasoline.

Engineers have to stuff that volume of gas into high-pressure tanks. Swearngin
has spent hundreds of thousands of dollars on high-pressure pumps.

Even with the bulky tanks, most of Swearngin's fleet is limited to a range of
200 miles - not enough to travel from Kansas City to St. Louis. That's not a
problem for airport bus drivers or parking enforcers, who don't stray from home
base.

But it tethers drivers who want to travel farther and who need natural gas
filling stations, which are still few and far between.

Fractal fill-ups

That's where Pfeifer's work comes in.

To explain why his carbons are so special, he pulls out a piece of cauliflower.
The vegetable buds repeat a whorling pattern.

"No matter how zoomed in or out you are, you still see the same pattern," he
said. The patterns are called fractals. Ferns and clouds and lungs are also
fractals.

Four years ago, Pfeifer discovered that the labyrinth of pore spaces in carbons
was fractal. The fractal nature of the interconnected tunnels makes Pfeifer's
carbons good at trapping gas and letting it flow in and out.

In a pressurized tank, molecules of natural gas still take up a lot of room.
But the narrow tunnels in Pfeifer's carbons are over one nanometer wide, just
the right size to pack in two natural gas molecules side by side.

And he only needs low pressures of 500 pounds per square inch to infuse the
carbon with natural gas. At lower pressures, Pfeifer isn't limited to
cigar-shaped tanks.

He envisions thin-walled tanks that could conform to unused spaces - for
example, the space under a pickup's flatbed. The analogy would be airplanes,
which take advantage of limited space by stuffing hollow wings with jet fuel.

Low pressures also mean cheaper pumps, because they can rely on cheaper hoses
and gaskets and compressors. High-pressure pumps - even the home version that
Honda sells for its natural gas-powered Civic - cost thousands of dollars.

From lab to road

Every square inch of Parag Shah's basement laboratory space is covered in
carbon soot. Shah, an MU graduate student in chemical engineering, has tinkered
with the carbon recipe, which starts with ground-up corncobs. Shah then marches
the granular nuggets through a series of chemical baths and stints in the oven.

Others have tried to make carbons from olive pits or coconut shells. An Atlanta
Gas Light project used peach pits to make working carbon tanks for a pickup -
but that project died in the late 1990s, when gasoline cost half as much as it
does today.

They also weren't able to store as much natural gas as Pfeifer, who says his
knowledge of fractals will help him optimize the carbons.

Phil Buckley, an engineer on the project at the Midwest Research Institute in
Kansas City, hopes the atmosphere for alternative fuel research is warmer
today. "The situation in energy today is a lot different then it was nine or 10
months ago," he said.

In another basement room, a grimy fan blows to keep acidic gases from the lungs
of Demetrius Taylor, an undergraduate student in physics and chemistry.

He pulls a lever on a hydraulic press that's packing Shah's charred bits into
hockey pucks an inch thick. He grabs one of the finished pucks, lightweight and
surprisingly sturdy given the holey network hidden within.

This week, Shah and Taylor plan to deliver 280 of the carbon pucks to the
Midwest Research Institute.

Engineers there will stick them into aluminum cylinders attached to the bed of
one of Swearngin's natural gas-powered pickups. All summer long, the pickup's
engine will draw from the low-pressure carbon tanks rather than its
high-pressure tank.

Pfeifer hopes the test will help him land a grant from the U.S. Department of
Energy this summer. His current funding, from the National Science Foundation,
will be exhausted soon.

Taylor realizes that, ultimately, they have to interest the automotive
companies.

"Why isn't anyone kicking down our doors? We still have to prove ourselves," he
said.

ehand@xxxxxxxxxxxxxxxxx 314-340-8250


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