A diesel powered fuel cell.
Posted 9/6/2001
Penn Engineers Develop Fuel Cell That
Uses Liquid Diesel, The First Such
Device To Run On A Widely Available
Fuel
PHILADELPHIA – Chemical engineers at the University of
Pennsylvania have developed a prototype fuel cell that’s the first to
run on a readily available liquid fuel source, in this case ordinary
diesel fuel. The work nudges fuel cells closer to viability, offering the
promise of compact, portable power sources that offer much more
bang for the buck than combustion engines or existing batteries.
Scientists, corporations and the military are all interested in fuel cells,
which are far more efficient and less polluting than other energy
sources. Work to develop commercial fuel cells, however, has been
hindered by the limited fuel sources on which they have been known
to run.
"There used to be a saying that you could run a fuel cell on any fuel as
long as it’s hydrogen," said Raymond J. Gorte, professor of chemical
engineering at Penn and the lead author of a Journal of the
Electrochemical Society paper reporting the finding.
Gorte and colleague John M. Vohs, professor and chair of chemical
engineering at Penn, shook the fuel cell world in March 2000 with the
publication of a Nature paper in which they reported developing a fuel
cell that could run on butane, the first fuel cell to operate on a fuel
other than hydrogen. With the development of a fuel cell that runs
directly on liquid diesel of the type sold at gas stations, the team has
sidestepped the thorny problem of "reforming" fuels to hydrogen to run
fuel cells.
"In our earlier work, we were unable to feed liquid diesel to the fuel
cell because we did not have a means for vaporizing fuels that have a
low vapor pressure at room temperature," Gorte said. "This paper
demonstrated that we could feed these liquids to a fuel cell using a
method analogous to a fuel injector in an internal combustion engine
and still get stable operation of the fuel cell."
Much past research with fuel cells has focused on the messy question
of how best to process, or "reform," available hydrocarbon fuels such
as diesel into pure hydrogen, an expensive and inefficient proposition.
The Penn fuel cell is the first to run directly on hydrocarbons, without
requiring complicated reforming into hydrogen either within the
device itself or at specialized filling stations. Generating electric
power through controlled electrochemical reactions rather than
combustion, its only emissions are water, carbon dioxide and heat.
Smaller than a penny, the prototype fuel cell developed by Gorte,
Vohs, graduate student Hyuk Kim and postdoctoral researcher
Seungdoo Park operates in a furnace set at 700 degrees Celsius. A
commercial, self-contained fuel cell would ideally generate that heat
itself using the fuel placed in it.
Although unlikely to replace household batteries for small appliances
and portable electronics, researchers have suggested that fuel cells
might be appropriate for powering cars and laptop computers.
"We are excited by the progress that Professor Gorte and his
colleagues are making in the area of direct oxidation of hydrocarbon
fuels using solid oxide fuel cells," said David Bauer, team leader for
the Solid Oxide Fuel Cell project at the Ford Research Laboratory in
Dearborn, Mich. "The ability to utilize conventional fuels with little
or no reforming is particularly important in transportation applications
where fuel storage and system packaging are such critical issues."
Fuel cells could also make possible electric generators that operate on
propane or butane. Gorte’s team is interested in developing a
relatively small, five-kilowatt fuel cell. Such a unit, placed in a
home’s basement, could be used to generate electricity from natural
gas, using the excess energy to heat the home or its hot water.
"It’s much more efficient to produce energy on-site than it is to make it
many miles away," Gorte said.
The U.S. military regards fuel cells as a possible source of portable
"palm power" for soldiers carrying electronic devices. Together with
Honeywell, Penn researchers have recently been awarded $1.8
million by the U.S. Army and the Defense Advanced Research
Projects Administration to develop a coffee-can-sized fuel cell
capable of generating power equivalent to 50 D-cell batteries. The
military is particularly interested in diesel-run fuel cells because
diesel’s low vapor pressure makes it less explosive and therefore
safer; the Penn fuel cell also runs on the hydrocarbons toluene and
n-decane.
DARPA has indicated to the team that it would like fuel cell
technology to find civilian applications. "We believe this is very
doable and that this technology should be very easily modifiable for
many applications," Gorte said.
Gorte, Vohs, Kim and Park’s work with solid oxide fuel cells was
funded by the Office of Naval Research and published in the July
issue of JECS.
Note: This story has been adapted from a news release issued by University Of
Pennsylvania for journalists and other members of the public. If you wish to quote
from any part of this story, please credit University Of Pennsylvania as the original
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sciencedaily.com |
