Road to Greener Cities
By Nana Koram / Intern
November 16, 2001
Fuel cell technology
has a surprisingly long history-scientists have been digging into
its mysteries since 1839-but it finally appears to be moving out
of the research laboratory into the marketplace where it is destined
to become an important new power source for everything from trucks
and buses to computers and cell phones.
In March 1998,
Chicago became the first city in the world to run fuel cell-powered
buses. These days, tourists in London can explore the city in fuel
cell-powered taxis. Several companies are competing to develop fuel-cell-powered
bicycles. Only a few years ago, fuel cells cost a prohibitive $5,000
per kilowatt, the equivalent of buying an engine for $250,000, but
have now dropped to below $300 per kilowatt. In order to compete
with the internal combustion engine (ICE), the price must continue
to fall to the $30 per kilowatt range. A number of leaders in the
transportation industry are now predicting that fuel cell prices
will continue to drop and it will begin to replace the ICE in a
number of applications.
If or when the
internal combustion engine is relegated to the museum, the benefits
will be substantial. Fuel cells are naturally low-emission. Without
adding catalytic converters and other emission-reduction devices,
fuel-cell vehicles produce less than 10 percent of the air pollution
that spews out of the tailpipes of today's automobiles. So they
will be good for the environment.
will also have a positive impact on the economy. They have about
twice the fuel efficiency of comparable internal combustion engines.
So, if they gained only a 20 percent share of the domestic auto
market, fuel-cell cars would allow the United States to cut its
oil imports by 1.5 million barrels per day, thus reducing America's
dependency on oil-producing nations.
They are also
elegantly simple electrochemical devices that convert chemical energy
to electricity with high efficiency and with few moving parts, so
their operation and maintenance requirements are minimal. Fuel cells
sound almost too good to be true and their amazing potential is
one of the reasons why scientists have continued to study them for
more than 160 years. It was also what attracted me to the laboratory
of Charles Lukehart when I selected a research laboratory for an
internship in my Communication of Science, Engineering and Technology
professor of chemistry at Vanderbilt University, is one of a hundreds
of scientists who have become intrigued by the challenge of this
simple, yet sophisticated system. Although many of the problems
that have kept fuel-cell technology from commercial success have
already been solved, there is still a need to reduce the initial
cost of fuel-cell systems before they can live up to their full
potential and Lukehart has spent the last six years attacking this
interest in chemistry started by watching his brother
In person, Lukehart
is a tall gentleman with keen eyes, and a surprisingly soft voice.
He grew up in a small town in Pennsylvania and first developed an
interest in chemistry by watching his older brother working in a
makeshift chemistry lab in the basement of their home. David Lukehart,
now an industrial engineer, would regularly collect lead bullets
from practice ranges and melt them down, shaping the molten metal
into whatever he fancied at that particular moment. Being the younger
brother, Lukehart was banned from touching anything in his older
brother's lab. Somehow, this prohibition fed the younger Lukehart's
fascination with chemistry, and guided him to a career as a chemist.
As a result, he graduated from Pennsylvania State University in
1968 with a B.S. in chemistry.
In the process,
Lukehart decided that he preferred inorganic over organic chemistry
because he was attracted to the diverse compositions and interesting
colors of inorganic compounds. He then went on to the Massachusetts
Institute of Technology (MIT) where he obtained his doctorate in
inorganic chemistry in 1972. The following year he married Marilyn
McKinney, a pharmacist whose work involves mainly organic chemistry,
and with whom he now has three children.
fact that they both relate to chemistry, they have trouble discussing
their work. That is because the different branches of chemistry,
like those in many other scientific fields, are becoming increasingly
specialized, making it increasing difficult for outsiders to understand
what is going on.
two doctoral students working with him on fuel cells. As a research
intern, I had the opportunity of working closely with Eve Steigerwalt,
who is originally from Germany. She is about 5 feet 3 inches tall,
with short dark brown hair and a welcoming smile. She says that
she majored in chemistry simply because "I was good at it." She
got her best grades in chemistry so her parents encouraged her to
stick with it. But it wasn't until she was a university undergraduate
that Steigerwalt discovered that she actually liked the subject!
After graduating from University of Virginia in 1994, Steigerwalt
decided to continue her studies in the field she had grown to love
and she chose Vanderbilt for graduate study.
It was Steigerwalt
who introduced me to the inner workings of the fuel cell. It is
very simple. Two separate electrochemical reactions occur in fuel
cells: an oxidation half-reaction occurring at the anode and a reduction
half-reaction occurring at the cathode. Each half-reaction requires
the use of a catalyst to increase its rate. The catalyst that works
best on both half-reactions is platinum, a very expensive metal.
in Lukehart's lab is focused on improving the efficiency of direct
methanol fuel cells. There are two basic kinds of fuel cells currently
under development: those that use hydrogen for fuel and those than
use methanol. Hydrogen fuel cell technology is more advanced. Hydrogen
fuel cells were used to power the Apollo spacecraft and provide
electricity for the space shuttle. This type of fuel cell also has
the benefit of operating with zero emissions: Its only byproduct
is water. On the other hand, hydrogen is a difficult fuel to handle
and hydrogen fuel cells can explode if they malfunction. Methanol
is much easier to handle and not nearly as explosive as hydrogen,
but methanol fuel cells are not quite as clean, producing about
a tenth of the emissions as a comparable ICE.
A direct methanol
fuel cell, as the name suggests, runs on methanol. Inside the cell,
a catalyst made of platinum (Pt) and ruthenium (Ru) metals catalyzes
or speeds up the conversion of the chemical energy from the methanol
to electrical energy. Since platinum is so expensive, a natural
approach to reducing cost is to use as little platinum as possible.
Unfortunately, when the amount of platinum is reduced, the catalyst's
performance also drops to a point where the methanol fuel cell becomes
completely impractical. So Lukehart decided to explore ways to boost
the efficiency of the catalyst without increasing the amount of
platinum used in its production.
Making an effective
catalyst is a four step process: First, you create material that
consists of molecules that each contain one atom of platinum and
one atom of ruthenium. Next, you convert this material into a nanocomposite.
Then you characterize the nanocomposite that you have prepared so
that you have some idea how it came out. Finally, you determine
its effectiveness by putting it in a small bench version of a fuel
cell and measure how much electrical power it produces.
Lukehart build a test fuel cell was both fascinating and surprising.
I somehow expected a fuel cell to be a very high-tech, complicated-looking
piece of equipment. But he built it out of very simple materials:
copper wire, glue, water and a special type of thin, flat conductor
easily obtained in a chemical store. A voltmeter was clipped on
to measure the voltage and an ammeter was attached to measure the
current that the cell produced. The end result was about the size
of my thumb and looked like something even I could have put together.
my own catalyst
of my internship was creating my own catalyst.
To make a material
with molecules that consist of just one ruthenium and one platinum
atom I had to first create a ruthenium dimer, molecules that consist
of two linked ruthenium atoms. The lab had platinum dimer on hand,
purchased from a chemical supply store. So I didn't have to make
that as well. But I did have to combine the two to form molecules
of platinum-ruthenium dimer. This part of the experiment proved
to be rather boring and tedious. After making my first batch of
Pt/Ru dimer, I put a sample in a Nuclear Magnetic Resonance (NMR)
machine to analyze it. Unfortunately, my NMR spectrum showed some
unexpected features, suggesting that the result of my synthesis
was not pure. Eve was very encouraging and assured me that this
was a common part of the research process. However, it meant that
I had to start the synthesis process all over again.
The next step,
making my dimer into a nanocomposite, went quite smoothly. To begin
with, I combined the Pt/Ru dimer with carbon powder in a series
of steps called multi-deposition. I divided the Pt/Ru compound into
three parts and each part was combined with the carbon particles
separately. Eve explained that it was done this way to ensure that
all of the Pt/Ru molecules combined with the carbon. Then, using
a microwave oven, the material was heated to complete the process
of creating the nanocomposite. When the material was being heated,
the carbon particles became red hot. Watching the carbon sparks
through the microwave window reminded me of fireworks. However,
the process is very long and drawn out and became slightly boring
after the first couple of weeks.
In the characterization
step, I was introduced to the X-ray diffraction machine, which measured
the size of the particles in my nanocomposite and confirmed the
composition of the nanocrystals that had formed. The smaller and
more separate the crystals, the more efficient the catalyst would
be. Electron microscope images indicated that the crystals in my
material were small and a number of them had fused together instead
of remaining separate. This was very disappointing because I had
worked extremely hard for several weeks to create them. Now I was
faced with the possibility that my final catalyst would not work
as efficiently as I had hoped. But there was nothing to do except
move on to the next step.
The final step
in the process was to put the catalyst into the makeshift fuel cell
and test its efficiency. The greater the voltage and the higher
the current produced, the more effective the catalyst. Unfortunately,
due to the fusing of the crystals formed in my nanocomposite, the
current I obtained from my fuel cell was low, indicating that my
catalyst was not working fast enough.. I was a little disappointed
that my catalyst was not as powerful as it should have been, but
the fact that it worked at all made me really happy. I felt like
a real chemist!
into the unknown
Working in a
research lab is nothing at all like working in a class lab. With
a class lab, the results of the experiment are always known. For
example, in my organic chemistry labs, we learned about different
reactions in lectures and our labs consisted mainly of performing
these reactions. We always had the textbook to alert us when something
was going wrong. For example, the textbook would let us know that
a blue compound should be formed at the end of the first half of
the reaction. So, if you did not obtain a blue compound, you knew
that something was wrong and that you may need to restart the experiment.
In a research
lab, by contrast, there are no textbooks to warn you when you are
going wrong. Most of the experiments done in research labs have
never been done before. Research is sometimes a trial and error
process, and you do not always know if you are doing something wrong
until you get to the end of the experiment. Even though researchers
can double check the compounds they make at each step using sophisticated
instruments like NMR or X-ray diffraction machines they don't know
how successful the experiment has been until the very end. It's
a bit like groping around in the dark in an unfamiliar room. You
can't see what is ahead of you or if you're going in the right direction.
You just have to keep on trying until you make it to your destination.
A final lesson
The most important
lesson I stumbled upon while working with the Lukehart group is
that research is a long process. Major discoveries do not happen
overnight. Research work can take years to complete but it is often
worthwhile in the end. Scientists have a genuine thirst for knowledge
that keeps them going even in the dark and they consider finding
the answers to puzzling questions to be one of the best rewards
for their work.