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Fuel-Cell
DRIVERS
WANTED
by Todd Clark and Rick Jones
I
f you were to ask middle level students what type of car they
would like to drive when they get their driver’s license, they
would no doubt respond with “a sports car” or an SUV. Although they are years away from being licensed drivers, most
have spent considerable time contemplating their dream car.
Suggesting that maybe they should consider a fuel-cell car or a hybrid
vehicle may generate some laughs, but may also pique their curiosity.
Recently, President Bush commented that the greatest environmental progress made in this century will be through technology
and innovation (Bush 2003). His administration has committed
$1.7 billion over the next five years
for research on the use of fuel cells
for personal transportation (Abraham
2003). While the political climate
seems favorable for the development
of fuel-cell vehicles for personal transportation, the market’s demand may
not be so favorable. Nonetheless,
middle level students will be the next
generation of drivers and voters, and they
need to be able to make informed decisions
regarding the nation’s energy and transportation policies and understand how such decisions impact our environment.
PHOTOS COURTESY OF THE AUTHORS
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Summer 2004
Todd Clark is a science education advisor in the
Office of Science at the U.S. Department of Energy in Washington, D.C. Rick Jones is a high
school science teacher and Einstein Fellow from
Billings, Montana.
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FIGURE 1
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Chemical equations
(1)
This is the combination of two other chemical reactions,
one at the cathode:
O2 + 4H+ + 4e¯ → 2H2O
(2)
and one at the anode:
2H2 → 4H+ + 4e¯
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FIGURE 2
The combined chemical reaction for fuel cells is simply:
2H2 + O2 → 2H2O
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(3)
Fuel-cell technology
Fuel cells generate electricity by the reverse reaction of
electrolysis of water. In the electrolysis, electrical current
causes water molecules to separate into their component
gases: two-parts hydrogen and one-part oxygen. In a fuel
cell, hydrogen combines with oxygen to produce electricity, heat, and water (see Figure 1 for the chemical equations used in a fuel cell).
The U.S. Department of Energy (DOE) has committed resources to help teachers and the general public understand the science behind this new technology and the
benefits and disadvantages of fuel-cell technology (see
critical-thinking questions in Figure 2).
Start your engines
As an initial introduction, it may be helpful to have the
students brainstorm what they know about hydrogen, the
sources of hydrogen on Earth, and its potential uses. Ask
students if it is possible to race a model car using only distilled water as fuel or how NASA provides safe electrical
power aboard the space shuttle.
The idea for using hydrogen and oxygen to produce
electricity has been around for about 100 years and practical use of fuel cells to provide electrical power for space
craft has been a reality for more than 40 years. Students
may be provided with the materials necessary to design
and carry out several experiments that will allow them to
separate hydrogen and oxygen from water. From these explorations, students will have the necessary conceptual
understanding of electrolysis.
More than just a car race
In May of 2003, in conjunction with the DOE’s National
Science Bowl, 50 students from around the country participated in the First Annual Fuel-Cell Car Challenge at
the National 4-H Center in Chevy Chase, Maryland. Students had approximately 12 hours to design, construct,
and race their cars in two events: driving up an inclined
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Critical-thinking questions
• What would be the advantages and disadvantages of
hydrogen as an “energy currency” relative to our current
use of carbon-based fuels for energy storage?
• There was some expectation that battery-storage electric
vehicles would be the next generation of personal
transportation. Why does that seem unlikely today? How
are fuel-cell vehicles different from electric vehicles and how
are they similar? Do the same drawbacks that apply to
electric cars with batteries apply to fuel-cell vehicles?
• Fuel-cell cars will initially be more expensive than gasolinepowered cars. How should consumers decide if the
additional expense is warranted? Should the government
provide incentives for drivers to purchase alternatively fueled
vehicles? Why or why not?
• The infrastructure of gasoline stations throughout the
country to provide fuel for gasoline-powered cars was built
up over many decades. How would an infrastructure to
provide hydrogen to fuel-cell cars be different and is there
a best method for making this transition, if it occurs?
FIGURE 3
Materials list
• Thames and Kosmos Hydrogen Fuel-Cell Car Kit (plastic
car body with water reservoir removed)
• One empty juice box (with 10-cm x 3-mm plastic straw)
• One 6-speed gearbox kit (Tamiya)
• One bag “OO” gears, shafts, and accessories for
2-mm shaft (Solar World)
• Two high-speed, 2.54-cm-diameter racer wheels for 3-mm
axle with matching O-ring (Pitsco)
• Two 5-cm-diameter pulley wheels for 3-mm axle with
matching O-ring (Sargent Welch)
• Four brass sleeves (3-mm x 1-cm)
• One 30-cm x 3-mm brass axle rod
• Four alligator clips
• Two 30-cm length pieces of 20-gauge copper wire
• One bottle instant bond cement
• Four 5-mm cable staples and 4 small wood screws
• One roll electrical tape
• One utility knife
• One set small (jeweler’s) screwdrivers
• One 15-cm x 50-cm x .6-cm piece foam core
• One 15-cm x 30-cm x .6-cm piece balsa wood
• One 7.5-cm x 46-cm x .6-cm piece balsa wood
Summer 2004
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Racing student-designed fuel-cell cars up an inclined plane.
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products of the incomplete combustion of
hydrocarbons.
Students also discover that another advantage of using a fuel cell to generate
electricity is that there are no moving
parts, making it more efficient than a generator. Like batteries, fuel cells can be connected in series and in parallel to meet different electrical loading requirements. In
addition, the output of a fuel cell—water—can be converted back into hydrogen
and reused as fuel.
Competitions with fuel-cell-powered
model cars can help teachers integrate
several science areas. Students learn
about chemistry when they study the chemical reactions
that produce electricity and water in fuel-cell operations.
Students apply their knowledge of physics when they study
gear ratios, friction, Newton’s laws, and the center of
gravity in constructing their model cars. Students engage in engineering when they work as a team to design,
modify, redesign, and test their vehicles. Finally, students
learn about communication when they work with teammates to develop a division of labor that will allow them
to construct their cars in a timely manner. n
plane with increasingly steeper angles and a head-to-head,
double-elimination speed race. In this competition, students were provided key components, such as a fuel cell,
in addition to other materials like balsa wood and juice
boxes (for adapting this competition for use in your classroom, see the complete list of materials in Figure 3).
Students designed vehicles that were as varied as their
personalities, and the time limit was still long enough to
allow for multiple designs and redesigns as students explored their understanding of gear ratios, torque, friction,
and Newton’s laws of motion. The winning team for the
inclined plane test used impressive gear ratios (1,300:1)
to climb a 44-degree incline, while the winning team for
the speed race used a three-wheel design (to reduce friction) with a long, narrow chassis to help the car align
quickly with the guide wire.
The competition, while exciting, was secondary to
learning about how fuel cells operate, engineering design
principles, and cooperative problem-solving skills.
Abraham, S. 2003. Remarks prepared for Secretary of Energy Spencer Abraham at International Energy Agency Ministerial Working Dinner, Monday, April 28, 2003, Le Meridian Etoile Hotel
Paris, available at www.evworld.com/databases/shownews.cfm?
pageid=news290403-06
Bush, G.W. 2003. Comments made by President George W. Bush
at the National Building Museum, February 6, 2003 www.white
house.gov/news/releases/2003/02/20030206-12.html.
Driving is learning
Internet resources
By building and racing these cars, students learn firsthand
two advantages of using fuel-cell
technology: (1) the fuel is hydrogen, which is the most abundant
element in the universe and (2)
the product of the internal reacExplore Fuel cells at
www.scilinks.org.
tion is water (see Figure 2), which
Enter code SS070402
is far more benign than the many
DOE fuel cell information—www.eere.energy.gov/hydrogen
andfuelcells/education.html
How fuel cells work—science.howstuffworks.com/fuel-cell.htm
Junior Solar Sprint Rules—www.nrel.gov/education/student/
natjssrules.html
Model fuel-cell car kits—www.thamesandkosmos.com/store/
fuelcell1.html and www.heliocentris.com/products/school.html
National Middle School Science Bowl—www.scied.science.doe.gov/
nmsb/default.htm
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Summer 2004
References
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