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Is a Hydrogen Car in Your Future?
Alternative Energy Sources
Standards
3.2.12B, 3.4.10B, 3.7.12A, 3.8.12B & C
Background
Solar cells are examples of useful electrical technology as they can transform the
sustainable energy of sunlight into electricity. However, we often need electrical power
when sunlight is not available, for example at night time. This means that we want to
collect the maximum sunlight possible with a stationary solar cell and store it for later use.
If a solar cell is connected to an electrolyzer (fuel cell), the radiant energy of the sunlight
can be stored as hydrogen and oxygen gas. A fuel cell can use these gases to make
electricity when it is needed. The conversion of energy from one form to electricity is the
principle behind any electrical generator. Electrical generators include solar panels, diesel
or gas engine generators, hydroelectric turbines and fuel cells.
A solar cell contains layers of two types of silicon. Photons of light striking its
surface knock electrons loose from one layer. The electrons are drawn to the other layer. If
the two layers are connected through an external circuit, electric current will flow through
that circuit. As more light is supplied to the solar cell, more current is generated. This flow
of current may be thought of as similar to a waterfall and has two values that are easily
measured. One measurement is like the height of the waterfall, which is a fixed value. This
is the electric potential and is measured in volts. The other measurement is like the amount
of water that falls down the waterfall, and allows us to actually do work with the water.
This is called the current and is measured in amperes (or simply amps). Thousandths of an
ampere are called milliamperes, or mA.
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Electrolysis is the use of an electric current to take a compound apart. Water,
formula H2O, is a compound containing two atoms of hydrogen and one atom of oxygen.
This investigation will introduce a way to break up water with electricity by having it flow
through an electrolyzer (fuel cell.) The electricity to break up the water will come from the
solar panel. The solar panel converts light into current. This current splits water into
hydrogen and oxygen in the fuel cell. The hydrogen and oxygen are then converted back
into current in the fuel cell. The current drives the electric motor of the car.
Since the early 1960s car companies have been working on fuel cell cars,
producing prototypes with impressive features such as a traveling distance of 200 km with
one hydrogen filling. Although little has been done towards commercializing a hydrogen
powered vehicle the recent threat of California’s zero-emission policy has caused car
companies to respond.
Today the car companies are on the verge of producing fuel cell cars in quantity.
These cars meet all the needs today’s customers demand. Several police and fire
departments in the USA possess fuel cell powered vehicles. Some European towns have
changed part of their public transportation bus fleet to fuel cell powered busses. British
Columbia, Canada plans to have the first hydrogen bus fleet ready for public transportation
during the Winter Olympics 2010.
Guiding Questions
What are some potential positives and negatives to using solar energy?
Other than gasoline, what energy sources could be used to power a motor vehicle?
What are some challenges involved with mass producing non-gasoline powered vehicles?
Knowing the volume of consumed hydrogen gas and the total distance covered in meters,
explain how to calculate the gas mileage in miles per gallon for the Fuel Cell Kit Car?
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Equipment
Car with motor
Load measurement box
Distilled water
500 Watt utility light
Ruler
Safety
Wear safety goggles
No open flames
Distilled water only
Keep minimum distance of 20 cm (8 inches) between light source and solar panel
Do not concentrate light
Do not touch the hot surface of the solar panel or lamp
Procedure
1. Place the fuel cell upside down (numbers facing down) on the flat
surface.
2. Remove the stoppers.
3. Pour DISTILLED water into both storage cylinders until the water reaches the tops
of the small tubes in the center of the cylinders.
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4. Tap the fuel cell lightly to help water flow into the area surrounding the membrane
and metal current-collecting plates.
5. Add more water until it starts to overflow into the tubes in the cylinders.
6. Place the stoppers back onto the cylinders. Make sure no air is trapped inside the
cylinder.
7. Turn the reversible fuel cell right side up.
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8. Plug one end of the red patch cord into the red jack of the solar panel (1) and the other
end into the red jack of the fuel cell (3).
9. Repeat step 8 with the black patch cord and the black jacks (2, 4).
10. Align the solar panel with the light source keeping a minimum distance of 20 cm (8
inches).
11. Turn on the light.
12. When the hydrogen storage cylinder is filled to a little more than 12ml, turn off the
light and record the exact volume in ml of hydrogen gas.
13. Unplug the patch cords from the reversible fuel cell.
14. With the red and black terminals facing towards the front of the car, place the
reversible fuel cell into the notches on the model car until it audibly clicks into place.
15. Connect the red (positive) banana jack with the red (positive) terminal.
16. When the car is in racing position connect the black (negative) banana jack with the
black (negative) terminal.
17. When the car stops moving, measure the total distance traveled in meters.
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Data
Consumed volume of hydrogen gas _______ mL
Total distance traveled _______ m
Calculations
1. Using your data, calculate the gas mileage for the Fuel Cell Kit car in miles per gallon.
Show all work.
2. Assuming the lab was performed at standard temperature and pressure (STP), show the
necessary work to convert the gas volume in ml of hydrogen to liquid volume in ml of
hydrogen.
3. Recalculate the gas mileage of the fuel cell kit car in miles per gallon using the liquid
volume of hydrogen from the previous question.
Questions
1. Write the chemical reaction for electrolysis.
2. Write the reaction that is occurring within the fuel cell while it is powering the car
motor?
3. Why are the products of the hydrogen fuel cell reaction preferable to the products of
gasoline combustion?
References
Revised from Heliocentris Dr FuelCellTM Model Car Laboratory Manual, Heliocentris
Energiesysteme GmbH, Rudower Chaussee 29, 12489 Berlin, Germany
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Teacher Notes.
The Solar Panels are most fragile. They must not be bent!
Make sure students do not place the artificial light source any closer than the 20 cm noted
in the procedure.
Distilled water ONLY must be used in the fuel cells. Students must wash and rinse hands
thoroughly before handling the fuel cell. Unwashed and un-rinsed hands contain
harmful ions.
Approximate time:
About 15 minutes to set up.
About 15 minutes to charge the fuel cell.
About 10 minutes to “race” the cars.
Can be done in one standard non-block class period.
Answers to Questions:
Guiding Questions
1.
What are some potential positives and negatives to using solar energy?
Answers will vary.
2.
Other than gasoline, what energy sources could be used to power a motor
vehicle?
Electricity, solar, biofuels etc.
3.
What are some challenges involved with mass producing non-gasoline
powered vehicles?
Politics surrounding oil production/consumption and the profits involved,
patents, rebuilding car production plants, time and resources for research and
design
4.
Knowing the volume of consumed hydrogen gas and the total distance
covered in meters, explain how to calculate the gas mileage in miles per
gallon for the Fuel Cell Kit Car?
Convert ml to gallons using standard conversion factors. Convert meters to
miles using standard conversion factors. Divide miles by gallons.
Calculations
1.
Using your data, calculate the gas mileage for the Fuel Cell Kit car in miles
per gallon. Show all work.
Convert meters to miles (1 mile = 1609 m). Convert ml to gallons (1 gallon =
3785 ml). Divide miles by gallons.
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2.
Assuming the lab was performed at standard temperature and pressure (STP),
show the necessary work to convert the gas volume in ml of hydrogen to
liquid volume in ml of hydrogen.
Convert gas ml to liters ( 1 liter = 1000 ml). Convert liters of gas to moles (1
mole = 22.4 L). Convert moles of hydrogen to grams ( 1 mole = 1.00794 g H).
Use the density of liquid hydrogen to convert grams to liquid ml (density of
liquid hydrogen = .07 g/ml)
3.
Recalculate the gas mileage of the fuel cell kit car in miles per gallon using
the liquid volume of hydrogen from the previous question.
Divide miles per liquid volume in ml.
Questions
1.
Write the chemical reaction for electrolysis.
Electricity + 2H2O
2H2 + O2
2.
Write the reaction that is occurring within the fuel cell while it is powering the
car motor?
2H2 + O2
Electricity + 2H2O
3.
Why are the products of the hydrogen fuel cell reaction preferable to the
products of gasoline combustion?
Water is not harmful to the environment and gasoline engine emissions such
as nitrogen gas, carbon dioxide, carbon monoxide, hydrocarbons and
nitrogen oxides are contributing to global warming.
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