Page 6 - Fuel Cell Student Edition

they were running low on electrolyte when we left alert screen from the rover’s positioning system
and all of the heavy lifting and long distance travel
has boiled off the rest. We are on emergency battery
power now and we’re stuck out here in the middle of
desolation, until we find an alternate energy source
for the rover. No one is responding to our hailing
attempts through the onboard radio.
ENGINEER’S LOG:
NOVEMBER 13, 2041 06:01 PST:
While staring at my breakfast energy bar’s
shiny packaging I had an idea! If I could build an
electrochemical cell from the some of the metals
and chemicals at the supply depot, then I may
be able to generate enough power to get us back
home. The gravity here is only 16.7% of the gravity
on Earth. If I unload all of the tools and supplies
the energy requirements should go down by 62%.
In first gear traveling at about one kilometer per
hour, the energy production rate required for me
to keep moving on a smooth path would only be
about 7-10 kW.
I’ll also need some accessory power for the
hydraulic pump so I can steer this rig. At 25% of
the normal operating flow rate I’ll need about 412
watts to hold the course. The lunar positioning
system receiver which is essential for navigation
uses about 5 watts. This is all very doable since I
should be able to get 100 W/kg out of any decent
cell. The battery should have enough energy
storage capacity to make the rover accelerate to
its operating speed if I charge it for a while with
the fuel cell. I’m going to ask Hoshi to help me
take an inventory of the materials on board and
figure out what kind of cell we could build. We may
live after all!
ENGINEER’S LOG:
NOVEMBER 13, 2041 12:37 PST:
After spending nearly four hours staring at the on
board computer I was shocked to see the flashing
6 TOTAL REDOX™ – FUEL CELLS
readout. A new path had been remotely uploaded
to the rover! This path leads back to the outpost in
a roundabout way but it is more efficient than I’d
thought possible. I didn’t figure out who uploaded
it until the outpost contacted me some 30 minutes
later. Plissken intercepted my original distress
message and informed the HAWC engineering team
of the problem, but they didn’t want to contact me
until they had a solution.
One of the engineers on Earth plotted this course for
us to follow and uploaded a schematic of a Zinc-Air
Fuel Cell to the rover’s computer. Zinc-Air Fuel Cells
used to be commonplace. The military used them
in drones and radios. They were also adopted for
many civilian medical device uses. Luckily for me,
there are both large amounts of zinc and carbon to
be found aboard my rover. The panels surrounding
the drive motors use zinc sheet metal and we picked
up carbon filter media from the supply depot for
our water systems. The electrolyte will be sodium
hydroxide-based degreaser concentrate from the
supply depot. If the engineer’s calculations are
correct, I should be able to place a few zinc plates
in small parts containers and use my plastic part
pouches as an electrical barrier between the carbon
filter material and the zinc sheet electrodes. I’ll use
the onboard oxygen supply to slowly bubble through
the bottom of the cell, which should improve
performance.
ENGINEER’S LOG:
NOVEMBER 14, 2041 02:01 PST:
According to the engineer’s plans, I need to deliver
13.5kW of power, which works out to 1125 amps
at 12V. To keep from frying the wires with that
much current, I’ll use one of our universal voltage
converters right after the cell to change the potential
to 90V. This will allow the fuel cell to put out a much
more manageable current of 150 amps. I’ll need to
find or improvise some 7mm diameter wires just to
carry that much current.
TOTAL REDOX™ – FUEL CELLS 7