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7/29/2019 Hydrogen Fuel Cell Efficiency

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Table of Contents

Hydrogen Fuel Cell Efficiency Test

Introduction 2

Problem 5

Hypothesis 6

Safety 7

Materials 8

Procedure 9

Data and Results 12

Sources of Error 15

Conclusion 16

Applications 17

Bibliography 19

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Introduction

A Hydrogen Future

In todays world with rising gas prices and growing dependence on foreign oil

hydrogen seems to be the perfect solution as a clean alternative fuel. When stored as an

element, hydrogen would be a good fuel to power vehicles with fuel cells or by internal

combustion. Hydrogen is the most abundant element in the universe and it is pollutant-

free (since the only emission is water). However, there is one problem with hydrogen;

that is it can only be used as a way to store energy. There are no places on the earth to

mine hydrogen for use; energy has to be invested to produce the hydrogen. Therefore

hydrogen, if used as fuel, would be a way to redistribute energy from power plants for

use with vehicles. However, in order to know the economical benefits of hydrogen, the

efficiency of hydrogen needs to be calculated.

Fuel cells are an efficient way of using

hydrogen without the need for combustion. A fuel cell

use combines both hydrogen and oxygen them back

into water and create energy. A hydrogen fuel cell is

made up of two plates, two electrodes, and a MEA

(Membrane Electrode Assembly). Hydrogen is fed into

the fuel cell on the anode side of the fuel cell where the

hydrogen flows past the electrodes and the MEA. On

the other side of the MEA, pure oxygen or oxygen from

the air is flowing over the MEA, depending on the fuel cell type. The MEA works,

because of a platinum electro catalyst and in the PEM membrane, which acts as a solid

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proton (ionized Hydrogen atom) conductor. The platinum electro catalyst is created by a

carbon mat laced with tiny platinum pieces; this mat is then pressed onto to both sides of

the membrane made of nafion. These pieces of platinum facilitate the ionization of the

hydrogen atom. The electrons can not travel through the PEM (polymer electrolyte

membrane) due to their negative charge and are forced to go around in a circuit. This

flow of electrons produces electrical energy. The ionized hydrogen atoms and electrons

can then chemically combine with oxygen to form water and a small amount of heat. The

use of pure oxygen compared to the use of air poses a question on how to maximize the

output of a fuel cell. Since air is composed of only about 20% oxygen would pure

oxygen make the fuel cell run more efficiently?

The process of producing hydrogen in this experiment will be done by a reverse

PEM fuel cell electrolyzer. The reverse PEM fuel cell electrolyzer does the exact same

process as a fuel cell, but in reverse. As a electrical current is forced through the fuel cell

hydrogen atoms attach to the platinum catalyst release their electrons and flow across the

nafion layer to negatively charged platinum catalysts on the other side. On the other side

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hydrogen atoms regain an electron and combine with each other. This in result produces

hydrogen on one side of the fuel cell and oxygen on the other side.

The overall purpose of this project is to investigate which method of using

hydrogen will maximize the efficiency hydrogen. The experiment will also try to answer

how big the differences in efficiencies of using a pure oxygen fueled fuel cell compared

to an air fueled fuel cell. If the efficiency of oxygen fueled is much greater than air

fueled would it still be worth it to store the pure oxygen on an hydrogen powered car or

for other purposes. As this experiment is carried out it should be remembered that

hydrogen is only a way to store energy, and therefore the question will also be asked, Is

it even worth it at all to use hydrogen as a means of energy distribution? In conducting

this experiment, we hope to find the most efficient way to use hydrogen.

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Problem

How efficient is hydrogen in storing and releasing electrical energy? The method of

producing hydrogen will be reverse fuel cell electrolysis. Two methods of extracting the

chemically stored energy in hydrogen, by means of a fuel cell, involve using the

hydrogen with pure oxygen (generated during electrolysis) or oxygen extracted from air.

Which fuel cell will be the most efficient at extracting energy from hydrogen, and would

it be worth it in a hydrogen economy to store pure oxygen?

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Hypothesis

When producing hydrogen from water with electrical energy, the methods of a reverse

fuel cell electrolyzer will be tested. As the hydrogen is converted from potential

chemical energy to electrical energy, two fuel cells will be tested; one using pure oxygen,

the other using oxygen from air. The efficiency of a fuel cell fed by pure oxygen should

have the greatest efficiency over the air fed fuel cell.

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Safety

Hazardous Materials

Hydrogen is highly flammable and can combust easily if exposed to a flame or extreme

high temperatures. Hydrogen if pure without any chance to disperse into the air is

poisonous. First of all I will be under the supervision of a parent. Second to prevent leaks,

I will double check all of my equipment with water. In addition, in the event of a small

leak, hydrogen disperses into the air easily; it will not be a major explosive hazard. To

keep safe the amount of hydrogen being produced will be kept under the maximum of 10

milliliters in this lab and will not be nearly enough to cause a powerful explosive ignition

that would cause harm or bodily injury. During its first test, the electrolyzer and fuel cell

will be observed from a safe distance for extra precaution.

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Materials

Tools

Exacto Knives

Package of Q-tips

Hand Drill

Wire Cutters Crimp Tool

Drill Bits- 7/64 and 3/16 inch bits

Pliers

Hole Punch 3/16 inch from Mc Master

Metal File

Materials

12 x 12 inch Graphite Foil from Mc Master, part #9571K63

4 x 1 inch Nickel alloy foil from Mc Master, part #8912K241

12 x 12 inch thin gauge silicone rubber sheet .02 inch thick from Mc Master, part#86435K63

2 Insulated binding posts with Banana Jacks from Radio Shack, part #274-661 a

Crimp on Ring Terminals (not spade) to fit 10 or 12 gauge stranded wire

4 Bolts (plastic) that would properly and tightly fit in a 7/64 inch hole

Small plastic nuts (to fit on 7/64 inch bolts)

0.3 mg/cm Membrane Electrode Assembly from fuel cell store, item code 599708

2 Barb splicer hose connectors 1/8 x 1/8 inch

Battery Terminals (hook up to power supply

1/8 inch Plastic Tubing

10 or 12 gauge wire

Underwater Repair Epoxy Putty

2 voltammeters

2 current probes

Lab pro

Computer with logger pro software

4 C-clamps

Cell phone charger rated at 3.7 volts

6 alligator clips to fit 10 or 12 gauge wire

Syringe

Barbed splicers

Hydrogen Starter Kit (comes with oxygen feed PEM fuel cell and PEM

electrolyzer) from fuel cell store, item code 535608

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Procedure

Building the Fuel Cell

1. Cut out 2 pieces from the Nickel alloy foil with the cutting tools as shown intemplate #1 show to make the anode and # 5 cathode

2. Be extremely cautious and be gently when drilling a hole in the anode and cathodemake sure holes will match

3. Smooth and flatten the boards after drilling

4. Next, cut out 1 piece of graphite like template #2, smooth the edges, and engravewith a pencil the graphite, then drill the holes in the graphite and smooth it out. Thispiece will direct hydrogen flow over the MEA

5. Cut out the other graphite plate according to template #4. This piece directs air pastthe oxygen side of the MEA and allows water to drain from oxygen side.

6. Insert the 1/8 barbed splicer hose connector and insert the connector throughconnector both end plate and graphite plate. Place a splicer in both hydrogen in andout ports

7. Prepare a very some of the underwater epoxy putty and seal the outside of the bardsplicer at the points where it will be contacting the plate, then let the underwaterepoxy putty dry.

8. Cut out and punch the 2 Mylar surrounds according to the template #3. Place theMEA between the Mylar surrounds.

9. Place plastic screws through holes drilled in templates starting with template # 1 andin increasing order with the # 5 template on the bottom

10. Seal and make air tight with extra pieces of silicon rubber if necessary, tighten boltsand fasten c-clamps on two the fuel cell. Check to see if air tight by flowing waterthrough fuel cell.

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Testing Procedure

1. Using Labpro amp meters, voltmeters, the power source, an electrolyzer, a fuel

cell, and the electrical load, construct the following experimental set up:

2. When testing, be sure to keep the environment of the test site constant. This

includes average temperature, light exposure, etc of the experimental setup. Beforerunning the electrolyzer, make sure the valves on the oxygen and hydrogen pipes

are closed. Also, make sure that the storage tanks and all pipe segments are filled

with water and that no gas is present in the system. For each trial, produce 5

milliliters of hydrogen and store it in the storage tanks as seen in the abovediagram.

3. While producing the hydrogen with the electrolyzer, record the input amperes andvoltage from the Labpro probes installed in the above configuration. Set the

Labpro software, LoggerPro, to record data every .1 seconds. Disconnect thepower supply from the electrolyzer after 5 milliliters have been produced and savethe LoggerPro data file.

4. After 5 milliliters of hydrogen have been produced and stored in the tanks(allowing the input energy to produce hydrogen and amount of hydrogen used in

each experiment to be a control), prepare the LoggerPro equipment and open the

valves on the hydrogen and oxygen pipes connecting the storage tanks to the fuel

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cell assembly. Set LoggerPro to record data every .2 seconds and record the

amperage and voltage of the output until all of the hydrogen in the storage tank has

been exhausted.

5. Perform steps 2 through 4 for the both fuel cells. For the air fed PEM fuel cell,

disconnect the oxygen storage tank and release all produced oxygen.

6. Experimentation will include two sets of experiments. These experiments will test

the pure oxygen fuel cell and air fed full cell. The experiments are designed to findthe most efficient fuel cell.

7. After collecting the data, using LoggerPro software, plot the data in graphs of

output and input voltage and amperage. Using the softwares integral function andstatistics function, find the integral of the amperage (amp-seconds or coulombs)

and the mean amperage and voltage. To calculate the amount of joules of energy

used, multiply the integral of the amperage by the voltage (amp-seconds times

voltage). Finally, calculate the percent efficiency by dividing the output joules bythe input joules. Record these pieces of data in a table similar to the following.

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Results

Air fed Fuel Cell

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Trial # Coulombs

Time Running

(sec)

Average

Voltage

Average

Amperage Average Watts Joules Efficiency

1 Input 45.97 104.6 1.755 0.4392 0.7708 80.68 17.65 %

Output 25.59 1384 0.5564 0.01115 0.006204 14.24

2 Input 41.96 91.10 1.769 0.4608 0.8152 74.23 17.45 %

Output 22.89 2021 0.5659 0.01133 0.006412 12.95

3 Input 37.87 84.70 1.732 0.4472 1.775 65.59 19.32 %

Output 23.19 2025 0.5464 0.01145 0.006256 12.67

4 Input 51.10 115.0 1.728 0.4445 0.7681 88.30 19.97 %

Output 31.37 2748 0.5622 0.01142 0.006420 17.73

5 Input 42.14 97.27 1.731 0.4333 0.7500 72.94 18.49 %

Input 24.58 2194 0.5486 0.01121 0.006150 12.48

6 Input 40.20 92.00 1.715 0.4372 0.7498 68.94 17.02 %

Output 22.66 1987 0.5178 0.01140 0.005903 11.73

7 Input 39.26 92.19 1.763 0.4261 0.7512 69.22 18.72 %

Output 23.71 2073 0.5464 0.01144 0.006251 12.96

8 Input 48.91 105.0 1.536 0.4657 0.7153 75.13 18.98 %

Output 26.47 2326 0.5586 0.01138 0.006129 14.26

9 Input 43.09 99.79 1.722 0.4320 0.7440 74.20 17.43 %

Output 23.17 2009 0.5583 0.009116 0.005089 12.94

10 Input 39.23 97.11 1.696 0.4041 0.6854 66.53 18.77 %

Output 22.33 1891 0.5596 0.01181 0.006609 12.49Average 18.38 %


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Oxygen fed FuelCell

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Trial # Coulombs

Time Running

(sec)

Average

Voltage

Average

Amperage Average Watts

Total

Joules Efficiency

1 Input 40.55 90.93 1.704 0.4459 0.7598 69.10 25.55 %

Output 19.98 1791 0.8836 0.01115 0.009852 17.65

2 Input 36.50 84.19 1.696 0.4340 0.7361 61.90 23.29 %

Output 16.75 1484 0.8607 0.01129 0.009717 14.42

3 Input 42.41 92.38 1.704 0.4591 0.7823 72.27 24.47 %

Output 20.81 1847 0.8498 0.01126 0.009569 17.68

4 Input 29.29 70.39 1.701 0.4161 0.7078 49.82 24.70 %

Output 14.65 1246 0.8401 0.01176 0.009880 12.31

5 Input 39.73 90.48 1.729 0.4391 0.7592 68.69 24.43%

Input 19.81 1668 0.8472 0.01187 0.01006 16.78

6 Input 34.32 82.12 1.746 0.4178 0.7297 59.92 24.44 %

Output 16.58 1386 0.8832 0.01196 0.01056 14.64

7 Input 41.13 91.14 1.715 0.4513 0.7740 70.54 25.32 %

Output 20.86 1713 0.8563 0.01218 0.01043 17.86

8 Input 39.05 90.00 1.760 0.4339 0.7637 68.73 23.83 %

Output 18.96 1581 0.8637 0.01199 0.01036 16.38

9 Input 49.08 96.86 1.710 0.5067 0.8665 83.93 26.34 %

Output 25.96 2004 0.8517 0.01295 0.01103 22.11

10 Input 44.56 91.63 1.758 0.4863 0.8549 78.34 26.03 %

Output 23.58 2010 0.8648 0.01173 0.01015 20.39

Average 24.84 %


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Air Fed vs. Oxygen Fed Fuel Cell Efficiency

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Sources of Error

The experiment yielded a 24.84% and 18.38% efficiency. According to the Rocky

Mountain Institute, pure oxygen fed or atmospheric oxygen fed fuel cells typically gets

3560% efficiency. The Department of Energy states that hydrogen PEM fuel cells have a

range of 50-60% efficiency. From these two sources, the experiment was low. This may

be due to the fact that the Department of Energy tests were fabricated using high quality

fuel cells; while the experiment conducted tested a homebuilt fuel cell and a store-bought.

There is a possibility since the exact same Membrane Electrode Assembly was used on

both fuel cell that it could have a problem or flaw. In addition there are several factors

present in the experiment that can be considered possible sources of error. These include

leaking hydrogen gas, and resistance in the wiring of the experimental setup. The

experimental setup involved using a system of valves that have the potential to leak

hydrogen gas. The air fed fuel cell may not have been perfectly air tight even though it

was tight enough to avoid leaking water, thereby decreasing the efficiency of the cell.

Additionally, a varied amount of resistance in different wire configurations could also

have contributed to decreasing the efficiency of the fuel cell. Furthermore, the pressure of

the stored hydrogen gas was not monitored. This may have contributed to the varied input

and output energy values, because of the possibility of different amounts of hydrogen

being produced. This meant that one of the experimental constants, the amount of

hydrogen gas produced, may have varied a little from trial to trial. Next time the

experiment is run it should be done under a constant pressure, with better wiring, and

using higher quality fuel cell.

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Conclusion

The oxygen fed fuel cell has the highest efficiency. The overall efficiency on

average was 24.84%, and the average efficiency of the air fed fuel cell was 18.38%. The

oxygen fed fuel cell has an efficiency that was a 6.46% greater than the air fed fuel cell.

This demonstrates that pure oxygen makes the fuel cell can make a fuel cell run more

efficiently.

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Applications

The two fuel cells yielded different efficiencies. The oxygen fed fuel cell had an

efficiency of 24.84% and the air fed fuel cell had an efficiency of 18.38%. Since the

differences in their efficiency were only 6.46%, pumping pure oxygen into the fuel cell

doe make a noticeably change the efficiency of the fuel cell. It is about a 35% increase in

the efficiency of the fuel cell.

If PEM fuel cells were to be implemented in vehicles and other products, it would

probably still be more economical to use air fed PEM fuel cells over oxygen fed ones

because oxygen fed fuel cells require additional systems to store the pure oxygen. Pure

oxygen fed fuel cells would need not only a hydrogen storage system but also a pure

oxygen storage system, which may end increasing the efficiency by 6.46% from having

the fuel cell fed oxygen directly from the atmosphere. However, the same could not be

said in industrial situations in which energy could be stored and without a need to move

the system and efficiency is the most key part of the operation. In such situations it may

be worth the cost to store oxygen. Further experimentation and analysis of hydrogens

use as different forms of energy storage will have to be made if hydrogen eventually

becomes part of the transportation and energy infrastructure.

Further experimentation could be done with higher quality fuel cells and testing

could even be done on internal combustion engines which use hydrogen gas rather than

gasoline, and its efficiency compared with that of a fuel cell. Overall, the experiment did

demonstrate hydrogens capacity to store energy, although the efficiency was low. This

was shown in the experiment by the ability of the system to take in energy to make

hydrogen gas in less than 100 second and then release its energy over a period longer

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than 2000 seconds, over 20 times longer than it took to produce. This would make it a

viable option for use in vehicles or other electronics in the future.

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Bibliography

Cook, Brian. "An Introduction to Fuel Cells and Hydrogen Technology." Fuel Cell

Store.Com. Dec. 2001. 15 Feb. 2007

.

Gillespie, Ronald J., David A. Humphreys, N. C. Baird, and Edward A. Robinson.

Chemistry Second Edition. Ed. Elaine Ober. 2nd ed. Needham Heights: Allyn and

Bacon Inc., 1989. 810-811.

"How Does a Fuel Cell Work?" Fuel Cell Store.Com. 15 Feb. 2007

.

"How They Work: PEM Fuel Cells." FuelEconomy.Gov. U.S. Department of Energy. 15

Feb. 2007 .

"Types of Fuel Cells." Energy. Rocky Mountain Institute. 20 Mar. 2007

.

"Types of Fuel Cells." Hydrogen, Fuel Cells and Infrastructure Technologies Program.

US Department of Energy. 22 Mar. 2007

.

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