NASA Hunch Final Paper
Electrolysis and Fuel Cells in Microgravity Flight Dates: April 8th and 9th 2014 Principle investigator Steven R. Walk, PE New Horizons Governor’s School of Science and Technology (GSST) PM 520 Butler Farm Road Hampton, VA. 23666 757-766-1100 ext. 3393 [email protected]
Co-Investigators William Archer, Kathleen Jordan, Sarah Selim, and Bethany Wissmann Team Members Justin Cloutier, Benjamin Cratsley, Charles Haggard, Manisha Iruvanti, Richard Kazmer, Sam Kim, Scot MacKenzie, Daniel McNamara, Brady Reisch, Edward Schuler, Robert Smyth, and Correy Xu NASA Mentors Adam Ben Shabat [email protected] Florence Gold [email protected] Final Report Completion Date: May 23, 2014
Goal The International Space Station (ISS) and future space exploration needs a way to efficiently supply oxygen. Currently, the space station relies heavily on shipments of oxygen from Earth. However, this system has many flaws as it requires the astronauts to essentially ration their air. For many labor intensive tasks, such as repairing equipment or exercising, rationing adds complexity and constraints. The astronauts also complain about times in which they are all together for an interview and began to produce too much carbon dioxide from all the talking. The need for a system to produce breathable air is important also for future long-term life in space. One solution to this problem employs plants for a natural process; however, this approach entails the astronauts to tend to the plants and risks introducing additional microbes to the ISS or other planets. A better solution would be the use of artificial photosynthesis, a solar-powered electrolysis system. This oxygen-producing electrochemical process has been demonstrated in laboratory settings using a variety of designs and several different catalysts. The challenge will be to select an appropriate system, design and build a container to house the system, and monitor the system’s performance in microgravity. The first phase in development will be testing an electrolysis system in microgravity. Because this will have a hydrogen output, a fuel cell will be implemented to use up the hydrogen. The electrolyzer will run an electric current through distilled water causing the water to “break” into two elements, hydrogen and oxygen. When the hydrogen and oxygen pass through the Proton Exchange Membrane (PEM), the hydrogen is able to pass through and the oxygen gets trapped behind the membrane, effectively separating the hydrogen and oxygen.
Figure 1. Electrolysis involves splitting water molecules into gaseous oxygen and hydrogen. The hydrogen is able to pass through the membrane and be released on the cathode side while the oxygen is released on the anode side. (http://phys.org/news/2013-06-artificial-photosynthesis.html)
Objectives This experiment attempted to determine if through electrolysis, energy could be produced through a fuel cell in zero gravity. The efficiency of a system on earth was compared to that of a system run in microgravity. A Reversible Proton Exchange Membrane (PEM) functioning as an electrolyzer was turned on, which split the water into oxygen and hydrogen. The oxygen was allowed to escape into the perforated Lexan box, acting as a local oxygen source, and the hydrogen was transported to the second Reversible PEM functioning acting as a fuel cell. To ensure that no pressure built up from storing the hydrogen, the hydrogen was immediately used by the fuel cell. A voltmeter and ammeter were used to measure the output of the fuel cell in order to detect if the fuel cell was using the hydrogen. The voltmeter was used to measure the voltage and the ammeter was used to measure the current. The energy produced by the fuel cell was dissipated in a resistor. The system was running for the entire flight in hyper gravity and microgravity. Data from the voltmeter and ammeter were recorded once in each microgravity cycle. However, the flyers were continually monitoring the output reading of the voltmeter and ammeter to ensure that the fuel cell was dissipating the hydrogen. The hydrogen quantity was calculated by the measuring the power output of the fuel cell. Knowing the hydrogen quantity, the produced oxygen quantity was calculated. An identical experiment was performed on the ground for comparison. It was expected that the system in microgravity would produce oxygen
with one third efficiency of the system on the ground. The currents measured were not significantly different, however, the voltage measurements were. A two-tailed T-test provides a P value, which states if the differences between two data sets are statistically significant or not. Statistically significant is a term used to describe differences in data sets that are not due to chance, but are attributable to the independent variable, which in this experiment is the presence of gravity. A two-tailed T-test was run on the voltage measurements and yielded a P value of 5.92x10-11. Another observed difference was the dropping of the voltage and current during transitions from hyper-gravity to zero-gravity and from zero-gravity to hyper-gravity.
Figure 2. The experiment involved two commercial off-the-shelf PEM/Fuel Cells connected to a voltmeter and an ammeter. The experiment was housed in a Lexan box during the flight in micro-gravity.
Methods and Materials Materials Inventory 1. Reversible PEM
2. Industrial Strength Velcro
3. Tubing
4. 18 gauge insulated wire
5. Lexan Box
6. Water
7. Resistors
8. Zip ties
9. 1.5 V Batteries (AA)
10. Electrical Tape
11. 3D Printed Brackets
12. Electrical Switch
13. Screws
14. Voltmeter/Ammeter
15. Gore-tex
16. Duct Tape
17. Seam Sealer
18. Plastic Base Plate
19. Battery box
20. Foam padding
Methods One commercial off-the-shelf PEM cells was connected to two AA batteries. Water was pushed to the PEM performing electrolysis using a five ml syringe. The hydrogen produced by the first PEM cell during electrolysis was directed through tubing to the second PEM cell functioning as the fuel cell. The oxygen produced by electrolysis was released into the Lexan box that contained the experiment. Holes were drilled into the sides of the box to prevent the unlikely buildup of gases. The fuel cell was connected to a 50 ohm load. The current and voltage produced by the fuel cell were measured using an ammeter and a voltmeter, respectively. The system was turned on at the beginning of the flight and measurements were taken at each microgravity parabola. During the ground experiment conducted after the 0G flight, with the same system, measurements were taken every 30 seconds.
Figure 2. The experiment involved two commercial off-the-shelf PEM/Fuel Cells connected to a voltmeter and an ammeter. The experiment was housed in a Lexan box during the flight in micro-gravity.
Results There were not many differences between the control ground experiment data and the flight data (Table 1). The currents measured were not significantly different. However, a twotailed T-test was run on the voltage measurements and yielded a P value of 5.92x10-11, which shows that the differences between the voltages produced on the ground and in 0G are statistically significant. Another observed difference was the dropping of the voltage and current during transitions from hyper-gravity to zero-gravity and from zero-gravity to hyper-gravity; however specific measurements were not taken observing this phenomenon. During these times the voltage and current measurements would drop to values as low as 0.6 volts, and the current would drop to values as low as 15 mA. Table 1: This table shows the results of the statistical analyses, including the averages, standard deviation and p-values given by the t-test run on the zero-gravity and one-gravity experiments. The P-value shows that the differences in the voltage measurements are most likely not attributable to chance. The small standard deviations show that there was little variation in the measured values. Zero-G Voltage AVG
Zero-G Current AVG
One-G Voltage AVG
One-G Current AVG
0.851944444
16.62
0.8400625
16.57
Zero-G Voltage SDEV
Zero-G Current SDEV
One-G Voltage SDEV
One-G SDEV
0.007655588
0.165260737
0.000771902
0.013165612
Voltage P-value
Current P-value
5.92E-11
0.083914373
Discussion & Conclusion The results showed that the voltage between the two experiments was significantly different, while the current was not. However, this can most likely be attributed to the life of the fuel cell itself, not the differences between electrolysis in microgravity and earth gravity. In designing the experiment, it was noted that on the first run voltages could be as high as 1V; the
output voltage of the cell dropped after multiple uses. Because the fuel cell was run first in zero gravity, the output voltage would be expected to be higher. While not quantitatively proven, this is the assumption for the significantly different voltages. Therefore, the results would show that there is no measureable difference between running fuel cells in a zero gravity environment and on earth. However, before definitive conclusions can be reached more research should be done on the differences of electrolysis in the zero gravity and one gravity environments. Further experimentation should be done, however, on why the output of the cell drops during a significant change in gravity (either zero- to hyper- or hyper- to zero). This is a phenomenon that has not been published in literature and could be useful in long-term space exploration, with gravity constantly changing.
Acknowledgements The Governor’s School for Science and Technology PM Session would like to thanks Dr. Florence Gold, for her mentoring and support in drafting documents and designing the experiment. We would like to thank Mr. Adam Ben Shabat for his guidance and aid in designing the experiment and designing and printing items on the 3D printer. Additionally, we would like to thank Ms. Tammy Cottee and Mr. Timothy Wood for supporting our team through managing our budget and ordering parts for our team. We would also like to thank Mrs. Vikki Wismer and Dr. Rhett Woo for introducing our team to NASA HUNCH. Lastly, we would like to thank the Governor’s School for Science and Technology for funding our trip to Houston.
References Bard, Allen and Marye Anne Fox. "Artificial Photosynthesis: Solar Splitting of Water to." 16 November 1994. Document. Barry, Patrick L. Breathing Easy on the Space Station . Ed. Dr. Tony Phillips. 13 November 2000. NASA. . College, Boston. Researchers find rust can power up artificial photosynthesis. 11 October 2013. Web. . Electrolysis of water using an electrical current. n.d. Web. . Fukunaka, Y, et al. "Water Electrolysis under Microgravity." n.d. The Electrochemical Society. Document. Layton, Julia. How Artificial Photosynthesis Works. n.d. Web. . Lister, S and McLean G. "PEM fuel cell electrodes." 2003 November 2003. Science Direct. Document. Microbiology, American Society for. Bacteria use hydrogen, carbon dioxide to produce electricity. 19 May 2013. . Wisconsin-Madison, University of. In hydrogenation and hydrogenolysis chemical reactions, water adds speed without heat. 17 May 2012. Web. . Zhao, Zhi-Gang. In-Situ Formation of Cobalt-Phosphate Oxygen-Evolving Complex-Anchored Reduced Graphene Oxide Nanosheets for Oxygen Reduction Reaction. 23 July 2013. Web. .
Co-Investigators William Archer, Kathleen Jordan, Sarah Selim, and Bethany Wissmann Team Members Justin Cloutier, Benjamin Cratsley, Charles Haggard, Manisha Iruvanti, Richard Kazmer, Sam Kim, Scot MacKenzie, Daniel McNamara, Brady Reisch, Edward Schuler, Robert Smyth, and Correy Xu NASA Mentors Adam Ben Shabat [email protected] Florence Gold [email protected] Final Report Completion Date: May 23, 2014
Goal The International Space Station (ISS) and future space exploration needs a way to efficiently supply oxygen. Currently, the space station relies heavily on shipments of oxygen from Earth. However, this system has many flaws as it requires the astronauts to essentially ration their air. For many labor intensive tasks, such as repairing equipment or exercising, rationing adds complexity and constraints. The astronauts also complain about times in which they are all together for an interview and began to produce too much carbon dioxide from all the talking. The need for a system to produce breathable air is important also for future long-term life in space. One solution to this problem employs plants for a natural process; however, this approach entails the astronauts to tend to the plants and risks introducing additional microbes to the ISS or other planets. A better solution would be the use of artificial photosynthesis, a solar-powered electrolysis system. This oxygen-producing electrochemical process has been demonstrated in laboratory settings using a variety of designs and several different catalysts. The challenge will be to select an appropriate system, design and build a container to house the system, and monitor the system’s performance in microgravity. The first phase in development will be testing an electrolysis system in microgravity. Because this will have a hydrogen output, a fuel cell will be implemented to use up the hydrogen. The electrolyzer will run an electric current through distilled water causing the water to “break” into two elements, hydrogen and oxygen. When the hydrogen and oxygen pass through the Proton Exchange Membrane (PEM), the hydrogen is able to pass through and the oxygen gets trapped behind the membrane, effectively separating the hydrogen and oxygen.
Figure 1. Electrolysis involves splitting water molecules into gaseous oxygen and hydrogen. The hydrogen is able to pass through the membrane and be released on the cathode side while the oxygen is released on the anode side. (http://phys.org/news/2013-06-artificial-photosynthesis.html)
Objectives This experiment attempted to determine if through electrolysis, energy could be produced through a fuel cell in zero gravity. The efficiency of a system on earth was compared to that of a system run in microgravity. A Reversible Proton Exchange Membrane (PEM) functioning as an electrolyzer was turned on, which split the water into oxygen and hydrogen. The oxygen was allowed to escape into the perforated Lexan box, acting as a local oxygen source, and the hydrogen was transported to the second Reversible PEM functioning acting as a fuel cell. To ensure that no pressure built up from storing the hydrogen, the hydrogen was immediately used by the fuel cell. A voltmeter and ammeter were used to measure the output of the fuel cell in order to detect if the fuel cell was using the hydrogen. The voltmeter was used to measure the voltage and the ammeter was used to measure the current. The energy produced by the fuel cell was dissipated in a resistor. The system was running for the entire flight in hyper gravity and microgravity. Data from the voltmeter and ammeter were recorded once in each microgravity cycle. However, the flyers were continually monitoring the output reading of the voltmeter and ammeter to ensure that the fuel cell was dissipating the hydrogen. The hydrogen quantity was calculated by the measuring the power output of the fuel cell. Knowing the hydrogen quantity, the produced oxygen quantity was calculated. An identical experiment was performed on the ground for comparison. It was expected that the system in microgravity would produce oxygen
with one third efficiency of the system on the ground. The currents measured were not significantly different, however, the voltage measurements were. A two-tailed T-test provides a P value, which states if the differences between two data sets are statistically significant or not. Statistically significant is a term used to describe differences in data sets that are not due to chance, but are attributable to the independent variable, which in this experiment is the presence of gravity. A two-tailed T-test was run on the voltage measurements and yielded a P value of 5.92x10-11. Another observed difference was the dropping of the voltage and current during transitions from hyper-gravity to zero-gravity and from zero-gravity to hyper-gravity.
Figure 2. The experiment involved two commercial off-the-shelf PEM/Fuel Cells connected to a voltmeter and an ammeter. The experiment was housed in a Lexan box during the flight in micro-gravity.
Methods and Materials Materials Inventory 1. Reversible PEM
2. Industrial Strength Velcro
3. Tubing
4. 18 gauge insulated wire
5. Lexan Box
6. Water
7. Resistors
8. Zip ties
9. 1.5 V Batteries (AA)
10. Electrical Tape
11. 3D Printed Brackets
12. Electrical Switch
13. Screws
14. Voltmeter/Ammeter
15. Gore-tex
16. Duct Tape
17. Seam Sealer
18. Plastic Base Plate
19. Battery box
20. Foam padding
Methods One commercial off-the-shelf PEM cells was connected to two AA batteries. Water was pushed to the PEM performing electrolysis using a five ml syringe. The hydrogen produced by the first PEM cell during electrolysis was directed through tubing to the second PEM cell functioning as the fuel cell. The oxygen produced by electrolysis was released into the Lexan box that contained the experiment. Holes were drilled into the sides of the box to prevent the unlikely buildup of gases. The fuel cell was connected to a 50 ohm load. The current and voltage produced by the fuel cell were measured using an ammeter and a voltmeter, respectively. The system was turned on at the beginning of the flight and measurements were taken at each microgravity parabola. During the ground experiment conducted after the 0G flight, with the same system, measurements were taken every 30 seconds.
Figure 2. The experiment involved two commercial off-the-shelf PEM/Fuel Cells connected to a voltmeter and an ammeter. The experiment was housed in a Lexan box during the flight in micro-gravity.
Results There were not many differences between the control ground experiment data and the flight data (Table 1). The currents measured were not significantly different. However, a twotailed T-test was run on the voltage measurements and yielded a P value of 5.92x10-11, which shows that the differences between the voltages produced on the ground and in 0G are statistically significant. Another observed difference was the dropping of the voltage and current during transitions from hyper-gravity to zero-gravity and from zero-gravity to hyper-gravity; however specific measurements were not taken observing this phenomenon. During these times the voltage and current measurements would drop to values as low as 0.6 volts, and the current would drop to values as low as 15 mA. Table 1: This table shows the results of the statistical analyses, including the averages, standard deviation and p-values given by the t-test run on the zero-gravity and one-gravity experiments. The P-value shows that the differences in the voltage measurements are most likely not attributable to chance. The small standard deviations show that there was little variation in the measured values. Zero-G Voltage AVG
Zero-G Current AVG
One-G Voltage AVG
One-G Current AVG
0.851944444
16.62
0.8400625
16.57
Zero-G Voltage SDEV
Zero-G Current SDEV
One-G Voltage SDEV
One-G SDEV
0.007655588
0.165260737
0.000771902
0.013165612
Voltage P-value
Current P-value
5.92E-11
0.083914373
Discussion & Conclusion The results showed that the voltage between the two experiments was significantly different, while the current was not. However, this can most likely be attributed to the life of the fuel cell itself, not the differences between electrolysis in microgravity and earth gravity. In designing the experiment, it was noted that on the first run voltages could be as high as 1V; the
output voltage of the cell dropped after multiple uses. Because the fuel cell was run first in zero gravity, the output voltage would be expected to be higher. While not quantitatively proven, this is the assumption for the significantly different voltages. Therefore, the results would show that there is no measureable difference between running fuel cells in a zero gravity environment and on earth. However, before definitive conclusions can be reached more research should be done on the differences of electrolysis in the zero gravity and one gravity environments. Further experimentation should be done, however, on why the output of the cell drops during a significant change in gravity (either zero- to hyper- or hyper- to zero). This is a phenomenon that has not been published in literature and could be useful in long-term space exploration, with gravity constantly changing.
Acknowledgements The Governor’s School for Science and Technology PM Session would like to thanks Dr. Florence Gold, for her mentoring and support in drafting documents and designing the experiment. We would like to thank Mr. Adam Ben Shabat for his guidance and aid in designing the experiment and designing and printing items on the 3D printer. Additionally, we would like to thank Ms. Tammy Cottee and Mr. Timothy Wood for supporting our team through managing our budget and ordering parts for our team. We would also like to thank Mrs. Vikki Wismer and Dr. Rhett Woo for introducing our team to NASA HUNCH. Lastly, we would like to thank the Governor’s School for Science and Technology for funding our trip to Houston.
References Bard, Allen and Marye Anne Fox. "Artificial Photosynthesis: Solar Splitting of Water to." 16 November 1994. Document. Barry, Patrick L. Breathing Easy on the Space Station . Ed. Dr. Tony Phillips. 13 November 2000. NASA. . College, Boston. Researchers find rust can power up artificial photosynthesis. 11 October 2013. Web. . Electrolysis of water using an electrical current. n.d. Web. . Fukunaka, Y, et al. "Water Electrolysis under Microgravity." n.d. The Electrochemical Society. Document. Layton, Julia. How Artificial Photosynthesis Works. n.d. Web. . Lister, S and McLean G. "PEM fuel cell electrodes." 2003 November 2003. Science Direct. Document. Microbiology, American Society for. Bacteria use hydrogen, carbon dioxide to produce electricity. 19 May 2013. . Wisconsin-Madison, University of. In hydrogenation and hydrogenolysis chemical reactions, water adds speed without heat. 17 May 2012. Web. . Zhao, Zhi-Gang. In-Situ Formation of Cobalt-Phosphate Oxygen-Evolving Complex-Anchored Reduced Graphene Oxide Nanosheets for Oxygen Reduction Reaction. 23 July 2013. Web. .
