In the summer of 1969, an estimated one million spectators packed Florida highways and open beaches to witness a historic event.[i] Apollo 11, the first spaceflight designed to land humans on the moon, was set to launch from Kennedy Space Center on July 16th. Every television screen in America displayed the profound moment when the spacecraft lifted up from Earth. Five days later, Neil Armstrong became the first man to walk on the moon. The endeavor seemed almost magical from civilians’ perspective, as most were unaware of how Apollo 11 made the journey. Perhaps surprisingly, it wasn’t gallons of fossil fuel and heavy-duty combustion that powered this mission to space. It was pure oxygen and hydrogen.

The alkaline fuel cell, or AFC, transforms oxygen and hydrogen into electricity. First developed by British inventor Francis Bacon in 1932, these cells store hydrogen and oxygen as liquids at cryogenic temperatures.[ii] These elements undergo an electron transfer chemical reaction, generating enough electricity to power spacecraft. Additionally, the reaction produces heat and clean water as byproducts, providing a drinking source for astronauts. Professor John Davidson from the University of Cambridge studied fuel cell functionality within the context of space exploration extensively, and his research indicates that the AFC suited the Apollo 11 perfectly for a few reasons. First, fuel cells are very light, so the space shuttle would not need to be weighed down by conventional fuel tanks carrying petroleum. And perhaps most importantly, Davidson’s research demonstrates that AFCs are efficient, generating electricity at a faster rate than the best solar panels of the 1960s.

NASA has continued using fuel cell technology to power missions, integrating new fuel cells as AFC design has evolved through several iterations. The modern fuel cell’s structure is shown in Figure 1; its most important feature is the proton exchange membrane (PEM), a material that resembles kitchen plastic wrap. The PEM is responsible for blocking all negatively charged particles and letting positively charged ions flow through. A layer of platinum catalyst is added on either side of the PEM, with the left and right sides performing different functions. On the right side, the catalyst interacts with hydrogen, splitting hydrogen molecules into protons and electrons. These protons and electrons then travel through the PEM sandwiched between catalyst layers, and only the protons flow to the left side. On this side, the platinum catalyst facilitates the reaction of these protons and oxygen, producing clean water as a byproduct. The flow of charged particles through the components is harnessed as electrical energy. The entire process, which occurs in seconds, takes up the space of a standard dinner plate, and produces no toxic byproducts — seems like the best of all worlds.

Given the clear advantages, why don’t we incorporate hydrogen fuel cells into other aspects of our lives? Joan Ogden, Professor of Environmental Science at UC Davis, explores this question in her 2006 Scientific American article entitled “High Hopes for Hydrogen.” Specifically, she considers the impact that hydrogen fuel cells could have on the automobile and transportation industries. On the surface, hydrogen fuel cell-based automobiles seem like the perfect solution to a pressing problem. With the number of passenger vehicles expected to triple between 2005 and 2050, reforming the transportation fuel economy to stop greenhouse gas emissions and slow oil use remains imperative. Ogden details the promise of a hydrogen-powered automobile future given fuel cells’ high efficiency and low environmental footprint. While she acknowledges that the transition won’t be an easy sprint, she expresses a strong hope that this marathon is both worthwhile and within reach. After all, hydrogen and oxygen are both readily available, right? Scalable production of AFCs seems doable. However, while both elements are present in two easily accessible sources, air and water, it is actually quite difficult to harvest hydrogen on a large scale. While we can extract hydrogen from a small cup of water using a thin wire, whole lakes of water would be necessary to extract enough hydrogen for use in the transportation sector, making traditional electrolysis non-viable. Biomass gasification, heating large amounts of organic materials such as wood and crop waste, is also being explored as a potential large-scale harvesting method. In 2016, Dr. Azduwin Khasri’s research group from the University of Malaysia’s Chemical Engineering Department even reported that biomass gasification is the most efficient hydrogen production method. However, Khasri’s work also acknowledges that burning organic materials produces significant greenhouse gas emissions, defeating the original purpose of fuel cell integration.

Adding to the challenge, another question remains: how do we deliver hydrogen cheaply to so many dispersed sites? Could we have networks of underground pipes to deliver hydrogen to fuel stations as we currently do with natural gas? This solution could work, but the hydrogen would have to be kept at extremely high pressures, and maintaining this type of environment in pipes that are miles long is quite expensive. While 17 countries announced programs to develop this infrastructure in the late 1990s and early 2000s, over 20 years later universal systems to support commercial fuel cell-based automobiles still do not exist.

Physics Today editor David Kramer acknowledges this disappointing performance and points out that it creates a chicken-and-egg problem as illustrated in Figure 2: We cannot deploy fuel cell-powered automobiles without large-scale infrastructure, but why would we invest in these expensive infrastructures to support a technology still in development?

Ogden’s initial characterization of the hydrogen transportation transition as a doable marathon therefore stands corrected. There may, in fact, be no finish line. By the early 2010s, scientific news articles switched from echoing sentiments of “high hopes” to “fact or fantasy?” in direct response to the pattern of unfulfilled overpromises in the hydrogen-based transportation sector. For example, in 2010, the German government promised to establish over 1,000 filling stations that would be operational by 2020. Mike Millikin, editor of the German magazine Green Car Congress, reported that by 2016, 20 stations had been built. Additionally, as further research was conducted regarding the applications of AFCs to cars, scientists found that hydrogen cars are only half as efficient as traditional cars. Elon Musk, founder of pioneering automobile company Tesla, communicated similar ideas to reporters at the 2015 Automotive New World Congress. He described fuel cell vehicles as “very silly” because “the best future hydrogen technology cannot compete against current battery technology.” However, insights from this new research did not completely eliminate the promise of fuel cell technology. In fact, over the past ten years, fuel cells have become more common in several areas of life.

Ironically, the failures of the hydrogen automobile fuel economy catalyzed this technological transformation. The two primary roadblocks to hydrogen fuel cell-based transportation were harvesting hydrogen cleanly and transporting the fuel over long distances. Naturally, scientists asked, “What if we used a fuel source that could be obtained with little environmental footprint? What if we employed these technologies on small but impactful scales to reduce the need for large-scale infrastructure?” These considerations gave rise to a new and promising application of fuel cells: fuel cell-enabled medical technologies.

Energy researcher Qian Xu and his colleagues from Jiangsu University were certain that medical devices would benefit greatly from fuel cell integration because they require a stable and efficient power source. Traditionally, most medical devices have relied on conventional lithium-ion batteries, which require regular replacement. While replacing a battery seems simple, the process involves an invasive procedure of device removal and re-implantation, causing considerable pain to patients. On the other hand, a fuel cell-based medical device would last a lifetime. Given these benefits, AFC-based implantable medical devices (IMDs) have come to the forefront of both sustainable energy and medical technology research. IMDs include everything from hearing aid implants to blood glucose meters, so they interact very closely with the human body. Therefore, scientists embarked on a quest for a fuel source that is biocompatible.

The Department of Bioengineering at Tohoku University was one of the first groups to meet this challenge. In 2011, Professor Takeo Miyake and his colleagues developed a fuel cell that could generate electricity by using glucose present in the blood. Their data show that the fuel cell can generate current with a maximum density of 12.8 microwatts per cubic meter, nearing the capacity of primitive batteries. The amount of generated power also acted as an indication of blood glucose level. This research was particularly innovative because the output power revealed important information about patient health. Additionally, this research made a giant leap by setting an important precedent: Fuel cells for medical applications can use the human body’s own organic compounds as the fuel source and microbial tissue as a catalyst, making this technology biocompatible.

However, biological catalysts are not always the optimal option for fuel cells in medical devices. For example, in 2019, a Dartmouth research group led by Dr. Rahul Sarpeshkar patented a platinum catalyst-based fuel cell to provide energy for neural implantation. Neural implants are technological devices that connect directly to an organism’s brain to record activity, so they require a consistent amount of power over the measurement period. The mechanism of this platinum-based fuel cell involves the oxidation of glucose in cerebrospinal fluid, passage through the platinum catalyst, and the subsequent generation of flowing electrons. Platinum displays optimal biocompatibility, so the fuel cell was not rejected by patients’ immune systems. Platinum fuel cells have also been integrated into compact breath alcohol measurement devices. For these applications, a platinum electrode and acidic catalyst layers act as an electrochemical sensor, generating a voltage proportional to the concentration of alcohol. In 2014, company BACtrack released this product, which has since performed relatively well and was even named the top breathalyzer product of 2021 by Insider Magazine. The device is shown in Figure 3. Insider writer Ariana DiValentino noted the device’s fast warm-up time, a feature enabled by fuel cell technology. Around the same time, Professor Daniel Scherson and his team at Case Western Reserve University developed a fuel cell-based portable device to treat chronic wounds. The device extracts oxygen from the air for electricity generation, and most impressively, has the same dimensions as a standard mobile phone. Evidently, fuel cell-based medical devices have already revolutionized standard small-scale medical devices, and researchers are continuing to improve the stability and efficiency of these technologies.

While hydrogen is not a magic bullet for universal clean energy generation, fuel cell technologies present advantages that other energy sources cannot offer. Consider a military base in a remote location where natural gas is out of reach. Providing power to this base becomes easy with transportable fuel cells, and according to journalist Rita Boland from SIGNAL Magazine, the U.S. Army has already begun developing fuel cell generators that can be used anywhere. Conversely, consider a high-rise building in the center of metropolitan Atlanta where the power goes out suddenly due to a hurricane.  The Stationary Fuel Cell Collaborative, a group of company leaders and citizens aiming to influence fuel cell policy, describe the impact that AFCs could have in natural disaster situations on their blog. Fuel cells can provide over 1,500 hours of backup power while taking up very little space at the top of the building, and in 2020, fuel cells enabled just that during Hurricane Sally. These fuel cells are powered by everything from molten carbonate to solid oxides, with each material presenting new sets of properties and advantages.

Ogden’s high hopes for hydrogen may unfortunately be dampened by recent energy research, but fuel cells are continuing to challenge the status quo across a wide range of industries, playing an increasingly instrumental role in our lives. While hydrogen fuel cells powered Neil Armstrong’s small step for man, they simultaneously powered a giant leap for mankind—a shift in perspective surrounding the functionality of fuel cells. As scientists continue taking small steps in fuel cell research and integration, exciting giant leaps are on the horizon.

More to Explore

Ahmad, Anis Atikah, et al. “Assessing the Gasification Performance of Biomass: A Review on Biomass Gasification Process Conditions, Optimization and Economic Evaluation.” Renewable and Sustainable Energy Reviews, vol. 53, 2016, pp. 1333–1347., https://doi.org/10.1016/j.rser.2015.09.030.

Boland, Rita. “Fuel Cells Power Military Bases.” SIGNAL Magazine, 16 Jan. 2015, https://www.afcea.org/content/fuel-cells-power-military-bases.

Borgschulte, Andreas. “The Hydrogen Grand Challenge.” Frontiers, 12 April 2016, https://www.frontiersin.org/articles/10.3389/fenrg.2016.00011/full.

DiValentino, Ariana. “The 5 Best Breathalyzers to Confirm Your Blood Alcohol Content Is Low Enough to Drive.” Insider, 11 June 2021, https://www.insider.com/guides/health/best-breathalyzer.

Frangoul, Anmar. “Elon Musk Has Strong Views on Hydrogen. Not Everyone Agrees.” CNBC, 31 Dec. 2021, https://www.cnbc.com/2021/12/06/elon-musk-has-strong-views-on-hydrogen-and-not-everyone-agrees.html.

Hall, Ellie. “Powering Apollo 11: The Fuel Cell That Took Us to the Moon.” Department of Chemical Engineering and Biotechnology, 18 July 2019, https://www.ceb.cam.ac.uk/news/powering-apollo-11-fuel-cell-took-us-moon.

“Hydrogen Refueling Station in Ulm Opens; 21 Hrs Now in Germany.” Green Car Congress, 15 July 2016, https://www.greencarcongress.com/2016/07/20160715-ulm.html.

Jiao, Kui, et al. “Designing the next Generation of Proton-Exchange Membrane Fuel Cells.” Nature News, Nature Publishing Group, 14 July 2021, https://www.nature.com/articles/s41586-021-03482-7.

Kowalski, Kathiann M., and Energy News Network July 15 Kathiann M. Kowalski. “NASA’s New Moon Mission Reignites Fuel Cell Research at Ohio Lab.” Energy News Network, 16 July 2019, https://energynews.us/2019/07/15/nasas-new-moon-mission-reignites-fuel-cell-research-at-ohio-lab/.

Lee, Sze Ying, et al. “Waste to Bioenergy: A Review on the Recent Conversion Technologies – BMC Energy.” BioMed Central, BioMed Central, 16 May 2019, https://bmcenergy.biomedcentral.com/articles/10.1186/s42500-019-0004-7.

Miyake, Takeo, et al. “Enzymatic Biofuel Cells Designed for Direct Power Generation from Biofluids in Living Organisms.” Energy & Environmental Science, The Royal Society of Chemistry, 20 Oct. 2011, https://pubs.rsc.org/en/content/articlehtml/2011/ee/c1ee02200h.

Ogden, Joan. “High Hopes for Hydrogen.” Scientific American, 1 September 2006, https://www.scientificamerican.com/article/high-hopes-for-hydrogen/.

Rapoport, Benjamin I., et al. “A Glucose Fuel Cell for Implantable Brain–Machine Interfaces.” PLOS ONE, 12 June 2012, https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0038436.

Sazali, Norazlianie, et al. “New Perspectives on Fuel Cell Technology: A Brief Review.” Membranes, MDPI, 13 May 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7280957/.

Scherson, Daniel. “A Portable Oxygen Concentrator for Wound Healing Applications.” Abstract: A Portable Oxygen Concentrator for Wound Healing Applications (2014 ECS and SMEQ Joint International Meeting (October 5-9, 2014)), Ecs, https://ecs.confex.com/ecs/226/webprogram/Paper43127.html.

Xu, Qian, et al. “The Applications and Prospect of Fuel Cells in Medical Field: A Review.” Renewable and Sustainable Energy Reviews, Pergamon, 18 Sept. 2016, https://www.sciencedirect.com/science/article/pii/S1364032116305317#bib63

 

[i] “50 Years Ago: The Journey to the Moon Begins (July 1969) NASA History.” Moon: 50 Year Journey—Satellite Missions—Eoportal Directory, https://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/moon-50-year-journey.

[ii] “Alkaline Fuel Cell.” Alkaline Fuel Cell—an Overview/ScienceDirect Topics, https://www.sciencedirect.com/topics/engineering/alkaline-fuel-cell.

 

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