Hydrogen Fuel Cells

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Hydrogen Fuel Cells

In 1838, a Swiss professor by the name of Christian Friedrich Schoenbein discovered a new type of energy source. It was similar to a battery but did not require recharging. In 1839, Sir William Robert Grove, an engineer and lawyer, put this newfound phenomenon into effect by inventing the "gas battery." Known as a fuel cell in today’s terms, it is an electrochemical device that converts energy from a chemical reaction directly into electricity using a continuous supply of fuel. Hydrogen, the world’s simplest and most abundant element, is used in most fuel cells. Since the discovery, however, the world has not quite mastered this technology.[1]

If the technology of fuel cells could be put to use, it would have many uses. Fuel cells could be used to power a variety of electrical items including cell phones, vacuums, automobiles, homes, and even cities. The ability to produce effective, efficient fuel cells would be a triumph, especially because fuel cells do not produce any polluting emissions and do not rely on supplies of foreign oil. Today, many automobile companies are incorporating fuel cells into their designs. Concept cars that use this technology as fuel have already been developed. Although the world has not yet been able to market fuel cells due to high costs and a need for further technological mastery[2], fuel cells are expected to be environmentally and economically beneficial in the future.

The Chemistry of a Functioning Hydrogen Fuel Cell A fuel cell is a device that converts molecules of hydrogen and oxygen into water. This process releases energy that can be harnessed in order to power direct current electrical devices. The process of converting hydrogenand oxygen is relatively simple. First, there needs to be a continuous supply of hydrogen and oxygen; second, a negative anode and a positive cathode are needed to secure the cell; third, a catalyst must be present in order for a reaction to occur; fourth, a membrane is used as a conduit; and finally, an external circuit is required to create an electrical current.[3] (See Figure 1)


Figure 1
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Figure 1

To begin the process, a supply of hydrogen is pressurized and fed into the negative anode. The anode has channels etched into it that evenly disperse the hydrogen over a catalyst. The pressurized oxygen is fed through the positive cathode which also contains etched channels in order for the oxygen to spread out evenly and to provide a place for the oxygen and hydrogen to recombine as H2O.

The catalyst, usually made of powdered platinum, allows the reaction to occur and is applied to a very thin carbon paper or cloth placed between the proton exchange membrane and anode. This membrane is made of a specifically treated material that conducts the positively charged ions of hydrogen, but not the negatively charged electrons. The platinum has a very rough surface to increase surface area and aids in splitting the hydrogen into two H+ ions and two electrons.

2H2 => 4H+ + 4e-

Once the catalyst splits the hydrogen atom, the electrons are sent through the anode and into the external circuit. On the cathode side, oxygen gas is also forced through the catalyst, which splits the O2 into two oxygen atoms with negative charges.

O2 => 2O-

The negatively charged oxygen atoms attract hydrogen ions and recombine with the hydrogen ions and electrons that have passed through the circuit. Water molecules then form on the cathode side and are forced out the etched pathways as exhaust.

O2 + 4 H+ + 4 e- => 2H2O

The net reaction equals:

2H2 + O2 => 2H2O

By repeating this process and by stacking many fuel cells on top of one another, a large current of electricity can be created.

Benefits In the United States, six million barrels of oil are burned by passenger vehicles alone. This is equivalent to 85% of total daily oil imports.[4] If hydrogen fuel cells were utilized in new automobiles, they would reduce the United States’ dependence on foreign oil. For example, if only ten-thousand vehicles were running on non-petroleum fuel, the oil consumption would decrease by nearly seven million gallons per year.4

Hydrogen fuel cells in cars would also dramatically decrease the amount of pollution caused by today’s gasoline combustion engines. Millions of tons of the greenhouse gas carbon dioxide are released into the atmosphere every year.4 According to the U.S. Department of Energy, hydrogen powered vehicles produce only water vapor as a product. If just ten percent of passenger cars ran on hydrogen fuels, the U.S. could decrease oil needs and eliminate one million tons of regulated air pollutants and 60 million tons of carbon dioxide per year.4

While recent concerns have questioned the safety of storing hydrogen in a fuel cell, safety tests performed by the Ford Motor Company in May of 1997 found that storage of hydrogen in fuel cells is actually safer than the storage of gasoline.[5]

The use of hydrogen fuel cells would have a positive impact on the economy. Possible new markets for fuel cells include steel production and electronics and electrical control industries. Many thousands of new job opportunities could be created, improving the overall job market and economy of the United States.

Challenges for Hydrogen Fuel Cells In spite of the obvious benefits, many challenges need to be overcome before hydrogen fuel cells can become widespread. Infrastructure, cost, and efficiency are all concerns that need to be addressed before this source of energy would be considered practical for common use. First of all, the cost of distributing hydrogen gas to dispersed locations is very high. It is produced in large quantities for industrial use at a reasonable price, but the United States’ infrastructure would have to change dramatically in order to distribute hydrogen across the country. Constructing pipelines for hyrogen would present more problems, such as financing, security, environmental impact, and perceived safety.[6]

Hydrogen storage would be a problem as well. Since hydrogen is a light gas, less of it is contained in the same amount of space as heavier gases, which adds to the cost of transportation.[7] It is also not cost-effective to produce hydrogen from gas, oil, or coal. To save money and not lose energy in the process, hydrogen gas would need to be made from a renewable source. It currently costs more than $2000 per kilowatt to generate power from a fuel cell, compared to $35 per kilowatt for an internal combustion engine. Furthermore, the lifetime for driving a car that is run on hydrogen fuel cells is only 1/5 of that of a car run on an internal combustion engine.7 To reduce this cost, less expensive catalysts and membrane materials must be found.

Future Implications Hydrogen fuel cells have the potential to become a clean, inexhaustible source of energy. Once an affordable, safe method of producing hydrogen gas and manufacturing hydrogen fuel cells is developed, the country may move toward a hydrogen-based economy.

In the long-term, the U.S. could see a decreased rate of pollution and environmental destruction with increased use of hydrogen fuel. Humans could benefit from improved health as a result of better air quality.[8] Politically, the U.S. would no longer be dependent on other countries for its energy needs because it would be able to produce its fuel domestically. There are certainly barriers to the development of a hydrogen-based economy. Aside from the technological development needed, a new hydrogen infrastructure would have to be developed that would govern the production, distribution, and consumption of hydrogen as a fuel. In spite of the challenges, hydrogen fuel is a promising future technology.

Researched and written by: Hope Kassube, Adam Sievert, Brent Toth, Amy Tran


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Footnotes

  1. ^  Prohaska, Don. “The Birth of a Fuel Cell-But Who is the Father.” 13 August 2001. <http://www.efcf.com/media/ep010813>.
  2. ^ “Energy Advances at DRI.” Desert Research Institute. 27 September 2005. <http://www.dri.edu/Projects/Energy/Fuelcells/Fuelcells.html>. (accessed October 2005).
  3. ^ Nice, Karem. "How fuel cells work." Howstuffworks. <http://science.howstuffworks.com/fuel-cell.htm>. (accessed September 2005).
  4. ^ “Hydrogen Fuel Cells.” <http://www.bullnet.co.uk/shops/test/hydrogen.htm>. (accessed September 2005).
  5. ^ “Hydrogen and Fuel Cells” Center for Renewable Energy and Sustainable Technology. <http://www.crest.org/hydrogen/index.html>. (accessed September 2005).
  6. ^ National Academies Press; The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs. <http://www.nap.edu/books/0309091632/html/2.html>. (accessed September 2005).
  7. ^ Purdue University; Engineers Face Major Challenges to Make Fuel-Cell Cars Reality. <http://news.uns.purdue.edu/html4ever/2005/050510.Agrawal.fuelcells.html>. (accessed September 2005).
  8. ^ “Healthy Hydrogen.” Mechanical Engineering. Oct 2005, Vol. 127, Issue 10.
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