Are Fuel Cells Actually Clean?

Written by Cameron DeWith

Fuel cells have been used for decades in space exploration, but it seems that the technology is only becoming more and more relevant to our world. The increasing significance of fuel cells persuaded me to choose this topic for a blog post. I hope that you find this topic as interesting as I did! Enjoy!

How do Fuel Cells Work

There are many types of fuel cell systems. The variations of fuel cells differ based on the electrolyte used. I will explain the workings of a fuel cell using hydrogen since the bulk of systems use that as fuel. Fuel cells contain an electrolyte surrounded by an anode (negative electrode) and a cathode (positive electrode). The hydrogen goes to the anode where its protons are separated from its electrons by a catalyst. From there, the protons move through the anode and the electrolyte on their way to the cathode. Meanwhile, the electrons go through a circuit to the cathode, generating electricity in the process. Oxygen from the air is fed into the cathode where it meets up with the protons and electrons to form water. Ultimately, fuel cells convert the chemical energy of a fuel (commonly hydrogen) directly into electrical energy, with the only byproducts being water and heat.

Applications of Fuel Cells

Fuel cells have many varying applications in space, power generation, and transportation.

• NASA started developing fuel cell systems for use in space in the late 1950s. Since then, they have been used aboard space missions because they are able to produce electricity and clean water. Fuel cells were also a logical choice for space exploration because they are highly efficient.
• Thousands of fuel cells are in use around the world for primary power or backup power. These systems are logical because they don’t emit toxic gases and are extremely quiet.
• Fuel cells are also available in vehicles. They offer the ability to fill up in a few minutes (like gas) while avoiding the release of any fossil fuels. Currently, the technology is present, but there is very little infrastructure available to make it competitive in the global market.

Advantages of Fuel Cells in Transportation

Because there are many applications of fuel cells, I will focus on the advantages and disadvantages of fuel cells in one area: transportation. I will focus on this one application in particular because fuel cells can be directly compared to two other systems, combustion engines and electric batteries, which are also available in vehicles.

• Fuel cells convert chemical energy to electrical energy at a much higher efficiency than combustion engines. Fuel cells convert the chemical energy directly to electrical energy, avoiding the combustion step.
• In stark contrast to combustion engines which emit carbon dioxide and other gases that are harmful to both humans and the environment, fuel cells don’t release pollutants into the atmosphere. In fact, fuel cells only emit water.
• Fuel cells are much quieter than combustion engines because they have very few moving parts.
• Both batteries and fuel cells supply electrical energy. However, fuel cells last longer because they receive a constant supply of fuel and oxygen. Batteries, on the other hand, only carry a limited supply of fuel and oxidant which diminishes as the battery is used.

Disadvantages of Fuel Cells in Transportation

Fuel cells also contain some disadvantages when compared with combustion engines and electric batteries in the application of transportation.

• Sossina M. Haile noted in her study, Fuel cell materials and components, that “reduction of cost and system complexity remain significant challenges” (2003, p. [Page 5999]). In current fuel cell technology, platinum is normally the catalyst on the anode. Because of its limited supply, platinum is expensive and significantly brings up the cost of fuel cells. As the cost and complexity of fuel cells reduces, the technology will be able to compete against combustion engines and electric batteries.
• The infrastructure available for fuel cell vehicles remains, at present, very limited. Gas stations are available in large numbers for combustion engines and electricity is readily available for electric batteries, but there are very few places to fill vehicles up with hydrogen. This limited supply has created high prices for hydrogen.
• Hydrogen is very reactive, so it most commonly exists as a part of either compounds or molecules. These compounds and molecules must split apart in reactions in order to produce pure hydrogen. Commonly, pure hydrogen is made from methane. This process emits carbon dioxide and other harmful gases. Hydrogen is also derived from water through electrolysis. This process splits hydrogen and oxygen by use of electricity. This process does not emit any harmful substances. However, the electricity used to split hydrogen apart from oxygen needs to come from somewhere. Currently, most of our electricity comes from sources that emit greenhouse gases. So, whether the hydrogen comes from methane or water, harmful gases are emitted somewhere in the process. In this regard, electric batteries are likely more environmentally friendly than fuel cells at present.

Conclusion

Sarah Nightingale noted in an article that “hydrogen is only as clean as the energy used to produce it” (2019). Personally, I think that fuel cells offer potential to a future where environmentally friendly ways of producing hydrogen have been introduced. Currently, however, fuel cells are not fully ‘clean’.