A fuel cell is kind of like a battery. Both have a cathode, electrolyte and an anode and can be used to power an external load. The biggest difference is that instead of a fixed amount of energy that a battery holds, a fuel cell can keep generating power as long as you feed it a fuel gas, which can be hydrogen or larger hydrocarbons like methane or propane in some cases. In most cases, the energy is generated by oxidizing the hydrogen fuel resulting in the formation of water.
Figure 1. Fuel cells are categorized by the electrolyte used to conduct the ionic species.
There are several different types of fuel cells that are characterized according to the electrolyte used and the mobile ionic species. Most fuel cells use a liquid electrolyte, which has a higher conductivity capable of delivering a higher power output. Low temperature fuel cells like the proton exchange membrane (PEM) and the alkali fuel cell (AFC) will require some external reforming or gas removal system at the anode or cathode. On the other hand, a solid oxide fuel cell (SOFC) using a ceramic, like yttria-stabilized zirconia, as the electrolyte. Because conductivity is lower is solids, SOFCs need to operate at temperatures around 1500F which allows for internal reforming and thus more fuel flexibility. However, it’s not very likely an SOFC will be powering your car!
Why don’t I have a fuel cell in my home yet?!
While the underlying operating principle was developed in the early 1800’s, it has taken nearly 200 years to see the beginning of commercial application. As with many technical areas, timing is everything. In the late 1890’s, the emergence of the internal combustion engine dominated the energy generation landscape. It wasn’t until the 1950’s and 1960’s, when NASA began looking for a power source for the Apollo and Gemini space missions, that fuel cells began to be seriously considered. However, the technology was still expensive at a cost of nearly $600,000 per kW. It would take another 30 years before the automotive industry would begin to develop fuel cells for widespread distribution.
What is good old Uncle Sam doing about??
There are many challenges that remain to meet the DOE target of $30/kW. Funding in the area of fuel cells consists not only of improving performance of the system, but also hydrogen production, storage, and distribution, all of which limit the implementation of fuel cells. Funding through the Department of Energy has varied over the last 10 years. After peaking in 2008 with over $200 million, requested funding for next fiscal year is $100 million. Some funding programs have worked to engage multiple players in the research and development space. The Solid State Energy Conversion Alliance (SECA) began in 1999 and aimed to establish a collaboration between the federal government, private industry, academic institutions and national laboratories. This past year, the Advanced Research Projects Agency – Energy (ARPA-E) has solicited proposals for distributed energy generation technologies and set high technical goals for multi-functional solid oxide fuel cell systems that are a combination of storage (traditionally batteries) and fuel cells (traditionally only conversion).
While some companies have been emerged in the fuel cell space, there still exist sizable barriers to entry for many different market segments. But like many other technologies, it will most likely have a place in a diverse energy generating future.
If you are interested in some more resources, make sure to check out: http://www.energyclub.gatech.edu/wp-content/uploads/2014/08/Fuel-Cell-Fundamentals.docx
The views expressed in this article are solely those of the author. There is no implied endorsement of ideas or concepts by the Energy Club or the Georgia Institute of Technology.