ABSTRACT
Fuel cells have been used in many National Aeronautics and Space Administration (NASA) projects. The initial capital cost is still a significant barrier for adoption, but numerous designs have been investigated in recent years. This chapter presents numerous designs of fuel cells ranging from conventional hydrogen fuel cells to advanced high-temperature solid oxide fuel cells. Conversion efficiencies (actual and theoretical) are also presented with accompanying examples.
The advantages and disadvantages on the use of fuel cells are discussed in this chapter. There are now numerous manufacturers of fuel cell systems, such as Ballard, Inc. Hence, the student is shown some calculations for basic economic analysis. The main barriers for adoption are pretty much dependent upon the source of fuel, such as hydrogen, methane, or other combustible gaseous materials derived from renewables, such as biofuels. Many hybrid vehicles are now equipped with fuel cell systems taking advantage of cheaper compounds, such as phosphoric acids or similar cheap organic acids or bases, in the designs. Numerous government-related projects are described that are mainly used for powering unmanned aircraft systems. Finally, the future of fuel systems is discussed.
