Fuel Cell Dogmas Revisited

Abstract

In spite of the fact that the development of fuel cells is a scientific and technological process, the process, itself seems to be largely determined by the human factor. By a number of examples it will be shown that this development and the creative process necessary for its progress is sometimes hindered by strong beliefs and frequently repeated statements that within themselves hold some truth but do not represent the whole truth. They can be regarded as ‘fuel cell dogmas’. Often implicit assumptions or particular boundary conditions lie behind the dogma. These assumptions or conditions may be altered in the course of the developments or for specific applications. Sometimes the dogma is essentially a rumor that is conveniently accepted by newcomers in the field. An example of the latter is the ban on the use of LiNa carbonate electrolyte in a MCFC instead of LiK because of its supposed higher corrosiveness. Nowadays LiNa is accepted as the new standard electrolyte in a MCFC. The most famous dogma is that fuel cells are more efficient than heat engines because they are not limited by the Carnot efficiency. Yet it is not always true, not even in the reversible limit. For a long time polymer fuel cells were considered to be inherently too expensive because of the membrane and the Pt catalyst. They were considered only suitable for niche markets such as space applications. As we know now General Motors believes differently. Other dogmas are: - Fuel cells have a higher efficiency than heat engines. - A fuel cell converts Hydrogen into power and heat. - Nernst loss is always proportional to utilization and inevitable. - To be economically feasible the fuel gas utilization should be as high as possible. - To be economically feasible the fuel cell should be operated at the highest possible power density. - A fuel cell always has two inlets and two outlets. - In order to use solid fuels in a fuel cell they must be gasified first. - Only low temperature fuel cells are suitable for automotive applications. These and other dogmas will be critically analyzed in terms of the underlying assumptions and boundary conditions. New options that are revealed by breaking through the dogmas are briefly sketched.