Alkaline Fuel Cell

The alkaline fuel cell (aka the Bacon Fuel Cell) is one of the most efficient fuel cell designs there is. It is a somewhat commonly used base for fuel cells in vehicles, by NASA for space exploration, and more.

An Alkaline Fuel Cell (AFC) uses hydrogen and oxygen to produce water, heat, and electricity. The water is pure and thus drinkable (potable), which makes it a good choice for NASA as a secondary benefit.

An AFC can be as much as 70% efficient.

How Alkaline Fuel Cells Work

An AFC works in the same way most hydrogen fuel cells work. The hydrogen is introduced on one side and the oxygen on the other. In between are the anode, electrolytes, catalyst, and cathode.

The fuel cells get the "alkaline" in their name from the alkaline aqueous solution (electrolyte) used. Because of this alkaline state, the fuel cells are capable of being "poisoned" with carbon dioxide (CO2), usually as a mis-conversion of potassium hydroxide into potassium carbonate. For this reason, most AFCs have pure oxygen injected or use specialized air scrubbers (cleaners) to purify the air before it enters the cell.

For this reason, these types of fuel cells can be expensive to build in terms of energy and resources for a mobile (vehicular) platform. For this reason, more than one design is being used in automotive.

The common NASA-based design is a "static electrolyte" setup in which the electrolyte is not flowing. These are more efficient in terms of power output, but require pure oxygen be injected rather than atmospheric air.

The other design is a "flowing electrolyte." This has a moving electrolyte, which requires more space inside to allow the flow, lowering efficiency through extra resistance. These do not require as stringent a cleaning on the oxygen source, however, and the electrolyte can be flushed and replaced. These are more common in automotive designs.

New innovations in AFC design have meant that they are getting cheaper to manufacture and capable of higher outputs in their design.

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