**1.6. Brief Description of Fuel Cell Type**

#### *1.6.1. AFC*

"AFC" was one of the first fuel cell technologies developed and was originally used by NASA space shuttle missions to produce electrical energy and water onboard spacecraft. The fuel cell uses a solution of potassium hydroxide as an electrolyte and can use a variety of non-precious metals as a catalyst at the electrodes. This fuel cell has high performance due to the rate at which chemical reactions take place in the cell. They are also very efficient in space applications with efficiencies up to 60%[10].

The major setback of this fuel cell is carbon dioxide poisoning of the electrolyte. Even little concentration of carbon dioxide in air can adversely affect its operation, making it necessary to purify the hydrogen and oxygen before use. This affects the cell's lifetime and incurs additional cost. AFC stacks have at least 8000 average operating hours and to make it eco‐ nomically viable for large-scale utility operations, operating times exceeding 40,000 hours are needed. This is possibly the most significant hindrance to its commercialization.

**Figure 4.** Showing components of alkaline fuel cell (www.fuelcellmarkets.com)
