Fuel Cell - UPSC Science & Technology Notes | Testbook.com

Defining a Fuel Cell

A fuel cell is a unique device that generates electric energy through a chemical reaction.

• Fuel cells function using a positively charged ion (Hydrogen) and an oxidizing agent (oxygen).
• There exist various types of fuel cells, but all of them consist of a cathode, an anode, and an electrolyte that allows positively charged (hydrogen) ions to move between the two sides of the fuel cell.
• Fuel cells are distinct from batteries as they require a continuous supply of fuel.
• Both batteries and fuel cells generate direct current (D.C).

How Does a Fuel Cell Work?

The functioning of a fuel cell involves the passage of hydrogen and oxygen into a concentrated solution of sodium hydroxide via carbon electrodes. The reactions in the cell can be represented as follows:

Cathode Reaction: O2 + 2H2O + 4e– → 4OH–

Anode Reaction: 2H2 + 4OH– → 4H2O + 4e–

Net Cell Reaction: 2H2 + O2 → 2H2O

However, the rate of this electrochemical reaction is relatively slow. This limitation is overcome with the help of a catalyst such as platinum or palladium. To increase the effective surface area, the catalyst is finely divided before being incorporated into the electrodes.

A block diagram of a fuel cell is provided below for better understanding.

• The first fuel cell was utilized by NASA in its satellites and space capsules.
• Fuel cells can serve as power backup in commercial and residential buildings.
• Fuel cells can be arranged in stacks like series and parallel connections depending on the requirement of higher voltage (series) and current (parallel).