What is a Fuel Cell?

About Fuel Cell

• A fuel cell is a device that generates electricity by a chemical reaction.
• Fuel cells can be used in a wide range of applications, providing power for applications across multiple sectors, including transportation, industrial/commercial/residential buildings, and long-term energy storage for the grid in reversible systems.
• Working:
  • A fuel cell consists of two electrodes—a negative electrode (or anode) and a positive electrode (or cathode).
  • Both electrodes must be immersed in and separated by an electrolyte, which may be a liquid or a solid but must, in either case, conduct ions between the electrodes in order to complete the chemistry of the system. 
  • A fuel, such as hydrogen, is supplied to the anode, where it is oxidized, producing hydrogen ions and electrons. 
  • An oxidizer, such as oxygen, is supplied to the cathode, where the hydrogen ions from the anode absorb electrons from the latter and react with the oxygen to produce water. 
  • The difference between the respective energy levels at the electrodes (electromotive force) is the voltage per unit cell.
  • The amount of electric current available to the external circuit depends on the chemical activity and amount of the substances supplied as fuel.
  • A single fuel cell generates a tiny amount of direct-current (DC) electricity. In practice, many fuel cells are usually assembled into a stack. 
• Advantages of Fuel Cells:
  • Fuel cells have lower or zero emissions compared to combustion engines. Hydrogen fuel cells emit only water, addressing critical climate challenges as there are no carbon dioxide emissions.
  • There are also no air pollutants that create smog and cause health problems during the operation of a fuel cell.
  • They are quiet during operation as they have few moving parts.
  • They can operate at higher efficiencies than combustion engines.
  • A fuel cell resembles a battery in many respects, but it can supply electrical energy over a much longer period of time.
    • This is because a fuel cell is continuously supplied with fuel and air (or oxygen) from an external source, whereas a battery contains only a limited amount of fuel material and oxidant that are depleted with use.

Q1) What are electrodes?

An electrode is a conductor that is used to make contact with a nonmetallic part of a circuit. Electrodes are commonly used in electrochemical cells (see Figure 1), semiconductors like diodes, and in medical devices. The electrode is the place where electron transfer occurs.

Source: Isro tests futurist fuel cell system that could power space station 

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