Introduction




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What is a Fuel Cell?

A Fuel Cell is a device that converts chemical Energy (Potential Energy) directly into electricity via a modified oxidation process. The process also produces heat, water and possibly CO₂ depending upon the fuel used. A fuel cell is comprised of an electrolyte, surrounded by two electrodes. The underlying procedure is that oxygen and hydrogen pass over a distinct electrode, thus creating electricity.

The hydrogen enters the fuel cell through the anode while the oxygen enters through the cathode. The hydrogen breaks apart at a molecular level as it travels the fuel cell towards the cathode. The traveling hydrogen molecules create a current on their travel towards the cathode before they are united with the oxygen into a molecule of water. All that the process emits into the surrounding atmosphere is heat and water. Fuel Cell operates in reverse of electrolysis. In a Fuel Cell, hydrogen fuel and an oxidizer (Oxygen or Air) pass through separate porous metal plates separated an electrolyte bath. The hydrogen plate operates as an anode, converting the hydrogen molecules into hydrogen ions and electrons.

	2H₂(g)+O₂ (g) = 2H₂O(l)+572KJ
	1 gm of Hydrogen would give 143 KJ of Energy

A Fuel Cells always consists of two reactions:

* Oxidation: Reactants lose electrons

(lose H; gain O; generates Electrons)

* Reduction: Reaction gain electrons

(Gain H; lose O; Uses up electrons)

H₂ (g) = 2H⁺ + 2 e^- (Oxidation)

1/2O₂ + 2H⁺ +2 e ^- = H₂O (l) (Reduction)

The above reactions are called as "Redox Reactions" and always occur in pairs

Overall Reactions:

H₂ +1/2O₂+ 2H⁺ +2e^- = 2H⁺ +2 e^-+H₂O (l)

H₂+ 1/2 O₂= H₂O

Sir William R. Grove invents fuel cell in 1839. However Fuel cells capable of producing significant power were not developed until 1959 when Francis T. Bacon introduced an alkaline fuel cell capable of producing 5,000 watts (5kW). Bacon's fuel cell served as a starting point for the fuel cells developed by NASA and used to provide electrical power on both the Gemini and Apollo spacecraft. As a result of NASA's work, fuel cells were shown to be capable of efficient and reliable electrical power generation.

Unfortunately, the fuel cells of that era were also inherently expensive due to the large amount of platinum needed to manufacture the fuel cells. In the late 1980s and early 1990s, significant reductions in the amount of platinum needed for PEM fuel cells were obtained. Much of this work was performed at Los Alamos National Laboratory (LANL), a government (U.S. Department of Energy) owned facility located in Los Alamos, New Mexico. In 1996 and 1997, Mahlon S. Wilson of LANL developed a smaller, simpler class of fuel cells that relies on ambient air pressure for oxygen and on its own water generation for humidification (instead of pumps and fans, which are needed in other types of fuel cell technologies). Mr. Wilson improved PEM technology by designing a round fuel cell stack in which hydrogen is delivered through a central tube that also houses the bolt that holds the stack assembly together.

Terminologies:
Electrodes:	Electrical Conductors placed in the cell as sites for a chemical reaction.
Anode:	where oxidation takes place and it generates electrons
Cathode:	where reduction takes place by attracting electrons
Volt:	The difference in electrode potential
Amperage:	the rate at which electrons flow

Advantages of Fuel Cells

Fuel cells have a number of advantages over conventional power generating equipment:

· High efficiency

· Low chemical, acoustic, and thermal emissions

· Flexibility

· Reliability

· Low maintenance

· Excellent part-load performance

· Modularity

· Fuel flexibility