Hydrogen Fuel Cells

 Fuel cells are devices that produce electrical energy through electrochemical processes, without combusting fuel and generating pollution of the environment. Hydrogen fuel cells operate by mixing hydrogen and oxygen to produce water and electricity. The electricity can then be used to provide power to homes and businesses or to power cars and other vehicles. Some experts believe that internal combustion engines (ICEs) that are fueled by hydrogen are just as important. Hydrogen could be used as fuel for transportation by creating internal combustion engines for vehicles that run on hydrogen or hydrogen fuel mixtures.

Using hydrogen in fuel cells

A fuel cell works sort of like a battery. In hydrogen fuel cells, the hydrogen is converted to electricity through an electrochemical reaction converting the chemical energy of the reactants directly into electrical energy. However, there is an important difference between them, which lies in the way the chemical energy is transformed into electrical energy. A battery uses the chemical energy stored within the reactants inside the battery, whereas a fuel cellconverts the chemical energy provided by an external fuel/oxidant mixture into electrical energy. Thus, batteries use chemical energy until the reactants are completely depleted and, at the end of their lifetime, they can either be recharged or just thrown away. Fuel cells, on the other hand, can provide electrical output as long as the supply of fuel and oxidant is maintained. There are several types of hydrogen fuel cells. Some use phosphoric acid as an electrolyte (a substance that conducts electricity). Others use molten carbonate as electrolytes.

The reactions that produce electricity take place at the electrodes. Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes.

Hydrogen fuel cells are classification

Hydrogen fuel cells are classified primarily by the kind of electrolyte they use. This determines the kind of chemical reactions that take place in the cell, the kind of catalysts required to enable the reaction, the temperature range in which the cell operates, and the fuel required. These characteristics, in turn, affect the applications for which these cells are most suitable. There are several types of fuel cells, each with its own advantages, limitations, and potential applications, including:

• Superior energy efficiency (for example, fuel cells are 2-3 times as efficient as international combustion engines and for co-generation applications, fuel cells can achieve energy efficiencies of over 80 percent)

• Utilizes a variety of fuels including: hydrogen, methanol, natural gas, formic acid, ethanol

• Zero to near-zero emissions

• Versatile and scalable - can be applied in micro, portable, stationary, and transportation power applications • Low maintenance costs, design freedoms and quiet operation

PEM hydrogen fuel cells

The most common type of hydrogen fuel cells in use is the proton exchange membrane (PEM) fuel cell which deliver high-power density and offer the advantages of low weight and volume, compared with other fuel cells. General Electric first invented this fuel cell in the 1960s as a source of electrical power for the Gemini spacecraft. Though they were expensive, these fuel cells were efficient producers of energy.

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