Types of fuel cell.
Fuel cells are classified into four types on the basis of the materials used for the electrolyte and are further classified into three types by operating temperature: high-temperature, mid-temperature, and low-temperature types.
|
The fuel-cell temperature in degree celsius |
Type of fuel cell |
Material of electrolyte |
Generation output | Use |
| 1000 | Solid-oxide fuel cells(SOFCs) | yttria-stabilized zirconia | Several to several hundreds thousands of KW(50% to 60%) | in industry and as distributing power supplies |
| 650 | Molten-carbonate fuel cells(MCFCs) | Molten alakline carbonate | Several hundred to several hundreds thousands of KW(45% to 60%) | in industry and as distributed power supplies |
| 190 | Phosphoric acid fuel cells(PAFCs) | phosphoric acid | Several tens to several thousands of KW(35% to 45%) | in utilities and industry |
| 80 | Polymer-electrolyte fuel cells(PEFCs) | polymer memebrane | Several to 300KW(30% to 40%) 40% Phosphoric acid | in homes and in mobile and portable devices for small businesses |
High-temperature fuel cells
Their durability and reliability need improving
Solid-oxide fuel cells (SOFCs), which operate at temperatures ranging from 700 to 1000°C, and molten carbonate fuel cells (MCFCs), which operate at approximately 650°C, are characterized by their rapid chemical reactions and high generation efficiencies. (Their rapid chemical reactions remove the need for expensive platinum.) SOFCs and MCFCs can be fed with various types of fuel. The high-temperature exhaust heat they generate can be used for various purposes. However, their high operating temperatures prevent the use of a variety of materials for their components. It also takes a long time to start and stop them. Their characteristics make them suitable for eventual use in large-scale industrial facilities. More durable and, so, reliable SOFCs and MCFCs are being developed. Commercializing such fuel cells will take a while longer.
Mid-temperature fuel cells
Phosphoric acid fuel cells are highly reliable.
Phosphoric-acid fuel cells (PAFCs), which operate at a temperature of approximately 200°C, are relatively efficient. PAFCs have been researched and developed for longer than any other type of fuel cell. They are the only type of fuel cell whose durability and reliability have been proven. Their proven performance has contributed to their commercialization and is expected to contribute to their widespread use.
Low-temperature fuel cells
Their durability needs proving.
Polymer-electrolyte fuel cells (PEFCs) are easy to handle because they operate at temperatures as low as 80°C. There are increasing expectations for the widespread use of stationery solid-polymer fuel cells in homes.
2.
Ultracapacitors : are electric storage devices that can be recharged very quickly and release a large amount of power. In the automotive market, they cannot yet compete with Li-ion batteries in terms of energy content, but their capacity is improving every year.
The lead-acid battery has low energy density and power density a result of which a lot of them are needed for high energy applications. They are generally used in low voltage applications.
The Nickel Cadmium battery and Nickel Metal Hydride battery have higher power densities in comparison to the lead-acid battery.
The lithium-ion battery has an energy density ranging from 100-265 Wh/kg along with a high power density making it very suitable for automotive applications.
The fuel cell has very high energy density but low power density which come with challenges of its own like storage of fuel within the car among others. If a system has a high energy density then it is able to store a lot of energy in a small amount of mass. This demonstrates the relationship between energy density and power density. For example, Fuel cells will have very high energy densities, with relatively low power densities.