Generating electricity through electro-chemical reaction!
Principle of generation
Electrolysis of water
Junior high school students experiment with the electrolysis of water, passing electricity through platinum electrodes to separate water (H2O) into its hydrogen and oxygen components.
How does a fuel cell generate electricity?
Using a process which is the reverse of water electrolysis, fuel cells produce water by combining hydrogen and oxygen, which generates electricity and heat.
Hydrogen is fed to the anode where catalysis releases hydrogen ions (H+) and electrons (e-). The electrolyte is a material which allows ions to pass through it, but blocks electrons. The hydrogen ions (H+) released in catalysis travel through the electrolyte to the cathode while electrons blocked by the electrolyte are taken out to generate electricity. Oxygen (O2) is fed to the cathode where catalysis separates it into two oxygen atoms. Those oxygen atoms, electrons (e-) travelling from the load and hydrogen ions (H+) passing through the electrolyte combine to produce water (H2O).
Types of fuel cells
Fuji Electric has commercialized phosphoric-acid fuel cells.
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.
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.
History of Fuji Electric’s fuel-cell research and development
We at Fuji Electric were a pioneer in researching and developing phosphoric-acid fuel-cell packages in Japan. We have supplied them to customers in capacities ranging from several kW to 5MW. We have extensively researched the use of various fuels for fuel cells. We constructed a factory dedicated to manufacturing phosphoric-acid fuel cells earlier than any other company. We have evaluated the durability of such fuel cells over the years. 1998 is the first year we began selling our commercial model incorporating the know how we had accumulated. In addition to phosphoric-acid fuel cells, we have developed polymer electrolyte fuel cells. We have also developed alkaline, molten carbonate and solid oxide fuel cells. We are fully committed to continuing our efforts to promote the widespread use of fuel cells.
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