Fuel cell
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A fuel cell converts the element hydrogen into electricity by chemically mixing it with oxygen, from which results water. It is like a battery that is constantly fed with fuel. It is an important part of the hydrogen economy. Note, though, that, unlike oil, hydrogen is not found in nature and is not an energy source, but an energy carrier. It has to be produced first, and if this is done by burning fossil fuels, it does not help against climate change. But, the hydrogen fuel cell will help against climate change in future, because scientists are trying to find new ways to make hydrogen without using fossil fuels.
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[change] How to get energy
Water is a molecule that consists of one oxygen atom and two hydrogen atoms. It takes energy when separating into oxygen and hydrogens. And it releases energy when they are put back together. A fuel cell does the latter. Hydrogen (the energy source) and oxygen (which can come in the form of plain air) are put into the fuel cell, separated by a screen that will only let positively charged hydrogen (H+) through to the oxygen (O). At the hydrogen side, a metal plate helps the electrons of the hydrogen atoms to split off (it acts as a catalyst). The now positively charged hydrogen atoms pass through the screen, while the electrons enter an electric circuit. This produces the electricity required. At the other end of the electrical circuit, it connects to the oxygen side, where the electrons then combine with the positively charged hydrogen and the oxygen to form water (which then comes out the exhaust pipe). These three (H+, O and electrons) 'want' to combine and thus 'pull' the electrons through the electric circuit, which then creates the desired energy.
[change] Efficiency
Fuel cells make electricity by reacting oxygen and hydrogen. Efficiency is very good(about 40~60%). They have a maximum efficiency of 80% if exhausting heat is used during reacting process. Also, fuel cells can use various fuels, for example, natural gas, methanol, LPG(Liquid Petroleum Gas), naphtha, kerosene etc. This is because it is easy, not only to gain energy sources, but to not burn a fuel source as well. Fuel cell technology is one of the future energy sources that will play a part in environmental conservation.
[change] Feature
The general features of fuel cells are that, firstly, it is possible to develop higher efficiency cells. Just like a silicon computer chip, there is almost no end to how far this can be streamlined and made into very energy efficient energy source. Because of its higher efficiency than caloric power generation, fuel cells can reduce the price of caloric energy sources. Furthermore, the emission of NOx, and CO2(carbon dioxide), makes it respectively 1/38 and 1/3 lower than coal or caloric power generation. As for noise, fuel cells tend to be very quiet.
Secondly, it is advantageous to determine the location. It can be located in the center of a city. So a fuel cell plant is economically provided with energy.
Fuel cells can be classified by a type of inner electrolyte. For instance, phosphoric acid fuel cells are for low temperatures. It is used in cell phones and automobile power supplies that require high currents because it is much safer. Alkali fuel cells usually consist of K(OH)2(pottasium hydroxide). Methanol fuel cells are used by reacting methanol electrochemistrically. This type of fuel cell is a better choice for simpler system. But methanol fuel cells have low output densitied as its reacting rate is slow.
[change] Types of Fuel Cells
Phosphoric Acid fuel cell (PAFC) - Phosphoric acid fuel cells are commercially available today.
Proton Exchange Membrane fuel cell (PEM) - These fuel cells operate at relatively low temperatures (about 175°F), have high power density, can vary their output quickly to meet shifts in power demand, and are suited for applications, such as in automobiles, where quick startup is required.
Molten Carbonate fuel cell (MCFC), Solid Oxide fuel cell (SOFC), Alkaline fuel cell (AFC),Direct Methanol fuel cell (DMFC), Regenerative fuel cell , Zinc Air fuel cell (ZAFC) , Protonic Ceramic fuel cell (PCFC), Microbial fuel cell (MFC)
[change] Applications
There are many uses for fuel cells — right now, all of the major automakers are working to commercialize a fuel cell car. Fuel cells are powering buses, boats, trains, planes, scooters, forklifts, even bicycles. There are fuel cell-powered vending machines, vacuum cleaners and highway road signs. Miniature fuel cells for cellular phones, laptop computers and portable electronics are on their way to market. Hospitals, credit card centers, police stations, and banks are all using fuel cells to provide power to their facilities. Wastewater treatment plants and landfills are using fuel cells to convert the methane gas they produce into electricity. Telecommunications companies are installing fuel cells at cell phone, radio and 911 towers. The possibilities are endless.
