Most of automobile manufacturer around the world are working on alternative sources to power up the vehicles. CNG, Hybrid, Plug in Hybrids, Electrics as well now the more talked about FCV (fuel cell vehicles). Many FCV are on roads around the world. The technology seems very sophisticated but principle is simple. Mind you this principle is not that simple as we have seen in form of that famous "Water Kit" aka Agha waqar "Paani wali gari".. Lot or research is going on in form of test vehicles and prototypes. BMW, TOYOTA, HONDA, HYUNDAI, MERCEDES all are working on introducing their lineup. The F cell is very expensive at this time and the FCV are very expensive to own but by 2017 these will be as cheap as today's gasoline powered small cars.
Toyota is working on introducing FCV by 2015 for general public in USA, specifically California where there are more than 100 Hydrogen pumps operational already. Next generation of Prius might be introduced with FC option as well along with Hybrid and plug in hybrids. Read https://www.pakwheels.com/forums/news-articles-driver-education-safety/216416-hybrids-plug-hybrids-full-electric-understanding . I went over few websites and mostly Fuel Economy to compile all this info for our understanding about Fuel Cells. I am no way an expert on this. So all credits to original researchers.
Basics:
Fuel Cell is a device that uses Hydrogen (or Hydrogen rich fuel) and oxygen to create electricity. Fuel cell is more energy efficient than combustion engines and the hydrogen used to power them can come from variety of sources. If pure hydrogen is used as a fuel, fuel cell only emits heat and water, eliminating concerns about air pollutants or greenhouse gases.
Fuel Cell Components:
- Fuel cell stack: One of the more common types of fuel cell is PEM (Polymer Electrolyte Membrane) fuel cell. The PEM fuel cell consists of an electrolyte membrane sandwiched between an anode (negative electrode) and a cathode (positive electrode).
- PEM: The PEM is a thin, solid, organic compound, typical the consistency of plastic wrap and about as thick as 2 to 7 sheets of paper. This membrane function as an electrolyte: a substance that conducts charged ions (in this case protons), but does not conduct electrons. This allows the solution to conduct electricity. This membrane must be kept moist to conduct particles through it.
- Anode/Catalyst: The anode is the electrode at which oxidation (loss of electrons) takes place. In a fuel cell, the anode is composed of platinum particles uniformly supported on carbon particles. The platinum acts as a catalyst, increasing the rate of oxidation process. The anode is porous so that hydrogen can pass through it.
- Cathode/Catalyst: The cathode is the electrode at which reduction (gaining of electrons) takes place. In a fuel cell, the cathode is electrically positive. The cathode is composed of platinum particles uniformly supported on carbon particles. The platinum acts as a catalyst, increasing the rate of the reduction process. The cathode is porous so that oxygen can pass through it.
- Flow Plates: Flow plates perform several important functions. 1. They channel hydrogen and oxygen to electrodes, 2. They channel water and heat away from the fuel cell, and 3. They conduct electrons from the anode to the electrical circuit and from circuit back to the cathode.
The chemical reaction:
- Hydrogen fuel (H2) is channeled to the anode, where the catalyst separates the hydrogen's negatively charged electrons from the positively charged protons.
- The membranes allow the positively charged protons to pass through the cathode, but not the negatively charged electrons. The negatively charged electrons must flow around the membrane through an external circuit. This flow of electrons forms an electrical current.
- At the cathode, the negatively charged electrons and positively charged hydrogen ions (protons) combine with oxygen to form water (H2O) and heat.
The fuel cell stack:
- Fuel cell: The amount of power produced by a fuel cell depends on several factors, including the fuel cell type's cell size, temperature at which it operates, and pressure at which the gas is supplied to the cell. A single cell can produce less than 1.16 volts. Barely enough electricity for even the smallest applications.
- Fuel cell stack: To increase the amount of electricity generated, individual fuel cell are combined in series, into fuel cell stack. A typical fuel cell stack may consist of hundreds of fuel cells.
USES:
Fuel cells are flexible technologies and have a broad range of applications.
- Stationary power: Stationary fuel cells units can be used to backup power, power for remote locations, stand-alone power plants for towns and cities, distributed generation for buildings and co generations (in which excess thermal energy from electricity generation is used for heat)
- Portable power: Fuel cells can be used to power a variety of portable devices, from handheld like cell phones and radios to larger equipment such as generators. They can be used for almost any application typically powered by batteries but can last up three times longer before refueling.
- Transportation: This is the most exciting and important application of fuel cells. Fuel cell can be used for propulsion. Application includes cars, trucks, buses, trains, ships and submarines. They have been used to provide auxiliary power on spacecraft for decades.
Fuel Cell Vehicles:
FCVs run on hydrogen gas rather than gasoline and emit no harmful tailpipe emissions. Several challenges must be overcome before these vehicles will be competitive with conventional vehicles, but the potential benefits of this technology are substantial. FCVs look like conventional vehicles from the outside, but inside they contain technologically advanced components not found on today's vehicles. The most obvious difference is the fuel cell stack that converts hydrogen gas stored on board with oxygen from the air into electricity to drive the electric motor that propels the vehicle. The major components of a typical FCV are illustrated below.
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Watch how Fuel Cell works: http://www.dailymotion.com/video/x19jq7l_how-fuel-cells-work_travel
Credits. Alternative Fuel Vehicles
Also many other number of online resources