what are hidrogen fuel cells?
365248
Fuel Cell is a device in which the energy of a chemical reaction is converted directly into electricity. Unlike a battery, a fuel cell does not run down; it operates as long as fuel and an oxidant are supplied continuously from outside the cell. Several companies are developing fuel cells that they hope will replace conventional internal-combustion engines in automobiles over the next few decades.\n\nHydrogen Fuel Cells:\n\nIn a hydrogen fuel cell, hydrogen is supplied to the fuel cell’s anode, and an oxidant, commonly the oxygen present in air, is supplied to the cathode. The fuel cell strips electrons from the hydrogen atoms. These electrons move from the anode through the electric circuit to the cathode, creating an electric current that can be tapped to provide power. The electron-deficient hydrogen atoms meanwhile pass through the electrolyte to the cathode. There the electrons that passed through the circuit recombine with the electron-deficient hydrogen atoms. Oxygen (from the air) reacts with this reformed hydrogen, producing water. Water produced at the cathode has to be removed continuously to avoid flooding the cell.\n\nHydrogen fuel cells hold great promise as low-pollution automobile engines if certain difficulties can be overcome. Water, the only waste product of a hydrogen-oxygen fuel cell, is nonpolluting and can be used to cool the engine. The oxygen the cells need is readily available in air. Hydrogen, however, is not so readily available, and there is no existing delivery system to convey hydrogen to all the places people would need it to power their cars. In addition, pure hydrogen is not abundant enough to provide power for all the cars on the road today. Instead, hydrogen would need to be extracted from other substances, a process that requires energy. This energy could conceivably be provided by nonpolluting and sustainable energy resources, such as wind or solar power
732233
Producing hydrogen electrolytically.  A very current topic and of interest to all persons paying for gasoline.
183390
Note that fuel cells do not operate on a thermal cycle. The fuel cell contineously replenishes its rxtant by converting energy from an external source (hydrogen /Oxygen) to electricity (1st law in ref to cons of energy)
406711
The Hydrogen atom is a donor/acceptor for the electron, it's kinda like a battery, or a hydroelectric energy plant. Imagine the electron is water it wants to get somewhere, and it turns a wheel (ATP Snythase) to create ATP to get there. That is a "big picture" the details you'll have to look up.
95444
Some tips...\n--Use a strong electrolyte (substances that will break up into ions [almost] completely in solution), the higher the concentration, the better.  Also you need to be careful on which electrolyte you choose.\n--Try not to use an over volttage (a voltage over the minimum necesary to electrolisize the water.  Insread, try to use a very high current, higher current = more production of gasses.  To increase current without increasing voltage, reduce resistance.\n--Place the electrodes close together to reduce internal resistance in the cell.\n\nEven by doing these things, you cannot hope to get much better than about 50% efficency doing water electrolysis, maybe 65% if you are good.\n\nThere are yahoo groups out there devoted to just such a tast as Hydrogen production through water electrolysis (I have one infact), they can also give advice based on experience.
51965
Hmm...  If I remember the physics right, it goes like this: Take two parts hydrogen and one part oxygen and mix them in a chamber with a catalyst and a proton exchange membrane and you get water and electricity.
970781
Potential of Hydrogen.
847347
Please follow the links\nhttp://www.alternative-fuel.biz\nhttp://www.fuel-cell.cc
1045890
Its best to think of hydrogen as a 'battery' rather than a power source.  Because we don't have incredibly abundant supplies of free hydrogen on earth, it is not practical for use as an initial energy source.  You are also right in your assertion that it will always take at least as much energy to create hydrogen as we can get by using it, in accordance with the first law of thermodynamics.  \n\nHydrogen is, however, viable as an environmentally friendly fuel to operate vehicles.  This is because the conversion of hydrogen into energy is essentially pollution free and is of high efficiency.  Thus if we use an environmentally friendly power source, such as solar power, to produce the hydrogen, we can run vehicles in an essentially pollution free manner.  As a result, a switch to hydrogen fuel cell vehicles would allow reductions in the overall emissions of our national power production to be reflected in reduced total energy cycle emissions of our vehicles.
567769
Well, yes, all of these answers are pretty much correct.  They don't run on water, they run on the hydrogen in the water and then they reintegrate the hydrogen and oxygen to produce water as a by product.  Here is a neat little company (That I own stock in) that is working on this:\nhttp://www.ballard.com/\nBallard Power Systems (BLDP) for you home gammers.  \nAlso an interesting site for "water" based power systems for energy production is here:\nhttp://www.fce.com/\nThey are also working on fuel cell (water) batteries for lap tops.  Some of the laptops are actually going to a methane battery instead of hydrogen however.  \n\nPretty kewl huh?
585397
i built a simple one using seveal pairs of stainless steel knives and caning jars. It wasnt feasable for practical use, but it was a good demonstration of fuel cell theory. I used solution of water and baking soda. \nThe stainless steel knives were used because stainless steel contains nickle which is a catylyst for the full cell process. (platnuium is much better catylyst, but much more expensuve.) I combined the cells in seriese and ran a curent over them until bubles apear on the knives and then removed the current.\nNext i put a led light over the leads of the cells, and then it lit for about 5 seconds as it absorbed the hydrogen and converted it to electricity.\nIt operated similar to a capisitor in this setup.
986906
You could use the batteries to electrolyse brine (ordinary table salt dissolved in water), causing chlorine and hydrogen gas to build up. If you could contain the hydrogen and chlorine somehow and let it build up to high pressure, you could let the pressure propel the rocket, or (if you allow air/oxygen in somehow) you could ignite the hydrogen.\n\nTry searching electrolysis on google for more info if you don't know what I'm talking about.
566985
I believe your question needs a bit of restructuring.Hydal power is itself stored energy in form stored water at a higher level.Energy is usually released when water is allowed to fall down over turbine i,e potential energy is converted to kinetic energy of turbine blades.
682808
I think you are talking about Roger Billings. http://www.roger.billings.name/\n\nIt seems that he is using hydrogen fuel cells to try to provide power to cars. Hydrogen fuel cells need hydrogen and oxygen to operate.  Billings is working on electrolyzing water to generate hydrogen and oxygen.  Electrolyzing means he applies a large voltage to the water in order to split up the hydrogen and oxygen that naturally form water (H2O).  \n\nI don't know about the involvement of the government or the military.  I think cars that run on hydrogen fuel cells today have to carry a tank of hydrogen in the car, which can be very dangerous.
205637
Methanol battery is a fuel cell design.\nSo how does a fuel cell work? "The fuel cell is based on the reverse principle of water electrolysis...[Fuel cells] work by having hydrogen and oxygen react to generate electricity..."
561309
That is an excellent and timely question.  But the answer must have two parts when you say cheap, realisitic & practical method.  First, ou can split water (H2O) into hydrogen and oxygen (both having commercial value) by electrolysis using simple electrodes and an electric current.  But you must supply the energy.  If you use oil or gas that competes with the existing and growing demand for fuel and heating gas.  However, power can be supplied from coal (in expensive poluting power plants) or from solar energy.  Daystar is starting production of a flexible film photovoltaic solor cell that is expected to produce cheap electricity.  If almost all the roofs in the country were shingled with their product the hydrogen economy would be a cinch (and Daystar would be very happy!).  Secondly, there are also plans to design and construct huge nuclear power plants that operate so hot that they can directly dissociate water into hydrogen and oxygen.  The plants would be very expensive but the hydrogen (and oxygen) should be relatively cheap and no greenhouse gases would be produced.
645274
At standard temperature and pressure hydrogen is a colorless, odorless, nonmetallic, univalent, tasteless, highly flammable diatomic gas. Hydrogen is the lightest and most abundant element in the universe. It is present in water, nearly all organic compounds and in all living organisms. Hydrogen is able to react chemically with most other elements. Stars in their main sequence are overwhelmingly composed of hydrogen in its plasma state. The element is currently used primarily in fossil fuel upgrading. Other uses include as a lifting gas, as an alternative fuel (see Hydrogen economy), and more recently as a power source in fuel cells.\nHydrogen can be prepared in several different ways but the economically most important processes involve removal of hydrogen from hydrocarbons. Commercial bulk hydrogen is usually produced by the steam reforming of natural gas. At high temperatures (700–1100 °C), steam (water vapor) reacts with methane to yield carbon monoxide and H2.\n\nCH4 + H2O → CO + 3 H2 \nThis reaction is favored at low pressures but is nonetheless conducted at high pressures (20 atm) since high pressure H2 is the most marketable product. One of the many complications to this very optimized technology is the formation of coke or carbon:\n\nCH4 → C + 2 H2 \nConsequently, steam reforming typically employs an excess of H2O.\n\nAdditional hydrogen from steam reforming can be recovered from the carbon monoxide through the Water gas shift reaction:\n\nCO + H2O → CO2 + H2 \nOther important methods for H2 production include partial oxidation of hydrocarbons:\n\nCH4 + 0.5 O2 → CO + 2 H2 \nand water electrolysis.\n\nIn the laboratory, H2 can be generated by treatment of many metals with acids or base.\n\nZn + 2 H+ → Zn2+ + H2 \n2 Al + 6 H2O → 2 Al(OH)3 + 3 H2 \n\n\n\nA hydrogen economy is a hypothetical future economy in which the primary form of stored energy for mobile applications and load balancing is hydrogen (H2). In particular hydrogen is proposed as a fuel to replace the gasoline and diesel fuels currently used in automobiles.\n\nHydrogen production is a large and growing industry. Globally, about 50 million metric tons of hydrogen were produced in 2004; the growth rate is about 10% per year. The energy in the current flow corresponds to about 200 gigawatts. Within the U.S., production was about 11 million metric tons, or 48 GW (10.8% of the average U.S. total electric production of 442 GW in 2003). Because hydrogen storage and transport are so expensive, most hydrogen is currently produced locally, and used immediately, generally by the same company producing it. As of 2005, the economic value of all hydrogen produced is about $135 billion per year.\n\nCurrently, hydrogen production is 48% from natural gas, 30% from oil, and 18% from coal; water electrolysis accounts for only 4%.\n\nThere are two primary uses for hydrogen today. About half is used to produce ammonia (NH3) via the Haber process, which is then primarily used directly or indirectly as fertilizer. The other half of current hydrogen production is used to convert heavy petroleum sources into lighter fractions suitable for use as fuels. This latter process is known as hydrocracking. Because the world population and the intensive agriculture used to support it are both growing, ammonia demand is growing. Hydrocracking represents an even larger growth area, as rising oil prices encourage oil companies to extract poorer source material, such as tar sands and oil shale.\n\nStorage is the main technological problem of a viable hydrogen economy. Some attention has been given to the role of hydrogen to provide grid energy storage for unpredictable energy sources, like wind power. The primary difficulty with using hydrogen for grid energy storage is that converting power to hydrogen and back is not cheap.\n\nHydrocarbons are stored extensively at the point of use, be it in the gasoline tanks of automobiles or propane tanks hung on the side of barbecue grills