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Many reasons, such as lack of infrastructure, cost, inefficiency, etc. See the link below for details.

Galen makes a good point about the risks since the Hindenburg was destroyed very quickly and it was filled with hydrogen gas. The main problem is economic - it takes much more energy to separate water into it's component gases, hydrogen and oxygen, than you can derive from either combusting the gases or putting them into a fuel cell. It's less efficient than a battery in other words so why add the extra step of producing hydrogen and losing more of the energy you want for your car?

There are also safety concerns with it. Hydrogen gas is very flammable so a tank inside your car might mean that the gas will kill you even if it doesn't explode. It's a tiny molecule that can easily escape from tanks and connections that would contain most gases. Turning it into a liquid solves one problem but then you have to keep it at a very low temp and if it leaks you get exposed to -423F temp which would kill you almost instantly.

In what way are gas tanks no safer than hydrogen tanks? Gas will leak out and can be ignited, the vapors can make you sick. Hydrogen gas can displace the air you need to breath if it leaks out and the tank can easily explode and kill you. Liquid hydrogen is worse in some ways.

Check the link to see how safe hydrogen fuel is, there's a reason it's mostly used to power rockets: http://www.amazon.com/Specialty-Board-Games-1876-H...

The problem is not safety, it is cost ans fuel. Right now, fuel cells cost a lot, much more than internal combustion engines.

We don't have a good supply of Hydrogen gas for fuel. The most efficient method of getting Hydrogen is from natural gas, which helps the environment very little. Electrolysis is also expensive an inefficient at this time.

Refueling and storing are also an issue. Hydrogen is harder to pump than gas because it is a gas; it must be pumped at high pressure at low temperatures. An airtight seal must also be maintained to keep too much Hydrogen from leaking out. Pumping Hydrogen into the fuel tank is simply not as user-friendly as pumping a liquid such as gasoline, thus requiring more skill and vigilance.

You are mostly correct. There is no incentive for oil producers to cut their own throats by manufacturing something they can't sell fuel for. And unfortunately most of the answers here are perpetrating the myth that turning water into fuel violates the laws of physics. These are the same people who said the Write brothers couldn't fly and all the other advancements that mankind has made over the years couldn't be done.

Hydrogen doesn't have to be stored. It can be manufactured on board. It produces about 7 times more power than gasoline. And a good mid step is using this hydrogen production with gasoline to improve performance and mpg. It can be done inexpensively and is far superior to the scam congress purchased in the way of Ethanol, which has dozens of unintended consequences. Additionally new vehicles do not need to be invented or manufactured. Every conventional car/truck on the road today can be retrofitted to benefit from adding HHO to their fuel, usually by way of the intake manifold. Older cars are easier to convert than newer ones. Once again Congress doesn't want anything to do with this because they can't line their own pockets by supporting it.

Pioneers in the hydrogen field such as Stan Meyer, have been killed to prevent their discoveries from being made public. There are several hobbyists attempting to re-learn his methods and secretes. And eventually I'm sure someone will make the necessary break through. Then the objective will be staying alive long enough to make the discoveries public! (It's worse than being an enemy of the Clinton's!)

There was a new video on Youtube today showing a new vehicle under test that does in fact use water for fuel. In fact, the best place to learn about this science is Youtube. Zerofossilfuel seems to be the top researcher. He is selling nothing, all his discoveries are in the public domain and anyone is free to duplicate his designs. Check it out.

Warning. There are a lot of scams out there right now. Don't be fooled. There is a 99.9% chance if you buy from these people on the internet (Ebay and others), you will be disappointed.

I would say the greatest things that keep hydrogen atm from being a good fuel source is making it cheaply and then building the infrastructure to support it. Plus BMW is the only car company with a hydrogen combustion engine ready to go and hydrogen fuel cells are still a couple years off to be cheap enough for a vehicle. As far as predetenation that is simple to solve use less compression ratio in the cylinder, the problem with most modern cars is they use a very high compression ratio 10 to 1 ratios and since Hydrogen burns faster then gas and expands faster it is alot harder on the engine so use 9 to 1 ratio and it is alot easier for a cylinder to take it. Alot of modern evidence on the Hindenburg was because of that mess they used to coat the blimp it was far more dangerous then the hydrogen. You can store Hydrogen in other formats one current one that works is metal hydrides but the storage ratio is pretty low in existing formulas about 2-3% which is to little so a 600liter tank would only hold 12 liters of hydrogen. It is alot more then you can store in compressed hydrogen tanks and it is 10 times safer since the gas won't release unless the metal hydrides reach 500 degrees so a car accident isn't likely to set it off.

What source do you base the statement that hydrogen tanks would explode and that is a lie. Look up the Hindenburg. If they were to get punctured, and ignited, you could have a problem.

Next, how do you extract hydrogen? How much does it cost? How many fuel stations do you know of? Things take time. People have to buy hydrogen vehicles, and refuel them. If there are no refueling stations, people won't buy them, if people don't buy them no one will set up refueling stations. (watch the movie catch 22).

If you believe in conspiracy theories, you surely believe in global warming. If we have high prices due to China and India using more fuel, do you really want more supply? more supply means more pollution, more global warming. You want to blame the government, but you think America wants to be behind other countries and you think we can stop the other countries from producing a vehicle.

Everything has plus and minus. You like hybrids? the pollution from mining nickle is the tradeoff.

Considering that most hydrogen these days is made from steam reforming of methane I doubt the oil companies would lose out unless we switched to a different production method (which they'll probably end up involved in anyway).

Hydrogen can be dangerous if mishandled although the fact that it is lighter than air does provide some safety benefits (since an emergency vent valve will send it all up, away from you) which would make a properly designed hydrogen vehicle less likely to catch fire in a way that will kill its occupants than a petrol powered vehicle (although cars don't catch fire and blow up very often in real life). LPG is much scarier than hydrogen (having the worst aspects of hydrogen and petrol) and is quite widely used despite that and can be quite safe when well maintained.

The Japanese hydrogen car runs on hydrogen on demand. It does not have a large tank to store the hydrogen. It makes it just before it is used. When the car stops the car stops making the hydrogen. It's a lot safer than a car with a full tank of gasoline.

Hydrogen powered cars are now a reality!

The main problem why they are not mainstream however is because of the technology currently used for producing hydrogen - currently hydrogen is produced from hydrocarbons such as oil and natural gas which is a fossil fuel (same old boat).

The future lies in producing hydrogen cheaply and cleanly preferably without using fossil fuels in the process and that's where fuel cells come in...

Fuel cells can produce electricity which will either power your vehicle by converting hydrogen taken from renewable sources such as methanol (provided that methanol was originally made from biomass for example). or;

Alternatively a fuel cell can be used to produce and then burn the hydrogen directly as in a conventional combustion engine.

A fuel cell can convert ordinary tap water (with a base added as the electrolyte) into H2 + O and burn this as fuel too but cracking H2O is not very efficient - Yet!

For my part I think the Direct Methanol Fuel Cells (DMFC) is part of the future. This type of fuel cell directly extracts the hydrogen from the chemical METHANOL (CH3OH) far easier if not cheaper than electrolysis with water, and is less dangerous than carrying compressed hydrogen tanks as the hydrogen is produced on demand directly at the source - only as and when you hit the accelerator pedal.

Methanol suppliers and related energy technologies for the UK http://www.wilson2u.com/

We are not yet there, technologically.

Current hydrogen-fueled engines are plagued with problems such as preignition and backflash. The greatest challenge is that in-cylinder injection requires hydrogen-to-air mixing in a very short time (approximately 5 ms at 5000 rpm). Incomplete mixing can produce misfire, high NOx emissions, reduced efficiency, and power loss.

I have seen a hydrogen powered incinerator by a manufacturer. It seems like a good and clean source of energy. However, the problem with the hydrogen powered technology is that it is too costly to put up one (too many components), it is too costly to operate (high power required) and it is too bulky to fit in any car. I don't think anyone appreciate driving a truck out just to buy grocery or to go work .

So I hope that answers your question.