about hydrogen cars??

[OIKOS]

help, everybody... i am doing a presentation about hydrogen cars

anybody know about hydrogen cars???
does it run by water or.......

and the top speed,.... how much $$ per gallon....???



thanks...

 

[ElFenix]

are there any at all yet? i wasn't aware that there were.

 

[OIKOS]

just some information about it..... u know.... school project...

 

[XZeroII]

Um, if YOU are the one who is supposed to do the presentation, then maybe YOU should do the research? Hu? Hu? Hu?

 

[Ladies Man]

it will increase global warming by releasing water vapor in the air
put that in there and see the reaction

 

[atom]

It doesn't really run on water, or else it would be a water powered car not a hydrogen powered car.

Theoretically water is one of the mediums that would be used to store hydrogen. They would split the hydrogen from the oxygen and then release the oxygen as emissions. This technology is a long way off though.

The type of hydrogen powered cars most likely to be on the road soonest would store liquid hydrogen directly. I don't think performance is too bad, BMW converted some of it's 7 series cars to use hydrogen and it was supposed to go over 140MPH. Mazda had a hydrogen burning rotary car that did something like 150 KM/H.

 

[etech]

Originally posted by: atom
It doesn't really run on water, or else it would be a water powered car not a hydrogen powered car.

Theoretically water is one of the mediums that would be used to store hydrogen. They would split the hydrogen from the oxygen and then release the oxygen as emissions. This technology is a long way off though.

The type of hydrogen powered cars most likely to be on the road soonest would store liquid hydrogen directly. I don't think performance is too bad, BMW converted some of it's 7 series cars to use hydrogen and it was supposed to go over 140MPH. Mazda had a hydrogen burning rotary car that did something like 150 KM/H.

I don't think so. Water is not used to "store" hydrogen. It consists of hydrogen and oxygen. I have seen no proposals to use water for electrolysis on a car. It just would not be plausible. Liquid hydrogen would not be stored on a car. It is too cold and too hazardous to store in a car. Storage is still one of the big hurdles to overcome before hydrogen powered cars become a practical solution.
The emission of a fuel cell is water as the hydrogen recombines with oxygen.

OIKOS
Go to howstuffworks.com and search on fuel cell. The articles there will give you a good start. Be sure to read the one on the hydrogen economy.

 

[Zebo]

Los Alamos is the king in this type of reaserch Here you go, and download and read the 36 page PDF it's an excellent primer.

 

[silverpig]

I doubt that hydrogen combustion cars will ever be used. What will probably happen is we'll see hydrogen fuel cell cars (there are a few prototypes out and they work well... it's just hydrogen storage and cost that are factors now really).

Water will NEVER be used as a medium to store the hydrogen. Why? Because you have to put energy into the water to get the hydrogen out, and then you have to burn the hydrogen to get the energy back. The burning is much less than 100% efficient, so you will ALWAYS come out with an energy defecit.


How it will work is coal, nuclear, solar, and hydroelectric plants will electrolyse water into hydrogen and oxygen. The hydrogen will be put into tanks and shipped to your local fuel station.

 

[rgwalt]

There are lots of different hydrogen technologies... You can either burn hydrogen directly in an engine, thereby improving emissions, or you can use hydrogen with oxygen in a fuel cell to generate electricity. You can obtain hydrogen from two sources... either water or hydrocarbons. Removing hydrogen from water is done via a process known as electrolysis. In this process, electricity is used to cause water molecules to dissociate and liberate hydrogen and oxygen. Removing hydrogen from hydrocarbons can be done via a variety of processes, but is most commonly done via auto-reforming and water-gas shift reactions (both processes are used in series).

Storage and transportation of gases, especially hydrogen which is highly flammable, is difficult and dangerous. This fact combined with a lack of a nation-wide distribution system means that the first "hydrogen powered cars" will actually produce hydrogen from hydrocarbons in an auto-reformer and water-gas shift system. Since gasoline pumps already exist and people know how to use them (a surprisingly important factor), gasoline will likely be the medium from which hydrogen is extracted in cars. This hydrogen will be burned either in a modified combustion engine or will be used in a fuel cell.

Ryan

 

[OIKOS]

sniff...sniff.....

thanks.... everybody...

 

[rgwalt]

These fine people are correct, but a couple of clarifcations... Electrolysis is only about 50% efficient, meaning it takes twice as much energy to liberate a given amount of hydrogen than would be produced when that hydrogen is re-combined with oxygen to form water. That being said, you also have a reduction in efficiency in combustion. So, water will never be used as a on-vehicle fuel source until we have fusion reactors under our hoods.

Secondly, liquid hydrogen is only "cold" when at atmospheric pressure. You can store hydrogen as a liquid at room temperature, but it has to be at very high pressure. This poses a very dangerous problem, too.

Ryan

 

[Cycad]

Ahhh the hydrogen car, I bet I ride around on a unicorn first. Fossil fuel for life.

 

[OIKOS]

what are some disadvantages about fuel cells???

 

[Insidious]

I just finished a project at work where we made a fuel cell powered transit (city) bus.

We stored gaseous H2 for fuel. It was made available via electrolysis.

Another solution that has been utilized in other projects is a device called a reformer which
can extract H2 from fossil fuel (gee, way to go guyz..... kinda self-defeating)

Expect to see Hybrids (combination of IC and electric propulsion) for the next few years
with fuel cell cars a very real player in the next decade.

(you can also expect to see stationary fuel cells as sources for electrical power in industry)

-Sid

 

[NeoPTLD]

Originally posted by: rgwalt
These fine people are correct, but a couple of clarifcations... Electrolysis is only about 50% efficient, meaning it takes twice as much energy to liberate a given amount of hydrogen than would be produced when that hydrogen is re-combined with oxygen to form water. That being said, you also have a reduction in efficiency in combustion. So, water will never be used as a on-vehicle fuel source until we have fusion reactors under our hoods.

Secondly, liquid hydrogen is only "cold" when at atmospheric pressure. You can store hydrogen as a liquid at room temperature, but it has to be at very high pressure. This poses a very dangerous problem, too.

Ryan

No you can not store liquid hydrogen at room temperature regardless of pressure. There is a factor called "critical temperature" and once you're above that temperature, you can not keep it liquefied regardless of pressure applied. The critical temperature of liquid H2 is way below room temp.

 

[Insidious]

Originally posted by: OIKOS
what are some disadvantages about fuel cells???

expense, non-optimized technology, no infrastructure to get the fuel to the vehicles, and the fact
that somewhere along the line people are going to realize that despite cleaning up our vehicles,
we will make one big friggin mess with the H2 production. (last I heard, electrical power plants
are also of the devil....)

and last, but not least..... powerful people who have interest in the fossil fuel industry :disgust:

 

[Insidious]

Originally posted by: NeoPTLD

No you can not store liquid hydrogen at room temperature regardless of pressure. There is a factor called "critical temperature" and once you're above that temperature, you can not keep it liquefied regardless of pressure applied. The critical temperature of liquid H2 is way below room temp.

The above is just not true!

 

[conjur]

Some info on Honda's fuel cell vehicles:

Link 1

Link 2 (PDF)

 

[NeoPTLD]

Originally posted by: Insidious

Originally posted by: NeoPTLD

No you can not store liquid hydrogen at room temperature regardless of pressure. There is a factor called "critical temperature" and once you're above that temperature, you can not keep it liquefied regardless of pressure applied. The critical temperature of liquid H2 is way below room temp.

The above is just not true!

Hydrogen's critical temperature is -240C
Definition of critical temperature

You can keep LH2 in dewer flask, but it will lose so many % every day and you can not "store" liquid hydrogen indefinitely like you can propane. Think twice before you open your big mouth and scream I'm wrong.

 

[rgwalt]

Originally posted by: NeoPTLD

Originally posted by: rgwalt
These fine people are correct, but a couple of clarifcations... Electrolysis is only about 50% efficient, meaning it takes twice as much energy to liberate a given amount of hydrogen than would be produced when that hydrogen is re-combined with oxygen to form water. That being said, you also have a reduction in efficiency in combustion. So, water will never be used as a on-vehicle fuel source until we have fusion reactors under our hoods.

Secondly, liquid hydrogen is only "cold" when at atmospheric pressure. You can store hydrogen as a liquid at room temperature, but it has to be at very high pressure. This poses a very dangerous problem, too.

Ryan

No you can not store liquid hydrogen at room temperature regardless of pressure. There is a factor called "critical temperature" and once you're above that temperature, you can not keep it liquefied regardless of pressure applied. The critical temperature of liquid H2 is way below room temp.

OK, you are right. The CT for hydrogen is around -400 F. However, you can store it as a supercritical fluid at room temperature and high enough pressure. At these pressures you can't classify the hydrogen as a liquid or a gas.

Ryan

 

[Insidious]

Nice linkies!

(ultra-caps.... we abandoned them when we found out they were highly flamable and gave off arsnic gas when on fire.
yes.... we did have a fire)

 

[Insidious]

You can keep LH2 in dewer flask, but it will lose so many % every day and you can not "store" liquid hydrogen indefinitely like you can propane. Think twice before you open your big mouth and scream I'm wrong.

Well then, let me say it again.... YOU ARE WRONG!
I have witnessed the storage of LIQUID H2 in non-cooled tanks

 

[etech]

Originally posted by: rgwalt

Originally posted by: NeoPTLD

Originally posted by: rgwalt
These fine people are correct, but a couple of clarifcations... Electrolysis is only about 50% efficient, meaning it takes twice as much energy to liberate a given amount of hydrogen than would be produced when that hydrogen is re-combined with oxygen to form water. That being said, you also have a reduction in efficiency in combustion. So, water will never be used as a on-vehicle fuel source until we have fusion reactors under our hoods.

Secondly, liquid hydrogen is only "cold" when at atmospheric pressure. You can store hydrogen as a liquid at room temperature, but it has to be at very high pressure. This poses a very dangerous problem, too.

Ryan

No you can not store liquid hydrogen at room temperature regardless of pressure. There is a factor called "critical temperature" and once you're above that temperature, you can not keep it liquefied regardless of pressure applied. The critical temperature of liquid H2 is way below room temp.

OK, you are right. The CT for hydrogen is around -400 F. However, you can store it as a supercritical fluid at room temperature and high enough pressure. At these pressures you can't classify the hydrogen as a liquid or a gas.

Ryan

Any idea what pressure is necessary?

One trivia fact. Liquid hydrogen is so cold that it can condense oxygen from air. If liquid oxygen drips onto asphalt it can start a fire.

 

[NeoPTLD]

Originally posted by: Insidious

You can keep LH2 in dewer flask, but it will lose so many % every day and you can not "store" liquid hydrogen indefinitely like you can propane. Think twice before you open your big mouth and scream I'm wrong.

Well then, let me say it again.... YOU ARE WRONG!
I have witnessed the storage of LIQUID H2 in non-cooled tanks

You saw liquid H2 "kept" in a non cooled tank, but you didn't see it stored indefinitely.

If I poured liquid nitrogen into a drinking glass, there will be liquid nitrogen in there for some minutes and by your definition, I have witnessed storage of liquid nitrogen, because I have successfully kept it for several minutes