Scientific Question - Hydrogen Cars
Discussion
At the moment the world is going mad about MMGW (of which I am a definite sceptic).
This morning I was watching Top Gear where James May does a road test of the Honda Clarity the hydrogen Fuel cell car, which as Jay Leno said in that episode could be the saviour of the petrol engine by allowing us to conserve petrol and use it for weekend thrashes and hydrogen cars during the week.
Now my understanding of a hydrogen fuel and its production is very limited however I know the only emission is water. Now have we created water? or are we reusing water that already exists? I guess my question is, are we increasing the amount of water in liquid form on the planet? So in a hundred years can we expect, “Global Flooding/Wetness” claims.
This morning I was watching Top Gear where James May does a road test of the Honda Clarity the hydrogen Fuel cell car, which as Jay Leno said in that episode could be the saviour of the petrol engine by allowing us to conserve petrol and use it for weekend thrashes and hydrogen cars during the week.
Now my understanding of a hydrogen fuel and its production is very limited however I know the only emission is water. Now have we created water? or are we reusing water that already exists? I guess my question is, are we increasing the amount of water in liquid form on the planet? So in a hundred years can we expect, “Global Flooding/Wetness” claims.
Edited by JakeS on Sunday 28th February 00:01
The good thing about hydrogen cars is that the raw material for the fuel is readily available - water is 2 parts hydrogen, 1 part oxygen.
The bad thing is that water doesn't contain much energy. So you have to put energy into water to seperate it into hydrogen and oxygen which you can then use as fuel.
But that energy has to come from somewhere in the first place. If it comes from renewables or nuclear power then you are looking at clean energy. If it comes from oil/gas/coal - where most of our energy in the uk comes from - then it's actually worse than using petrol.
The bad thing is that water doesn't contain much energy. So you have to put energy into water to seperate it into hydrogen and oxygen which you can then use as fuel.
But that energy has to come from somewhere in the first place. If it comes from renewables or nuclear power then you are looking at clean energy. If it comes from oil/gas/coal - where most of our energy in the uk comes from - then it's actually worse than using petrol.
Currently hydrogen is expensive to make, and very difficult to store and distribute cost effectively. Apart from that it's wonderful. The technology bods are trying to find a way of creating it cheaply and storing it at ambient temperature at ambient pressure (and energy density) in a similar way to standard hydrocarbon fuels. Quite a challenge. I was involved with robot fuelling systems for this stuff 15 years ago (robots because of the VERY high presssures involved and the risk of a serious accident), and it still hasn't made much progress. Unless they can crack those issues, then the costs, safety issues, and distribution network development costs will remain so high as to make it infeasible.
ETA (and energy density)
ETA (and energy density)
Edited by paul.deitch on Sunday 28th February 00:06
paul.deitch said:
Currently hydrogen is expensive to make, and very difficult to store and distribute cost effectively. Apart from that it's wonderful. The technology bods are trying to find a way of creating it cheaply and storing it at ambient temperature at ambient pressure in a similar way to standard hydrocarbon fuels. Quite a challenge. I was involved with robot fuelling systems for this stuff 15 years ago (robots because of the VERY high presssures involved and the risk of a serious accident), and it still hasn't made much progress. Unless they can crack those issues, then the costs, safety issues, and distribution network development costs will remain so high as to make it infeasible.
Quite right. Even the American Space Programme is looking to Kerosene instead of hydrogen for the new generation of heavy lift rockets because it's safer, cheaper and easier to use. If you take water and apply energy to it (in the form of electrolysis I think?) you can split it into hydrogen and oxygen. In the right conditions (a fuel cell), you can make that hydrogen and oxygen re-combine and when it does so it will release some of that energy, so the hydrogen car works.
The problem is that the energy you have to use in the first place is a LOT more than the end result.
The problem is that the energy you have to use in the first place is a LOT more than the end result.
crofty1984 said:
If you take water and apply energy to it (in the form of electrolysis I think?) you can split it into hydrogen and oxygen. In the right conditions (a fuel cell), you can make that hydrogen and oxygen re-combine and when it does so it will release some of that energy, so the hydrogen car works.
The problem is that the energy you have to use in the first place is a LOT more than the end result.
You can also do it by chemical reaction, but then the oxygen tends to get locked in another compound which is even harder to break down.The problem is that the energy you have to use in the first place is a LOT more than the end result.
To answer the OP's question directly - which you have done, albeit not explicitly - the Hydrogen already exists in the water on the planet so there is no net increase in water. Hydrogen cars will not result in a sudden massive rise in sea levels - probably.
You can of course run a conventional petrol engine on hydrogen too. We have three transit vans which do this and retain the ability to run on petrol. So you can run "clean" where you need to (City centres, etc) and still have the range to make the vehicle practical at a far lower cost than a fuel cell. See here
As has been said the infrastructure is currently the challenge.
Dave
As has been said the infrastructure is currently the challenge.
Dave
crofty1984 said:
If you take water and apply energy to it (in the form of electrolysis I think?) you can split it into hydrogen and oxygen. In the right conditions (a fuel cell), you can make that hydrogen and oxygen re-combine and when it does so it will release some of that energy, so the hydrogen car works.
The problem is that the energy you have to use in the first place is a LOT more than the end result.
35x for electrolysis.The problem is that the energy you have to use in the first place is a LOT more than the end result.
There are other methods to extract hydrogen from water, such as aluminium, which will draw oxygen from the water leaving the hydrogen, but this is brief as the oxydised aluminium forms a protecting layer drastically reducing the reaction, mixing the aluminium with gallium, the gallium acts as a catalyst causing the oxidising layer to seperate and allowing the high speed reaction to continue.
Resulting outputs are aluminium oxide, gallium and hydrogen.
Converting the aluminium oxide back to aluminium and oxygen takes much less energy than electrolysis, but is not the so called holy grail of carbon neutral as carbon dioxide is typically formed converting the aluminium oxide back to aluminium.
Hydrogen is very impractical as an automotive fuel. Its energy density is very low, but extremely volatile. Its used in rockets because for the resulting energy output for its very low weight. (affects something called ISP)
Storage is a nightmare, fuel cells are expensive, complicated (although principally simple) and if designed badly prone to exploding.
Electric propulsion is the way forward, the technology for an electric transmission has existed for years.
The problem's the power source, batteries/capacitors are heavy and impractical for long distance.
Hybrid's create something that is over complicated and expensive, but realistic short term.
Biofuels are viable from a technical perspective, but create huge political issues.
ETA: The long term realistic solution is something along the lines of a micro-fusion reactor, but at the moment something like this is fairy dust as they can't get a big reactor to run at net.
Edited by annodomini2 on Sunday 28th February 11:49
As a chemical engineer... student 
... I am aware of the huge interest in producing hydrogen in viable quantities and competive prices. Whoever does get to this, and i believe they will (eventually), will become obscenely rich beyond their wildest dreams, or at least make their company very happy. There are some interesting possibilities with adapted bacteria etc, that have potential but expect the technology to improve as it becomes increasingly hard to use fossil fuels, and when people realise that the majority of biofuels have far more negative impact than conventional stuff.
I like the ideal of hydrogen as a fuel, given it can be used in conventional petrol engines with little modification, though a significant drop in power and efficiency. Fuel cells provide a far more efficient though hideously dull solution.
There are obvious storage issues which are slightly worrying - keeping anything under pressure is a potential hazard, but this may not end up being as significant a problem as it is now.
... I am aware of the huge interest in producing hydrogen in viable quantities and competive prices. Whoever does get to this, and i believe they will (eventually), will become obscenely rich beyond their wildest dreams, or at least make their company very happy. There are some interesting possibilities with adapted bacteria etc, that have potential but expect the technology to improve as it becomes increasingly hard to use fossil fuels, and when people realise that the majority of biofuels have far more negative impact than conventional stuff. I like the ideal of hydrogen as a fuel, given it can be used in conventional petrol engines with little modification, though a significant drop in power and efficiency. Fuel cells provide a far more efficient though hideously dull solution.
There are obvious storage issues which are slightly worrying - keeping anything under pressure is a potential hazard, but this may not end up being as significant a problem as it is now.
The laws for conservation of energy mean you will never get out more than you put in. You will never create 'new' stuff without using 'old' stuff.
The prinicple of perpetual motion is a wonderful thing but not in an environment where there is friction or resistance of any kind.
However an ideal would be solar energy charging a driving force, either battery or fuel cell.
But then were back to the beginning. You have to make the solar cells first.
So you've used energy and matter.
The prinicple of perpetual motion is a wonderful thing but not in an environment where there is friction or resistance of any kind.
However an ideal would be solar energy charging a driving force, either battery or fuel cell.
But then were back to the beginning. You have to make the solar cells first.
So you've used energy and matter.
I can't remember the compound used, but I'm pretty sure you can catalyse hydroven from high temperature/pressure steam. In an ideal world, this would use solar energy from (poor) tropical countries. To increase the power density it would be nice to use the recovered carbon from CO2. That way, oil tankers could transport it without any need for cyro storage. Expensive, but not beyond the realms of billionaire oil companies.
Mighty Flex said:
As a chemical engineer... student ... I am aware of the huge interest in producing hydrogen in viable quantities and competive prices. Whoever does get to this, and i believe they will (eventually), will become obscenely rich beyond their wildest dreams, or at least make their company very happy. There are some interesting possibilities with adapted bacteria etc, that have potential but expect the technology to improve as it becomes increasingly hard to use fossil fuels, and when people realise that the majority of biofuels have far more negative impact than conventional stuff.
I like the ideal of hydrogen as a fuel, given it can be used in conventional petrol engines with little modification, though a significant drop in power and efficiency. Fuel cells provide a far more efficient though hideously dull solution.
There are obvious storage issues which are slightly worrying - keeping anything under pressure is a potential hazard, but this may not end up being as significant a problem as it is now.
this is the most sense i've seen regarding the numerous threads on hydrogen powered cars.... I am aware of the huge interest in producing hydrogen in viable quantities and competive prices. Whoever does get to this, and i believe they will (eventually), will become obscenely rich beyond their wildest dreams, or at least make their company very happy. There are some interesting possibilities with adapted bacteria etc, that have potential but expect the technology to improve as it becomes increasingly hard to use fossil fuels, and when people realise that the majority of biofuels have far more negative impact than conventional stuff. I like the ideal of hydrogen as a fuel, given it can be used in conventional petrol engines with little modification, though a significant drop in power and efficiency. Fuel cells provide a far more efficient though hideously dull solution.
There are obvious storage issues which are slightly worrying - keeping anything under pressure is a potential hazard, but this may not end up being as significant a problem as it is now.
it is always assumed that water electrolysis or natural gas reforming are the only ways of making hydrogen, but we haven't scratched the surface of production or storage methods yet. demand will drive the research.
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