Every time I hear about Hydrogen as a fuel it's being used via a fuel cell.
How come it isn't just burnt like LPG?
Can understand for electricity generation as no point converting energy again but for transport? Is it massively more efficient?
Like the title says probably a div question but springs to mind every time it comes up.

At the moment they havnt found a safe and efficient way to store it I believe. I am sure that once they sort that out it will become very prevalent as a fuel as there are huge reserves of it globally but again I think they are having issues extracting it

It's the most abundant element in the universe BUT producing hydrogen takes lots of energy currently.

H2 is not a fuel source, it is just a medium. It's most abundent form on earth is in H2O, removing the H2 from O is a reversal of the combustion reaction (or whatever is done in the fuel cell) and therefore takes the same amount of energy.

This means your still left with the requirement of an energy source to seperate H2 from O. Saying producing hydrogen currently takes a lot of energy is like saying bikes currently will not freewheel uphill, it's not going to change (as long as we are getting H2 from water).

Doesn't really answer the original question but I'd maybe guess electrical is more efficient than combustion despite there being more stages involved. H2 wouldn't be used for power plants (ignoring fusion) because you would be using electricity in the first place to extract it, it's more that H2 is a convenient medium for transporting energy, think of it like a battery. It's better than a battery because it doesnt require heavy and rare Lithium and it doesnt lose performance in the same way that a battery does

I asked one of the researchers at work the same question (we've got a variety of hydrogen powered vehicles). Apparently using it in a fuel cell is massively more efficient than burning it.

>it's not going to change (as long as we are getting H2 from water).

Your words not mine 🙂

I guess in reality it will require nuclear fusion to be tamed in order for the large amounts of energy reqd for hydrogen production to be cheaply available. That or we'll all be driving round in fusion powered cars 🙂

H2 wouldn't be used for power plants (ignoring fusion) because you would be using electricity in the first place to extract it, it's more that H2 is a convenient medium for transporting energy

Ah, and there we get into the tipping point on whether its better to transmit electrical power over long distances in cables, or to produce hydrogen at point of generation and storing then pipelining it – clearly theres a possibility that hydrogen generation and storage might get us around the continuity of supply problem caused by 'green' sources, especially tidal and wave power, making the prospect of the UK being a major net fuel exporter a real possibility

'>it's not going to change (as long as we are getting H2 from water).

Your words not mine'

Sorry I'm not sure what your getting at? my point was that the energy of formation of elements is something that cannot be changed. Yes I know that with fusion the power output is greater than this initial energy requirement but the initial energy requirement is not going to changed. Unless you mean that we're going to get H2 somewhere else, I guess we could suck it out of the sun with a big straw, I don't know I'd like to be enlightened!

Zulu-Eleven, personally I reckon Algae's digesting CO2 then processed to make Biofuels is the most promising way forward at the moment as it sticks to our current infrastructure, much denser energy/area/year compared to other biofuels too.

It's more efficent to use it in a fuel cell, and the car is loads simpler. You don't need a gearbox or clutch, and you don't need regular oil changes, spark plugs, air filters etc etc etc etc. Electric motors are much better suited to automotive uses than IC engines.

As for piping Hydrogen about, I have often thought this. For example, Iceland can generate unlimited amounts of Hydrogen emissions-free from geothermal power, and they could ship it around the world and become the new Saudi Arabia.. only problem is energy density. A tankerload of crude oil can power loads of cars and trucks, and can fill people's central heating tanks, make roads, plastics, paints and all that stuff. A tanker load of H2 will power many fewer cars and trucks, and do none of the other things. Plus it'd have to be stored under pressure and there'd almost be as much weight of tanks and pressure equippment as there would fuel.

FWIW I think biofuel from algae and cellulose will be the things that save the private car.

Or you could do what that Scottish island does and use a wind turbine to generate the hydrogen and also pressurise it.

Molgrips, at the moment we've already got a nice big existing network of high and low pressure pipelines sprawling all over Europe which takes huge volumes of natural gas, should be quite easy to transfer the network over to storing Hydrogen instead. build a few local distribution hubs so we don't have to truck it too far for vehicle use, Fuel cell in every home plugged in where the central heating boiler was…

Zulu – I don't think the existing as infrastructure will work for hydrogen – pressures too high / temp too low and the molecule too small and slippery.

Some good comments on here

But do you remember exploding hydrogen in Chemistry?

The trick is to find a technology to recombine H with air (the O2 bit) in an efficient and controllable process, which is what Hydrogen Fuel Cells are all about.

And you have to get the H into the car without releasing it or risking an explosion = Canister

The other thing to note is that a fuel cell is only more efficient than a IC engine if you are mixing the Hydrogen with Oxygen. But if you are mixing it with Air then the efficiency falls back in line with IC (before you factor in the comparative efficiencies of producing and transporting the respective fuels). Their efficiency falls as the load on the cell increases too. So to get that increased benefit you need to be producing/transporting/ bottling Hydrogen and Oxygen and being careful not to mix them up on the way. Eau the Humanity

I'm not sure what effort and energy goes into the commercial production of oxygen, but it costs me a few bob when I buy it, so I'd guess quite a lot

Fuel Cells are really old technology, as in early 1800s old. I think if they were ever going to find a real commercial application they would have done so by now.

I misread the title and thought it said DIY hrdrogen to power cars – now that would be an interesting thread to follow!

Fuel Cells are really old technology, as in early 1800s old. I think if they were ever going to find a real commercial application they would have done so by now.

Not the case. Technology changes a lot but more importantly so do economic conditions. What's not economical one decade becomes viable the next.

As for DIY hyrdogen – just get any car with a carburettor. Just fit the fuel line to a tank of H2, tweak the mixture and voila – it'll work. They managed to get a car to run on Mythbusters just by squirting H into the carb from a hose!

just thought i'd but in with some facts to readress the armchair scientists.

1) hydrogen doesn't have to come from water, its a hell of a lot easier to take a hydrocarbon (oil) strip the hydrogen from that and burry the carbon somewhere.

This is commonly known as pre-combustion carbon capture (as the hydrogen then gets burnt in a power station, but you could in theory do anything with it). The alternative is post-combustion carbon capture where the air is purified (strip the N2 from the O2) before the burners, then the exaust gas is burried.

2) fusion and hydrogen fuel cells are two different things, you'd be amazed how many people get them confused.

3) you don't nececeraly need electricity to produce hydrogen, theres research being done to find a way of doing it with waste heat, unfortunately you need nuclear powerstation levels of heat for most of the teoretical methods to work.

4) saying hydrogen is the most abundant fuel source in the universe is like saying converting CO2 back into fuel is the solution to our energy problems, this is actualy a fairly straight foreward process, but no one does it as the aim in most reactions is to turn fuel into CO2 efficiently, not the other way arround.

Burning hydrogen produces water vapour, which is a worse greenhouse gas than CO2: hardly the green fuel of the future then, but there again the greens never let facts spoil a good lie story

Burning hydrogen produces water vapour, which is a worse greenhouse gas than CO2: hardly the green fuel of the future then, but there again the greens never let facts spoil a good lie story

I think you'll find it's a bit more complicated than that.

Oh and what do you think you get when you burn HYDROCarbon?

hydrogen doesn't have to come from water, its a hell of a lot easier to take a hydrocarbon (oil) strip the hydrogen from that and burry the carbon somewhere.

it requires less energy to remove hydrogen from hydrocarbons than from water, but a) we're already running out of them b) carbon is a lot harder to dispose of than oxygen 🙁

Zarquon, please do entertain me by explaining why water vapour is a worse greenhouse gas that CO2 🙂

Are you referring to the shorter atmospheric lifetime of water, or is the equivalent radiative forcing of water higher, or perhaps you're referring to the various positive and negative feedback effects of atmospheric water.

Those scientists with their theories and facts!!

FYI it's hard to control the amount of water vapour in the atmosphere due to 70% of the planet's surface being covered in it. It's called "weather".

MB radiative forcing, look it up. Shorter lifetime is hardly going to make water vapour a greenhouse gas is it? Look at the plethora of data on the relative importance of water vapour as a greenhouse gas compared to Co2 in the earths atmosphere.

Yes burning hydrocarbons also produce water. What I'm pointing out is that just switching to hydrogen as a "green" fuel is not necessarily the panacea that it is touted to be. A bit like fusion creating large amounts of neutron radiation, that nobody seems to discuss either.

Shorter lifetime is hardly going to make water vapour a greenhouse gas is it?

Wooosshhhhhhh!

What I'm pointing out is that just switching to hydrogen as a "green" fuel is not necessarily the panacea that it is touted to be

I'm only a lowly engineer but it strikes me that if we could burn Hydrogen as a fuel source we could simply condense the waste water vapour into liquid before releasing into say a river perhaps? Not exaclty a difficult problem to deal with is it.

The point is that water vapour is generally considered more of a feedback effect for the other greenhouse gases precisely because of the shorter atmospheric lifetime. If it gets warmer (due to other GHG's, changes in solar irradiation or whatever toasts your muffin) the atmosphere can hold more water vapour but only up to a certain point – when it rains, forms clouds etc etc.

However, I agree that there will be impacts from the generation and use of hydrogen as a fuel. The other option is to travel less and use less energy. Any volunteers?

I'm only a lowly engineer but it strikes me that if we could burn Hydrogen as a fuel source we could simply condense the waste water vapour into liquid before releasing into say a river perhaps? Not exaclty a difficult problem to deal with is it.

where it will evaporate and enter the atmosphere as water vapour….

where it will evaporate and enter the atmosphere as water vapour….

And exactly how is that any different to the evaporation that takes place as part of the natural water cycle? Especially if the hydorgen was generated by the electrolysis of oh lets say seawater.

either your troling, or stupid enough to be classified as an animal and shot, either way I'll be sportign and give you a head start while I fetch mi' gun.

Any challenge to your orthodoxy and you act like animals. TINAS that is just plain offensive. Actually, the role of water vapour will become important if the planet heats up, as concentrations in the upper atmosphere increase.

if you dont believe me look here http://www.newscientist.com/article/dn11652-climate-myths-cosub2sub-isnt-the-most-important-greenhouse-gas.html

Oh and before you jump all over me, read through to the end, the part that says that water vapour in the future will become hugely important.

Yes I was being provocative, and the residence time will prevent this as an issue, but as a breaching experiment you

<fail>

Did you click the link in my previous post or did you find that article all by yourself. No one has said that water vapour doesn't play a part in the greenhouse effect but that article does not back up your argument that

water vapour, which is a worse greenhouse gas than CO2

in fact it demonstrates quite the opposite.

I for one have no problem with challenging orthodoxy but such challenges need to backed up with facts.

Zarquon, I believe the tone was set by your post accusing the 'greens' of lying.

… and yes, I did bite 😉

OK I've read the article, which rather confirms the obvious that we already have so much water that making a bit more won't make any difference in itself.

what do you propose then, a polytunnel coverign 2/3of the planet to prevent water evaporation from the sea?

Water vapour as a GHG is a part of the model, but not part of the problem, warming results in more evaporation of the water and therefore higher concentations in the atm. But the reverse is true, reverse the warming and the water will condense again. The ammount of water in the atm. is in equilibrium with the sea, so you cant get a runaway scenario where increacing water in the atm. leads to warming and more water.

Get your facts right before spouting retoric that went out of fasion in the 90's, your sounding like a tabaconist claiming smoking isn't bad for you.

your sounding like a tabaconist claiming smoking isn't bad for you.

but it isn't bad for you, if you don't do it, in fact you benefit from increased tax revenues and the fact that it kills off smokers before they can claim their pensions, poor loves.

This reason:

Ian Munro – Member

I asked one of the researchers at work the same question (we've got a variety of hydrogen powered vehicles). Apparently using it in a fuel cell is massively more efficient than burning it.

To the question
[/quote]How come it isn't just burnt like LPG?

because is only a liquid at about -260°C/-430°F
dont think a engine would like that to much, not sure what it would come down to once its under pressure like lpg.

Not educated to a high enough level to fully understand the workings of thermo-dynamics but get the gist. My favourite statement/mnemonic for the basics is (and I can't remember who originated it) is:-

1st Law of Thermo-dynamics – "You can never win the game"

2nd Law of Thermo-dynamics – "You can't break even"

3rd Law of Thermo-dynamics – "You can't get out of the game"

Sooner or later everything runs down. Now cracking the Hydrogen Fusion problem would probably get us all the energy that we can possibly use before the race finds another way to pop it's clogs, but we seem to be struggling with that one.

I was amazed to read recently that even our "best" nuclear weapons only release something like 4 or 5% of the available energy for any given size. Just an amazing demonstration of how much energy is available even in our tiny pocket of the universe.

Maximum temperature for liquid hydrogen is -240C, the critical temperature.

For example, Iceland can generate unlimited amounts of Hydrogen emissions-free from geothermal power, and they could ship it around the world and become the new Saudi Arabia.

Sweet! Iceland is only up there! We're the closest people to it. Quick, invade!!!