Hydrogen home heating

Should not that be, "never let the perfect be the enemy of the good"?, or is there a jocular reference that is making a whoosh sound as it passes over my head.

Hydrogen sounds like a nice clean fuel. When burned, it returns to the water from which it was derived.

No particulates, because no carbon!

A delight for any politician who does not thoroughly understand the subject, but wants to jump on the bandwagon!

But not without some disadvantages.

Very little in life is ALL advantages.

1 ) Requires energy to electrolyse from water.

From hydrocarbon fuel, liberates Carbon Dioxide, so not a "green" process.

(Sea water entering a battery liberates Chlorine from the salt within the sea water, Sodium Chloride )

2 ) To store Hydrogen in liquid form requires high pressures. Many years ago, someone converted a Hillman Imp to run on Hydrogen. The gas cylinders were so heavy and large that there was only space for the driver left.

Look at a picture of a road tanker transporting Hydrogen.

3 ) Hydrogen is quite explosive, when mixed with air. There have been numerous examples of explosions resulting from it being produced when Lead acid batteries are charged. In some cases the injuries have put people in hospital. It most certainly blows the cells out of the battery casing! (Seen it happen! )

Recently, two houses have been demolished by what seems to be a gas explosion. Gas containing some Hydrogen.

4 ) Hydrogen when burned may well produce temperatures high enough to oxidise the Nitrogen in the combustion air.

Exactly the problem that we have with almost every form of combustion today

5 ) Hydrogen does not have the energy density of hyrdocarbon fuels ( No carbon to burn, so less energy from combustion ).

JCB have just exhibited a Hydrogen fuelled 3CX, and are enthusiastic about the fuel, but have not mentioned how the fuel is stored, it's capacity compared to the gas oil that powers the machine normally.

If Hydrogen is to be used as the power source for road vehicles, infrastrucure needs to provided.for refuelling.

Probably neither quick or economic to install.

This all sounds sceptical, but euphoria is contagious without thought.

Howard    EMOJIS, I hate'em!

Edited By Howard Lewis on 19/05/2021 12:14:52

Howard Lewis said:

5 ) Hydrogen does not have the energy density of hyrdocarbon fuels ( No carbon to burn, so less energy from combustion ).

Not true. It has one of the highest energy densities (W/g) of any fuel. The real problem is H2 is very light so that gram has a lot of volume, even when liquified.

Robert G8rPI.

Hydrogen cannot be liquified except at cryogenic temperatures. The critical temperature is -240C, so only 33 degrees from absolute zero. The boiling point at one atmosphere is -253C, so unless pressurised AND cooled, it can only be liquified for temperatures within 20C of absolute zero.

Practicable bulk storage has of necessity to use very high pressures, and thus energy per overall unit weight is less than for petroleum fuels.

Not true

Correct, but (from the net) “up to 800 bar, so that hydrogen can be reach a volumetric density of 36 kg/m3, almost half as much in its liquid form at normal boiling point.”

800 bar is about double the usual pressure used. Work it out - petrol is around 700-750kg in the same volume.🙁

On second thoughts, don’t bother - the energy content of hydrogen is not even in the same ball park as petrol or diesel on a volume basis.

Neither is it on a weight basis if you include the mass of the storage container. Remember that the configuration of even 400 bar storage is likely to be an assembly of small diameter tubes to fit the space, rather than a single container which would necessarily be either spherical or large diameter cylindrical. Fancy any of this under the seats of your car?

Edited By V8Eng on 19/05/2021 15:01:54

Paper Tiger Howard

Houses flooded by water! Water containing some hydrogen!

Hydrogen poses similar risks to natural gas (methane) except that, being lighter, it is even more likely to disperse in the event of a leak.

Like methane it is odourless, so a scent marker will need to be added, just as we do for natural gas.

One problem is that the smaller molecules will escape more easily through porosity. Probably not enough to cause significant explosion risks, but increasing system losses.

Neil

This page is very interesting:

so-just-how-dangerous-is-hydrogen-fuel/

Hydrogen as vehicle fuel is a new thing and there would be a learning curve which would include developing safety procedures, but it all looks manageable. It is widely used in industry and mostly treated with respect because it does have two tricky properties. Leakages can spontaneously combust, and it can burn with a nearly invisible flame.

Incidentally, the BOC safety advice is not to extinguish burning hydrogen leakage unless the leak can be totally stopped.

It would be necessary to use "zero carbon" energy to make it. Production from fossil fuel is likely to be less efficient than just burning that fuel directly. As with electric cars in the UK, for the next ten years it will be remote CO2 emissions, not zero emissions.

I've read that Germany uses excess wind power to make hydrogen which is pumped into the gas main. As they have a limit on how much hydrogen is allowed they are working on converting hydrogen to methane using Sabatier process.

This might or might not be sensible, depends on the energy balance. The CO2 emitted when you burn the methane would be balanced by that absorbed making it

Hydrogen as vehicle fuel is a new thing

Really ?

BMW had a fully functional hydrogen 7 Series saloon running in the '80s. One of it's features was a hydrogen sensor in the cabin that automatically opened the windows to prevent a potentially explosive concentration of gas if there was a leak - unsuprisingly the insurance industry were not too keen on this safety feature !

Hyundai have had a test fleet of hydrogen fuelled cars (iX 35s IIRC) running in the UK for several years. Wider roll out will be limited by the cost & the scarcity of refuelling points (17 at the moment, apparently). Given that some have struggled with refuelling LPG cars at around 7 Bar, 700 Bar for hydrogen would be a much greater challenge.

As stated earlier in respect of fusion - hydrogen is fuel of the future ..... and always will be.

Nigel B.

I've read that Germany uses excess wind power to make hydrogen which is pumped into the gas main.

Germany also has a pretty catastrophic (for the land & crop diversity) subsidised biogas production regime, the product of which is also added to mains gas.

Nigel B.

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... and it would appear, from the link I posted yesterday, that Toyota has joined the club

**LINK**

https://www.itm-power.com/h2-stations/rotherham-wind-hydrogen-station

Nice to see that they require users to be trained

MichaelG.

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Interestingly ... a DVLA check on the pictured car shows it to be powered by ‘electricity’

Edited By Michael Gilligan on 19/05/2021 19:27:26

And the russians flew a airliner on H2 in 1988, the TU-155.

Dispite this ZeroAvia have claimed to be the biggest h2 powered aircraft despite having a 250kW motor but only 100kW fuel cell.....and a big battery. It also crashed near Cranfield last month. Looks lie forced landing due to power loss. They may have got away with it but for a ditch at the end of the field they landed in.

Robert G8RPI.

Liquid oxygen is liquid at normal air pressure after having been extracted by fractional distillation albeit at its mind numbing minus temperature, if kept at its relevant temperature it remains liquid at normal air pressure. Is liquid hydrogen still liquid when kept at the relevant temperature and normal air pressure, I.e. 1 atmosphere. Storage would not be such a problem if this is so and the hydrogen could be stored in the same way as liquid oxygen in insulated storage vessels. Liquid oxygen has its problems when being handled, we used to be ultra careful when handling it. Dave W

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According to Wikipedia: Yes ...

To exist as a liquid, H₂ must be cooled below its critical point of 33 K. However, for it to be in a fully liquid state at atmospheric pressure, H₂ needs to be cooled to 20.28 K (−252.87 °C; −423.17 °F).^[3]

MichaelG.

I can't understand why we can't go back to producing hydrogen from the coking process. The coke produced, could be put back int the ground as a a waste product, if we want to go carbon free.Houses used to be on 'Town gas ' until the early seventies when we changed over to methane.

Town gas was 50% CO which is what killed you before you suffocated. The CO burns to our favourite, CO2, so the greenies reading this are having a fit. You could use biomass, instead of coal but soon they will put preservation orders on every tree in the world lest someone use them on a bonfire.

IIRC there were sponge type matrices trialled many yeasr ago as a storage medium for hydrogen within cylinders to reduce the speed at which hydrogen could escape in the case of rupture.
Apparently carbon nanotubes are the contemporary solution

https://www.chemistryworld.com/news/carbon-nanotubes-for-hydrogen-storage/3000742.article

Wan't there a project in a desert part of the states to focus sunlight and create a direct fusion between water and CO2 or methane... something rings bells..??

pgk