Hydrogen home heating

[MacolmParticipant @macolm]

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.

[duncan webster 1Participant @duncanwebster1]

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

[Ex contributorParticipant @mgnbuk]

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.

[Ex contributorParticipant @mgnbuk]

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.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by mgnbuk on 19/05/2021 19:07:23:

Hydrogen as vehicle fuel is a new thing

Really ?

BMW had a fully functional hydrogen 7 Series saloon running in the '80s. […] etc.

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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

[Robert Atkinson 2Participant @robertatkinson2]

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.

[SamsarandaParticipant @samsaranda]

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

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Samsaranda on 19/05/2021 19:40:01:

[…]

Is liquid hydrogen still liquid when kept at the relevant temperature and normal air pressure, […]

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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.

[steveteeParticipant @stevetee]

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.

[BazyleParticipant @bazyle]

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.

[pgk pgkParticipant @pgkpgk17461]

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

[not done it yetParticipant @notdoneityet]

Stevetee,

Producer gas and water gas were products of basically burning fossil fuel – coal.

Producer gas was, one could say, a product of incomplete combustion of coal – leaving behind coke. The process was exothermic.

Water gas was produced by passing steam over that same coking system when hot enough

Making water gas was very much endothermic but produced a higher calorific fuel (no nitrogen in it, for a start!).

The usual mode of operation was to heat the system by passing air over the hot coals and then use water until the temperature dropped too low. The common system was, therefore, to maintain temperature by passing air and some steam over the coals to maintain the system temperature.

The gas produced was stored in low pressure gasometers and distributed fairly locally – often one in a large town – hence the name ‘town gas’.

Still a fossil fuel burning system (both in manufacture and usage), which we want to get rid of. So a non-starter.

All parts of the country were on natural gas by the very early 70s. Gasometers were retained mainly in steel producing locations as coke was needed for the steel manufacturing process🙂 . Our new school, in 1963, was converted to natural gas by the middle 60s.

Hope that enlightens you on the topic.

Edited By not done it yet on 19/05/2021 22:34:08

[V8EngParticipant @v8eng]

 

Edited By V8Eng on 19/05/2021 22:53:14

Edited By V8Eng on 19/05/2021 22:53:40

[SamsarandaParticipant @samsaranda]

Michael

Many thanks for your reply, I thought that hydrogen was liquid at normal air pressure but I wasn’t 100% sure. Dave W

[Nigel Graham 2Participant @nigelgraham2]

Some gasholders (not "gasometers" ) were retained in various places even after all the network was on natural gas.

The last of the two at Weymouth was taken out of use within only the last decade or so, and scrapped two years ago, last year maybe, complete with the buddlia bushes growing on its top. Yet the gas-works itself – with retort as well as producer and water gas, plant – had been demolished in the 1960s. The gas-holder had been retained as part of the local distribution point but it seems the primary pipework takes that role now.

The town gas-works' primary product was retort gas, produced by distilling the coal in sealed retorts heated externally by coke already made by that process. It and producer gas, which was made in a separate process from some of the coke (not raw coal) were carbon-monoxide. Water gas, also from coke, is mainly hydrogen.

'

Somewhere I have the proceedings of a 1980s symposium on the wood alternative, making gas from wood in small-scale power-plants. The wood was to be distilled in retorts and the gas used in i.c. engines driving alternators. Most of the proceedings covered the forestry side – the choice of tree best suited to this. Mainly willow as I recall, as it grows rapidly.

[steveteeParticipant @stevetee]

I hadn't realised that town gas wasn't hydrogen, but a mix of H2 and CO. Well theres that idea dead in the water then…

[not done it yetParticipant @notdoneityet]

Posted by stevetee on 19/05/2021 23:57:30:

I hadn't realised that town gas wasn't hydrogen, but a mix of H2 and CO. Well theres that idea dead in the water then…

Don’t forget the nitrogen in the gas that diluted it (and would obviously reduce the flame temperature) and some carbon dioxide mixed in as well.🙂

[not done it yetParticipant @notdoneityet]

Posted by Nigel Graham 2 on 19/05/2021 23:37:39:

…..'

Somewhere I have the proceedings of a 1980s symposium on the wood alternative, making gas from wood in small-scale power-plants. The wood was to be distilled in retorts and the gas used in i.c. engines driving alternators. Most of the proceedings covered the forestry side – the choice of tree best suited to this. Mainly willow as I recall, as it grows rapidly.

Nothing new. Wood was used, as an alternative to petrol, when fuel was in short supply. WWII saw some novel designs for collecting the gas in a bag on the roof of the car. I think one or two even made conversions back in the fuel crises of the 1970s, but doubtless one-offs that were made just because it could. Not particularly relevant to modern cars, even back then – although THIS GUY did it jus a decade, or so, ago.

Check this out, if interested enough. **LINK**

Even some tractors had wood gasifiers fitted in WWII. Not, I would think, for excessively hard working applications – but maybe they were….

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Nigel Graham 2 on 19/05/2021 23:37:39:

[…]

Somewhere I have the proceedings of a 1980s symposium on the wood alternative, making gas from wood in small-scale power-plants. The wood was to be distilled in retorts and the gas used in i.c. engines driving alternators. Most of the proceedings covered the forestry side – the choice of tree best suited to this. Mainly willow as I recall, as it grows rapidly.

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… which reminds me :

Late sixties, if I recall correctly … I read that, in appropriate climates, the most efficient ‘total cost’ way of using Solar Energy was to grow ‘Water Hyacinth’ and burn it.

https://en.wikipedia.org/wiki/Eichhornia_crassipes

May no longer be true, because technology has progressed [*]

MichaelG.

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* This was at the time when people were using central-heating radiators as solar panels for heating domestic water

Edited By Michael Gilligan on 20/05/2021 08:48:01

[Robert Atkinson 2Participant @robertatkinson2]

Posted by pgk pgk on 19/05/2021 21:35:31:

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

I think that was metal hydride storage rather than a safety device.

[SillyOldDufferModerator @sillyoldduffer]

Posted by stevetee on 19/05/2021 20:23:40:

I can't understand why we can't go back to producing hydrogen from the coking process. …

Not really going back! Most of the world's Hydrogen is made today by a close relative of the Town Gas process described by NDIY.

Instead of spraying water on to white hot coke, it's done by reacting steam at about 1000°C with Natural Gas at about 300psi in the presence of a catalyst to produce a mix of steam, Carbon Monoxide and Hydrogen. Then the mix is passed over another catalyst to produce Carbon Dioxide and more Hydrogen before the Carbon Dioxide is removed by absorption. The output is almost pure Hydrogen.

Oil refineries are the biggest single user of Hydrogen. They use it to crack heavy oils to make petrol etc and also to remove Sulphur (nasty stuff). Next largest use is Fertilizer production, without which we all starve! Saudi Arabia makes more Fertilizer than anyone else because their oil fields are gassy at it would otherwise be flared off. Hydrogen has many other important applications; welding, Hydrochloric Acid, Margarine, as a coolant, and extracting metals. The Tungsten used in HSS and Carbide is obtained with Hydrogen.

The only reason Hydrogen is made from steam is Natural Gas happens to be cheap at the moment. Unfortunately Natural Gas is a declining resource; shortages will develop over the next 20 years causing prices to rise sharply, and this way of making Hydrogen will become uneconomic. So alternative sources will soon be needed, and cheap electrolytic Hydrogen made by surplus green energy is a practical option.

Personally, I don't believe there's much future for Hydrogen as a transport fuel – too many difficulties as already explained! But there's no technical reason why Hydrogen can't be mixed into the existing gas distribution system and burned in diluted form for domestic heating. My guess though is most Hydrogen will go to industry, especially to make fertilizer.

Dave

[duncan webster 1Participant @duncanwebster1]

I think there is some confusion in terminology. The stuff that used to be in the gas mains supplying domestic premises, at least in the UK was coal gas, produced by heating bituminous coal in a closed retort. It's typical analysis by volume was Hydrogen 45%, Methane 33%, Carbon Monoxide 10%, Ethylene 5%, Carbon Dioxide 1%, Nitrogen 6%. Calorific value 568/618 BThU/Cu.Ft. These figures from Mechanical World Year Book 1950. The residue was coke, some of which was used to heat the retorts, some as a scrubber medium to clean the gas, and the rest sold

Producer gas is made by burning coke in a limited supply of air to produce Carbon Monoxide. All the Google results suggest that steam was admitted at the same time to make a mix of what I've always known as Producer Gas and Water Gas. The typical analysis by volume of this mix was Carbon Monoxide 25%, Hydrogen 16%, Carbon Dioxide 5%, the rest (54%) is Nitrogen. Because of the nitrogen content its calorific value is 120/150 BThU/Cu.Ft. Figures from same source. It was not used in town gas mains.

Producer gas was also known as suction gas. Many early gas engines ran on it, in the village of my childhood there was a sawmill driven by a big suction gas engine which used sawdust and offcuts as fuel. You could hear its slow steady beat from a mile or so.

[SillyOldDufferModerator @sillyoldduffer]

Posted by duncan webster on 20/05/2021 17:53:49:

I think there is some confusion in terminology. The stuff that used to be in the gas mains supplying domestic premises, at least in the UK was coal gas, produced by heating bituminous coal in a closed retort. It's typical analysis by volume was Hydrogen 45%, Methane 33%, Carbon Monoxide 10%, Ethylene 5%, Carbon Dioxide 1%, Nitrogen 6%. Calorific value 568/618 BThU/Cu.Ft. These figures from Mechanical World Year Book 1950. The residue was coke, some of which was used to heat the retorts, some as a scrubber medium to clean the gas, and the rest sold

…

Duncan's right about Producer Gas, but has missed that Water Gas was a major constituent of so called Coal Gas as described above. It's true the terminology is blurred.

In their day Gasworks were high-technology! Roasting coal in a retort produces many different valuable chemicals in small but useful quantities. With increasing heat:

• Watery: Ammonium Carbonate, Hydrosulphide, Sulphite, and Chloride
• Oily: Paraffin, Naphthalene, Pyrene and Chrysene.
• Gases
  • unsuitable for Town Gas: Hydrogen Sulphide, Carbon Dioxide, Carbon Bisulphide, Nitrogen, Oxygen and Ammonia
  • suitable for Town Gas: Ethylene, Acetylene, Methane, Propene, Butene, plus vaporous cyclic and straight chain hydrocarbons (mainly Naphthalene, but also Toluene, Benzene and Xylene). In early town gas these were important because the main use of gas was lighting and they burn with a bright flame.

Roasting coal doesn't produce Hydrogen or Carbon Monoxide in significant quantities. Instead they were made in the gasworks by spraying hot coke immediately after roasting with water. Most of the coke remains unchanged and was sold as a clean fuel, but the water and some carbon react to produce the mixture of Hydrogen and Carbon Monoxide called Water Gas. Water Gas was always made and added to 'Coal Gas' before distribution.

Several advantages:

• Spraying water on coke that's already white hot after roasting produces more fuel gas at almost zero cost.
• The mixture sold to customers is tamer and easier to manage than coal gas.
• The heat value of gas sold to customers can be kept constant by diluting coal gas with Water Gas as required. It allows different types of coal to be roasted around the country, or in the gasworks, without customers having to adjust a multitude of burners to compensate.

Before gas was was distributed, a well-engineered combination of physical and chemical processes were staged to extract impurities and valuable by-products. In 1880 a new Gasworks was one of the most impressive technical achievements on the planet, only knocked on the head when Natural Gas and Oil became cheaper…

Dave

[Ian ParkinParticipant @ianparkin39383]

There was an article in the times today (Sat 22nd) page 21 about JCB developing a hydrogen fuelled IC engine

using pressurised hydrogen tanks

it produces no co and nearly zero N0X…..just water out the exhaust

so where does the water come from? if you feed an engine with h2 and atmospheric air (turbocharged) and burn it what happens to the hydrogen and oxygen? Is it destroyed? Or does it recombine to form water?

as i said I’m not a chemist

[Nigel Graham 2Participant @nigelgraham2]

Ian –

Your last question is the correct answer.

Two atoms of Hydrogen combine with one of Oxygen to create a molecule of H20 (please forgive the full-size rather than correct subscript 2!). I.e., a molecule of water.

The two gases, which are elements, are not "destroyed". Elements are formed of atoms that cannot be destroyed except by nuclear processes. Instead, chemical combinations simply stick the elements together to form compounds with, usually, physical and chemical characteristics vastly different from those of the individual elements. This is important, as I will show.

For example, in our case here:

– Hydrogen and Oxygen are colourless, odourless, taste-less gases, of quite different densities.

– Hydrogen is flammable but does not intrinsically support combustion (though it would certainly add to a fire).

– Oxygen is not flammable, but certainly supports combustion (high-rate oxidation that emits heat).

– Hydrogen burns in the presence of Oxygen, by the two gases combining to form water….

… which is a colourless, odourless, taste-less, fairly dense liquid that is neither flammable nor supports combustion!

'

Since both gases can be derived by electrolysing water the nett trade is neutral, since the exhaust from them is water-vapour that merely joins that already in the atmosphere naturally. The total exhaust from an i.c. engine will also contain some Nitrous Oxides, but a science-teacher explained to me that these can be, and are, broken down by catalytic converters using urea – the "Ad-Blue" fluid you see sold in garages.

The problem from any "green" point of view is that water is a deceptively simple compound with some very odd properties and abilities including enormous molecular strength. So though breaking lots of it into worthwhile volumes of Hydrogen and Oxygen by electrolysis produces no awkward by-products, it demands a lot of electricity that has to be generated….. somehow.

'

From a Phsyics point of view, it absorbs a certain amount of energy (as electricity) to divorce the hydrogen from the bigamist oxygen, but when that hydrogen is then burnt the chemical reaction repays the energy (as emitted heat). Though the balance is never achieved in practical processes because they can never be 100% efficient.

'

There is actually nothing very new in all of this except that using hydrogen as a direct fuel in an i.c. engine has always proven difficult in the past, I believe due mainly to its combustion characteristics. I think the gas mixture compressed in the engine cylinder tends to detonate rather than "simply" burn, but I am not sure of that.

Nor is there anything new in storing hydrogen compressed into cylinders, and oxy-hydrogen rather than oxy-acetylene has long been the better combination for underwater flame-cutting. (The torch is lit before submerging it!)

Safety fears are somewhat specious because a cylinder of hydrogen is not only no more intrinsically dangerous than one of LPG, but leaking hydrogen can be vented to rise and disperse in the atmosphere. LPG and petrol vapour are fairly dense, collecting in low points such as car floor-pans and boat hulls. I think it is also non-toxic, though will suffocate if it displaces the oxygen available. The disadvantage is that hydrogen is odourless so a leak may not be evident, but that could be overcome with a suitable "scent" as is added to the mains supply of odourless methane that is natural-gas.

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