Hydrogen home heating

[Speedy Builder5Participant @speedybuilder5]

[Speedy Builder5Participant @speedybuilder5]

I was following the discussion on BBC radio 2 (Other stations are available). Wherby the current gas supply could be slowly turned over to being 100% hydrogen. Gas appliances (Boilers mainly) would be converted / replaced to burn hydrogen. Some installations could even be hydrogen fuel cells producing both heat and electricity.

I get the drift of all this, but how will the electricity be made to produce the hydrogen in the first place? Would the cost to the planet of making renewables outweigh the advantages of clean hydrogen appliances ??

Could we get to the state where we are oxygen depleted as we start to turn it all back into water again ?

Will we be in a continuous fog of mist ?

just a few random thoughts – back to the workshop now.

Bob

[Nigel BennettParticipant @nigelbennett69913]

I believe that most of the hydrogen made today is by splitting up fossil fuels, the residue of which process is – erm – carbon dioxide.

So assuming that we change this to electrolysing sea-water via renewables, we're still going to burn the stuff one way or another, which is going to heat up the planet as well… We're all doomed.

Serves us bloody right as a human race for producing so many children.

[J HancockParticipant @jhancock95746]

If the hydrogen is derived from the constituent parts of water then no, all should be in equilibrium.

But, if derived by stripping it from a hydrocarbon somehow , then yes, we will all be gasping for 'air'.,like now.

[old martParticipant @oldmart]

Oxygen depletion cannot happen when hydrogen is produced, remember that the source, water is H2O. As the hydrogen is produced, so is oxygen. Producing the hydrogen in the first place efficiently enough may happen eventually. Meanwhile we will have to put up with the smug faces of electric car owners ZERO EMMISSIONS, and saving the planet.

[Clive HartlandParticipant @clivehartland94829]

Electric cars with non recyclable Lithium batteries, as big a problem as Nuclear waste.

Why not power cars with hydrogen as some are at the moment.

Using hydrogen in the homes will be far worse danger as we have enough houses blown up with ordinary gas!

[duncan webster 1Participant @duncanwebster1]

I read that with current technology and using electricity to decompose water we'd be better off by a fair margin just using the electricity direct.

Around where I live they have enough difficulty keeping the methane in the gas mains, keeping hydrogen in is a whole different ball game. The flammable limits of hydrogen are also much wider, but to counter that if it can escape upwards it will as it is so buoyant. The explosions at Fukushima were caused by hydrogen build up.

[V8EngParticipant @v8eng]

I remember the mass conversion to North Sea gas.

If a similar process is suggested for Hydrogen I shall certainly be going off grid and moving as far from other premises as Practical.

Edited By V8Eng on 18/05/2021 15:47:40

[SillyOldDufferModerator @sillyoldduffer]

Posted by Speedy Builder5 on 18/05/2021 14:21:20:

 

…

how will the electricity be made to produce the hydrogen in the first place? Would the cost to the planet of making renewables outweigh the advantages of clean hydrogen appliances ??

Could we get to the state where we are oxygen depleted as we start to turn it all back into water again ?

Will we be in a continuous fog of mist ?

…

Hydrogen is easily made by electrolysing water. As the other product is Oxygen, burning electrolytic Hydrogen doesn't deplete Oxygen. Energy from the sun is free. Once solar panels have set up the electricity they produce is much cheaper than coal. Relative costs of Coal vs Solar:

____________ Coal ______ Solar
Set-up $2900/kW  ____  $3700/kW : 20% cheaper to build a Coal Power Station
Running Cost $33/MWhr $8/MWhr : Solar electricity at least 75% cheaper than coal

The cost of solar electricity is set to drop as panel technology improves.

The big advantage of coal is power stations can respond to changing demand at any time. The main disadvantage of Solar is it only generates during daytime good weather, when demand could be low. Unfortunately, although solar produces dirt cheap electricity, it's likely to be at the wrong time

What's needed is a way of storing or usefully consuming excess solar electricity. One option is to make Hydrogen from it, and then burn the Hydrogen to heat homes, run hybrid cars, or fuel cells. Low prices will attract other users to off-peak energy, such as charging parked electric cars.

Traditionalists know it's far too expensive to make Hydrogen from coal generated electricity and might assume the same rules apply to solar. They don't! It's economic to make Hydrogen with surplus solar energy with the added advantage burning Hydrogen is almost pollution free. Burning petrol creates a lot of water too: the watery part of car exhaust isn't a problem, mist or otherwise.

Hydrogen is difficult stuff to handle: I'd expect it to be diluted rather than used pure in a home heating system. That's not new though – UK coal gas was 50% Hydrogen calmed down with Methane, Carbon Monoxide and Ethylene. What could possibly go wrong!

Dave

Edited By SillyOldDuffer on 18/05/2021 15:42:51

[Swarf, Mostly!Participant @swarfmostly]

Posted by Nigel Bennett on 18/05/2021 14:47:31:

SNIP

So assuming that we change this to electrolysing sea-water via renewables, we're still going to burn the stuff one way or another, which is going to heat up the planet as well… We're all doomed.

Serves us bloody right as a human race for producing so many children. Different sort of 'SNIP' !!

OK to electrolyse fresh water but I've got my doubts about sea water! I'm sure I've seen submarine movies where ingress of sea water into the battery produces chlorine!?!?!?

Best regards,

Swarf, Mostly!

[Phil WhitleyParticipant @philwhitley94135]

It is almost a full circle as the old coal derived town gas was mainly hydrogen, and of course, was lighter than air, and so if there was a leak, it floated away. An old friend of my dads who worked for the gas board said at the time of conversion from town gas to the heavier than air north sea gas, that explosians would happen more often. I have thought about running IC engines on hydrogen, but the main problem is that it burns much hotter than petrol and produces more Nox, and that IS dangerous to humans. Given that the evidence for "catastrophic" global warming is weakening all the time, and that the tiny percentage of atmospheric CO2 that is man made wouldn't make any difference to the temperature of the planet if we eliminated it, I think the demonising of gas is ridiculous, of all the carbon based fuels, it is the most efficient and cleanest burning for both home heating, and power generation. If we all go over to electricity for heating, we will need a MASSIVE increase in power in winter, way beyond the capacity that is even planned at the moment, and although it may be very efficient at the home, 20% of power put into the electricity grid is lost!

Phil

[pgk pgkParticipant @pgkpgk17461]

Politicians find it convenient to make grandiose statements about how they shall save us all – usually in some future time when they are no longer responsible for any failure. The dewy eyed ideal is that more than enough Hydrogen will be electolysed using spare wind power so any losses in making the stuff don't matter. Oh, if it was so simple 'cos a hydrogen economy has potential – rapid fill-ups for transport, no carting heavy batteries and zero pollution. And if it was that simple you could route the leccy via tthe grid and have H2 producing plants dotted about major conurbations to save piping.
I like the idea of an H2 car but with cleaning up the water, some needed catalyst to be invented, refridgeration and pressurisation I'd guesstimate less than 20% power recovery from the leccy and major costs.

I vaguely recall soem american inventer who has hs own H2 plant at home powered by his own wind and solar…

pgk

[BazyleParticipant @bazyle]

We can't just go back to using H2 in the gas mains as it leaks out – small molecules. Seems kind of inefficient to use electricity to make gas to heat homes. Might as well use the electricity directly. Even if making H2 enables you to store solar energy more easily overnight it would still probably be better to use it in a central generator as the heat byproduct could be used in district heating and electric home heating, especially via heat pumps, would be more efficient.

[old martParticipant @oldmart]

I'm not sure if it's true, but it was said that during the life expectancy of a wind turbine, the ammount of electricity produced would not equal its initial enviromental cost.

A new type of nuclear energy will be needed to eventually make the costs start to add up in the right way, hopefully, but not in my lifetime.

[Ian Johnson 1Participant @ianjohnson1]

Interesting topic, I think Hydrogen is the future fuel, even though the chemical industry has been using hydrogen as a by product of chlorine manufacturing for over a hundred years.

There is a lot of activity from companies like Toyota and recently JCB developing hydrogen powered piston engines. And there is a trial in NE UK with a mix of natural gas (ch4) and hydrogen into home boilers.

Hydrogen can be made from a variety of raw materials, such as methane (ch4), only problem is capturing the waste carbon. Or water which only produces oxygen as a by product.

And of course nuclear power will provide the electricity for electrolysis with Rolls Royce small modular reactors in every town.

Exciting times!

IanJ

[Ian ParkinParticipant @ianparkin39383]

I’m not a chemist but I’m sure a few of you are..

when you electrolyse water to get hydrogen and oxygen how much do you get ?

say 1 litre of water how much o2 and h is there

we then tank the hydrogen and feed it to a car engine and mix it with air then burn it

what comes out of the exhaust?

water i understand and surely nitrogen and the other trace gases in air (water vapour too)

but what has produced the energy?

so all the hydrogen hasn’t burnt and has recombined with some oxygen to make the water

[Gordon Smith 1Participant @gordonsmith1]

Look up Avogardro's number.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Gordon Smith 1 on 18/05/2021 18:53:58:

Look up Avogardro's number.

.

’phone a friend

MichaelG.

.

Sorry, couldn’t resist that

[pgk pgkParticipant @pgkpgk17461]

In a perfect world you'ld get 200gm hydrogen from a kilo of water but unless the water is perfectly pure there has got to be a load of waste – either distilling the stuff or forcing it through a semi-permeable membrane. Whatever you do there are the non pure water parts to get rid of and the costs.

Use in a car as example is likely more efficient through a fuel cell than used to run a reciprocating engine – and should require less in the way of lubricants/pollutants but still leads to needs for rare earth magnets, coolants, insulators etc all which have their production costs and dirty footprints

Apparently 1kg of Hydrogen has 33KWH density which if totally recoverable through a fuel cell would give a tesla model3 type car a range of around 120miles in good conditions and save a few hundred Kg in battery weight

Taking the oxygen out of the air used to combine with the H2 is immaterial since you released that amount of O2 when the water was initially split.

With all the overheads of production, refigeration compression and storage and transport it;s a reasonable guess that it;d take some 200+KWH of leccy to get you that 33KWH to the wheels…

pgk

[old martParticipant @oldmart]

The hydrogen would have to be compressed to get a worthwhile ammount in a vehicle, maybe even to liquid form. Petrol is bad enough around a crashed vehicle the hydrogen might be worse. If the hydrogen was kept as a refrigerated liquid, there would have to be constant venting, and using a garage to park in would cause additional problems.

[J HancockParticipant @jhancock95746]

Don't worry, leave it to SAGE and the politicians , they'll sort it , like they have Covid.

[duncan webster 1Participant @duncanwebster1]

Posted by Gordon Smith 1 on 18/05/2021 18:53:58:

Look up Avogardro's number.

What's he got to do with it?

1 litre of water weighs 1kg, the atomic weights are H = 1, O = 16, and H2O is 18 (molecular weight if we're being pedantic), so from 1 kg water you get 2/18 = 0.11 kg hydrogen and 0.89 kg oxygen.

[old martParticipant @oldmart]

You are part way there, Duncan, if I have interpreted google correctly, the volume increase between liquid form hydrogen and the gas is 851, and with oxygen, 860.

[duncan webster 1Participant @duncanwebster1]

Ian's question was how much oxygen and hydrogen there would be, not the volume change from liquid to gas

[not done it yetParticipant @notdoneityet]

A few inaccuracies and some mild real explanations.

Methane is less dense than air.

Phil appears to be a ‘climate change denier’ and very much pro fossil fuels.

BEVs are much the best option at the present time. The charge/discharge cycle is higher than other energy conversions.

Apparently 1kg of Hydrogen has 33KWH density which if totally recoverable through a fuel cell would give a tesla model3 type car a range of around 120miles in good conditions and save a few hundred Kg in battery weight

Electrolysis water is, at present, no better than 70% efficient. Fuel cells are likely not much better than 50% efficient. Adding in storage and delivery that is about 50kWh to deliver about 16kWh for motive power, so forget that 120 miles. Remember, too that hydrogen cannot be liquified for car use – it needs to be cooler than about 20K (-253 Celsius) before it can be liquified by pressure. Don’t forget that the gas bottle, to carry any appreciable hydrogen load, weighs a good deal, too!

Looking at last month’s wind generation, we would need about 20 times the current installed capacity. That capacity would certainly produce a lot of energy for potential storage at most times. In April, we would have needed about 140 Dinorwigs of pumped storage. Hydrogen could be stored in worked out oil wells or stored as liquid ammonia. But unfortunately not much of any of these options are available at present.

Boffins are, of course, working on it. Much more knowledgeable than the average for this forum.🙂

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