Hydrogen as a replacement for Natural Gas

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cvb
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Hydrogen as a replacement for Natural Gas

Post by cvb » Sat Nov 14, 2020 12:48 pm

Somebody, government type, is thinking of replacing natural gas to homes with hydrogen. This would be for over a million people.

I think it sounds stupid and dangerous but it well out of my wheelhouse.

Does anybody have any ideas/knowledge?

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Martin Y
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Re: Hydrogen as a replacement for Natural Gas

Post by Martin Y » Sat Nov 14, 2020 1:13 pm

I was sceptical because I assumed the stuff would just leak, but it seems not. I gather you can substitute a percentage of natural gas with hydrogen (somewhere around 18-20%) without having to change burners or deal with new problems like some metals becoming brittle or flames becoming invisible. One of the universities is running a pilot scheme. There was a thread about it on the old forum.

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Martin Y
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Re: Hydrogen as a replacement for Natural Gas

Post by Martin Y » Sat Nov 14, 2020 1:19 pm

... so if you can build a low carbon process that generates hydrogen you could probably just add it to the natural gas supply so long as it's less than 20% and save a lot of carbon. But about 95% of current hydrogen production is from fossil fuels.

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Martin Y
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Re: Hydrogen as a replacement for Natural Gas

Post by Martin Y » Sat Nov 14, 2020 1:23 pm

Mrs Y tells me it's Keele. Project called HyDeploy.

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bjn
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Re: Hydrogen as a replacement for Natural Gas

Post by bjn » Sat Nov 14, 2020 4:01 pm

That's my understanding as well. The old school coal gas used to have a significant proportion of hydrogen in it.

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Martin_B
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Re: Hydrogen as a replacement for Natural Gas

Post by Martin_B » Sat Nov 14, 2020 11:47 pm

If you increase the hydrogen content above ~20% then you run into problems with temperature controlled burners (hydrogen burns at a slightly different temperature to methane), optical controlled burners (hydrogen burns at a different colour - mostly clear - compared to methane) and also metering stations; hydrogen and methane have different calorific values, so unless you are constantly measuring the hydrogen content you don't know how much energy value the gas has.

Also, hydrogen is just a smaller molecule than methane and metal pipes which don't leak any natural gas might not be so leak-tight for hydrogen. Water pipes are considered to leak somewhere from 10-25% of the water pumped into them prior to reaching the end user; the national gas grid pipework leaks a tiny fraction of a percentage of it's contents. Plus, any leaks have the potential to create flammable clouds (hydrogen also has a much wider flammable range (4-75%) than methane's 5-15% in air, and has a much lower required ignition energy, which makes ignition more likely).

Added to that is an issue known as Hydrogen Induced Cracking (HIC) in which hydrogen in a gas can combine with the carbon in carbon-based steels, which weaken the metal and can cause cracks. Stainless steels are better at resisting this, but much of the national grid pipework is built of metal which would be susceptible to HIC. If you get HIC in pipework it becomes more brittle, less able to handle temperature changes with expansion & contraction, less able to handle pressure changes, and more likely to fail catastrophically.

HIC occurs more rapidly at high temperatures but at ambient temperature the amount of hydrogen/carbon interaction in low quality carbon steel is non-zero and can occur even with small amounts of hydrogen present (certainly less than 20%) and is cumulative, so any hydrogen absorption will weaken the pipe permanently.

So this sounds like a great idea to the non-engineer, but a technical challenge to someone with some knowledge of the British national grid pipework (old, cheaply built and already in need of replacement for some sections). It's not that this can't be done, but it won't be cheap.
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Re: Hydrogen as a replacement for Natural Gas

Post by Grumble » Sun Nov 15, 2020 7:32 am

I’m no expert on HIC, but doesn’t it mainly occur with hydrogen produced as a result of corrosion, which is initially H. rather than H2? H. will form H2 quite quickly and it’s the formation of H2 that’s the main cause of interstitial cracking, is my understanding. You can create the same effect by forcing H2 in under a higher pressure, but the gas network isn’t a high pressure system. Not saying it won’t be a problem at all, but how much of a problem is not an easy question to answer.
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Re: Hydrogen as a replacement for Natural Gas

Post by science_fox » Sun Nov 15, 2020 10:44 am

Martin_B wrote:
Sat Nov 14, 2020 11:47 pm
any leaks have the potential to create flammable clouds (hydrogen also has a much wider flammable range (4-75%) than methane's 5-15% in air, and has a much lower required ignition energy, which makes ignition more likely).
But Hydrogen is so much lighter than methane that clouds are unlikely, like He, H2 doesn't form clouds it just escapes upwards unless there'e a really impermeable ceiling above you. It's the difference between 4% and 5% that's potentially the concern, not that H2 is flammable at 75%.

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Re: Hydrogen as a replacement for Natural Gas

Post by rockdoctor » Wed Dec 23, 2020 4:55 pm

Martin Y wrote:
Sat Nov 14, 2020 1:23 pm
Mrs Y tells me it's Keele. Project called HyDeploy.
They should have gone with "HyDeHigh"

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Sciolus
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Re: Hydrogen as a replacement for Natural Gas

Post by Sciolus » Wed Dec 23, 2020 7:03 pm

Energy White Paper says:
To achieve net zero emissions, we will have to transition completely away from traditional natural gas boilers for heating homes on the gas grid. There are currently around 1.7 million fossil fuel boiler installations every year 159 but by the mid-2030s we expect all newly installed heating systems to be low-carbon or to be appliances that we are confident can be converted to a clean fuel supply. There is no single technology alternative to fossil fuels.

Electric heat pumps and hydrogen, green gas and shared heat networks all have their part to play. So, while we are clear on the eventual outcome, we will be flexible in how we achieve it, always looking for the most cost-effective, consumer-friendly approach and open to innovative solutions.
And various stuff specifically on hydrogen which I CBA to quote.

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bjn
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Re: Hydrogen as a replacement for Natural Gas

Post by bjn » Thu Dec 24, 2020 12:21 am

Michael Liebreich (who founded Bloomberg New Energy Finance) has two good write ups on hydrogen. One about the supply side and another on the demand side.

In short, renewables generated hydrogen is going to get cheap, but it isn’t going to be as broadly applicable as many hope. It won’t be cheap enough and won’t be able to compete with even cheaper renewably generated electricity. Though it will have a few good use cases, especially as a chemical feedstock to a range of processes, but even there, direct use of electricity could even sneak in (eg: directly refinement of steel using electricity rather than a reducing chemical).

For domestic heating it’s going to be out completed by modern heat pumps, you get around 4x as much heat by directly driving a heat pump with a electricity as you do from using the same electricity to crack water then burn the hydrogen. Plus you can drive heat pumps in reverse to cool a building down.

For industrial heating, something like 78% of demand can be met by existing technologies using electricity directly, possibly up to 99% with new technologies coming on line (eg efficient heat pumps that can hit 280C). H2, even at the envisaged cheaper prices, can’t compete with that.

As for ground transportation, he makes the same argument I always have, it’s profoundly inefficient. To quote.
From a public policy perspective, the real killer for H2FC cars is their wind-to-wheel (or solar-to-wheel) inefficiency. Driving a small family car 100km, whether H2FC or BEV, uses 15kWh of motive energy at the wheels. For the BEV, taking into account losses on the grid and in the battery cycle and drive train, that translates into a need to generate 25kWh at the plant where the electricity is generated. The equivalent for the H2FC car, given losses in electrolysis, compression, transport, storage and reconversion of hydrogen, is at least 50kWh. Put simply, hydrogen cars are half as efficient as BEVs – and there is no reason in physics to think that will change. There is reason why Elon Musk calls them “fool cell” cars.
This holds true for trucks, trains and buses as well. His estimate of a 6 tonne battery for a long haul truck capable of driving several hundred miles over a regulation 4.5 hours stint, is pretty much in line with my estimate a while back.

Aviation, and especially shipping, are the likely use case for hydrogen, or synthetic fuels created with green hydrogen. Even there, advances in solid state batteries make it likely that even aviation will end up using electricity on short hall flights in the near term.

The final thing he discusses is grid backup for renewables, covering the last percentages of demand that can’t be covered by interconnects, short term batteries, hydro, overbuilding etc... He sees this as very viable, storing either H2 or a derivative such as ammonia or methanol in vast quantities to be used to fill the gaps in generation. All at system prices inline with current grid prices in europe. Stonkingly cheap renewables being balanced out by much expensive peaking H2 based power generation.

So basically, chemical feedstock, long distance shipping and aviation plus grid level generation.

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Re: Hydrogen as a replacement for Natural Gas

Post by sTeamTraen » Sat Dec 26, 2020 6:33 pm

I have a fantasy idea of future fuelling stations for cars where you drive up and fill your fuel cell with hydrogen that is made in real time by electrolysing water with solar-generated electricity. I presume this could only be possible somewhere in the desert in Utah with a couple of square kilometres of panels behind the station, but it would be very cool.
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Re: Hydrogen as a replacement for Natural Gas

Post by dyqik » Wed Jan 13, 2021 4:45 pm

This is a potentially interesting development that somewhat changes the efficiencies of hydrogen - a wind turbine that generates hydrogen locally. It's not a magic bullet, but it could remove some of the inefficiencies in generating hydrogen from renewable sources - voltage conversion, AC-DC conversion, etc.

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Re: Hydrogen as a replacement for Natural Gas

Post by bjn » Wed Jan 13, 2021 5:47 pm

dyqik wrote:
Wed Jan 13, 2021 4:45 pm
This is a potentially interesting development that somewhat changes the efficiencies of hydrogen - a wind turbine that generates hydrogen locally. It's not a magic bullet, but it could remove some of the inefficiencies in generating hydrogen from renewable sources - voltage conversion, AC-DC conversion, etc.
Strikes me as odd to put the electrolysis equipment in the wind turbine, as you then need to collect it from your widely spread set if turbines and pump the stuff to shore. Capex is going to be much more than for cables and a single big electrolyser sitting on shore, I don't see any operational advantage that makes up for that. There maybe.

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Re: Hydrogen as a replacement for Natural Gas

Post by dyqik » Wed Jan 13, 2021 6:02 pm

bjn wrote:
Wed Jan 13, 2021 5:47 pm
dyqik wrote:
Wed Jan 13, 2021 4:45 pm
This is a potentially interesting development that somewhat changes the efficiencies of hydrogen - a wind turbine that generates hydrogen locally. It's not a magic bullet, but it could remove some of the inefficiencies in generating hydrogen from renewable sources - voltage conversion, AC-DC conversion, etc.
Strikes me as odd to put the electrolysis equipment in the wind turbine, as you then need to collect it from your widely spread set if turbines and pump the stuff to shore. Capex is going to be much more than for cables and a single big electrolyser sitting on shore, I don't see any operational advantage that makes up for that. There maybe.
The collection work is the kind of work that's already done with on-shore gas drilling etc., so maybe it's not such a big deal. I could see it on land first, I guess.

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Re: Hydrogen as a replacement for Natural Gas

Post by bjn » Wed Jan 13, 2021 7:43 pm

dyqik wrote:
Wed Jan 13, 2021 6:02 pm
bjn wrote:
Wed Jan 13, 2021 5:47 pm
dyqik wrote:
Wed Jan 13, 2021 4:45 pm
This is a potentially interesting development that somewhat changes the efficiencies of hydrogen - a wind turbine that generates hydrogen locally. It's not a magic bullet, but it could remove some of the inefficiencies in generating hydrogen from renewable sources - voltage conversion, AC-DC conversion, etc.
Strikes me as odd to put the electrolysis equipment in the wind turbine, as you then need to collect it from your widely spread set if turbines and pump the stuff to shore. Capex is going to be much more than for cables and a single big electrolyser sitting on shore, I don't see any operational advantage that makes up for that. There maybe.
The collection work is the kind of work that's already done with on-shore gas drilling etc., so maybe it's not such a big deal. I could see it on land first, I guess.
It's still more expensive than laying wire.

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Re: Hydrogen as a replacement for Natural Gas

Post by dyqik » Wed Jan 13, 2021 8:05 pm

bjn wrote:
Wed Jan 13, 2021 7:43 pm
dyqik wrote:
Wed Jan 13, 2021 6:02 pm
bjn wrote:
Wed Jan 13, 2021 5:47 pm


Strikes me as odd to put the electrolysis equipment in the wind turbine, as you then need to collect it from your widely spread set if turbines and pump the stuff to shore. Capex is going to be much more than for cables and a single big electrolyser sitting on shore, I don't see any operational advantage that makes up for that. There maybe.
The collection work is the kind of work that's already done with on-shore gas drilling etc., so maybe it's not such a big deal. I could see it on land first, I guess.
It's still more expensive than laying wire.
That's not an alternative solution on its own.

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