# Hydrogen in the gas grid

Gold Member

## Summary:

A trial has commenced at Keele Unversity in the UK where 20% Hydrogen, produced from wind and solar, is injected into the domestic gas supply. In this way it can be stored and then utilised by existing domestic burners. Can this be a quick solution to reducing domestic CO2 emissions? Or is it better to use battery storage and use the electricity?

## Main Question or Discussion Point

A trial has commenced at Keele University in the UK where 20% Hydrogen is injected into the domestic gas supply. In this way it can be stored and then utilised by existing domestic burners. Can this be a quick solution to reducing domestic CO2 emissions? Or is it better to use battery storage and use the electricity? https://www.bbc.co.uk/news/science-environment-50873047
What is the best way of using wind and solar for electric cars? Is the domestic heat pump a better long term investment for home heating?

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mfb
Mentor
Electricity -> hydrogen isn't a very efficient process. Electricity store and electric heating would be more efficient. Heat exchangers instead of raw electric heating would make it even better. Combined you can easily win a factor 5. Is "renewables but we can't control when" really so much cheaper than electricity storage? Sure, it is better than doing nothing, but overall it doesn't look like something that is worth scaling up.

pbuk
Gold Member
Or is it better to use battery storage and use the electricity?
You are missing the point - there are many more efficient ways to use energy for space heating and domestic hot water, they all require time and money invested in every dwelling to use them. In order to get near to zero carbon we HAVE to invest this time and money, but it will take decades and £billions invested in individual homes as well as infrastructure to do it, whereas...

Can this be a quick solution to reducing domestic CO2 emissions?
...domestic CO2 emissions in the UK could possibly be reduced by up to 20% almost overnight using this solution.

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Sure, it is better than doing nothing, but overall it doesn't look like something that is worth scaling up.
It is a very common misconception that it'll be for free if the electricity itself is cheap.

BWV
ITSM the correct cost / benefit is whether a marginal KW of electricity generated by renewables is better utilized in the grid or being converted to H to reduce emissions from the domestic burning of natgas for heat and cooking. Assume equal transmission losses, the electricity should go to the grid until it is close to 100% renewable (which will not happen for decades). The KW sent to the grid either:
A) replaces a KW generated by coal, which has around 2x the greenhouse gas emission
B) replaces a KW generated by Natgas, but with greater efficiency than using that KW to create H

Also, given a marginal dollar to invest, it would have greater impact using that dollar to provide natgas to poor countries that burn solid fuel (greater greenhouse gas emission plus a host of health benefits) than it would to replace natgas with H in rich economies

pbuk
Gold Member
The KW sent to the grid either:
A) [notreplaces a KW generated by coal, which has around 2x the greenhouse gas emission
B) replaces a KW generated by Natgas, but with greater efficiency than using that KW to create H
The context of the article is the UK where, as stated in the article, approximately 85% of homes are heated by natural gas which is piped to each home and used in a system something like this. How can a kW of electricity sent to the grid be used in such a system?
Edit (restated for clarity): How can a kW of electricity sent to the grid replace the kW produced by burning the gas that heats the water in such a system to heat my home?

mfb
Mentor
How can a kW of electricity sent to the grid be used in such a system?
In the same way all other electricity is used in the grid.
The UK got rid of most of its coal power plants, so additional renewables will mainly replace gas. Burning gas in homes to heat them and using electricity from renewables is more efficient than burning gas to produce electricity and using renewables to produce hydrogen to burn in the houses.

pbuk
Gold Member
In the same way all other electricity is used in the grid.
I have edited my post as the point I was trying to make was not clear.
Burning gas in homes to heat them and using electricity from renewables is more efficient than burning gas to produce electricity and using renewables to produce hydrogen to burn in the houses.
It may be more efficient, but it also produces more CO2.
Edit: This is only true if you assume that the low-carbon energy used to produce hydrogen could have been used to reduce fossil fuel consumption. Already in the UK, at times this is not the case - and in the near future perhaps even more so.

Personally I think there are better long-term solutions than replacing natural gas with 100% hydrogen in domestic boilers, but that doesn't mean that it is not worth investigating mixing hydrogen into the domestic natural gas supply for a short-term gain.

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BWV
The context of the article is the UK where, as stated in the article, approximately 85% of homes are heated by natural gas which is piped to each home and used in a system something like this. How can a kW of electricity sent to the grid be used in such a system?
Edit (restated for clarity): How can a kW of electricity sent to the grid replace the kW produced by burning the gas that heats the water in such a system to heat my home?
you seem to be missing the point that electricity generated from renewables is a finite resource. The point is that its better to use that electricity to replace electricity generated by fossil fuels in the grid before the much less efficient process of using that electricity to create H to burn for heat or cooking

Staff Emeritus
2019 Award
Can this be a quick solution to reducing domestic CO2 emissions?
No. Apart from the excellent point that burning natural gas to create electricity to make hydrogen is less efficient than burning the natural gas at point of use, it's focusing on a tiny part of the problem.

In the US (where numbers are easily available) 12% of GHG emissions are from the commercial and residential sectors, and 89% of that is natural gas, or 10.7%. Replacing 20% of this - by magic, not by the inefficient process described above - would change US emissions by 2%, or world-wide emissions by 0.3%.

The UK is ~10x smaller, so we're talking 0.03% or so.

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BWV
mfb
Mentor
It may be more efficient, but it also produces more CO2.
No it doesn't.
You'll produce 1 kWh of electricity from renewables in the next hour. What do you do?
- regulate down a natural gas power plant to produce 1 kWh less. It will reduce CO2 emissions by 400 g.
- produce hydrogen with an energy content of maybe 0.3 kWh, send it to consumers. They burn it, saving a bit of natural gas in the process. You reduced CO2 emissions by 200 g (optimistic).

Once most natural gas power plants are out of business this might become more interesting as the first option won't exist any more. By that time hopefully most people switched to electric heating. Then this 1 kWh will save 400 g of CO2 again. Or, even better, switched to heat pumps, then it saves over 1 kg of CO2 emissions.

pbuk
Gold Member
In the US (where numbers are easily available) 12% of GHG emissions are from the commercial and residential sectors, and 89% of that is natural gas, or 10.7%. Replacing 20% of this - by magic, not by the inefficient process described above - would change US emissions by 2%, or world-wide emissions by 0.3%.
The question was not "will this have a dramatic effect on total global emissions", it was "Can this be a quick solution to reducing domestic CO2 emissions?" Let's redo your calculation: 89% of US commercial and residential emissions are from natural gas. Replacing 20% of this (assuming this can be done without creating additional emissions) could change US domestic emissions by 18%. That sounds like it's worth investigating - and even more so in the UK where the existing domestic energy infrastructure gives different challenges.
Apart from the excellent point that burning natural gas to create electricity to make hydrogen is less efficient than burning the natural gas at point of use
Of course it is, and burning coal to do it would be even worse. But if you could generate that hydrogen using surplus renewable capacity at times of low demand it wouldn't be. And even if you did burn gas to generate power for electrolysis there is the potential for carbon sequestration which is not possible when burning natural gas in a domestic boiler.
it's focusing on a tiny part of the problem.
In my experience that is how big problems are solved.

Tom.G
pbuk
Gold Member
pbuk said: It may be more efficient, but it also produces more CO2.
No it doesn't.
You'll produce 1 kWh of electricity from renewables in the next hour. What do you do?
- regulate down a natural gas power plant to produce 1 kWh less. It will reduce CO2 emissions by 400 g.
- produce hydrogen with an energy content of maybe 0.3 kWh, send it to consumers. They burn it, saving a bit of natural gas in the process. You reduced CO2 emissions by 200 g (optimistic).
OK, I understand where you are coming from. But what if the first alternative is not available because gas plants are already at minimum capacity? In the UK we already store surplus energy at times of high generation and low demand (mainly in pumped hydro), and as fickle renewable generation increases this will become a bigger issue (as I write this, wind is providing 45% of the UK's current power need because most people are in bed with the heating off and there are strong winds on our offshore wind farms).

I will edit my assertion accordingly.

Once most natural gas power plants are out of business this might become more interesting as the first option won't exist any more. By that time hopefully most people switched to electric heating. Then this 1 kWh will save 400 g of CO2 again. Or, even better, switched to heat pumps, then it saves over 1 kg of CO2 emissions.
Yes, by that time also we (again I am talking about the UK) should also have improved insulation which will reduce demand further. Let's assume that we don't achieve this until 2050; is it not wise to investigate the potential of achieving a material reduction in GHG emissions 20 years earlier?

pbuk
Gold Member
At least here in the USA, many (most?) gas pipes are steel. Using Hydrogen in them brings up the problem of making the steel pipes brittle, leading to fractures... and a pure Hydrogen flame is invisible! (no incandescent Carbon to generate visible light.)

Not saying it can't be done, just that there are a lot 'unmentioned circumstances.'

Cheers,
Tom
This is less of an issue in the UK - we are already replacing much of our infrastructure (particularly the local network within 30 metres of buildings) with MDPE for safety reasons. Invisible flame is not really an issue because:
• this project is looking at a 20% H2 mix
• flames in domestic boilers are hidden
• flame failure devices are mandatory on (new since 2008) gas appliances in the UK - a real pain when trying to cook dinner!
It's probably time for some references:

...if you could generate that hydrogen using surplus renewable capacity at times of low demand...
Right now (and anywhere in the foreseeable future) it is a 'no'. With the low efficiency of the electricity => hydrogen conversion and the cost (CO2 footprint of building/maintenance/running included) of the relevant machinery this is a losing business for any other time but when seriously negative electricity prices dominating the market.
But by that time most utilities would be long out of the grid anyway.

While it is nice to know that the gas pipes can tolerate 20% hydrogen, this statement right now (and within the next few decades) has very little practical value.

Unless some new technology got developed to radically increase the productivity of hydrogen generation, there are far better solutions to reduce CO2 emission with available cheap electricity.

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mfb
Mentor
Let's assume that we don't achieve this until 2050; is it not wise to investigate the potential of achieving a material reduction in GHG emissions 20 years earlier?
I don't think anyone argued against research. You asked about wide-scale implementation. And that is not a good idea today. In the very rare cases where renewables cover so much that the energy can't be used at all this might be interesting - but setting up large electrolysis plants for something that happens once or twice per year isn't useful.

Staff Emeritus
2019 Award
Let's redo your calculation: 89% of US commercial and residential emissions are from natural gas. Replacing 20% of this (assuming this can be done without creating additional emissions) could change US domestic emissions by 18%.
Only if commercial/residential were 100% of US emissions. But it's 12%.

surplus renewable capacity at times
I don't think our problem is that we're drowning in "surplus renewable energy at times".

I've seen a few analysis that forecast that the cost of renewable hydrogen (REH2) will be close to, or slightly higher than, natural gas costs. On that basis, without a carbon tax to underpin the economics of change, the wholesale adoption of any hydrogen use case is unlikely.

russ_watters
Mentor
I've seen a few analysis that forecast that the cost of renewable hydrogen (REH2) will be close to, or slightly higher than, natural gas costs.
I'd like to see that analysis, because I can't imagine that being true. I'd bet it's an order of magnitude more expensive.

I'd bet it's an order of magnitude more expensive.
After following the green business for some time already I've started to ignore entirely every and all analysis based on experimental technology only instead of actual industrial practice.

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pbuk
Gold Member
I don't think I have asked anything - perhaps you are confusing me with the OP. This thread does seem to have wandered a little with some confusion over what we are talking about. Perhaps it's time to go back to @tech99's OP, with some editing for clarification:

Can this be a quick solution to reducing domestic CO2 emissions?
Can introduction of 20% H2 into the domestic (i.e. residential) natural gas supply be a quick solution to reducing CO2 emissions from homes in the UK?
It's possible, and because over 80% of homes in the UK use individual gas boilers for heating and hot water the short-term options for reducing domestic emissions are limited. Note however that even if it is feasible (the current HyDeploy trial is a small-scale investigation of this feasibility) there are other factors to be be considered. These include the environmental opportunity cost of the energy used to generate the hydrogen, in other words whether it would be better to use this energy to replace other GHG emissions particularly from fossil fuel fired power stations.

Or is it better to use battery storage and use the electricity?
This is not a short-term option for heating homes in the UK.

What is the best way of using wind and solar for electric cars?
I think this is a topic for a different thread.

Is the domestic heat pump a better long term investment for home heating?
It may well be - but the key words here are 'long term'. Replacing c.20 million gas boilers will take many years and many £ billions, and key decisions including what technolgy and how it will be paid for have not yet been taken in the UK. The Keele trial is looking at a less optimal solution that can be implemented quickly and cheaply while we are working towards the long term solution.

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I'd like to see that analysis, because I can't imagine that being true. I'd bet it's an order of magnitude more expensive.
Such reports are not too hard to find, @russ_watters, here's one, two, and three (though this last needs your details to get the underlying calcs) as examples of various price curves. Note that I've not seen any forecast that predicts really cheap REH2, hence my carbon tax comment. If it's not cheaper than incumbent natural gas, then without an external driver, change will not happen. Esp. because it's going to cost \$T to retool everything for hydrogen.

(I'm also aligned with @Rive's comment about ignoring forecasts for things that are not productionized. Probably REH2 will be cheaper...or more expensive...but don't ask me to be any more accurate than that )

mfb
Mentor
I don't think I have asked anything - perhaps you are confusing me with the OP.
...domestic CO2 emissions in the UK could possibly be reduced by up to 20% almost overnight using this solution.
And, as discussed, this isn't true. Wide-scale implementation now would increase CO2 emissions. It can only decrease CO2 emissions if the gas power plants have been replaced largely, at least in frequent times of peak renewable production.

pbuk
Gold Member
Okay, let me be exact: You didn't ask, you made a statement about wide-scale implementation.And, as discussed, this isn't true. Wide-scale implementation now would increase CO2 emissions. It can only decrease CO2 emissions if the gas power plants have been replaced largely, at least in frequent times of peak renewable production.
We are talking about two different things. I am saying that domestic CO2 emissions in the UK (i.e. emissions from people's homes) could possibly (i.e. making certain assumptions which have to be further developed and trialled) be reduced in the short term (i.e. years rather than decades) by introducing H2 into the natural gas supply.

You are saying that if this were done, the net effect would be to increase CO2 emissions because of the energy used in producing the H2. This may or may not be true, but it has no effect on the validity of my statement because I am talking about only the emissions from people's homes NOT the total emissions based on any assumptions about the energy used for H2 generation.

My final attempt to clarify what I am saying is to express it symbolically:
Let $G_0(UK) = G_0(homes) + G_0(other)$ and $G_1(UK) = G_1(homes) + G_1(H2) + G_1(other)$
My statement: $G_1(homes) < G_0(homes)$ your statement: $G_1(homes) + G_1(H2) > G_0(homes)$
Do you not agree that both these statements can be true?