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Ireland's gas infrastructure and domestic appliances can handle up to between 50% to 80% hydrogen admix. I'm hopeful we go this way soon with a wind energy surp

Ireland's gas infrastructure and domestic appliances can handle up to between 50% to 80% hydrogen admix. I'm hopeful we go this way soon with a wind energy surplus.

HPsquared 3y ago
Doesn't this increase the risk of gas explosions in houses? (Hydrogen has a wider flammability range than methane, particularly it is flammable in higher concentrations, =presumably bigger bang) Seems a bit dicey.
- Mvandenbergh 3y ago
  The latest quantitative risk assessment of hydrogen in a domestic context is that slightly greater explosion risk is outweighed by the slightly lower fire risk. Hydrogen has a wider explosion range... but most natural gas explosions are from small leaks accumulating basements or low spaces in houses which hydrogen won't do. It could instead accumulate under the roof but roofs are almost never sufficiently gas-tight to hydrogen to allow for substantial accumulation. Also, many leaks are in the mains or services under the road. Natural gas will flow along the outside of the pipe and through the soil and end up in the basements of nearby buildings. Again, hydrogen would not do this, it would diffuse up through the soil and disperse in the atmosphere. The big change is to boiler enclosures. These are currently designed to limit voids sufficiently to prevent natural gas explosions which require a minimum cell size of a meter or so to explode (regardless of concentration) rather than deflagrate. That same size for hydrogen is about 5cm so that is the largest acceptable void within the boiler enclosure which requires re-engineering of the way parts fit together and the use of non-h2 permeable foams and plastic spacers to avoid unacceptable voids.
stephen_g 3y ago
That doesn't sound correct... My understanding was that only quite recent appliances allow a mix of greater than about 30%, and networks can't be operated with a high mix without big upgrades (for 100% hydrogen I believe you need all the compressors to be about three times bigger than a natural gas network, so even getting over 50% H2 with the existing infrastructure doesn't sound right). All in all I'm convinced it's just not worth doing for residential when you look at the challenges and the terrible efficiency. Since the majority of appliances aren't 'hydrogen ready', it's better to just electrify.
- VagabundoP 3y ago
  I tried looking for my primary source on this, it was an interview with someone involved with the gas infrastructure here. They mentioned specifically that it was newer than in the UK (and I assume some other EU countries) and that's why it could handle the higher admix. They also have good numbers on the appliances that are in use, there's been grants for a large scale upgrade, all the boilers that have been installed under these programs are rated to 80% H2. I've no doubt you're right there would have to be significant upgrades done somewhere, but it might not be as big an issue for Ireland and I suppose it depends on how cheap that green hydrogen is for us, but we have to get there first. We'll use it for something.

Ireland's gas infrastructure and domestic appliances can handle up to between 50% to 80% hydrogen admix. I'm hopeful we go this way soon with a wind energy surplus.

HPsquared 3y ago

Doesn't this increase the risk of gas explosions in houses? (Hydrogen has a wider flammability range than methane, particularly it is flammable in higher concentrations, =presumably bigger bang) Seems a bit dicey.

Mvandenbergh 3y ago
The latest quantitative risk assessment of hydrogen in a domestic context is that slightly greater explosion risk is outweighed by the slightly lower fire risk. Hydrogen has a wider explosion range... but most natural gas explosions are from small leaks accumulating basements or low spaces in houses which hydrogen won't do. It could instead accumulate under the roof but roofs are almost never sufficiently gas-tight to hydrogen to allow for substantial accumulation. Also, many leaks are in the mains or services under the road. Natural gas will flow along the outside of the pipe and through the soil and end up in the basements of nearby buildings. Again, hydrogen would not do this, it would diffuse up through the soil and disperse in the atmosphere. The big change is to boiler enclosures. These are currently designed to limit voids sufficiently to prevent natural gas explosions which require a minimum cell size of a meter or so to explode (regardless of concentration) rather than deflagrate. That same size for hydrogen is about 5cm so that is the largest acceptable void within the boiler enclosure which requires re-engineering of the way parts fit together and the use of non-h2 permeable foams and plastic spacers to avoid unacceptable voids.

stephen_g 3y ago

That doesn't sound correct... My understanding was that only quite recent appliances allow a mix of greater than about 30%, and networks can't be operated with a high mix without big upgrades (for 100% hydrogen I believe you need all the compressors to be about three times bigger than a natural gas network, so even getting over 50% H2 with the existing infrastructure doesn't sound right). All in all I'm convinced it's just not worth doing for residential when you look at the challenges and the terrible efficiency. Since the majority of appliances aren't 'hydrogen ready', it's better to just electrify.

VagabundoP 3y ago
I tried looking for my primary source on this, it was an interview with someone involved with the gas infrastructure here. They mentioned specifically that it was newer than in the UK (and I assume some other EU countries) and that's why it could handle the higher admix. They also have good numbers on the appliances that are in use, there's been grants for a large scale upgrade, all the boilers that have been installed under these programs are rated to 80% H2. I've no doubt you're right there would have to be significant upgrades done somewhere, but it might not be as big an issue for Ireland and I suppose it depends on how cheap that green hydrogen is for us, but we have to get there first. We'll use it for something.