[iamthemonster]

I work for an oil and gas company. It has been specifically stated by my company that they are seeking support for hydrogen as a fuel because it adds value to their gas reserves - natural gas is roughly 75% hydrogen on a molar basis.

The idea is to stimulate demand for "green-ish" hydrogen (that is by grid-connected electrolysis); once demand for the hydrogen is there, it can be supplied by blue hydrogen. The O&G companies aren't super keen on green hydrogen made by dedicated renewables off grid, and they LOVE the approach of "we'll start off with grey hydrogen then we'll move to blue and green in the future".

This is very specifically a strategy to increase the amount of natural gas that can move from resources to possible reserves to probable reserve to proven reserves. That's how you increase the value of your company, which is how you get a fat bonus as a CEO.

You don't get a fat bonus by telling the truth or being right.

[jasonkester]

Can you define your hydrogen colors for us? It sounds like you have something interesting to say, but I can’t parse what it is out of your company’s jargon.

[MayeulC]

These are common terms. A random link: https://www.weforum.org/stories/2021/07/clean-energy-green-h...

* Green: produced from surplus renewable capacity (electrolysis)

* Black, brown, grey: convert various fossil fuels to hydrogen via steam reforming. Basically strip carbon from hydrocarbons, emitting a lot of CO2.

* Blue: same as black/brown/Greg but with carbon capture.

There are other (less common) shades as well.

[lambda]

There's also "white" which is naturally occurring pure hydrogen.

Mostly it's seen as being economically infeasible to extract, though there is one working well in the world, and some other potential sources that may be feasible to extract discovered recently.

But the big problem with hydrogen is that right now, the majority of the supply is grey/brown/black, which all emit CO2 to produce. Green is far more expensive, and the carbon capture needed for blue is also expensive and the methods of storage are dodgy.

The thing about green hydrogen is that it's more efficient to transmit and store electricity than convert it to hydrogen and distribute and store that, so it's basically just a worse way of utilizing green energy sources. The only reason hydrogen is at all economical is that grey/brown/black are cheap, and it's hard to see any path for green or blue to become competitive (and truly zero emissions for blue).

It's possible that we'll find reserves of white hydrogen and efficient ways to extract it, but that's purely speculative right now, while building renewable energy sources, electric distribution, and batteries can be done right now.

[AlexandrB]

And Green is a huge efficiency loss. I suppose if the energy used to do it truly "green" and "surplus"...

> As of 2022, commercial electrolysis requires around 53 kWh of electricity to produce one kg of hydrogen, which holds 39.4 kWh (HHV) of energy.

https://en.m.wikipedia.org/wiki/Electrolysis_of_water

[wisty]

20% loss isn't really "huge", is it?

10% of power is lost to distribution anyway. Batteries can also lose 10%.

The issue with hydrogen isn't producing it, it's that it's an absolute nightmare to transport and store. Hydrogen can soak into metals, causing them to become brittle - https://en.wikipedia.org/wiki/Hydrogen_embrittlement and it leaks if there's absolutely any chance of it possibly leaking (thanks to the small molecules, and its tendancy to cause everything it touches to go brittle), and can cause a very big bang if it does leak.

It might work well for planes (where power to weight is at an absolute premium) but for cars and buses the weight of a bigger but tamer battery just makes more sense. It's absolutely a good rocket fuel.

The issue isn't that it can't be green. The issue is that it's rocket fuel - high performance but dangerous and high maintenance. Putting rocket fuel in a bus is just dumb.

[theshrike79]

But then you have even more losses when you convert the hydrogen back to energy.

The formula is that 55kW of electricity used to generate hydrogen from water and then converted back to electricity in a gas turbine or fuel cell results in 15kW of energy.

That's a lot more than 20%.

Compare that to just storing the 55kW in batteries and using them to spin an electric engine. "Hydrogen economy" only makes sense if you have infinite free electricity or massive overproduction.

[ben_w]

> "Hydrogen economy" only makes sense if you have infinite free electricity or massive overproduction.

Or when batteries are really expensive and global production and/or geopolitics prevents a global power grid.

Both were the case 15 years ago (and geopolitics still prevents a global power grid today, but metal production has increased and is now sufficient).

Hydrogen wasn't entirely stupid back then; even though PV was more expensive than today, the trends were already clear.

Now? I think hydrogen is suboptimal for most users. But I wouldn't bet against the idea of someone, somewhere, likely in the arctic or antarctic circles, deciding that they really do need multiple months of energy storage, and for those specific weird edge cases I think it's at least possible they might decide a cryogenic liquid hydrogen tank the size of the space shuttle external tank, refuelled every summer by a comically large PV array that works 24 hours in some days, is less silly than 3 gigawatt-hours of batteries.

[thfuran]

And don't you lose a significant amount compressing it for reasonable storage as well? Or is that considered part of the generation loss?

[Loudergood]

Ok now added hydrogen losses due to distribution and storage.

[cjbenedikt]

Frequently the green energy used to split water is "surplus" energy. For example the bulk of offshore wind energy happens between 10pm and 2am when energy demand is at its lowest. That energy goes to waste if not stored in hydrogen. Hence, efficiency is irrelevant.

[SoftTalker]

When the energy is free (solar) efficiency doesn't matter, or at least not nearly as much.

Same reason the mob could sell their hijacked goods under wholesale prices... it was all profit no matter what.

[486sx33]

Then force all electric cars to be charged only by solar!

[486sx33]

Sure, but as long as we are burning natural gas, hydrogen is a bonus. Either use it or let it be wasted.

Using it to power public transportation is a great idea, if only we can get some better hydrogen fueling infrastructure. It should have a fair shake against electrics as electric vehicle power generation is using a lot of natural gas stations to charge up those cars !

[groone]

Red hydrogen: produce hydrogen from a thermochemical reaction between water, iodine, and sulfur at a high temperature, around 900°C, using the thermal energy from a nuclear reactor.

[D_Alex]

"Blue hydrogen" is commonly used for hydrogen produced from natural gas. If it is produced by steam reforming (most common), then the associated CO2 emissions are worse than if you just burn the natural gas directly.

"Green hydrogen" is usually hydrogen produced from water by electrolysis, using electricity from non-CO2 source, e.g. wind or electricity.

[ajb]

Blue hydrogen is supposed to capture the carbon. If its just emitted, then it's grey hydrogen: https://www.nationalgrid.com/stories/energy-explained/hydrog...

[tialaramex]

Right, if you "oops" don't have working capture because it's never been practical you're making "Blue" hydrogen in which your customers can tell everybody they're environmentally friendly but due to a technical hitch you are emitting lots of CO2. Maybe you can agree a token $1B fine, of course offset against the taxes you were already going to pay, and everybody carries on as before. Hooray for your profitable corporation and oops, too bad for the stupid humans who live on the gradually less inhabitable planet you're destroying.

This would only be really dumb if the corporation was owned by humans. Huh.

[1oooqooq]

1bi fine? i wish. they just sign up for those carbon buyback scams and won't cost more than 20mi, including the bribes.

[D_Alex]

You are entirely correct.

[krisoft]

Blue hydrogen is produced from natural gas.

Green hydrogen is produced from electrolysis of water where the energy is comming from a renevable source. (Imagine solar panels which are directly connected to an electrolysis plant.)

“Green-ish” hydrogen is produced from electrolysis of water where the energy is comming from the grid. (And thus as green as your grid is.)

[jasonkester]

Thanks. Any idea what “grey” would mean in this context?

[iamthemonster]

Grey hydrogen is produced from natural gas

Blue hydrogen is produced from natural gas with carbon capture

[originalvichy]

These are quite obvious for anyone who has been following energy tech at a surface level.

[thaumasiotes]

> natural gas is roughly 75% hydrogen on a molar basis

I thought it was methane. Wouldn't that be 80% hydrogen on a molar basis? (Or... 67%, if we're counting moles of molecular hydrogen?) Is the discrepancy coming from impurities, or different types of fuel, or what?

[D_Alex]

Natural gas is a mixture of methane and heavier hydrocarbons, the composition varies by region, depending largely on how the LPGs (propane and butane) are used. Ethane usually ends up in natural gas, unless there is a petrochemical complex nearby.

So, 80% is a theoretical maximum, which is never achieved in practice. 75% hydrogen looks pretty right.

[thaumasiotes]

I'm still curious about the measurement "on a molar basis". If you have 20 moles of methane, and you process that to separate out the carbon, you'll end up with 20 moles of some form of carbon and 40 moles of hydrogen gas, right?

[philipkglass]

I think that "on a molar basis" is there to clarify that it's counting by number of atoms rather than grams. On a gram-for-gram basis, methane is ~75% carbon.

[D_Alex]

"Molar" refers to a number of elementary entities, which could be atoms or molecules or w/e. So yes, if you are counting moles of H2 gas, but not if you are counting atoms...

[thaumasiotes]

But hydrogen gas is the only thing you can get from that reaction. There is a theoretical construct of monatomic hydrogen, also a gas, but you're guaranteed to get molecular hydrogen instead. And there will only be 40 moles of it. There isn't a way for you to end up with 80 moles of hydrogen product.

[iamthemonster]

I'm the original commenter, and quite simply you're right and I slipped up. It's not really using the terminology correctly for me to say "natural gas is ~75% hydrogen on a molar basis".

Whenever talking about hydrogen's physical properties etc on a molar basis, we'd be talking about H2. So if you had a mole of methane (CH4) we'd say you could make two moles of hydrogen (H2) out of it.

My point was really just that the gas companies' reserves of natural gas mean that they'll do anything to try to stimulate demand for blue/grey hydrogen, because their reserves of natural gas are reserves of hydrogen.

[D_Alex]

Ooh, I love pedantry contests!

Let's go back to your opening comment which was something like "I thought methane was 80% hydrogen on a molar basis". Methane does not contain H2 molecules, it contains 4 atoms of hydrogen. Plus one atom of carbon, which would indeed make it 80% hydrogen on a molar basis.

If that does not convince you: note also that atomic carbon is also a very unstable, and will auto polymerize into one of its allotropes (eg. C60 - buckyballs). And yet we count carbon by the atom.