Electronics > Power/Renewable Energy/EV's

Viability of Solar power -> Hydrogen -> Heat for priv./commerc. housing

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DanielPi:
Hi!

A friend of a friend is starting a company within the "energy creation/storage industry", haven't gotten a very clear explanation of exactly what it is they're going to do (third hand information only), but as I understand it they're going to make some sort of energy storage system which takes electricity from solar cells and somehow converts this to hydrogen (through electrolysis I guess?) and then stores it. This hydrogen is then converted to heat (through combustion I guess?) when power from the grid is expensive around dinner time/evening. I think it's supposed to be a thing in people's houses, so not only for commercial real estate.

I might have gotten some details wrong as this is only third hand information, but I'm fairly sure of the combination Solar power -> Hydrogen storage -> Heat (possibly electricity through fuel cell, but they have terrible efficiency?). Is it just me, or does this seem like no real benefit over regular Li-Ion power storage, which is very commercially available and established? Not to mention the technical difficulty of having these systems at private homes... I read in some other thread about hydrogen being pretty difficult to store properly.

Maybe it could scale better for commercial real estate? Or for offgrid living, but that's a pretty limited market though? (Not non-existent though...)

So I guess my question is how reasonable is this system? Even if I've gotten some details wrong, I don't see any "rectifying" detail that would make this more viable, or?

Regards,
Daniel

Wolfram:
Comparing hydrogen to batteries, the point where one becomes competitive over the other depends a lot on requirements of the application. It's obvious that batteries are the only practical solution for applications like mobile phones and laptops. For cases where more energy storage is needed, hydrogen might be a better option, or it might not, depending on specifics. Both technologies will be around for a long time to come, but I personally wouldn't put my money on gaseous hydrogen for home energy storage.

What's the required energy density? For less than tens of kWh, batteries are a clear winner here. Once getting to MWh scales, then hydrogen can be superior.

Peak vs. average power capability? Batteries can provide a much higher ratio.

Capital cost vs. cost per lifetime unit energy storage. Hydrogen takes more initial investment, but cost per energy stored can be lower. Both batteries and hydrogen infrastructure have finite life, so this one needs to be analyzed in depth on a per-application basis.

Safety requirements? Both H and batteries have potential safety problems, but they are very different and which one is better depends a lot on the application. For domestic use I'd greatly prefer batteries.

Cost of energy vs. cost of storage? Batteries have much better round-trip efficiency, but hydrogen can be cheaper per kWh.

Both fields are also in rapid development, especially alternative battery technologies prioritizing cycle life, cost and reliance on conflict minerals, over power and energy density.

Siwastaja:
99% likely total bullshit, do not get involved.

Hydrogen is now the buzzword, graphene being out of fashion.

It will be viable when properly engineered, but because the efficiency of storage will colossally suck no matter what, it's only viable as last resort storage medium, when the only other option is to not consume the electricity at all. We will see this happen within a few years, but only those with very solid actual engineering solutions to the problem of safe and cheap VERY large-scale storage will win. I simply don't believe any small startup has anything to offer here.

There are still way better low hanging fruits, even as simple as demand control, not to even speak of water based thermal storage.

f4eru:
Decentralized and localized seasonal storage of surplus solar could be a good application in a mid-term future for electrolysis + fuel cells.
It is not yet economically viable, but it could become in a decade or two.
Today, there is not enough solar surplus yet.
Today, we need massive investment into this solar surplus, and associated infrastructure.

An example of a pioneer in this :

But the big problem now is that hydrogen is used for 2 very bad and bounterproductive things :
- Greenwashing for fossil related companies, like nearly each oil company, which speak lengths of Electrolysis, but all use >99% of fossil based Hydrogen. Just  pure B.S. greenwashing.
- Many companies and research institutes, using stagnating H2 pilot projets as a way to harvest government subsidies [/b]

So yes, 99% of what you see on existing and upcoming H2 projects is just B.S. designed to get those juicy subsidies.

nctnico:

--- Quote from: Siwastaja on February 04, 2023, 03:04:04 pm ---99% likely total bullshit, do not get involved.

--- End quote ---
You can already buy hydrogen based energy storage systems (with H2 storage either in gas form or a metal hydrite). Their costs per kWh stored is way, way lower compared to Li-ion. Only problem is the high initial upfront cost which makes the payback time very long. So saying hydrogen home storage is BS is just wrong. Maybe you don't like it, but again: it exists, it is economic and useable for seasonal storage. Seasonal storage is what Li-ion is too expensive for.


--- Quote ---There are still way better low hanging fruits, even as simple as demand control, not to even speak of water based thermal storage.

--- End quote ---
Water based thermal storage is interesting indeed. You have brought this up before but I'm still wondering how well this would work for seasonal storage of heat (to use for hot water + heating) and whether the required volume of water gets prohibitive in terms of size.

IIRC I'm using about 30Gj of heat per year in the form of hot water (I'm on district heating which is charged by GJ so I know this number). Water has a heat capacity of 4400J/degree/liter. Say there is a temperature delta of 30 degrees, I would still need 227 cubic meters of water to store my annual heat usage (assuming 0 loss).

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