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

[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]

99% likely total bullshit, do not get involved.

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.

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

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).

[Kleinstein]

The efficiency of fuel cells is not bad. The problem is when used to gether with liquified H2 for the storrage or high pressure bottles. A problem with fuel cells can be the required maintenace in times when not used for a long time (e.g. keep humid and excess CO2 out). So the cells are not without problems.
For seasonal storage the efficiency is also not that important. Some heat can have a good use in winter. So the losses there don't hurt all that much. One just has to accept that storrage does not come for free, but excess PV power in summer does have a low values - so some energy lost is not that bad. At least one can use a good part of the excess that would otherwise get essentially unused.

Li-ion batteries are just to expensiven when used for only a few cycles per year - they are OK for the daily and maybe weekend cycle.

If one has grid conncetion it may still not be financially attractive to do the storrage at a small scale on local. There can be some savings from larger units, e.g. for compressors and the control. So small units (e.g. < 100 kW) may not yet be worth it.

[Marco]

Maybe for off grid dunkelflaute storage? Terrible round trip efficiency doesn't really matter for an emergency reserve, just cost competitiveness per kwh recoverable. High pressure storage tanks can be made relatively cheap, fuel cells will probably be affordable once they are made in bulk, how cheap can you make a high pressure electrolyzer?

Even if in mass production it could be competetive with a large battery system, it's likely not going to see mass production. As a boutique solution it would be way too expensive.

[nctnico]

Maybe for off grid dunkelflaute storage? Terrible round trip efficiency doesn't really matter for an emergency reserve, just cost competitiveness per kwh recoverable. High pressure storage tanks can be made relatively cheap, fuel cells will probably be affordable once they are made in bulk, how cheap can you make a high pressure electrolyzer?

Why would you need a high pressure electrolyzer? You can also store hydrogen in metal hydrites or other hydrogen compounds. Ammonia for example (although not ideal due to toxicity).

[Marco]

The system is complex enough for a small off grid system already without nitrogen capture, Haber Bosch and hydrogen regeneration.

Metal hydride I doubt is cost competitive with fiber glass high pressure tanks.

[NiHaoMike]

If it's for peak shifting HVAC on a timescale of hours to days, it would be hard to get any cheaper than thermal storage.

[nctnico]

If it's for peak shifting HVAC on a timescale of hours to days, it would be hard to get any cheaper than thermal storage.

You'd have to put some numbers on that. How much energy is to be moved from a home during summer and how much energy for hot water is needed during the day?

[NiHaoMike]

You'd have to put some numbers on that. How much energy is to be moved from a home during summer and how much energy for hot water is needed during the day?

A ton of air conditioning is defined as the cooling provided by a ton of ice melting over 24 hours, about as much as is stored in an "IBC tote". A ton of ice stores about 92kWh, or about 30kWh of electrical input to a heat pump to supply the same cooling. I think it's obvious that a container for a ton of ice is going to be far cheaper than 30kWh of batteries. And the container of ice won't mind staying fully frozen or fully melted for an indefinite amount of time, while the batteries will need to be derated to last.

There is, however, a huge advantage the batteries have over thermal storage: they can power all sorts of electrical loads, not just heat pumps. But as HVAC is the biggest part of residential energy use in most areas, it's worth having an economical storage solution for that.

As for hot water, Dave Jones recently installed a thermal storage heat pump water heater. You can check on the calculations he did.

[DanielPi]

Thanks for many really great answers! So I guess that's what I've missed: seasonal storage. But from what I gather from the answers so for, this doesn't really seem (down) scalable to a unit per house type of product.

[Siwastaja]

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.

And you are right that li-ion is way too expensive for seasonal storage, too, completely unpractical. Never said otherwise.

H2 is probably going to be an order of magnitude cheaper. But H2 will still be expensive enough that 99% of the small-scale projects working with it will colossally fail, or, as f4eru said, just work as a subsidiary con projects. As I said, H2 will be seen in the future, but during next 10 years, we have so many, much better low hanging fruits available. Even something as simple as demand control is still at its infancy.

Therefore, H2 is totally worth experimenting with, but in the meantime, do not believe anything that claims they are a practical solution right now. Same for battery storage; but at least battery storage is nearly useful for short-term (hours) load balancing.

[Wolfram]

99% likely total bullshit, do not get involved.

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.

Do you have a link to any available products with pricing and specifications? I didn't find anything.

[AlbertL]

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

Along with blockchain, AI/machine learning and nanotechnology!

[nctnico]

99% likely total bullshit, do not get involved.

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.

Do you have a link to any available products with pricing and specifications? I didn't find anything.

IIRC this one has been discussed on this forum before:
https://newatlas.com/energy/lavo-home-hydrogen-battery-storage/
But if you google for 'hydrogen electric storage home', you'll find several other products.

[Wolfram]

I did find the Lavo and the Picea systems, but no info on commercial availability or any specifications on the official websites. Also at 40 kWh storage (20 kWh electrical considering FC efficiency according to the linked article), it does not really qualify as seasonal storage. It also contains 5 kWh of lithium batteries as an energy buffer buffer, so it will have lifetime limitations like a pure battery-based system.

[nctnico]

I did find the Lavo and the Picea systems, but no info on commercial availability or any specifications on the official websites. Also at 40 kWh storage (20 kWh electrical considering FC efficiency according to the linked article), it does not really qualify as seasonal storage. It also contains 5 kWh of lithium batteries as an energy buffer buffer, so it will have lifetime limitations like a pure battery-based system.

I'm sure I have seen prices somewhere for the Lavo or a similar system. And you have to look at price per kWh stored. When using a fuel cell, you'll need to use a buffer battery for peak loads (more like a capacitor). But this battery will be far cheaper (even when it needs to be replaced a couple of times during the lifetime of the storage unit) compared to having an all-battery solution. These hydrogen based systems shouldn't be hard to extend to having a higher capacity as most of the cost is in the fuel cell & other parts. The storage itself is just a passive container.

[Siwastaja]

IIRC this one has been discussed on this forum before:

Typical vaporware. Can't buy it. Try harder.

[Ice-Tea]

[nctnico]

IIRC this one has been discussed on this forum before:

Typical vaporware. Can't buy it. Try harder.

Well, likely the Lavo system was too expensive. The first batch of units where offered for around 28k euro. IIRC even at that price, the cost per kWh stored is very competitive but payback time is around 30 years. But that doesn't mean the technology is not viable. A lot of my customers are startups and one of the criticial factors in having success is hitting the market at just the right time and being able to wait until the right time is there. Some of the startups take years before the market is ready for the technology they offer. Circling back to the question of the OP: in the end it is all about having enough cash to get a product ready at an economically viable price AND being able to wait until the market is ready to buy the product. Doing market research in order to pinpoint where the need is going to be and what an acceptable price will be, is the key to success.

One of my customers in particular is such an example. They have developed technology that is way ahead of anything available when they started. But no demand for their product at all. Fast forward a few years: scientific community and governments became interested and they where able to show a product at a production readyness level that simply killed any potential competitor out there. They are the defacto choice in their market segment. It just takes the right vision and enough money.

My estimation is that there will be a huge market for home electricity storage solutions after 2030 which starts ramping up around 2025 when subsidies on solar installations are starting to shut down.