Hydrogen PEM fuel cell based storage

anonymous

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Jun 5, 2021
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Hi,

This forum (and the Internet in general) seems to lack information about diy hydrogen PEMFC energy storage solutions. I can't tell why this is the case. Based on everything I've seen, building some system like this is doable.

This guy seems to have done a lot of work like this:
https://www.hydrogenhouseproject.org/

The efficiency is not stellar, but with metal hydride tanks you can potentially store a huge amount of energy. It might be much less expensive (than with batteries) to build a system that can last a week or two of rainy weather.

Any ideas?
 

upnorthandpersonal

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Because it's extremely complicated to do correctly. With the cost of LiFePO4 these days, it doesn't make much sense on a small scale DIY-friendly implementation. There are no off-the-shelf components readily available to make this easier.
 

svetz

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Not really too complicated IMO (video) although you do need some know-how & skills (a stack can be bolted together (getting a proper seal can be tricky), the Balance of other systems requires some decent plumbing skills). Materials for high efficiency (e.g., platinum catalyst (possible low-cost alternative?)) and parts like ultracapacitors and quality valves are expensive though. At least hydrogen leaks aren't GHGs.

The price of fuel cell stacks is expected to drop ~75% as production scales (ref). More on the costs here. You can DIY them too. EFoy has an 80 Ah kit for ~$3200; you can find them in the fuel cell store... but as mentioned ... pricey in terms of $/W currently.
 

anonymous

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Batteries would cost way too much for what I'm thinking ($50k-$200k). I would like to have off-grid power during cloudy weeks and low solar winter months. I only need a ~600W cell stack for my system but copious amounts of H2 storage (low pressure metal hydride tanks). If I am not mistaken, the cost of PEMFC and H2 storage would be lower than the cost of LiFePO4 batteries at this scale, someone correct me if I am wrong.

svetz, thanks for the links!
 

svetz

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You'd have to google around to get the prices. The fuel cell store has a 600W stack for $4320, hydrogen prices probably depend on where you live and if any local industry is using it. To know if your cost thoughts, e.g., $200k for batteries, are correct we'd need to know how many kwh storage you needed. @upnorthandpersonal talks about his setup on this thread, a 10kW solar system with 28kWh LiFePO4 battery, inverter, BMS and charge controllers for under $12k U.S. dollars.
 

anonymous

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The idea is to generate hydrogen from solar.

My 5kwh battery lasts maybe 8 hours. If I want to store 2 weeks worth of energy, I need a 210kwh battery. For a 2 months worth of storage (probably overkill) I would need a 930kwh battery. So, very much impractical.

Even with $4320 for a 600W stack (seems unreasonable) and assuming storage tanks, H2 generator and accessories can be obtained for a reasonable price, it should be much cheaper to build 210kwh+ hydrogen based storage than a lithium based one.

Now what I need to do is figure out how to get started.
 

svetz

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anonymous

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Sometimes it rains for a week and the panels don't generate much energy. 15 kWh isn't going to cut it. In winter it might be worse. It might snow and there would not be much sun for two weeks. Also, there is less energy produced in the winter due to the sun being lower in the sky and trees blocking it. It makes sense to have a long term storage that slowly gets drained in the winter but gets replenished with excess solar in the summer.

I've heard of the solar hydrogen generation idea. Hydrogen to electric conversion is low efficiency, so, it wouldn't make sense to use these instead of regular panels unless I am missing something. What's wrong with electrolysis?
 

copec

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I've done this deep dive before. For our scale, electrolyzer efficiency is ~75%, compression into high pressure cylinders ~80%, PEM fuel cells ~50%, which means we can recover about 30% of energy as electricity for long term storage. It seems that when it rains it pours and I don't think that would be an issue with PV, as most can generate a ton of excess when they don't need it.

I've researched how to build and repurpose things to make it as cheap as possible, but it would still be a big project with lots of potential failure points and hazards.

Related to me for long term energy storage is the need for heat as well. Search up micro co-generation and combined heat and power. Also, there are a few manufacturers of free piston sterling engines that have the same efficiency as PEM fuel cells, but with twice the life (35,000 hours vs 70,000 hours). https://www.qnergy.com/oem-product/

If I were on some land and had the space, I would low pressure store the hydrogen AND oxygen in large propane tanks and use a homemade alkaline fuel cell. If it is in a sealed off system and isn't exposed to even trace amounts of CO2 that poison the cells, it should last essentially forever.

I'm a fan of ammonia too. I wish there were essentially plug and play generators for it. It is almost exactly as easy to deal with as propane (my uncle has tankers of it that he uses to fertilize his barley farm with).
 
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