this post was submitted on 22 Aug 2024
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I'd be interested in home scale hydrogen electrolysis with excess solar energy even if only to sidestep the "use it or lose it" reality of off-grid solar.
Rather than just filling up batteries?
Thing about batteries is.
From an environmental standpoint, both mining the raw materials and producing the batteries uses a lot of energy and produces a lot of pollution.
Morally, many raw materials for batteries come from desperately poor conflict zones, so you have megacorps staffing mines with slavery and child labor, paying local warlords/dictators for permission to operate, having those warlords/dictators kill protesters and union organizers, etc.
If we can get a hydrogen economy working, and the equipment and technology don't need conflict minerals or polluting heavy industry to manufacture, it would be a boon for the world both practically and morally.
But that's a big if.
Hydrogen fuel cells need rare earth metals, too. Sodium and iron air batteries, in contrast, don't need a whole lot. For that matter, lithium batteries are opening up more abundant sources. People misunderstood what "reserves" means for minerals.
Hydrogen can be stored in underground caverns and that can be relatively easily scaled to TWh. Electrolysis and fuel cell can get you 70% or so of your electricity back. So it is less efficient then batteries. However there might be a place for hydrogen as seasonal storage. Also the storage makes sense as quite a few processes use hydrogen anyway.
So there is a use case, but right now we mostly should just add renewables and batteries. We are nowhere close to a solar/wind grid, which does actually need seasonal storage. Also grid size helps a lot and there are options such as burning waste.
Electrolysis of the most expensive process (PEM) is around 80% efficient by itself. The more common methods are 70%. Anything that uses it after that only drops it further. Fuel cells max out at 60%, which means that electrolysis to electrical output efficiently is about 50% altogether in the very best case.
Some of the better internal combustion engines are reaching about the same.
After my batteries are charged. I have 40kW, but excess would probably go toward the diesel powered implements I have, that way they can run more efficiently and reduce emissions.
B A T T E R I E S
I already have batteries.
M O R E B A T T E R I E S
There is a startup company I worked with called Solhyd that Is trying to do that.
The downside is they are trying to do per-panel electrical hydrolysis because it is flashy and sexy for investors when it makes compression a complete bitch and you need a ton of hydrogen tubing bringing the loose hydrogen everywhere to an expensive compressor instead of just bringing solar electricity to a safer location for the hydrolysis and compression to storage.