Was running some ideas w/ ChatGPT to try to find a solution that would work for storing excess energy from solar generation.
I was playing with the idea of having about 20 MWh of excess generation per year. Around 100kWh per day on good days.
Selling to the grid requires annoying permits and (depending on where) they don't pay well at all.
Batteries are like 1k€ per 10kwh, so they're good for a day or two of buffer storage, but not more.
Storing energy in water doesn't really work, you need insane amounts of water to store meaningful energy. Phase change materials like paraffin wax store more because it's latent heat of melting, but the size is still insane.
If you're thinking about storing heat, you probably want reversible chemical reactions, such as quicklime + water, or epsom salt + water which release a lot of heat, and then you recharge them by dehydrating them with heat. Epsom salt is probably the most interesting, it stores 190 kWh per ton and you can recharge it at 50-100C if you do so under vacuum. You can get close to these numbers using an off-the-shelf heat pump. But still, 20MWh equates to 100 tons of material, which is large and expensive.
An energy storage solution which is dumb NOT to pursue is vacuum drying. You can build a vacuum chamber and put lumber, garden produce, wood chips & things you want to burn, and you pull a vacuum in the chamber then use a heat pump to push heat into the chamber which causes the water to boil. The smart thing to do is run a pipe from the chamber to a condenser which is kept in cold water (pond, stream, swimming pool, etc) and because it's cooler than the chamber, it will condense out the water that is being vaporized from the stuff you're drying. This means you don't need to keep adding vacuum, just heat.
Tech Ingredients did this exact setup, except for vacuum distillation of wine. Once the vacuum is set, you don't need to add vacuum, just heat. And you only need to keep the hot side hotter than the cold side, and the reaction will continue to work.
https://www.youtube.com/watch?v=vUzKgjeljuI
Caleb James DeLisle
npub105…t88up
2026-03-18 18:11:42 UTC
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2026-03-18 18:11:42 UTCEvent JSON
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"content": "Was running some ideas w/ ChatGPT to try to find a solution that would work for storing excess energy from solar generation.\n\nI was playing with the idea of having about 20 MWh of excess generation per year. Around 100kWh per day on good days.\n\nSelling to the grid requires annoying permits and (depending on where) they don't pay well at all.\n\nBatteries are like 1k€ per 10kwh, so they're good for a day or two of buffer storage, but not more.\n\nStoring energy in water doesn't really work, you need insane amounts of water to store meaningful energy. Phase change materials like paraffin wax store more because it's latent heat of melting, but the size is still insane.\n\nIf you're thinking about storing heat, you probably want reversible chemical reactions, such as quicklime + water, or epsom salt + water which release a lot of heat, and then you recharge them by dehydrating them with heat. Epsom salt is probably the most interesting, it stores 190 kWh per ton and you can recharge it at 50-100C if you do so under vacuum. You can get close to these numbers using an off-the-shelf heat pump. But still, 20MWh equates to 100 tons of material, which is large and expensive.\n\nAn energy storage solution which is dumb NOT to pursue is vacuum drying. You can build a vacuum chamber and put lumber, garden produce, wood chips \u0026 things you want to burn, and you pull a vacuum in the chamber then use a heat pump to push heat into the chamber which causes the water to boil. The smart thing to do is run a pipe from the chamber to a condenser which is kept in cold water (pond, stream, swimming pool, etc) and because it's cooler than the chamber, it will condense out the water that is being vaporized from the stuff you're drying. This means you don't need to keep adding vacuum, just heat.\n\nTech Ingredients did this exact setup, except for vacuum distillation of wine. Once the vacuum is set, you don't need to add vacuum, just heat. And you only need to keep the hot side hotter than the cold side, and the reaction will continue to work.\n\nhttps://www.youtube.com/watch?v=vUzKgjeljuI",
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