I'd pour a slab and have a shed sized battery delivered if the $/kwh and cell longevity was favorable enough.
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Keep your wallet close, that time is rapidly approaching. Global demand for energy storage at this price and scale is voracious, and supply is spinning up to meet it.
https://about.bnef.com/blog/china-already-makes-as-many-batt...
https://www.iea.org/commentaries/the-battery-industry-has-en...
https://www.energy-storage.news/global-bess-deployments-soar...
https://rhomotion.com/news/global-bess-deployments-surpass-e...
How electric scooters are driving China's salt battery push - https://news.ycombinator.com/item?id=44161921 - June 2025
The world is going to be a very different place because this is going to be possible soon.
There’s a startup doing this at substations. They can network these batteries and then use the utilities’ extra wire capacity to redistribute energy throughout the grid.
The other flipping points are when these outcompete the all-in cost of making a new gas peaker plant and then the cost of bothering to turn existing plants on.
I guess my point is that cars and phones drove battery research towards energy density, but I still have three cord of firewood in an 8*12ft shed at the end of my driveway. Energy density is my last concern.
Yeah, that makes sense! The drive has been not only for higher density, but also lower cost. Sodium batteries were investigated for cost reasons (to avoid the Lithium) and it turns out that density isn’t as good (for now), but that’s okay for some cars and great for stationary storage. Enough demand to drive innovation. A cord of wood is hard to beat on cost!
My understanding on sodium is that it’s still early days. Most “sodium” batteries shipping today are hybrids with lithium (two sections, one bms) with poor cycle lifetimes, so there is a lot to figure out still. I haven’t personally seen or heard about CATL’s sodium batteries in the real world yet.
For those of us outside the US and used to other units, a cord [1] is of course 128 cubic feet or roughly 3.62 cubic meters. The wood is supposed to be well stacked (aligned, parallel, touching and compact) and if so, one cord is a pile measuring e.g. 4x8x4 feet. Wow, three cord is "a lot", in other words.
Cords of wood are usually around 18 million BTU of potential energy, which is 5000+ kWh. Wood stove efficiencies are all over the place, but modern ones are in the 70% range.