[mdaEyebot]

"Mechanical batteries" are a thing, like flywheels or hydroelectric reservoirs. Batteries store energy, the electricity that flows in and out is just one way to manifest that energy. You could measure it in Joules rather than Watt-hours.

At the end of the day, a chemical battery is a reusable bomb that is designed to go off very, very slowly.

[rz2k]

I wouldn't want to have tons of 600°C (1112°F) sand stored near a wood frame house or a forest either.

> Wood placed in an oven at 700°F. catches fire almost immediately. At oven temperatures of 450°-500°F., the wood gradually chars and usually ignites after several hours.

> “Pyrophoric carbon,” formed when wood slowly chars, absorbs and combines rapidly with oxygen. This produces heat which under certain conditions causes the charred wood eventually to catch fire at temperatures well below those required to ignite the original wood. Cases are recorded where wooden flooring in contact with steam pipes at 250°-300°F. has caught fire after years of EXPOSURE.-FACTORY MUTUAL RECORD.[1]

I disagree with most of the naysaying in this thread, but pretty much all energy storage that is easily accessed can also have a failure state that is difficult to handle. It would probably be impossible to save a structure with a 600°C blob resting against it.

[1] https://www.fireengineering.com/leadership/ignition-temperat...

[mdaEyebot]

I suppose a leak would be serious, but presumably these sorts of large-scale batteries would be buried in a containment unit.

Flywheel batteries are usually placed in small bunkers, because the failure mode of a giant rapidly-spinning concrete wheel jumping its bearings is not exactly pretty. Dams are usually designed with diversion channels and mechanisms to limit the damage if they burst. Etc.

Really, it's strange that we are so cavalier about lithium battery failures compared to the other sorts.

[datameta]

Surely the sand battery idea is more for centralized designs than for being somewhere in the middle of the woods? A chemical battery or a water elevation system would suite that locale better. Industrial regions where a sand battery would be used aren't traditionally known for their wooded nature.