Re:Giant 'sand battery' holds a week's heat for a whole town
by zdragnar on Wednesday March 13, 2024 @10:25PM
(#39700016)
Sand is actually pretty bad. Gravel is a little better, clay is best.
Sand is really only useful here because that much clay is usually significantly more expensive and would take forever to dry out.
Source: researched the shit out of and have built a rocket stove.
Since you burn the wood really fast, you need to delay that heat release. That's where sand comes in as a cheap and good enough material. There are also systems that heat water and store it in a tank, which also make sense if you want hot water in your house too.