But heat loss improves as the product is scaled up(heat loss is function of surface area, whereas total heat is a function of volume, which grows quicker than s

But heat loss improves as the product is scaled up(heat loss is function of surface area, whereas total heat is a function of volume, which grows quicker than surface area), so at a certain point you could make this big enough to let you store energy efficiently on a seasonal basis? Also the same reason elephants can't have metabolisms as fast as mice, or else they would spontaneously combust.