There are various research projects looking at storing waste heat, often for the purpose of more efficient defrosting. https://www.nature.com/articles/s44172-0

There are various research projects looking at storing waste heat, often for the purpose of more efficient defrosting. https://www.nature.com/articles/s44172-022-00018-3 https://www.nature.com/articles/s44172-022-00018-3