Timbuktu Chronicles writes –

“Sunny Steveson fabricated a self freezing system, he used an old 52 British thermal unit (BTU) air conditioner and tubes that he passed through the concrete walls to enter the freezing room. The air conditioner and the room get electricity from a 6KVA generator…The process takes 10 to 12 hours to fully freeze water and turn them into solid blocks of ice…he has the ability to build a cold storage and use his technology not only to freeze water and make ice, but also to freeze perishable products for the long term. He said, “The only difference between his invented concrete freezer and the imported one is that his freezer is made with concrete while the imported one is made with zinc.””Link.