Sure Chill is a cooling technology which is currently being used in medical refrigerators, but has wider potential in the future for domestic refrigerators and beverage coolers. According to BBC, the refrigerator 'can stay at 4C for more than 10 days without power, and is used mainly in Africa' to store vaccines and other medical supplies. It can be powered by electricity or solar and uses the physics of water to store energy, thus not relying on batteries.