System cools down 23F without power.

System made from a new material cools an item down about 23 degrees Fahrenheit.

Imagine a device that can sit outside under blazing sunlight on a clear day, and without using any power cool things down by more than 23 degrees Fahrenheit (13 degrees Celsius).

https://www.sciencedaily.com/releases/2019/10/191030170556.htm