This is quite nifty. A team of scientists from San Jose University have worked out a way to make ice with zero carbon footprint and no moving parts. There’s no electricity involved either. All you’ve got to do is keep the machine clean.
Here’s the science: A big mirror focuses the sun’s rays on a tube of coolant. The coolant evaporates and travels through pipes into a chamber where it’s absorbed by an unnamed material. When the sun goes down, this material slowly cools until it hits 40°C. At that point, the coolant turns to a liquid and due to pressure differences, it rapidly cools to below 0°C. You then put some water next to it, and voila, it’ll freeze. The next day, you just do exactly the same thing all over again.
This could be incredibly useful in tropical countries, or in places where the electricity supply is iffy, like war zones. The ice produced could be crucial for medical uses, or even for food storage and refrigeration. The whole system is completely sealed too, so if it doesn’t leak then you’ll never need to top it up.
The scientists reckon it can make 14 pounds of ice each day – but obviously, the bigger you make the machine, the more ice you’ll be able to get out. I’m sure that time will also produce more efficient models. You can’t get it yet because it’s just a prototype, but based on the brief science description above and a bit of knowledge of coolants, you might be able to put your own version together. If you do give it a shot, then be sure to let us know.