In a small town in central India, three teenagers invented a refrigerator that doesn’t require electricity and operates solely using salt. This device, called Thermavault, could revolutionize the system for storing medical resources in remote areas.
Thermavault was developed by high school students from Indore city – Dhruv Chaudhary, Mithran Ladhania and Mridul Jain. Their parents work in the medical field, and it was their stories during the pandemic that inspired the children: how to keep vaccines and transplant organs cold in areas without electricity?
This invention was the answer to this question. Thermavault won the 2025 Asia Earth Prize, which came with a cash award of $12,500. With these funds, they have already begun producing 200 prototype devices, which will be tested in 120 hospitals.
Simple approach
Thermavault technology is based on a simple chemical phenomenon: when certain salts dissolve in water, they absorb heat from the environment, thereby lowering the temperature. Although this phenomenon is described in textbooks, the idea of applying it in a portable cooling system was novel for these school students.
This path was not easy. Students initially tested 150 different salts and ultimately selected two effective components: ammonium chloride and barium hydroxide octahydrate. The first of these created stable cooling from 2°C to 6°C, which is ideal for most vaccines. The second component – barium hydroxide – enabled cooling below freezing point, which was necessary for delivering certain medical supplies or organs.
Modern solution without electricity
Thermavault is a clever combination of chemistry and insulation. Its structure contains a copper-coated chamber for storing vaccines or organs, surrounded by a saltwater mixture. When the salts dissolve, they cool the product inside – no electricity, no moving parts, just simple science.
Traditional cold boxes rely on frozen gel or ice, while Thermavault can be reused in field conditions. Once the cooling effect dissipates, if you boil the saltwater, the water evaporates and the salt can be reused. This makes it particularly suitable for areas without electricity – where finding a refrigerator is difficult, but heat sources are available.
Next steps for the Thermavault team
These teenagers, who have already won the prize money, are now working on bringing the device to the international level. Their plans include obtaining a WHO safety certificate and Gavi – a desire to cooperate with the global vaccine alliance and obtain a patent. They are supported by mentors appointed through the Earth Prize program.
Thermavault has already undergone initial practical trials – in particular, at the V One Hospital in Indore. Dr. Pritesh Vyas, who tested the device here, confirmed that it kept the vaccines cold for up to 12 hours. He said that with some improvements, such as a temperature monitoring sensor, this device could be vital for remote clinics.
Big impact – small team
This is not a simple scientific project – it reminds us that real innovation doesn’t always come from billion-dollar laboratories. Sometimes it emerges from curious teenagers, supportive teachers, and a lot of time spent on questions that don’t have answers on the Internet.
If Thermavault is successfully implemented, it can solve the biggest problem in global cooling infrastructure: creating a reliable, stable cooling system that works even without electricity.
Prepared by Navruzakhon Burieva
