Indian Students Innovate Electricity-Free Refrigerator, Winning Global Acclaim
A groundbreaking achievement in sustainable technology has caught the world’s attention.
Three high school students from Madhya Pradesh, India—Dhruv Chaudhary, Mithran Ladhania, and Mridul Jain—have developed a salt-powered refrigerator called the Thermavault. This cutting-edge device, which operates without electricity, promises to bring significant improvements to areas struggling with unreliable power access.
Dhruv, Mithran and Mridul / theearthprize.org
The trio’s innovation was recently recognized with the 2025 Earth Prize, which included a $12,500 award. With these funds, they aim to produce 200 units and distribute them to 120 hospitals to test their effectiveness in real-world scenarios.
The Thermavault utilizes ionocaloric cooling, a process that leverages the heat-absorbing properties of salts dissolving in water. Specifically, ammonium chloride is employed to reduce water temperatures by as much as 28°C. For colder temperatures, down to -10°C, a reaction involving barium hydroxide octahydrate and ammonium chloride is used, enabling applications that require freezing.
The refrigerator’s design includes a copper box encased in fiberglass wool and nitrile rubber, enhancing its ability to maintain cool temperatures over extended periods. Users can activate the cooling process by adding salt and water, then agitating the mixture. This leads to a consistent cooling effect, making it ideal for storing perishable goods and medicinal supplies without needing electricity.
Throughout their development journey, the students collaborated with Professor Mobin Shaikh from IIT Indore, a specialist in material sciences. By experimenting with 15 different salts and applying scientific principles like enthalpy and specific heat, they honed the refrigerator’s efficiency. Their diligence and innovation received high praise from both mentors and academic experts.
The Thermavault presents a significant advancement for communities in need of off-grid solutions, disaster-affected areas, and rural health facilities where electricity is scarce. By offering an eco-friendly method to preserve vital resources, these students are poised to make a substantial impact worldwide.
