Three teenagers from Indore, Madhya Pradesh, Dhruv Chaudhary, Mithran Ladhania, and Mridul Jain, transformed a school science lesson into an innovative solution for transporting vaccines and medicines. They developed Thermavault, a refrigerator that utilises salt and water to generate cooling without the need for electricity, batteries, or ice. The inspiration for this invention arose from challenges related to storing and transporting Covid-19 vaccines in rural areas lacking reliable electricity.

All three students have parents in the medical field, which exposed them to the difficulties healthcare workers face in delivering temperature-sensitive medical supplies to remote locations. Their invention has garnered significant attention, winning the 2025 Earth Prize for Asia, with a prize of $12,500. The team plans to use these funds to manufacture 200 units for testing at 120 hospitals.

Scientific Process Behind the Invention

The science behind Thermavault is intriguing. Certain salts, when dissolved in water, create a cooling effect. This occurs due to the separation of the salts into electrically charged particles known as ions, which absorbs energy from the surroundings, thereby lowering the temperature of the water. The students initially explored around 150 salts before narrowing their focus to approximately 20 potential candidates.

They utilised laboratory facilities at the Indian Institutes of Technology (IIT) to conduct experiments, although their early trials did not yield the desired cooling effect. A breakthrough occurred when their teacher recommended two compounds from their Class 9 science textbook: ammonium chloride and barium hydroxide octahydrate. Testing revealed that ammonium chloride could maintain temperatures between 2 and 6 degrees Celsius, suitable for many vaccines, while adding barium hydroxide octahydrate could achieve temperatures below zero.

After three months of research and experimentation, the students successfully developed a working prototype and began trials at local hospitals, demonstrating the practical application of their classroom learning.

Functionality of Thermavault

Thermavault is designed as an insulated plastic container with a copper lining. Medical supplies are placed within the copper section, while a salt-and-water cooling solution fills the space between the inner and outer walls. Unlike traditional cold boxes that rely on ice packs, this device leverages the cooling reaction of dissolved salts.

Another notable feature is the ability to reuse the cooling material without electricity. The ammonium chloride solution can be removed, heated to evaporate the water, and the remaining salt can be reused by dissolving it in fresh water to recreate the cooling effect. A doctor at V One Hospital in Indore reported that vaccines could be stored in Thermavault for approximately 10 to 12 hours.

The team believes their invention could significantly improve the transport of vaccines, medicines, and other temperature-sensitive supplies to areas where conventional refrigeration is unfeasible.

Recognition and Future Goals

Winning the Earth Prize has provided these students with an opportunity to advance their project beyond the classroom. This award recognises young individuals working on environmental initiatives, with winners selected globally. Chaudhary, Ladhania, and Jain received the Asia award in 2025 and aim to obtain Performance, Quality, and Safety certification from the World Health Organization (WHO).

They also aspire to present their technology to Gavi, an international alliance focused on improving vaccine access. This project exemplifies how school science can extend beyond textbooks, demonstrating that classroom concepts, when combined with research and mentorship, can lead to solutions for real-world challenges.

For these students, a lesson on salts and chemical reactions evolved into a meaningful endeavour to address healthcare issues affecting communities far beyond their educational environment.

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