IIT Bombay Unveils Solar Storage Tech to Replace Diesel Heaters in the Himalayas

Researchers from the Indian Institute of Technology Bombay (IIT Bombay) have unveiled a solution to tackle the harsh winters of the Himalayan regio, by bottling summer sunlight for use in winter. The innovative system uses a chemical process to store solar energy collected during summer and release it as heat in freezing months, offering a sustainable alternative to diesel-based heating.

The study, led by Dr. Sandip Kumar Saha and Dr. Chandramouli Subramaniam, proposes using thermochemical storage powered by strontium bromide, a safe, stable, and non-toxic compound. The method mirrors how batteries store electricity, but here, it stores heat. During summer, solar thermal collectors heat air, which dehydrates the strontium bromide crystals, effectively storing energy in chemical bonds. In winter, when moisture-laden air passes over the material, the reverse reaction releases the stored heat, providing warmth for months.

The team has developed a prototype capable of storing 500 kilowatt-hours of energy, enough to heat a small Himalayan home for up to four months. Each compact module is the size of two LPG cylinders and can be transported easily, even from sunny states like Rajasthan or Gujarat, to the Himalayan region.

Dr. Rudrodip Majumdar, who contributed to the project, noted that the motivation was personal as well as scientific, having witnessed firsthand the struggles of Himalayan communities dependent on firewood or diesel for heating. He emphasised that the reactors are durable, with thermochemical salts capable of handling 500-600 charging cycles without performance loss.

The research shows the Levelised Cost of Heating (LCOH) ranges from INR 33 to INR 51 per kWh, which is cheaper than diesel heating when factoring in fuel transport and carbon penalties. In Leh, the LCOH is as low as INR 31 per kWh. The team also noted potential applications for the Indian army in sub-zero camps.

While the technology is still awaiting real-world deployment, the IIT Bombay researchers believe that with field testing and policy support, their system could become a game-changer for energy-deprived cold regions, offering clean, smoke-free, and reliable heating. “Energy poverty should not exist in the 21st century,” said Dr. Majumdar, adding, “this is a step toward energy security for even the remotest communities.”