In a breakthrough that could reshape winter heating in India’s cold desert regions, such as snow-covered Leh, researchers at the Indian Institute of Technology Bombay (IIT Bombay) have developed a solar-powered thermal battery that can store summer heat for use in the harsh Himalayan winters. This heat storage system could offer a cleaner, long-term alternative to diesel heaters, which are carbon-heavy machines powered by costly fuel that must be trucked over perilous winter roads.  

In a recent study, the team of researchers: Ankush Shankar Pujari, Rudrodip Majumdar, Chandramouli Subramaniam and Sandip K. Saha have proposed using strontium bromide in a thermochemical storage system that aims to provide a clean and sustainable alternative to diesel heaters in high-altitude regions like Leh, where winter temperatures remain below freezing for months and households rely heavily on diesel heaters, an expensive and polluting option.  

“Energy poverty shouldn’t exist in the 21st century,” said Dr. Rudrodip Majumdar, a co-author of the study who worked on this project as a postdoctoral fellow at IIT Bombay and currently at the National Institute of Advanced Studies (NIAS). “We’ve seen people walk kilometers to collect firewood. Diesel becomes the only backup, but it’s costly and harmful.”  

How it works 

Strontium bromide has been the subject of many studies examining thermochemical storage. Much like a battery stores electricity, thermochemical storage stores heat in the form of chemical energy. Strontium bromide is chosen for its high energy density, chemical stability, non-toxicity, non-explosiveness, and environmental safety. 

The researchers developed a prototype that first uses solar thermal air collectors which harness sunlight to heat air in the summer. Next, this hot air is used to warm up a form of hydrated strontium bromide (hexahydrate). In this form, the strontium bromide crystals contain water molecules within their structure. During this heating process, the material undergoes an endothermic dehydration reaction, in which heat energy is absorbed, causing the expulsion of water molecules from its crystal structure. This reaction stores the absorbed solar energy as chemical potential in the resulting monohydrate salt. In winter, moist air passes through the charged salt, triggering a reverse reaction or rehydration. The process reintroduces the water molecules into the structure in an exothermic reaction, releasing the stored heat.  

Mr. Majumdar said that the technology is a sustainable solution in Himalayan regions, which face long, frigid winters. The population has limited access to sustainable heating options and usually depends on diesel or firewood. Therefore, what makes thermochemical storage particularly suited to these regions is its ability to retain energy over several months.  

Sharing his personal experience that led to the research, he said, “I went to the Chopta-Tungnath-Chandrashila trek and stayed in camps. The starry nights in the Himalayas are beautiful, but the night stay can turn very hostile. I’ve seen people struggling, walking ten kilometers just to collect firewood. Diesel becomes the only backup, but it’s a heavy polluter.”  

Cost-efficient and carbon saving 

To help the communities, a module capable of storing about 500 kilowatt-hours of energy was designed, enough energy to heat a small Himalayan home for up to four months, the team said.   

The whole setup consists of a simple, modular unit designed to be easy to transport and operate. It includes solar thermal collectors that heat air during summer, a reactor chamber filled with strontium bromide salt, and a small air circulation system to trigger dehydration and rehydration cycles. The reactor components are housed in a compact, weatherproof unit designed for Himalayan conditions and are insulated using glass wool. 

“Solar collectors are well-proven. Steel tanks have been made for years. The only new contribution is stabilising the thermochemical material and packaging it for daily life. This kind of long-term seasonal storage is made possible because the energy stored in the material is very stable. It does not degrade over time,” added Dr. Majumdar.  

The modest module doesn’t take up the entire room, either. According to Sandip Kumar Saha from IIT Bombay, who led the study, “Each storage module is roughly the size of two LPG cylinders and designed to be portable. They can be recharged in the summer at solar stations—possibly even in sunnier regions like Gujarat or Rajasthan—and trucked up to Himalayan towns just before winter.”  

“Once you deploy this material, you don’t need to change it. If you maintain the reactor with basic precautions, the operation and maintenance costs will come down. These are very sturdy reactors,” added Dr. Majumdar. 

The team said they have already tested the material through six full charging and discharging cycles in the lab, with no performance degradation. Thermochemical salts like strontium bromide are theoretically capable of 500 to 600 cycles, that means each unit could last years.  

While the upfront investment may be higher than diesel heaters, the study finds that thermochemical systems are more economical over time—especially in remote regions where diesel prices are inflated due to transportation costs and where the environmental impact, or potential penalties from carbon emissions, adds to the overall burden. 

“If we want to produce electricity from diesel today, it will cost us ₹50 per unit (kWh). If we add a carbon penalty, it could go up to ₹78 per unit. Then the thermochemical solution will be half the price,” Mr. Majumdar said. 

The study calculated the thermochemical systems’ Levelized Cost of Heating (LCOH), the average cost of producing usable heat over the lifetime of a heating system, to be between ₹33–₹51 per kWh in different Himalayan cities. This cost makes it competitive with or cheaper than diesel heating for daily use, especially when factoring in fuel transport and environmental costs. In Leh specifically, LCOH dropped to ₹31/kWh, the lowest among all locations (Darjeeling, Shillong, Dehradun, Shimla, Jammu, Srinagar, Manali, and Leh) studied. 

Dr. Chandramouli Subramaniam from IIT Bombay explained, “Such solar-thermal energy solutions for space-heating have been successfully tested in harsh climatic conditions for the Indian army at sub-zero temperatures. We are in the process of developing thermal storage solutions for round-the-year, smoke-free heating to camps for our Indian army stationed at such high altitudes.” 

Internationally, thermochemical storage has only been piloted in places like Germany, with limited large-scale adoption. In India, practical deployment in homes is yet to be tested, and initial costs remain relatively high compared to diesel heaters. The system also relies on adequate summer sunlight to charge the salt and sufficient winter humidity to release the stored heat—factors that vary across Himalayan regions. Still, the researchers believe that with field trials, policy support, and local engagement, technology can become a crucial part of a more sustainable and inclusive energy future. 

Image for representational purposes only.
| Photo Credit: E. Lakshmi Narayanan

With its advanced capabilities to identify chip defects, the Quantum Diamond Microchip Imager is a leap forward in semiconductor imaging. Representational
| Photo Credit: Reuters

The Indian Institute of Technology Bombay (IIT-Bombay) has entered a strategic partnership with Tata Consultancy Services (TCS) to develop India’s first Quantum Diamond Microchip Imager.

This advanced sensing tool will hold the potential to unlock new levels of precision in the examination of semiconductor chips, reduce chip failures and improve the energy efficiency of electronic devices.

Over the next two years, experts from TCS will work with Dr. Kasturi Saha, Associate Professor in the Department of Electrical Engineering of IIT Bombay, to develop the quantum imaging platform in the PQuest Lab.

This platform will enable better quality control of semiconductor chips, thereby improving product reliability, safety, and energy efficiency of electrical devices.

Semiconductor chips are essential to all modern electronic devices, making them smart and efficient. With the ability to process data and complete tasks, these chips act as the brains of devices across industries such as communications, computing, healthcare, military systems, transportation and clean energy.

Dr. Kasturi Saha said, “PQuest group at IIT-Bombay is excited to collaborate with TCS on developing a quantum imaging platform for the non-destructive examination of chips, leveraging our extensive expertise in quantum sensing to drive innovation. We aim to transform various sectors, including electronics and healthcare, and propel India forward through groundbreaking technologies and products aligned with National Quantum Mission’s Quantum Sensing and Metrology vertical.” 

Dr. Harrick Vin, Chief Technology Officer, TCS, said, “The Second Quantum Revolution is progressing at an unprecedented speed, making it imperative to pool our resources and expertise to build cutting-edge capabilities in sensing, computing, and communication technologies. This initiative will have a transformative impact on various industries and society, with applications ranging from electronics to healthcare, and beyond. By working together, we can drive innovation and create a brighter future for all.”

‘We are keen to collaborate with industry’

The collaboration between TCS and IIT-Bombay is aligned with the National Quantum Mission — an initiative by the Government of India to position the nation as a global quantum technology leader.

Prof. Shireesh Kedare, Director, IIT-Bombay, said, “This collaboration aims to develop a quantum imaging platform for the non-destructive examination of chips. We are keen to collaborate with industry to translate the ideas, innovations and research into the technologies and products through such collaborations as well as start-ups that will take India ahead.”

Wide application

As semiconductors continue to shrink in size, traditional sensing methods lack the precision and capabilities to detect anomalies in chips. The Quantum Diamond Microchip Imager can image magnetic fields, enabling a non-invasive and non-destructive mapping of semiconductor chips, much like an MRI at a hospital.

It uses the defects in a diamond’s structure, known as Nitrogen-Vacancy (NV) centres, together with the other hardware and software for detecting and characterizing anomalies in semiconductor chips. The diagnostic capabilities will have significant implications for failure analysis, device development, and various optimisation processes, Mr. Kedare explained.

With its advanced capabilities to identify chip defects such as current leakages and enable visualisation of three-dimensional charge flow in multi-layer chips, Quantum Diamond Microchip Imager is a leap forward in semiconductor imaging.

It will have wide applications in microelectronics, biological, and geological imaging, and fine-scale imaging of magnetic fields, among others. This project builds on TCS and IIT-Bombay’s dynamic partnership since the 1990s, spanning joint research projects, collaborative education programs, internships, faculty development programs, and more. IIT-Bombay was the first institute to be signed as an academic partner for TCS’ Co-Innovation Network, a platform driving industry-academia collaboration for pioneering solutions.