On India’s southeastern coast, at Kalpakkam in Tamil Nadu, a significant milestone in nuclear and clean-energy technology has been achieved. A reactor that has been operating for four decades has been used to produce hydrogen directly from water using its own heat rather than electricity, a feat that scientists describe as a global first.
On June 26, 2026, the Department of Atomic Energy inaugurated what it says is the world’s first hydrogen production facility powered by the thermal energy of a nuclear reactor instead of electrical energy. The facility is located at the Indira Gandhi Centre for Atomic Research (IGCAR) in Kalpakkam.
Although the plant is relatively small, its importance lies in demonstrating a new technological pathway rather than producing hydrogen on a commercial scale.
The facility generates hydrogen, a clean fuel that releases only water when burned, by using heat obtained directly from a nuclear reactor. It serves as a technology demonstrator designed to prove the feasibility of the concept under real operating conditions. Its purpose is not large-scale fuel production but validation of the technology.
Traditionally, clean hydrogen is produced through electrolysis, a process in which electricity is used to split water into hydrogen and oxygen. While effective, electrolysis consumes substantial amounts of electrical energy and remains relatively expensive.
The Kalpakkam facility follows a different approach. It employs the copper-chlorine thermochemical cycle, a method that relies primarily on heat rather than electricity to separate hydrogen from water.
Water molecules are difficult to break apart directly. Conventional methods require either large amounts of electricity or extremely high temperatures. The copper-chlorine cycle overcomes this challenge by using copper and chlorine compounds as intermediaries. Instead of attempting a single energy-intensive reaction, the process divides the task into several smaller chemical steps.
In this cycle, water first reacts with a copper-based compound. Through a series of controlled reactions, hydrogen and oxygen are released at different stages. By the end of the process, the copper and chlorine compounds are regenerated and returned to their original state, allowing them to be reused repeatedly. Only water is consumed, while hydrogen and oxygen emerge as the final products.
Although a small amount of electricity is still required, the overall electrical demand is significantly lower than that of conventional electrolysis.
One of the reasons the copper-chlorine cycle is particularly suited to nuclear applications is its relatively modest temperature requirement. The process operates at approximately 450 to 550 degrees Celsius, whereas many competing thermochemical hydrogen-production methods require temperatures exceeding 800 degrees Celsius.
This temperature range aligns well with the heat produced by nuclear reactors. Since reactors primarily function as large heat-generating systems, their thermal energy can be used directly in industrial processes instead of first converting it into electricity.
Normally, reactor heat is used to generate steam, which drives turbines to produce electricity. Each conversion stage results in some energy loss. By directly using reactor heat for chemical reactions, the Kalpakkam facility avoids some of these inefficiencies.
This approach, known as process heat utilisation, allows thermal energy to be applied directly to industrial applications. Studies suggest that such systems can achieve overall efficiencies ranging from roughly 37 to 54 percent, depending on how effectively waste heat is recovered and reused.
While the copper-chlorine cycle itself has been researched for years and was developed in India by the Bhabha Atomic Research Centre (BARC), integrating the technology with a functioning nuclear reactor had not previously been accomplished anywhere in the world.
Researchers have long demonstrated the chemistry in laboratory settings. However, scaling it up and connecting it to a live reactor environment presented a much greater engineering challenge. Industrial-scale systems must contend with issues such as corrosion, heat transfer efficiency, material durability, and chemical handling at larger volumes.
Successfully overcoming these engineering hurdles and operating the complete integrated system is what makes the Kalpakkam project a significant achievement.
The heat for the hydrogen-production facility is supplied by the Fast Breeder Test Reactor (FBTR), a 40-megawatt thermal reactor that uses liquid sodium rather than water as its coolant. Liquid sodium can efficiently transport heat at high temperatures, making it particularly suitable for fast breeder reactor technology.
The reactor has been in operation since the mid-1980s and has played a key role in testing fuels, materials, and technologies intended for India’s fast breeder reactor programme, including the larger 500-megawatt Prototype Fast Breeder Reactor.
For decades, the FBTR primarily served as a research platform. The addition of hydrogen production gives it a new role as a source of clean industrial energy.
The development is significant because it broadens the potential applications of nuclear energy beyond electricity generation. Nuclear-powered hydrogen production offers the advantage of continuous operation, unlike renewable energy sources such as solar and wind, which depend on weather and daylight conditions.
If successfully scaled up, nuclear hydrogen could help decarbonise industries that are difficult to electrify, including steel manufacturing, fertiliser production, oil refining, and other heavy industrial sectors.
For India, the project also fits into the broader vision of expanding the country’s nuclear programme and exploring new pathways for clean energy production. It demonstrates that nuclear reactors can serve not only as sources of electricity but also as providers of industrial heat capable of producing clean fuels.
The Kalpakkam facility therefore represents more than a technological experiment. It showcases a potential future in which nuclear energy contributes directly to hydrogen production, opening new possibilities for reducing carbon emissions while supporting industrial growth.
