By Subhasish Mukerjee

Data centres that heat swimming pools make for great media stories, but there is a deeper significance to the integration of waste heat into industrial processes. As the world wrestles with the great energy transition, a key consideration is how to make clean power efficient.

As other posts in this series have documented, India is one of the world’s most ambitious countries when it comes to energy. It seeks to be both clean and self-reliant, despite a heavy reliance on fossil fuels, especially coal, today. It is no surprise that India is also a leader in heat integration for clean power.

What makes India’s case special is its reliance on energy intensive processes such as fertilisers, steel and bulk chemicals where emissions cannot be abated by solar or wind power.

India also intends to be a world-leading digital nation. It has proven that it is has the skills and educational institutions to deliver on this but is now building the infrastructure to develop self-reliance in IT, with massive investments in data centres and networks.

All of this makes achieving efficiency through heat integration a key objective for India – and it is increasingly looking to solid oxide fuel cells and electrolysers to enable it to meet this objective.

How Heat Integration Works

While electrolysis processes require heat to activate the reaction, the fuel cell process generates heat through its exothermic nature. In both cases, excess thermal energy is generated that can be transferred or reused either directly or through heat exchangers. Heat integration dramatically drives up the efficiency of the processes and can lead to overall system efficiency increases from over 60% to over 90%¹.

But not all fuel cell technologies lend themselves to efficiency gains through heat integration. While the low operating temperatures of Proton Exchange Membrane and Alkaline (60 to 100^oC) mean that efficiency gains are not so great, the higher operating temperatures of solid oxide (450-630^oC for Ceres) dramatically push up the efficiency benefit of heat integration, delivering the 90%-plus system efficiency.

The core methodology of heat integration involves the strategic transfer of thermal energy between the fuel cell or electrolyser with the heat exchanger. This energy can then be converted directly into electrical energy or used to pre-heat water for the endothermic electrolysis process, significantly cutting the required electricity. This integration is typically achieved using a single or closely linked thermal management loop, which minimises thermal losses and maximises the transfer of heat.

How Indian Industries Stand to Benefit

Heat integration promises to be particularly significant in India across four core sectors:

• Oil and Gas Industry: The 90%-plus efficiency of heat-integrated solid oxide electrolysers can cut costs and reduce emissions by using the waste gases and flare systems as fuel sources in the production of hydrogen from water.

• Data Centres, Hospitals, and Commercial Buildings: These facilities require highly reliable, uninterrupted power and also have significant heating and cooling demands. Solid oxide fuel cell (SOFC) systems can provide both electricity and heat (or even cooling through integrated absorption chillers), significantly reducing energy costs and carbon footprints compared to conventional power and heating methods.

• Chemical Industry through Green Ammonia Production: Operating at high temperatures, solid oxide electrolysers can integrate directly with industrial waste heat streams to produce green hydrogen more efficiently. This green hydrogen is then used to create ammonia as part of the fertiliser production process. With 140 million farming households, India consumes close to 70 million tonnes of fertiliser annually but only produces 30 million tonnes domestically².

• Decentralised Power and Rural Applications: SOFCs can run on a variety of fuels, including natural gas, biogas and biofuels, making them suitable for off-grid or microgrid deployments in remote areas of India where centralised infrastructure is limited.

Ceres, through its India-based partner Thermax, is already on the path to providing highly efficient electrolysis through the planned manufacture of solid oxide electrolysis systems for India’s chemicals industry among others.

India’s industry and data centre sectors could soon be benefitting from the extreme efficiency that solid oxide enables through heat integration, helping the country to realise its energy and resilience ambitions.

¹ Weichai released world's first high-power fuel cell sofc

² Fertiliser import likely to jump 41% in FY26 on strong monsoon demand