Mihir Nandkeolyar, Director of Business Development, Global Data Centre Solutions at Johnson Controls, explains how heat capture technology is being used to channel waste heat from data centre operations to power cooling applications.
Data centres built around onsite generation are already sitting on an energy stream that can offset a major part of cooling demand: high-temperature waste heat. With absorption chillers, that thermal energy becomes the driver for chilled water production, allowing a substantial share of cooling to be delivered with minimal electrical input.
That shift is arriving at the right moment. The AI cycle is increasing deployment pace and compute density, but grid infrastructure is not expanding at the same rate. In many regions, operators face extended connection timelines, constrained capacity offers, higher energy costs, and uncertainty around when additional power will be available. In practice, the grid is becoming a gating factor for new capacity.
Onsite power is therefore moving into the centre of data centre design. Some forecasts suggest that by 2030, around one-third of data centres could be operating as fully onsite-powered campuses. And when generation is brought onsite, the thermodynamics are unavoidable: typically, only 35-50% of the fuel energy emerges as electricity, while the remainder is discharged as heat.
If that heat is captured rather than rejected, it can be repurposed to meet cooling needs, reducing dependence on electric chillers and avoiding further load on an already constrained grid.
Absorption chillers use waste heat as the driving force for cooling, replacing the mechanical compressor found in traditional refrigeration systems with a thermally driven process.
Thermal-driven chilling away from the grid
One pivotal approach is the application of absorption chillers to create a Combined Cooling and Power (CCP) plant. These plants recover otherwise wasted energy from gas turbines, fuel cells or engine-driven generators to power the thermally driven chiller to produce cooling.
Absorption chillers are not new; Johnson Controls deployed YORK absorption systems over a century ago and today have many thousands in operation worldwide. Their use has been common where thermal energy is more easily or economically available than electricity. Today's absorption chillers represent a major leap forward in cooling innovation, enhancing reliability and sustainable performance. Modern systems are engineered to maintain optimal operating conditions with ease, ensuring smooth, uninterrupted cooling even in demanding environments. By harnessing a combination of varying grades of waste heat as their energy source, next generation absorption chillers provide a powerful and sustainable alternative to traditional electric cooling, cutting energy and water use, reducing emissions, and helping organisations move toward a cleaner, more efficient future.
For this reason, their application at large data centres where vast amounts of high temperature waste heat is abundantly and economically available from onsite generation sources - is ideal. They also deliver significant energy efficiency benefits: for every 2 MW of cooling supplied, an absorption chiller needs only 20 - 25 kW of electrical input compared to 500 kW or more for an electric chiller. That's more than an 90% reduction in needed electricity.
Absorption chillers use waste heat as the driving force for cooling, replacing the mechanical compressor found in traditional refrigeration systems with a thermally driven process. In these systems the shifting concentration of the absorbent solution is both a powering mechanism and a heat transfer mechanism. Through a coordinated sequence of evaporation, absorption, generation, and condensation - each governed by changes in temperature and pressure - the refrigerant and absorbent circulate to produce chilled water.
Absorption chillers can be easily combined with other thermal management technologies if additional cooling demand is needed.
Scaling strategies when power is the limiting factor
Moving forward, data centres will not be defined by raw compute power alone, they will be defined by how intelligently they utilise energy, heat and water. Efficient cooling is quickly becoming an enabler for competitiveness in an increasingly constrained environment. Absorption chillers are reshaping what is possible in real time at onsite-powered data centres.
While some operators will remain stuck with long grid connection delays and rising energy costs, those operators that turn waste heat from a costly byproduct into a strategic resource gain a significant edge, becoming more efficient, resilient, and sustainable while delivering greater benefits to their communities.
By turning waste heat from a costly byproduct into a strategic resource, operators can become more efficient, resilient, sustainable and positively impact their communities.
