DATA CENTRE MANAGEMENT


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


How to cut the cost of cooling


Mihir Nandkeolyar makes the case for data centres using absorption chillers to convert onsite waste heat into cooling, to reduce electricity demand and ease grid constraints while improving efficiency and sustainability.


Mihir Nandkeolyar


Director business development global data centre solutions at Johnson Controls


www.johnsoncontrols.com I


n data centres that generate power onsite, the biggest untapped efficiency gain is often sitting in the form of rejected heat. Absorption


chillers can convert that high- temperature waste heat into chilled water, meaning a significant portion of the cooling requirement can be delivered with minimal electrical input. This is becoming less of an optimisation and more of a necessity. As AI accelerates buildouts and raises rack densities, many operators are running into the practical limits of grid supply. Delayed connections, constrained capacity allocations, rising and unpredictable electricity prices, and unclear timelines for reinforcement are increasingly common across major markets. The result is a shift in how data centres are designed and scaled: power strategy is now a gating factor.


14 Onsite generation is therefore


moving from a supplementary option to a core part of campus planning. Some forecasts suggest that by 2030, around one-third of data centres could be fully onsite-powered. Yet onsite power has an inherent inefficiency that can be turned into an advantage. Typically, only 35–50% of the fuel energy becomes electricity; the rest leaves as high-grade thermal energy. Instead of treating that heat as a disposal problem, operators can treat it as an input, using it to produce cooling and reducing the need to add more electrical load to an already constrained grid.


Taking load off 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


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 a 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.


Efficient cooling is quickly becoming an enabler for competitiveness in an increasingly constrained environment


Energy and water performance 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. ■


EIBI | MAY 2026


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