Cooling towers are the oldest technology in the data center thermal stack. Open-circuit evaporative systems that reject heat from a chilled water plant by evaporating water to atmosphere have been standard mechanical plant equipment for 40 years. The AI buildout is not eliminating them. It is changing which type dominates and forcing operators to confront the water consumption math that the industry has deferred for years.
The global cooling tower market for data centers was valued at $3.17 billion in 2024. At an 11.8% compound annual growth rate projected through 2034, that figure reaches $6.50 billion, roughly doubling in a decade. North America holds the largest current market share. Asia Pacific is growing fastest, with Singapore, Hong Kong, Tokyo, and Chinese hyperscale deployments as the primary drivers. China's liquid cooling tower demand alone is projected to exceed $2 billion as the country's AI data center construction program accelerates through 2028.
Traditional open-circuit cooling towers expose the process water directly to atmosphere. Hot water from the facility's chilled water plant enters the tower, flows over fill media, and is cooled by a combination of evaporation and sensible heat exchange with ambient air. The evaporated water carries latent heat away from the system. Open-circuit towers are thermally efficient and capital cost effective. They consume substantial quantities of water: traditional cooling towers account for approximately 30% of data center facility water usage, require ongoing chemical treatment for biological and scale control, and produce visible plumes that have become a community relations liability in jurisdictions watching data center water consumption closely.
Closed-circuit cooling towers (also called fluid coolers) use a heat exchanger coil or tube bundle inside the tower. The process fluid, chilled water or glycol mixture, circulates through the coil without direct contact with the external evaporating water. Heat transfers from the process fluid through the coil wall to the spray water that evaporates externally. The critical difference: the process fluid that circulates through facility CDUs, liquid cooling loops, and server-side cold plates never contacts the atmosphere or the external spray water. Contamination from airborne particulate, biological growth, and dissolved solids in the makeup water stays in the external spray circuit. The process fluid loop stays clean, extending component life in CDU heat exchangers, pump seals, and cold plate microchannels.
The thermal efficiency penalty is real. The added heat transfer resistance of the coil wall reduces cooling capacity by 10 to 15% compared to equivalent open-circuit designs, requiring larger equipment for the same heat rejection duty. For most AI data center operators managing high-value cooling loops connected to million-dollar GPU servers, the process fluid protection and reduced maintenance burden justify the efficiency penalty.
The market growth projection runs directly into a regulatory headwind that the 11.8% CAGR figure does not capture. Nevada has restricted evaporative cooling for new data center construction in certain jurisdictions. Arizona has moved in the same direction. The EPA's WRAP 2.0 initiative explicitly targets data center cooling water consumption as a federal priority, pushing operators toward recycled water supplies and closed-loop systems. When Google's cooling towers at The Dalles produce fog plumes dense enough to divert airport traffic and the story reaches state legislators, the regulatory response tends to follow within 18 months.
Operators who can demonstrate closed-loop or zero-makeup-water cooling architectures will have a materially different conversation with local water authorities during permit applications for new capacity. Operators proposing open-circuit evaporative systems in water-stressed regions are facing permit denials that did not exist five years ago. The market shift toward closed-circuit systems is partly technical preference and partly regulatory pressure. Both vectors are pointing the same direction.
Immersion cooling deployments are creating a specific demand category for closed-circuit fluid coolers. Single-phase immersion systems circulate large volumes of dielectric fluid through computing equipment and deliver it to an external heat exchanger for rejection. The heat rejection equipment of choice for large single-phase immersion deployments is a closed-circuit fluid cooler, where the dielectric fluid transfers heat to an intermediate water loop without atmospheric contamination of the fluid. As immersion cooling scales from pilot programs to production deployments, each new immersion facility is a new fluid cooler installation.
The market segment data shows immersion liquid cooling systems driving the strongest growth in cooling tower applications, with hybrid cooling systems second. The AI-specific demand for higher heat rejection capacity per unit footprint is also pushing manufacturers toward higher-efficiency designs. SPX Cooling Technologies, EVAPCO, and Kelvion hold the leading market positions, with those vendors plus roughly two others accounting for approximately 60% of total market revenue. The top five's concentration reflects both scale advantages in manufacturing and the purchasing patterns of hyperscale operators who consolidate supplier relationships across large capital programs.
The $3.17 billion to $6.50 billion growth story understates one dynamic: within the total market, the premium segment serving high-density AI cooling applications is growing faster than the aggregate 11.8% CAGR. Tier IV data centers, which have the most demanding uptime and cooling requirements, show the strongest cooling tower adoption by specification rigor. AI-driven management systems for cooling towers, which adjust fan speed, spray water flow, and heat rejection capacity in real time against actual compute load and ambient conditions, represent a $220 million opportunity by 2027 as operators recognize that static setpoint control leaves significant operating efficiency on the table.
The cooling tower market growth projections reflect genuine AI-driven demand for heat rejection capacity. What the aggregate number does not show is the regulatory pressure accumulating around open-circuit evaporative systems in water-stressed markets, and the premium operators are paying to specify closed-circuit systems that can survive permit scrutiny in Arizona, Nevada, Texas, and European jurisdictions with water use restrictions. The gap between "market growing at 11.8% CAGR" and "municipalities restricting evaporative cooling" will force operators toward closed-loop architectures faster than demand growth alone would predict. The vendors building that product line are better positioned than the ones optimizing the legacy open-circuit designs.