What is data center liquid cooling?

How it works

Air cooling delivers chilled air to servers and removes the warmed air. Liquid cooling brings a fluid close to the hottest components. A Congressional Research Service report describes direct liquid cooling as capturing heat near the chips before it has much effect on room air temperature.

A 2025 analysis in Nature, by authors at Microsoft and WSP Global, describes three approaches. Cold plates, also called direct-to-chip cooling, are small heat exchangers placed on high-power chips. A coolant loop carries heat out of the server. Some air cooling may still be needed. In one-phase immersion, whole servers sit in a tank of dielectric (electrically nonconductive) fluid that pumps push through them. In two-phase immersion, the fluid boils at a low temperature and the vapor condenses on a coil.

The Open Compute Project's cooling group lists five work areas: cold plates, coolant distribution units, immersion, door heat exchangers and heat reuse.

Why it matters

The Nature authors wrote that rising chip power will probably push data center heat loads beyond what current air cooling can handle. The International Energy Agency said in April 2026 that the power density of AI servers rose 11-fold between 2020 and 2025. It said density is set to increase a further fourfold by 2027.

The Nature study, a life cycle assessment comparing cold-plate and immersion-cooled data centers with air-cooled ones, found the liquid methods cut:

• greenhouse gas emissions by 15% to 21%
• energy demand by 15% to 20%
• water consumption by 31% to 52%

Microsoft says a data center design it launched in August 2024 recycles water through a closed loop and consumes none for cooling.

Where things stand in 2026

Nvidia describes its GB200 NVL72 rack, which holds 72 GPUs, as a liquid-cooled design. In the Uptime Institute's 2026 survey, 24% of respondents had some racks drawing 30 kilowatts or more, up from 19% in 2025. Most facilities had none. Uptime wrote in September 2026 that dense AI computing has boosted adoption of direct liquid cooling, mostly with water cold plates. But it said practices for running it at scale are still maturing.

The Nature paper says two-phase immersion fluids are PFAS, fluorinated chemicals. A restriction proposal from five national authorities covers PFAS. The European Chemicals Agency (ECHA) published it in February 2023. ECHA's Risk Assessment Committee adopted its opinion on the proposal in March 2026.