Closed-Loop Cooling Systems Used for AI Data Centers  - Using Chemicals to Reduce Consumptive Water Use by Grok

We asked Grok a Question- What are the most common chemicals used in the closed-loop cooling approach proposed by some AI Data Centers ?

So Yes, this is an AI generated article. To be honest, I thought it very timely to post an article about AI using AI and yes the use is not just the use of the water, but the consumptive use of water.

Notes in Red – are comments from the KNOW YOUR H20 Team and not the Grok.

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In closed-loop cooling systems for AI data centers, heat is absorbed from servers and components (e.g., via direct-to-chip methods like cold plates) and transferred through a sealed, recirculating fluid loop to external heat exchangers or chillers, without evaporation or ongoing water intake.  This approach minimizes water consumption (Consumptive Water Usage) compared to traditional evaporative cooling, making it suitable for high-density AI workloads that generate intense heat (up to 200+ kW per rack). The systems are designed for efficiency, with the fluid chosen for high thermal conductivity, low viscosity, corrosion resistance, and freeze protection.

Definitions:

Consumptive Water Use -  “Consumptive Water Uses:  Any consumptive water use of 20,000 gpd or more over a 30-day average from any water source is regulated. Consumptive water use is defined as water that is withdrawn either from groundwater, surface water, or from public water supplies, and is used in such a way that it is not returned to the Basin undiminished in quantity. Water is considered lost to the Basin when, for example, it is evaporated, transpired due to irrigation, incorporated into manufactured products, or injected underground. All consumptive water use for natural gas activities must obtain Commission approval.”  (Source: SRBC)  Note all definitions of consumptive water use are the same, it is important to determine which definition applies and this is typically related to the River Basin Commission that covers the project area or some other federal or state or multi-state agency.

Thermal Conductivity – “Thermal conductivity is the ability of a material to conduct heat, typically measured in watts per meter-kelvin (W/m·K). It quantifies how well heat is transferred through a material when there is a temperature difference across it.”   (Source: Duck Duck Go AI)

Common Recirculated Fluid (Glycol based)

The most common chemical recirculated in these systems is a glycol-water mixture, typically consisting of propylene glycol (or less commonly, ethylene glycol) diluted with water to a concentration of 25-30% glycol by volume. This solution serves as the heat transfer fluid, absorbing heat from IT equipment and circulating in a closed loop to dissipate it elsewhere. (Source: boydcorp.com)

Pure water or deionized water can also be used in some setups, but glycol additions are standard to prevent freezing (e.g., down to -15°C or lower), inhibit corrosion, and act as a biocide/fungicide.  (Source: boydcorp.com)

Propylene Glycol (Preferred): Non-toxic, safer for environments with potential leaks or human exposure, and commonly used in formulations like DOWFROST LC (Dox Chemical) or Coolflow DTX (Hydratech). It provides good heat transfer (close to water's efficiency) with added inhibitors for metals like copper in cold plates. Mixtures are pre-diluted with high-purity water (e.g., distilled or deionized) to avoid impurities that could cause scaling or reduced performance. (Source: datacenterfrontier.com)

Ethylene Glycol (Alternative): Offers slightly better thermal conductivity but is more toxic than propylene glycol, requiring careful handling and disposal. It's less favored in modern data centers due to environmental and safety concerns. (Source: hydratechfluids.com)

Additives in the Mixture: To enhance longevity (up to 5-8 years), the fluid often includes corrosion inhibitors (e.g., nitrite for steel, tolyltriazole for copper, organic acids for aluminum), biocides to prevent microbial growth, and pH stabilizers. These prevent buildup of dissolved metals, salts, or slime (biological agents) in the loop.  (Source: ketos.co)

Table 1. Summary of the Closed-loop Cooling Fluids.

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Alternatives and Considerations

For specialized setups like immersion cooling (a variant sometimes confused with closed-loop), dielectric fluids (e.g., fluorocarbons like 3M Fluorinert or synthetic hydrocarbons like PAO) are recirculated instead, as they are non-conductive and prevent electrical shorts. (Source: boydcorp.com)

Note: “PFAS, or per- and polyfluoroalkyl substances, are a group of synthetic chemicals that include fluorocarbons, characterized by multiple fluorine atoms attached to an alkyl chain. They are often referred to as "forever chemicals" due to their persistence in the environment and potential health risks” (Source: Duck Duck Go AI)

However, these are less common in standard closed-loop systems due to lower thermal efficiency and higher cost. Maintenance involves monitoring pH, glycol concentration, and inhibitor levels to avoid degradation, with periodic top-ups or blow-downs. (Source: ketos.co)

Companies like Microsoft and others adopting zero-water designs prioritize these fluids for sustainability, potentially saving millions of liters of water annually per site. (Source: middletowndatacenter.com)

Grok:  Did not specific mention the following:

Does the chemicals in AI closed loop systems include forever chemicals ?

“Yes, closed loop systems in AI data centers often use per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals," as refrigerants in cooling systems. These chemicals are persistent in the environment and can pose significant health risks.” (Source:  Duck Duck Go AI)

Article 1:  Artificial Intelligence: Data Centers Water Consumption – Thoughts for the Poconos and Northeastern Pennsylvania

Article 2: The Know Your H20 Comments on AI Development in Northeast Pennsylvania.

Article 3:  Artificial Intelligence (AI) Data Centers the Microsoft Zero Water Cooling System by Grok

Article 4: Google Data Center Approach Climate-Conscious Conservation Carbon Reduction by Grok

Article 5: Closed-Loop Cooling Systems Used for AI Data Centers Using Chemicals to Reduce Consumptive Water Use Grok

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End Of AI Generated Content

If you like long detailed responses – use Grok (X AI).   Short answers- Duck Duck Go AI

The cell phone and social media have done Great Hard to Young Adults – What will AI-Generated Friends, Communities, Porn, Worlds etc do to Human Interaction and Culture ? – Read “The Anxious Generation: How the Great Rewiring of Childhood Is Causing an Epidemic of Mental Illness” for some insights.

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