Water Consumption Concerns as Data Center Use Increases

10/8/2024

It’s a great time to be in the data center business according to JLL’s new U.S. Data Center Report, which indicates that the market has doubled in size in four years.  

“This incredible trajectory is being driven by our voracious fourth industrial revolution appetite for digital services; every application you use, photo you take and video you record generates content which consumes data center space and energy,” says Sean Farney, vice president, Americas Data Center Strategy, JLL. “Without restricting access or authoring capabilities – especially as each new generation becomes more digitally native – this growth will continue upward.” 

The growth in data centers is also being driven by artificial intelligence and machine learning applications, high performance computing, cloud computing, augmented and virtual reality, social media and autonomous vehicles, among other factors.  

“From what we've observed, this growth isn’t limited to certain regions of the country. There is a renewed focus on emerging, smaller markets as the established, major markets are seeing significant power delivery times,” says Justin Hsiao, mechanical senior project engineer, Stantec.  

With this growth in data centers comes the significant increase in the water required to keep them operating at peak levels. 

The need for water 

The type of end-to-end cooling systems required for data centers includes chillers, towers, heat exchangers, humidification, computer room air conditioning (CRAC) and computer room air handlers (CRAH).  

“There are many variables that go into defining a single number or ratio for how much water a facility uses,” Farney says. “But in general, a traditional data center can consume hundreds-of-thousands of gallons of water daily, with a portion of it lost during the evaporative process. Over time and across quantity, it can be substantial.” 

Christopher Wade, manager, regional technical and asset services, property management at Mapletree, says the primary water consumption methods typically required to keep data centers operational include: 

• Chilled water systems: Uses water to absorb heat generated by servers. The water is chilled in a cooling plant and then circulated through pipes to heat exchangers that cool the air inside the data center. The warm water is then returned to the cooling plant to be chilled again in a closed-loop system.  
• Direct air cooling: Uses external ambient air to cool the data center. The air is filtered and directed over the servers to remove heat, either directly or through air-handling units.  
• Evaporative cooling: A method which relies on the evaporation of water to remove heat from the data center. Hot air generated by the servers is passed over cooling towers where water is evaporated, and the heat is dissipated into the atmosphere.  
• Liquid immersion cooling: This advanced method involves submerging servers directly into a non-conductive cooling liquid that absorbs heat more efficiently than air or water-cooled systems. The heat is then dissipated via heat exchangers, and the cooling liquid is recirculated.  

The type of water consumption required for data center operations largely depends on the cooling system used. While traditional methods like evaporative cooling are highly effective at maintaining peak performance, they also demand large quantities of water, particularly in hot climates. 

“Chilled water systems, while still using water, offer opportunities for recycling and efficiency improvements,” Wade says. “Newer technologies, such as direct air cooling and liquid immersion cooling, are promising alternatives that significantly reduce water dependency. As sustainability becomes a key focus, data centers are increasingly adopting strategies to minimize water consumption, recycle water and shift to more efficient cooling technologies to address environmental concerns.” 

Saahil Tumber, mechanical discipline lead, Stantec, points out that only data centers that employ evaporative cooling (direct evaporative cooling, indirect evaporative cooling, etc.) or evaporative heat rejection systems(cooling towers, evaporative fluid coolers, etc.) have significant water requirements. The water consumption (peak gallons per minute, peak gallons per day, annual gallons per year) depends on a multitude of factors such as ambient weather conditions, thermal operating envelope within the data center (dry bulb and humidity range at inlet to IT equipment), type of cooling/heat rejection systems being deployed, water quality, etc.  

“The term WUE (water usage effectiveness) is a commonly used metric to quantify the water efficiency of a data center,” Tumber says. “It basically quantifies the water consumption (in liters) per kilowatt hours (kWh) of energy consumed by the IT equipment. The lower the WUE, the lower the data center’s water footprint. Depending on the factors mentioned before, we have seen annual WUE ranging from 0.01 L/kWh to 1.5 L/kWh or higher.” 

However, Farney points out that data center engineers are on the cutting edge of innovation and have created new technology to insure water sustainability.For example, at least two companies employ waterless cooling solutions that save millions of gallons of water annually.Google rolled out a data-driven framework with which to assess watershed health and responsible use.  

“Microsoft built a data center in San Antonio to leverage the municipal graywater program and obviate the use of millions of gallons of clean water,” Farney says. “It is this same innovation and sustainability consciousness that is driving an entirely new paradigm in data center heat removal; liquid cooling.This 'creative destruction,’ brought about by AI, uses liquid to cool servers and completely obsoletes the air cooling we've been using for the last several decades.The huge built-in benefit is that it consumes up to 40 percent less energy.” 

For years data center managers have been leveraging the outside air –“air-side” and “water-side” economization –to increase cooling sustainability. 

At a 707,000 square foot, a 120-megawatt data center Farney managed outside of Chicago, JLL was able to leverage outside air approximately 270 days a year for cooling purposes which positively impacted the facility’s PUE (a measure of energy efficiency) and sustainability efforts.  

“In recent years, many firms have moved towards low-, or no-water data centers that utilize a different type of chiller plant, adiabatic cooling, and other more environmentally friendly technology,” Farney says. “And now, AI technology’s steep increase in computer server power density has pushed us over the threshold at which air cooling is effective, into liquid cooling. And although a massive change for building design and operation, liquid cooling’s different variants all bring significant reduction in traditional CRAH/CRAC infrastructure, resulting in an approximately 40 percent decrease in carbon impact.”  

Maura Keller is a freelance writer based in Plymouth, Minnesota.