Chilling Out: Data Centers Find New Ways to Reduce Cooling Costs

As a result, demand is high for improved cooling systems—and the global data center cooling market is responding. The market is expected to grow from about $10 billion in 2021 to $25 billion by 2028—a compound annual growth rate of 14%.

Developing more effective cooling technologies that go beyond high-powered air conditioning (which previously was the standard) is a top goal for data centers and their providers.

“As the mission critical market grows, we’re continuing to see this trend become more and more prominent,” says Ben Burgett, project executive at Gray. “This is why we have to account for meticulous planning, and look for innovative solutions, as we design and build these facilities.”

Below are several leading cooling technologies for data centers to consider:

Air Cooling 

Two common air-cooling methods are CRAC (computer room air conditioning) and CRAH (computer room air handler). Cooled air is used to cool the entire room or individual racks/rows. These air-cooling systems must have carefully calculated layouts, including raised floors and specifically spaced racks, and be constantly monitored, to ensure steady circulation with no hot spots.

Hot aisle containment (HACS) and cold aisle containment (CACS) is a design element for air cooling where racks are separated and contained within their own systems to prevent hot exhaust air and cold intake air from mixing. “This balances the heat being generated, based on equipment location,” says Nick Vermiglio, senior solutions architect for Digital Transformation Solutions. “It can also be used to control changes in temperature within the data center.”

Liquid Cooling 

Liquid cooling (water or coolant) usually becomes the best choice when rack density increases to the point that air cooling is no longer cost-effective. Liquid cooling is typically cheaper than air cooling, and easier to manage. According to Netrality Data Centers, “some data centers have reduced their energy costs by 50% or more by switching to chilled water cooling.”

Two key types of liquid cooling are direct-to-chip and immersion cooling, with geothermal cooling as another option.

• Direct-to-chip cooling. Heat from the server is dissipated by sending coolant (typically a dielectric liquid) to cold plates that sit on a motherboard’s processors. A chilled water loop (part of the closed-loop system) carries the heat outside. The electronic components in the server are not in direct contact with the coolant. Conventional air-cooling infrastructure is still needed to provide airflow.
• Immersion cooling. This method actually submerges all the internal server components in a nonconductive dialectic fluid, which are then encased in a sealed container to prevent leakage. This is another closed-loop system where the heat generated by the server is transferred to the coolant, which is circulated and cooled and then returned back to the server compartment. An advantage of immersion cooling over air cooling is that servers can be packed more closely together, saving space.
• Geothermal cooling. This method of liquid cooling relies on the lower temperature of the earth to cool data center equipment. Coolant is circulated through a buried closed-loop piping system that dissipates the heat collected from the data center above into the cooler ground below. “Many data centers have already adopted this cooling method, including the American College Testing data center in Iowa City, the Prairie Bunkers Data Center Park in Hastings, NE, and Verne Global in Iceland,” notes Netrality Data Centers.

Evaporative Cooling

This is perhaps the simplest and lowest-cost method of cooling a data center. Air is blown across a series of wet pads, where the heat in the air is dissipated in the pads, creating cooler air that is then circulated throughout the data center. An evaporative cooling system can be up to 75% cheaper than traditional air cooling and is most effective in the American Southwest, where Microsoft plans to build two data centers in Arizona that will utilize evaporative cooling.

Submarine Liquid Cooling

Microsoft has tested the concept of data centers that operate from the bottom of the ocean. These underwater data centers were designed to use ocean water to cool the servers. In 2020, after two years of submerged operation, Microsoft announced that the servers in the underwater data center were eight times more reliable than those on land and plans to move ahead with advanced testing.

Don’t Forget Best Practices

Regardless of the data center cooling system being used, best practices go a long way toward improving efficiencies, especially through maintenance and monitoring of the cooling system—for example, tracking of temperature and humidity. Internet of Things (IoT) sensor technologies, artificial intelligence (AI), and data analytics technology are powerful, real-time tools for detecting variances and predicting maintenance schedules. Google’s use of AI, for example, has reduced its data center cooling costs by up to 40%.

“Artificial Intelligence, robotics, and other IoT technologies represent the next wave in controlling cost and efficiency within data centers,” says Vermiglio. “Temperature sensors, functional sensors, and flow sensors are just a few of the areas that IoT can address.”

A Cool Future

Conventional data center cooling methods simply won’t hold up under the “processing demands of AI, 5G wireless, IoT, and the rise of smart cities,” says Netrality Data Centers. “Advanced cooling methods, as well as promising new technologies, will be needed not only to ensure that data centers can keep up with data processing demands, but also to make data centers ever more sustainable.”