Microsoft: The Environmental Impact of Data Centre Cooling
Microsoft researchers have published findings in Nature that provide unprecedented insight into the environmental impact of data centre cooling technologies, measured across their complete lifecycle.
The two-year study marks the first time a comprehensive lifecycle assessment has been conducted on four different data centre cooling methods: traditional air cooling, cold plates, one-phase immersion and two-phase immersion cooling.
Husam Alissa, Director of Systems Technology in Cloud Operations and Innovation at Microsoft and leader of the lifecycle assessment study, emphasises the value of conducting these assessments during planning stages rather than retrospectively. “A lot of people do life cycle assessments after the fact,” says Husam.
“When we’re trying to make future design decisions, we typically look at total cost of ownership, performance, sustainability and other factors. We’re advocating in this paper for the use of life cycle assessment tools to guide engineering decisions early on and also sharing the tool with the industry to make adoption easier.”
The findings reveal that switching from traditional air cooling to cold plate technology – which Microsoft is currently deploying in its data centres – could reduce greenhouse gas emissions and energy demand by approximately 15% while cutting water consumption by 30% to 50% across the entire data centre lifecycle.
Cold plates are a type of direct-to-chip cooling where coolant is pumped in a loop to a flat container situated directly on top of the chips in a server rack. This method provides more efficient heat dissipation than traditional air cooling systems.
Microsoft says it has already begun implementing this technology in its facilities, alongside exploring other cooling innovations for future deployments.
Microsoft opens lifecycle assessment methodology to industry through research repository
In an effort to drive industry-wide progress, Microsoft is making its assessment methodology available through an open research repository. This move allows other companies to conduct their own lifecycle assessments using the same framework but with their specific operational data.
- Cold plate cooling can reduce emissions and energy use by 15% compared to air cooling
- Switching to 100% renewable energy could cut emissions by up to 90%
- Microsoft is making its assessment methodology available through an open research repository
“Our intention is not to say, ‘this is the right technology.’ They all could be. There are different circumstances that make you use a technology,” Husam says. “What we’re trying to do here is tell the industry, ‘Here’s how you build an end-to-end life cycle assessment that takes cooling into account. And here is a tool for you that you can customise to your specific needs and then make a decision.”
Microsoft energy grid transition could reduce emissions by up to 90%
Beyond cooling technology improvements, the Nature paper also examined the impact of transitioning energy sources. The research found that switching from a typical energy grid to 100% renewable sources could reduce greenhouse gas emissions by 85% to 90% regardless of cooling technology used.
Microsoft has set a goal to power its operations entirely with renewable energy. In locations where local grids cannot provide fully renewable energy, the company purchases equivalent amounts of renewable energy from other available sources.
The research team devoted significant time to gathering comprehensive supply chain data, though obtaining information about raw material extraction and manufacturing processes proved challenging. The team had to press suppliers for environmental impact data, with not all participating. To address these gaps, they developed formulas to estimate figures for future assessments. “Having the embodied emissions known, public and shared in databases could help accelerate life cycle assessment efforts,” adds Husam.
For data centre operators, the study reveals that cooling technology selection involves complex trade-offs between various environmental impacts. Cold plates and both immersion cooling technologies demonstrated reductions in greenhouse gas emissions of 15% to 21% over their entire lifecycles, with energy demand reductions of 15% to 20% and water consumption reductions of 31% to 52% compared to air cooling.
The two-phase immersion cooling showed particular promise for environmental impact reduction but currently uses liquid polyfluoroalkyl substances (PFAS), which face regulatory scrutiny in both the European Union and United States. This regulatory environment may limit future availability of this technology option.
“It was interesting to see that cold plates could be as good as the two immersion cooling methods,” says Teresa Nick, Director of Natural Systems and Sustainability for Cloud Operations and Innovation at Microsoft, and co-author of the paper.
The comprehensive nature of the assessment allows datacenter operators to make more informed decisions about which cooling technologies to implement based on their specific priorities and constraints.
“In a nutshell, we're trying to understand the trade-offs,” Teresa says. “You’re trying to understand the context of what you're doing and what the impacts are.”
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