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As data center density reaches about 20 kilowatts per rack and higher, the viability of ambient or free air data center cooling systems becomes questionable. Costs rise, and at a certain point, organizations simply cannot build systems capable of cooling the ultradense racks efficiently enough.
Companies are dabbling in new designs that rely on fjords, rivers and oceans. The work has potential but is in a nascent stage of development.
Traditional air cooling systems, such as sophisticated chillers, heating and air conditioning systems, are starting to reach their performance limits. When racks increase density, they have trouble supplying necessary cooling due to humidity control, airflow resistance and fan efficiency. The cooling hardware also consumes a lot of electricity, which increases costs and can negatively affect the servers in the event of failure.
Temperature fluctuations also exacerbate cooling effectiveness. During the year, temperatures range from freezing to 100 degrees Fahrenheit in many areas. Companies try to keep their data centers around 70 degrees Fahrenheit, which means that the data center cooling systems work extra hard during the peak periods and changing seasons.
Relying on water sources
New water-based cooling techniques are emerging to address overheating, but some suppliers are building data centers in locations close to -- and, in some cases, in -- natural waterways. The draw is twofold: Temperatures remain relatively constant year-round. Plus, water is a more efficient cooling option than air; it's at least 50 times more effective.
The problem is that water can leak and cause hardware damage, so companies are leery of using it in on-premises setups. But, as air-based cooling becomes too costly, some organizations are turning to natural resources as a way to cool data center hardware.
Green Mountain, which targets high-end data centers, built its Stavanger data center deep in the side of a mountain in 2013. The former high-security NATO ammunition storage facility is on the west coast of Norway and uses the cool water flowing from an adjacent fjord.
The company built two water basins inside the cooling station, and the intake mechanisms are 16 feet below sea level. This enables the data center's cooling system to have a natural supply of cool water through the use of gravity. The water is collected through pipes that are 328 feet deep, where the temperature is constant at 46 degrees Fahrenheit.
This water then goes through a heat exchanger and a closed-loop freshwater system that brings free cool water into the data center. The updated data center cooling design now supports densities from 20 kilowatts to 120 kilowatts per rack.
Nautilus Data Technologies Inc. is taking the idea one step further, using barges as floating data centers. The company is now building its first system in California's Mare Island Naval Shipyard. Once the data center is finished, the company plans to tow it to the Port of Stockton and have customers using its services by late 2019.
Facing new challenges
These industry projects have potential, but they face deployment challenges.
"Everyone is concerned about leaking," said Chris Brown, chief technology officer at Uptime Institute. "I live in Oklahoma and have seen severe rains create leaks in seemingly waterproof roofs."
These locations also need reliable and renewable power sources. The Stavanger center is situated near two hydroelectric power plants. The emphasis on renewable energy limits the number of potential locations for these data centers.
And the data centers must have comprehensive, high-speed communication lines to ensure network uptime, which can prove costly.
Because large-scale water-based cooling technology -- as well as these data center setups and management tools -- are still new, companies like Nautilus Data Technologies are still figuring out how to effectively combine them so everything runs smoothly.
There are also new environmental obstacles. In the case of Nautilus Data Technologies, it must be aware of factors such as algae, barnacles and sea life, as well as saltwater's ability to wear down any machinery.
As data center infrastructure continues to become more powerful and racks increase density, organizations will need data center cooling systems to meet performance and overheating needs. The current industry options are new and have potential but face many questions.
"Currently, a number of interesting concepts are being tested as the industry tries to address air cooling system limitations, but no silver bullet has yet emerged," Brown concluded.