Liquid cooling in data centers: a revolution in energy efficiency

As the backbone of the modern digital ecosystem, data centers host thousands of servers that process and store huge volumes of data. Servers that generate a considerable quantity of heat require efficient cooling solutions to maintain optimum performance and prevent breakdowns.

Among the emerging technologies, liquid cooling stands out as a key innovation to respond to data centers’ thermal and energy challenges.

What is Liquid Cooling?

Liquid cooling consists of using liquids, generally water or special coolants, to absorb and dissipate the heat from the electronic components. Unlike traditional air-cooling, which uses fans and air conditioners to maintain low temperatures, liquid cooling relies on the superior thermal properties of liquids for more efficient heat transfer.

The main types of liquid cooling

1. Water cooling

• Uses water as the coolant
• Includes systems where the water circulates through cooling blocks attached to the processors and other hot components.
• The hot water is then transported to heat exchangers where it is cooled before being recirculated

2. Immersion cooling

• This means that servers have to be immersed directly in tanks filled with non-conductive dielectric liquid
• The liquid absorbs the heat directly from the components, providing very effective cooling
• This type of cooling eliminates the need for fans and heat sinks, reducing noise and maintenance requirements

3. Direct Liquid Cooling (DLC)

• Uses special coolants that circulate directly through internal pipes built in to the servers.
• Offers very precise and localised cooling capacity that is ideal for high-power-density components

The benefits of Liquid Cooling

1. Improved energy efficiency

• Liquds have a greater thermal capacity than that of air, enabling more heat to be tiransferred with less energy.
• Reduces dependency on energy-intensive air conditioners and air cooling systems.

2. Increased power density

• Enables one to place more servers in a smaller space without the risk of overheating
• Facilitates the hosting of high-performance equipment requiring intensive cooling.

3. Reduces noise and maintenance

• Fewer fans and smaller mechanical components mean less noise and simpler maintenance.
• Immersion cooling systems, in particular, are virtually silent

4. Durability & ecology

• Less energy consumption reduces carbon emissions.
• Some solutions use environmentally friendly coolants, which are safe for the environment and reduce the ecological impact

The main challenges

1. High initial outlay

• Installing liquid cooling systems can be more costly than traditional air cooling solutions
• The long-term energy savings can offset these initial costs

2. Complex implementation

• Requires specialist technical skills for design, installation and maintenance.
• Existing data centers may need substantial modifications to accommodate new liquid cooling systems

3. Leak management and safety

• Although systems are designed to minimise risks, potential liquid leaks may be dangerous
• Regular maintenance and constant monitoring are essential to prevent accidents

Use cases & prospects

In January 2024, we announced a partnership with OVHcloud to host the liquid cooling solution developed by Europe’s cloud leader at our historic site in Marcoussis (Essonne).

Interconnecting OVHcloud toData4’s cooling systems directly on the cold water circuits means a saving of around 25% on electricity consumption compared with conventional air cooling, meeting the objective of reducing the carbon footprint.

“By starting with the client’s specific needs, we developed a tailor-made solution to enable the integration of its water-cooled server racks (liquid cooling). Like OVHcloud, we are very committed to measuring and reducing our carbon footprint and our dedicated environmental tools are very complementary (carbon calculator on the OVHcloud side and Green Dashboard on the Data4 side)”explains Alexandre Delaval, Data4 Country Director France.

“In addition to the bespoke colocation solutions provided by Data4 and the teams’ high degree of flexibility, this partnership with Data4 is fully in line with our objectives in relation to our environmental commitment,” explains Grégory Lebourg, OVHcloud Global Environment Director.

Many technology giants, such as Google, Microsoft and Facebook, are experimenting with and also deploying new technologies liquid cooling systems in their data centers. These companies are constantly looking for ways to reduce their carbon footprint and increase the efficiency of their operations. For example, Microsoft has tested servers immersed in tanks of coolant in Scotland, with promising results in terms of reducing energy costs and improving performance.

Conclusion

Liquid cooling represents a significant advance for the data center industry, offering a viable solution to growing heat management and energy consumption challenges. Despite the challenges relating to costs and complexity, the long-term benefits in terms of energy efficiency, power density and durability make them an increasingly attractive option for data center operators around the world. By adopting these technologies, data centers can not only improve their performance, they can also make a significant contribution to environmental protection.