Liquid immersion cooling fostering sustainable data centres

In the fast-paced world of data centres, sustainability and efficiency are paramount. Mr Amod Ranade highlights how single-phase liquid immersion cooling, championed by GRC, is revolutionising data centre technology, offering enhanced performance, reliability, and a greener future.

Data centres are the backbone of the modern digital world, powering everything from cloud services and artificial intelligence to e-commerce and social media. However, the rapid growth of technology and increasing demand for data processing capacity present significant challenges, especially in cooling. The traditional method of air cooling has been in use for decades. Still, with the ever-increasing power densities of modern chips, it is clear that a more efficient and sustainable approach is needed.

Data centre cooling
GRC (Green Revolution Cooling), a Texas-based company founded in 2009, has been at the forefront of revolutionising data centre cooling. Single-phase liquid immersion cooling, the technology they provide, has been around for over a decade but is gaining momentum as a viable solution to address the challenges of cooling high-performance computing environments. Over the past 14 years, GRC has deployed its solutions in over 21 countries, with a total capacity exceeding 18 megawatts. These installations encompass various applications, including national defence, supercomputing, AI, cloud services, and more.

One of the key factors that differentiate single-phase liquid immersion cooling is its remarkable efficiency. Traditional air cooling relies on three main variables: air temperature, airflow, and heat sink size. However, with the exponential increase in chip power consumption, especially in GPU-intensive servers used for AI and deep learning, air cooling faces limitations. The industry has recognized that traditional cooling methods are not sustainable for the future of data centres, and that’s where liquid immersion cooling comes into play.

The challenge of increasing chip power density
The need for innovative cooling solutions is understood when the dramatic increase in chip power density is considered. In 2009, the industry estimated that chips would consume around 130 watts, with some exceeding 400 watts by 2020. Coming near to 2025, we are looking at chips with a power consumption of up to 1000 watts. This substantial jump in power density presents a significant challenge for current air cooling technologies.

Air cooling can only do so much when confronted with the heat generated by high-power chips. Increasing airflow and reducing temperature can help theoretically, but they have practical limitations. Higher airflow means more energy consumption and larger heat sinks, which can lead to sustainability issues. As data centres are designed with a 10 to 15-year lifespan in mind, accommodating the power-hungry chips of the future becomes a pressing concern.

Single-phase liquid immersion cooling as solution
The single-phase liquid immersion cooling technology provided by GRC offers a promising solution to the challenges of traditional air cooling methods. This innovative approach involves immersing servers in a tank filled with a single-phase coolant that boasts thermal conductivity 1000 times greater than air. Unlike conventional air cooling, this method ensures that computer chips remain at lower operating temperatures, even when subjected to heavy workloads. The advantages of adopting this approach can be summarised in three key areas.

Firstly, it leads to enhanced performance. Lower chip temperatures allow data centre operators to consider overclocking the hardware, thereby extracting more computational power from the same set of components.

This cooling method contributes to improved reliability. Lower chip temperatures result in reduced thermal stress, which, in turn, extends the overall lifespan of the hardware. As a result, there is a decrease in the need for maintenance and repairs, ultimately enhancing the reliability of the data centre infrastructure.

The single-phase liquid immersion cooling technology promotes greater energy efficiency. By operating chips at lower temperatures, it becomes possible to use higher-temperature coolants, which may eliminate the need for energy-intensive refrigeration systems in data centres. This reduction in energy consumption has the potential to significantly lower Power Usage Effectiveness (PUE) ratios, leading to more sustainable and cost-effective data centre operations. This makes it an appealing choice for companies aiming to reduce their environmental footprint while maintaining high-performance computing capabilities.

Major players in the tech industry, including Google, Microsoft, and Intel, have recognised the potential of liquid immersion cooling. They are voicing their support for this technology, emphasising its ability to address the challenges of cooling and sustainability simultaneously. With the adoption of single-phase liquid immersion cooling, data centres can take a significant step toward a more efficient and eco-friendly future.

How single-phase liquid immersion cooling works
“Single-phase liquid immersion cooling is a simple idea that packs significant benefits. Servers are immersed in a tank filled with a single-phase coolant, eliminating the need for fans, which typically account for an average of 11% of the power consumption of the server. The coolant captures the heat generated by the servers and efficiently dissipates it. A coolant distribution unit with a pump helps circulate the coolant through the system”.

To reject the heat, a plate heat exchanger transfers it to a water loop. Depending on the specific deployment, the heat can be rejected into the environment using various methods, such as chillers, cooling towers, dry coolers, or adiabatic dry coolers. This flexible approach ensures that the cooling system can be tailored to the specific requirements of the data centre and its location.

Benefits
The benefits of single-phase liquid immersion cooling are evident and far-reaching. These advantages include enhanced energy efficiency. The ability to operate chips at lower temperatures and reduce the need for energy-intensive fans results in substantial energy savings. This is reflected in significantly lower PUE ratios, which can be as low as 1.1.

It improves reliability as lower chip temperatures lead to reduced thermal stress, which translates to longer hardware lifespan and increased system reliability.

Single-phase liquid immersion cooling contributes to sustainability goals by reducing energy consumption, carbon footprint, and water usage. Furthermore, it opens up opportunities to reuse or repurpose rejected heat.

The technology is well-suited for high-density computing environments, making it future-proof and adaptable for upcoming generations of high-power chips.

Data centre operators looking to build or upgrade their facilities should consider the benefits of single-phase liquid immersion cooling. This technology not only aligns with sustainability goals but also addresses the challenges presented by the ever-increasing power densities of modern chips. With the support and recognition of industry leaders, it’s clear that liquid immersion cooling is here to stay and will play a pivotal role in shaping the future of data centre technology.