Lenovo: Is Warm Water Data Centre Cooling the Future?

Lenovo is expanding its Neptune liquid cooling technology across its data centre products, a move that addresses the major thermal and energy challenges posed by modern AI environments.

As operators of data centres face escalating heat output from high-density computing, this technology offers an alternative to traditional air cooling.

The expansion comes as Lenovo holds top positions on both the Top500 and Green500 lists, with supercomputers that utilise Neptune for high-density and energy-efficient operations.

The design of Neptune targets a reduction in total facility power consumption. This addresses the growing recognition that conventional air cooling systems are reaching their capacity to manage the heat from dense AI and high-performance computing (HPC) systems.

According to Lenovo, servers equipped with Neptune technology can operate with up to 40% less power than air-cooled equivalents, which could provide a path to stable performance without increasing cooling costs.

A cooling model for AI scale

The growth in AI workloads has led to a substantial increase in heat generation, placing traditional air-based cooling systems near their operational limits.

The IDC & Lenovo CIO Playbook 2025 notes that sustainability is a key priority for technology executives, and this includes lowering the energy expenditure associated with cooling.

The Neptune Direct Water Cooling system functions by circulating warm water, at temperatures up to around 45°C, directly to processors and memory modules to capture heat at its source.

This approach contrasts with chilled water systems that typically require coolant at approximately 18°C, thereby removing the need for chillers and lessening the reliance on air handling equipment.

The technology, now in its sixth generation, is the result of over a decade of development and is supported by hundreds of patents.

Lenovo has also developed a new vertical liquid-cooled chassis to support accelerated computing within a smaller footprint. This system is entirely liquid-cooled, which removes the need for internal fans and could contribute to lower energy use throughout the data hall.

Integrating liquid cooling with net zero strategies

Neptune is a component of Lenovo’s strategy to achieve net zero carbon emissions by 2050, a goal validated by the Science Based Targets initiative.

The technology is designed to support long-term emissions reduction and energy efficiency targets by decreasing cooling needs and enabling warm water loops that can be integrated into existing facilities.

Demand for these solutions is growing in the Asia Pacific region, where electricity consumption from AI cloud services and other digital activities is increasing.

Lenovo projects that data centre consumption in the region could increase from 320TWh in 2024 to 780TWh by 2030. In this context, energy efficiency becomes more closely linked to commercial viability.

Kumar Mitra, Executive Director for Lenovo Infrastructure Solutions Group in Central Asia Pacific and Australia & New Zealand, says: “Across Asia Pacific, organisations are looking for AI infrastructure that is not only powerful but also fundamentally more energy efficient. Neptune gives our customers that advantage.

“Our leadership on the Top500 and Green500 rankings demonstrates the real-world impact of these innovations.

“As AI scales, solutions that combine performance with responsible energy use will define the next era of digital growth, and that is exactly what Lenovo is delivering.”

Performance in real-world deployments

The Neptune ecosystem uses a combination of Direct to Node warm water cooling, Rear Door Heat Exchangers and Thermal Transfer Modules within a closed-loop architecture.

Coolant flows through cold plates on the main components, and its temperature increases by around 10 to 15°C before it transfers heat into a separate facility loop. This method avoids chilled water and helps maintain stable performance even with high rack densities.

Lenovo’s ThinkSystem SR780a, which employs Neptune cooling, has achieved a Power Usage Effectiveness (PUE) of 1.1.

PUE is a ratio of total facility power to IT power, and a rating of 1.1 indicates that for every watt of computing power, only 0.1 watts are used for cooling.

Platforms using Neptune are operational in some of the world's most demanding computing environments. DreamWorks Animation reported a 20% performance improvement with lower cooling needs after adopting Neptune-cooled HPC systems.

The technology is also utilised by meteorological agencies in Korea and Malaysia, as well as various universities, research centres and digital content studios across the Asia Pacific region.

Several of the highest-ranking supercomputers on the Green500 list now feature Neptune systems, contributing to Lenovo's position in sustainable high-performance computing.