Lenovo: Can Warm Water Cooling Cut Data Centre Energy Use?

Lenovo is expanding its Neptune liquid cooling technology across its data centre portfolio, addressing the thermal and energy challenges presented by modern artificial intelligence environments. The move comes as data centre operators face escalating power demands.

Lenovo’s advancements in this area have contributed to its systems securing top positions on both the Top500 and Green500 lists that rank supercomputers on performance and energy efficiency, respectively.

Neptune's design is focused on reducing the total power consumption of a facility. Traditional air cooling methods are becoming insufficient for managing the heat generated by dense AI and high-performance computing (HPC) systems.

According to Lenovo, servers equipped with Neptune can operate with up to 40% lower power consumption compared to similar air-cooled systems, which could provide a way to achieve stable performance without increasing cooling costs.

AI workloads and rising energy demands

The growth of AI workloads has led to a substantial increase in heat generation, pushing conventional air-based cooling systems towards their operational limits. The IDC & Lenovo CIO Playbook 2025 highlights sustainability as a key priority for technology leaders, which includes lowering the energy expenditure associated with cooling.

Neptune's Direct Water Cooling circulates warm water to processors and memory modules to capture heat directly at its source.

Unlike traditional systems that require water to be chilled to around 18°C – an energy-intensive process – Neptune operates effectively with water temperatures up to approximately 45°C. This design can eliminate the need for chillers, reduce reliance on air handling equipment and improve the overall efficiency of high-density racks.

The sixth generation of this technology is the result of over a decade of development and is supported by hundreds of patents. Lenovo has also launched a new vertical liquid-cooled chassis to support accelerated computing within a smaller footprint, a fully liquid-cooled system that removes the need for internal fans.

Integrating liquid cooling into net zero strategies

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

By decreasing cooling needs and using warm water loops that can be integrated into existing facilities, the technology supports long-term goals for emissions reduction and energy efficiency. Demand for these solutions is growing in the Asia Pacific region, where electricity use from AI cloud services and digital platforms is increasing.

Lenovo projects that regional data centre energy consumption could climb from 320TWh in 2024 to 780TWh by 2030. In this context, energy efficiency becomes increasingly linked to commercial success.

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 closed-loop architecture that combines Direct to Node warm water cooling with Rear Door Heat Exchangers and Thermal Transfer Modules.

Warm coolant passes through cold plates on key components, and its temperature increases by around 10°C to 15°C before it transfers heat into a separate facility loop. This process avoids chilled water and helps maintain stable performance at high rack densities.

One of Lenovo’s systems, the ThinkSystem SR780a, which utilises Neptune cooling, has achieved a Power Usage Effectiveness (PUE) of 1.1. PUE is a metric that measures the ratio of a facility's total power to the power used by its IT equipment. A score of 1.1 indicates that for every watt of computing power, only 0.1 watts are used for cooling, a level of efficiency that is difficult to attain with air-cooled systems.

Neptune-powered platforms are already being used for some of the world's most intensive workloads. DreamWorks Animation saw a 20% performance boost with lower cooling needs after adopting Neptune-cooled HPC systems. The technology is also employed by meteorological agencies in Korea and Malaysia as well as various universities and research centres.