UK data centres, a critical backbone for the nation's digital economy, could see substantial reductions in their operational costs thanks to a new cooling technology. Startup Accelsius is championing a two-phase liquid cooling system that promises to keep powerful AI accelerators, such as GPUs, significantly cooler while allowing facilities to run their water systems at much higher temperatures. This innovation comes at a crucial time, with energy costs and the demand for data centre capacity continuing to climb.
Accelsius's research indicates that by switching from conventional single-phase coolants to two-phase fluids, similar to those found in refrigerators, data centres could operate their facility water systems at temperatures up to 54°C, or even 59°C with increased flow rates. This is a considerable increase from typical operating temperatures of around 45°C. The company claims that for every 1°C rise in facility water temperature, data centres could achieve roughly 4% in annual energy savings. Given the burgeoning data centre sector and ongoing pressures on electricity supply, these savings could amount to millions of pounds each year for UK operators.
The technology works by pumping these highly efficient two-phase coolants through cold plates attached directly to server hardware, capturing heat more effectively than current methods. In tests, Accelsius demonstrated that by retrofitting a Dell PowerEdge server equipped with eight Nvidia B200 accelerators, their NeuCool system could reduce GPU temperatures by as much as 14°C at the system level. This improved cooling efficiency offers operators a choice: either run existing hardware more efficiently at lower temperatures, free up power to deploy more computing capacity within the same footprint, or even potentially overclock chips for enhanced performance.
Beyond direct energy savings, the warmer waste heat generated by this system presents new opportunities. Accelsius CTO Rich Bonner highlighted that heat at 50-60°C is far more useful than 30°C waste heat, potentially opening doors for heat reuse applications, such as district heating schemes or industrial processes. Furthermore, the higher facility water temperatures mean dry coolers – essentially large industrial radiators – can be utilised more effectively and for longer periods throughout the year, reducing reliance on water-intensive evaporative coolers or other refrigerant-based systems, particularly during warmer months.
While the benefits are clear, widespread adoption will require data centre operators to consider modifications to their existing infrastructure. Accelsius's current test systems utilise custom cold plates and coolant distribution units specifically designed for two-phase coolants. Integrating such bespoke solutions into diverse and evolving hardware ecosystems, particularly for complex systems like Nvidia's NVL72, which integrates numerous GPUs and CPUs, presents an engineering challenge that the industry is actively addressing. However, the potential for significant cost savings and increased efficiency is a powerful driver for overcoming these hurdles.