Cooling technologies for data centres and telecommunication base stations – A comprehensive review

Data centres (DCs) and telecommunication base stations (TBSs) are energy intensive with ∼40% of the energy consumption for cooling. Here, we provide a comprehensive review on recent research on energy-saving technologies for cooling DCs and TBSs, covering free-cooling, liquid-cooling, two-phase cooling and thermal energy storage based cooling. The power usage effectiveness (PUE) and energy savings rate (ESR) data of the DCs and TBSs are analysed and compared with specific attention paid to the difference between the laboratory and commercial systems. The results indicate that the immersion liquid cooling has a lower PUE and a relatively higher ESR compared with other cooling technologies. The results also suggest a combination of multiple energy-saving technologies for cooling be a future trend to further improve the energy efficiency of the cooling systems. This article represents the first review that provides a comprehensive comparison of energy efficiency between different energy-saving cooling technologies for both the DCs and TBSs at different scales. The results also suggest that the use of these energy-saving cooling technologies in the future could achieve an average energy saving rate exceeding 50% and a reduction of carbon emissions by at least 0.4% compared to the traditional mechanical compression-based cooling.