China’s coal mines generate billions of cubic metres of water; researchers say it could help cool data centres | World News
China’s coal mines generate billions of cubic metres of water each year, and researchers say much of that resource could potentially be redirected toward cooling the country’s rapidly expanding data-centre infrastructure. In a review published in the Journal of Environmental Chemical Engineering titled The feasibility and prospects of coal mine water as a cooling medium for data centers, researchers led by Zaining Li assessed whether treated coal mine water could replace municipal make-up water in liquid-cooled data centres. They estimate that China’s data centres could consume more than 3 billion cubic metres of water annually by 2030, while coal mine water generation could reach an estimated 12.96 billion cubic metres that year. The authors conclude that, after appropriate treatment, the resource has sufficient quantity and potentially suitable quality for data-centre cooling, although they identify pilot-scale implementation as the next step.
Data centres could more than double their water demand by 2030
The review estimates that China’s data-centre water consumption will increase from approximately 1.3 billion cubic metres in 2024 to more than 3 billion cubic metres in 2030. The researchers link the increase to expanding cloud computing, high-performance computing and artificial intelligence infrastructure. More efficient liquid-cooling technologies can help reduce energy consumption and bring power usage effectiveness, or PUE, below 1.2, but the cooling systems can still require high-quality make-up water. The authors therefore examine coal mine water as one of several alternative sources that could reduce pressure on conventional freshwater supplies. As an indication of the industry’s existing scale, the review cites Alibaba’s fiscal 2024 disclosure of 0.036 billion cubic metres of water consumption.
Coal mining produces a huge but underused water stream
The opportunity exists partly because China’s enormous coal industry produces substantial quantities of mine water alongside the coal itself. The review notes that China produced 4.7 billion tonnes of raw coal in 2023 and estimates that approximately two tonnes of water are generated for every tonne of coal mined. That corresponds to roughly 9.4 billion cubic metres of coal mine water in 2023. The researchers describe the water as potentially attractive for cooling because underground mine water can have relatively low and stable temperatures. But untreated mine water is not automatically suitable for a data centre: its mineral composition can promote calcium carbonate scaling, corrosion and biofouling, creating risks for cooling equipment.
Treatment is essential before the water reaches cooling systems
The review therefore focuses heavily on how coal mine water could be treated to meet the quality requirements of liquid-cooling systems. Water chemistry varies between mining regions, so the researchers examine contaminants and characteristics including ammonia nitrogen, calcium hardness, chloride ions, turbidity, suspended solids and total hardness. They compare conventional multi-stage treatment approaches with an integrated electrochemical “short-flow” process and discuss technologies including oxidation, chemical flocculation, membrane separation, electrochemical treatment and biofiltration. The authors conclude that advanced treatment can bring coal mine water into compliance with cooling-water requirements, but they also stress that treatment has to be optimised for local water chemistry, operating conditions, energy use and seasonal variation.
The researchers estimate that treated mine water could be cheaper
The review’s economic analysis estimates a treatment cost of approximately 1.37 yuan per cubic metre for coal mine water, compared with 3.87 yuan per cubic metre for municipal water. On the assumptions used in the analysis, the additional treatment infrastructure could have an estimated payback period of 4.6 to 8.8 years. The paper also models environmental benefits under a broader scenario in which data centres improve PUE from 1.6 to 1.2 while integrating regional wind power, estimating a 93.8% reduction in annual carbon emissions. That figure should not be interpreted as the carbon reduction produced by substituting coal mine water alone, because the model combines several changes to the data centre’s energy and cooling system.
The proposal still needs to move from modelling to pilot projects
The researchers ultimately present coal mine water as a potential circular resource for China’s data-centre industry rather than a technology that has already been commercially proven at scale. Their review provides a framework for assessing water availability, treatment requirements, operating risks, economics and environmental effects, and they propose pilot implementations to test the approach under real operating conditions. The paper also points to China’s existing water-conservation and circular-economy policies, including the Water Ten Plan and measures associated with the 14th Five-Year Plan, as potential policy support for wider adoption. Although the analysis focuses on Chinese coal mines and data centres, the authors say the methods for assessing water quality, optimising treatment and managing risks could also be applied to other unconventional water sources internationally.
