Nanofluidic osmotic generator enhanced by data center waste heat recovery through hybrid water–air cooling with a heat pump

With the rapid development of artificial intelligence technology, data centers have become essential for offering computational resources. However, data centers suffer from the challenge of overheating, with a large amount of wasted low-grade thermal energy. In addition, nanofluidic osmotic generators face the drawback of a relatively low power output. Hence, the present work proposes a three-stage coupled energy utilization scheme, leveraging the temperature-sensitive characteristics of nanofluidic osmotic generators via thermal management of a data center. A hybrid water–air cooling strategy is applied to cool down server chips, and the recovered low-grade thermal energy is upgraded using an air-source heat pump (ASHP) to generate hot water, which serves as freshwater in a nanofluidic osmotic generator to enhance its power density. When the inlet velocity of the cooling water is 0.08 m s⁻¹ and the inlet air velocity is 4 m s⁻¹, the theoretical operating temperature of the server component in the data center is consistently maintained below 45.53 °C. Moreover, the cooling water from the data center is further heated by an ASHP to 56.78 °C for osmotic energy conversion. Under these circumstances, the power density of the nanofluidic osmotic generator is experimentally improved from 2.674 W m⁻² to 4.895 W m⁻² (i.e. by 83.06%) through thermal energy recovery from the data center under a 50-fold salinity-gradient ratio at neutral pH of 7, and it can be further enhanced to 5.443 W m⁻² by modulating the pH to alkaline conditions at 11. The current work offers an innovative pathway for data center thermal management and low-grade waste heat recovery with synergistic utilization of salinity-gradient energy.