A review of data center cooling technology, operating conditions and the corresponding low-grade waste heat recovery opportunities

The depletion of the world's limited reservoirs of fossil fuels, the worldwide impact of global warming and the high cost of energy are among the primary issues driving a renewed interest in the capture and reuse of waste energy. A major source of waste energy is being created by data centers through the increasing demand for cloud based connectivity and performance. In fact, recent figures show that data centers are responsible for more than 2% of the US total electricity usage. Almost half of this power is used for cooling the electronics, creating a significant stream of waste heat. The difficulty associated with recovering and reusing this stream of waste heat is that the heat is of low quality. In this paper, the most promising methods and technologies for recovering data center low-grade waste heat in an effective and economically reasonable way are identified and discussed.