Data Center Waste Heat Reuse: An Investment Analysis

Abstract

A thermo-economic analysis (TEA) of a novel cooling and enhanced heat recovery (CEHR) system for data centers (DCs) is presented. Three financial metrics (net present value—NPV, return on investment—ROI, and payback period—PP) are calculated for hot and chilled water generation. Hot water generation uses vapor recompression to produce water at approximately 75 °C. Chilled water generation builds upon the hot water generation scenario by feeding the hot water stream into an absorption chiller. Without considering the additional costs for connecting the infrastructure with the customer, a payback period shorter than 2 years is found for a hot water generation system for a base case assuming a 10-MW data center (DC) in Philadelphia, PA, when carbon (reduction) credits are included. Chilled water generation is found to be economically unfavorable in this location. Sensitivities of economics to data center power, hot water versus chilled water generation, geographic region, and carbon credits are evaluated for five additional global locations in Europe and Asia. The economies of scale enable favorable payback periods for integrating hot water generation for facilities beyond 7 MW. Hot water generation is especially favorable in Singapore when replacing natural gas-based heating or hot water heat pumps.