Signal Circular Economy Synergies and Trade-offs in Data Centres

Summary

Vlad C. Coroamă and Oana Dumbravă published a report on arXiv (cs.CY) on August 5, 2026, analyzing data center sustainability and circularity, arguing that Power Usage Effectiveness (PUE) is too coarse a metric, mixing cooling and power provisioning while wrongly attributing server fan consumption and transformation losses to IT energy, and measuring infrastructure rather than compute efficiency, even as compute energy is exploding. The report proposes better energy metrics covering compute efficiency, transformation efficiency, and cooling overhead. It identifies trade-offs between cooling energy and water, and between on-site and upstream water use: for 'wet' electricity, spending more on-site energy saves both electricity and upstream water, while 'dry' electricity presents a genuine trade-off. Waste heat recovery is noted to bring energy circularity but has limited uses and differing energy quality not reflected in current metrics, with the authors suggesting metrics should consider avoided energy through heat recovery rather than the amount recovered. The report interprets the 9R circularity framework in the data center context, covering product design, process design, business models, material choices, and operating conditions, and discusses the increasingly complex relationship between data centers and power grids, including battery storage and on-site generation as mitigation with their own trade-offs including noise, pollution, and greenhouse gas emissions.