From servers to services: modeling data centers as heat-active urban energy prosumers

The rapid expansion of cloud services has significantly increased the global energy footprint of data centers, which now account for approximately 2–3 % of global electricity consumption, a figure projected to rise to somewhere between 10 % and 51 % by 2030. While technological advances such as liquid cooling and high-temperature waste heat streams offer opportunities for improved energy efficiency, the integration of data centers into broader urban energy systems remains limited. This study investigates how data centers can transition from passive energy consumers to active prosumers through advanced heat recovery and flexible demand strategies. In this study, five system-level scenarios are modelled, varying by grid connectivity, renewable energy integration, and workload flexibility. Further, two distinct heat recovery approaches are compared: a legacy strategy that dynamically chooses between direct thermal reuse and electricity generation via an Organic Rankine Cycle (ORC), and an “exergy-aware” strategy that enforces continuous ORC operation and cascades the rejected heat from the condenser into a secondary heat pump. Using a multi-objective Mixed-Integer Linear Programming framework, the study reveals the trade-offs between data self-sufficiency and renewable energy utilization in an urban district case study comprising the EPFL campus in Lausanne. The results show that flexible computing workloads and integration with district heating networks can significantly enhance the buffering potential of data centers for variable renewable energy by up to 28 % in certain cases thereby reducing renewable curtailment, and support more efficient heat-electricity coupling by showing potential to supply up to 40 % of the heat demand of the campus. This work positions data centers as critical enablers of sustainable urban energy systems and offers a transferable modeling framework for their systemic integration. • Optimisation framework models data centers as prosumers in cities. • Legacy vs. exergy-aware heat recovery strategies are systematically compared. • Flexible data workloads improve PV alignment, boosting self-consumption up to 28 %. • Data centers can meet up to 40 % of district heat demand in the case study.