District heating networks (DHNs) are a key technology in the transition toward sustainable heat supply, increasingly integrating renewable sources and thermal energy storage. High-temperature aquifer thermal energy storage (HT-ATES) can enhance DHN efficiency by shifting heat production over time, potentially reducing both costs and greenhouse gas emissions. However, most life cycle assessments (LCAs) remain static, rely on average data, and neglect temporal dispatch dynamics and marginal substitution among heat sources for environmental evaluation. This study introduces a dynamic life cycle inventory framework that explicitly links HT-ATES-operation scheduling in DHNs with marginal life cycle data. The framework expands system boundaries to capture time-varying changes in heat composition, combines a district heating merit-order representation (distinguishing must-run and flexible capacities) with linear programming to determine least-cost dispatch, and translates marginally displaced technologies into environmental and economic consequences. Foreground inputs are derived from an existing third-generation DHN (heat demand, generation assets, efficiencies) and publicly available energy carrier cost data and are linked to consequential background inventory datasets (ecoinvent). The framework is demonstrated for one year of operation for an HT-ATES concept with 50 GWh of injected heat. Hourly resolved results identify the marginally displaced technologies and indicate annual reductions of 5.86 kt CO₂e alongside cost savings of EUR 1.09 M. A comparison of alternative operation schedules shows strong sensitivity of both economic and environmental performance to operational strategy. Overall, the proposed framework provides a replicable and adaptable basis for consequential assessment of HT-ATES operation in DHNs and supports strategic decision-making on seasonal thermal storage deployment in low-carbon heat systems.

High-Temperature Aquifer Thermal Energy Storage (HT-ATES) offers large seasonal storage capacities at low operation costs, enabling surplus-heat utilization and improving the environmental performance of district heating networks (DHNs). However, dynamic, prospective evaluations of HT-ATES integration in transforming DHNs remain insufficiently explored.We evaluate the environmental–economic performance of evolving HT-ATES capacity at three potential sites in a progressive, mostly renewable 3rd generation DHN in Mannheim, Germany. A generalized multi-model methodology couples geological subsurface modeling and thermohydraulic modeling with dynamic life cycle assessment and life cycle costing in future DHN technology scenarios and global development pathways. HT-ATES integration is benchmarked against non-integration and evaluated in a cost-effectiveness eco-efficiency analysis.Assessing 30 years of operation, cumulative greenhouse gas emissions savings range from 107 – 395 kt CO₂e. Avoided external costs savings range from 644 – 4 441 MEUR, and internal costs range from 0.12 MEUR savings to 9.5 MEUR additional costs. The middle-of-the-road pathway indicates savings of up to 142 kt CO₂e, 808 MEUR external costs, and 116 kEUR internal costs for the best performing location. Site-to-site differences are modest; outcomes are driven primarily by methodological and scenario assumptions. Sensitivity analysis reveals high responsiveness of economic outcomes, dominated by discount rate, heat-pump cost and lifetime, and characteristics of displaced heating technologies.Overall, HT-ATES consistently delivers substantial environmental gains and large avoided external costs for DHNs, but investment feasibility remains limited without policy support. The methodology applied represents a universal framework for integrated environmental–economic assessment of HT-ATES, applicable to different subsurface conditions and DHNs.

Multiple minor text corrections were made to the original publication