Aging-Aware Management of Motorized Energy Storage for Grid Flexibility Provision

With the rapid uptake of renewable energy resources on the electric grid, the demand for power system flexibility has witnessed significant growth in recent years. The intermittency and variability of renewable resources, such as solar and wind, cause challenges to maintain power supply-demand balances, a key requirement for reliable grid operations. To mitigate the adverse impact of renewable energy on grid stability and reliability, flexibility services are often procured through ancillary service markets in the form of frequency regulation and spinning and non-spinning reserves. Electrochemical energy storage, e.g., lithium-ion batteries, has gained popularity as a flexibility resource with rapidly growing installations nationwide, mainly targeting flexibility-related markets. However, recent studies showed provision of flexibility services can significantly reduce the battery lifespan, to as short as a few months for frequency regulation that involves the most aggressive power modulation. Other forms of energy storage, such as pumped storage hydroelectricity, flywheels, and thermal energy storage, which are mostly driven by electric motors, play an increasingly important role in meeting flexibility demand by virtue of the lower procurement costs compared to lithium-ion batteries. However, the accelerated aging impact on motor winding insulation, induced by speed modulation or duty cycling for flexibility services, remains largely unknown but represents a major barrier to technology acceptance among equipment manufacturers, system operators, and asset owners. This project will fill the knowledge gap by (1) conducting laboratory tests to gather empirical evidence on the impacts of flexibility provision on the lifetime of electric motors; (2) developing a calibrated numerical model to characterize motor aging behavior and estimate the service lifetime impact under dynamic operating conditions; and (3) synthesizing an aging-aware control strategy that strikes an optimal balance between the aging effect and financial gain for flexibility provision. With a specific focus on motor-driven thermal energy storage in commercial and residential buildings, the project aims to unlock the flexibility potential of demand-side resources and promote deeper renewable energy utilization by significantly reducing the lifecycle management and grid integration costs. This research effort will leverage the unique building control testing facilities and heat pump modeling expertise at Oak Ridge National Laboratory. The new knowledge generated in this study will help lay a theoretical foundation for designing next-generation thermal energy storage and control systems in support of a more reliable and sustainable electric grid, which aligns with the DOE's Grid-interactive Efficient Buildings (GEB) Initiative.