Energy Storage at Hospitals: A Comparison of Battery Storage and Thermal Storage

Hospital buildings represent some of the most critical infrastructure in the communities they serve, as their ability to function during power disruptions can be a matter of life and death. Historically, hospitals have relied on codified requirements for backup power, primarily through diesel or gas generators. However, as the energy transition accelerates, hospitals are exploring new ways to enhance resilience while meeting decarbonization goals.

This presentation introduces a conceptual hospital microgrid designed for California, incorporating a grid interconnection, solar photovoltaics, battery energy storage, an electric chiller, electric vehicle charging, a gas generator, and a boiler. The model is evaluated under two conditions: a grid-connected use case emphasizing cost optimization and emissions reduction, and an outage (islanded) use case focused on resiliency.

Particular attention is given to the role of the battery energy storage system, with scenarios comparing standard four-hour systems against longer-duration solutions exceeding eight hours. The analysis also considers the potential for thermal energy storage, particularly chilled water and ice systems—as either a complement to or replacement for electrochemical batteries.

Findings highlight the trade-offs between battery and thermal approaches in terms of reliability, cost, carbon impacts, and operational complexity. The presentation concludes with observations on the current state of energy storage adoption in healthcare facilities and outlines the opportunities and challenges facing hospitals as they balance resilience, regulatory compliance, and the imperative to decarbonize.