Evaluation of Peak Shaving Using Thermal Energy Storage in a Validated CHP and District Energy Model

TL;DR

This paper evaluates peak shaving using thermal energy storage within a validated combined heat and power and district energy model, demonstrating potential for improved energy savings and grid reliability.

Contribution

It introduces a fully integrated, validated model combining CHP, district cooling, and chilled water storage, enabling detailed analysis of peak shaving strategies.

Findings

Thermal storage can significantly reduce peak load.

Optimization improves energy savings over current strategies.

Model provides a foundation for further demand response analysis.

Abstract

There is currently a large federal effort to decarbonize the country's electrical grid as part of the clean energy transition. The elimination of fossil fuel fired systems, and their replacement with intermittent renewable sources and other electric equipment will require better load management techniques to ensure a reliable grid. One strategy for maintaining electric grid reliability utilizes peak shaving. Buildings, accounting for 40% of energy use in the United States, can account for an even higher percentage of energy during peak periods driven by high air conditioning loads during the summer, especially in hotter climes such as Austin, Texas. Many previous studies have modeled the effectiveness of building HVAC demand response methods such as temperature setpoint manipulation, pre-cooling, ventilation scheduling, and thermal energy storage. Thermal storage systems, due to their larger energy capacities, have been shown to be most promising for peak shaving. However, there is a lack of work integrating chilled water energy storage models with validated microgrid-district energy system models to fully capture the dynamics of the proposed strategies. Previously, a validated system model for power generation and heating was developed for the University of Texas at Austin (UT Austin). A new validated model integrates the 65 MW combined heat and power plant (CHP), with the campus' 45,000 ton district cooling system, as well as two chilled water storage tanks. While the existing campus system currently utilizes an operator driven peak shaving strategy utilizing thermal storage, optimization results show that there is room for further improvement and energy savings. The presented results quantify the peak shaving in MW and provide a foundation for further analysis.