The research project: Valuation of Thermal Energy Storage for Utility Grid Operators, demonstrated that the current method for estimating the electrical grid impact of Thermal Energy Storage systems does not fully consider the impact of energy savings that occurs during the hottest days of the year, which means that estimates are far lower than previously thought. By basing estimates on a “10-day average baseline,” the data drastically under-estimates the impact of disconnecting the cooling system from the electric grid when temperatures outside are very hot and the grid reaches its peak load conditions. The current method under-predicts its impact on the electric grid by as much as 77 percent, between 38 percent and 57 percent on average, and by a minimum of 3 percent. The current method does not adequately account for shifts in building loads due to holidays, weekends or extreme events, when thermal energy storage can save the most energy by disconnecting cooling from the grid.

“Power consumption is forecasted to grow, yet more than 72 gigawatts of electrical generating capacity has either already retired or is set to retire,” said, Mark Modera, director of Western Cooling Efficiency Center at University of California, Davis. “These factors have created an increasing urgency for power providers to find solutions that will allow them to accommodate the growing consumption needs and peak demand requirements in the U.S.”

These findings reinforce the sustainable, financial and connected benefits of thermal energy storage and provide a new approach for utility companies to consider to better estimate the electric grid impact of Thermal Energy Storage as they plan resources and service costs.

Whole-building simulations were used to model the electric grid impact of thermal energy storage systems. The simulations were performed on three building types using five types of cooling systems in three California climate zones. Trane^® TRACE 700 Load Design software simulated each building model and produced hourly cooling loads for each of the buildings. The cooling loads and ambient weather conditions were used to calculate the electric-grid impacts incurred from meeting the loads using each type of cooling system, as compared to using a thermal energy storage system.

Publication date: 4/24/2018

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