Cooler Buildings, Stronger Grid

Sept. 4, 2025 | By Julia Thomas | Contact media relations

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Blue Frontier is commercializing ESEAC technology by integrating it into its Dedicated Outdoor Air System. Installed in Florida, the 20-ton system pictured here controls temperature and humidity while operating primarily during periods of solar photovoltaic production. Photo from Blue Frontier

A game-changing technology developed by NREL in collaboration with Blue Frontier Inc. offers a solution to lower a building’s electricity bills and help reduce demand on the grid: the Energy Storing and Efficient Air Conditioner (ESEAC).

Designed for commercial use, ESEAC integrates energy storage, cooling, and humidity control into a single system, cutting peak air conditioning power demand by more than 90% and lowering electricity bills for cooling by more than 45%.

“This is a large step forward for air conditioning,” said Eric Kozubal, NREL senior engineer and co-inventor of the technology. “It’s a complete rethinking of how we condition air—and when we use electricity to do it. ESEAC shifts the most energy-intensive part of the process to off-peak hours, reducing costs and easing demand on the grid.”

A Different Approach to Cooling

Conventional air conditioners use vapor-compression refrigeration, cooling and dehumidifying air simultaneously. This coupling often requires overcooling followed by reheating to maintain comfort.

ESEAC takes a different approach by separating dehumidification from active cooling using a liquid desiccant system that absorbs moisture directly from the air, then using ultraefficient indirect evaporative air conditioning to precisely cool down the air. This method requires significantly less energy than conventional dehumidification processes, helping reduce operating costs. The system’s integrated energy storage also allows it to operate without running compressors during expensive peak demand periods.

The ESEAC cycle includes three key steps, each tied to a specific subsystem:

Step 1: Charging—A dilute salt-based liquid desiccant is separated into a high-concentration solution and pure water.

Step 2: Storage—The concentrated desiccant solution and pure water are stored for later use, decoupling energy input from cooling delivery.

Step 3: Discharging—The stored fluids are used to cool and dehumidify air, producing conditioned air while avoiding compressor use during peak hours.

The ESEAC system comprises three innovative sub-systems that together create an all-new air conditioning system: 1) The Electrically Driven Desiccant Regenerator uses >90% of the system’s electricity to separate a diluted desiccant solution into distilled water and concentrated liquid desiccant. 2) The Energy Storage tanks hold the separated fluids for later use. 3) The Conditioner dries and cools the air by using the stored concentrated liquid desiccant and distilled water, requiring minimal electricity to operate pumps and fans. The conditioner then absorbs moisture from the air and returns diluted desiccant solution to the storage tanks. Graphic by Joshua Bauer, NREL

"The ESEAC cycle separates and stores desiccant and water, enabling on-demand cooling and dehumidification,” said Jason Woods, NREL senior engineer and co-inventor. “This means the air conditioner can keep you comfortable all day but consumes the majority of its electricity when rates are low or renewable energy is available."

A year-long simulation in Miami, Florida, showed that a 20-ton ESEAC system reduced cooling-related electricity use by 38%, peak demand by 93%, and annual electricity costs by 45%. Over 15 years, this amounts to an estimated $165,000 in savings per unit.

Built-In Storage That Supports the Grid

By shifting energy use away from peak periods, ESEAC eases demand on the electric grid, helping utilities flatten demand curves and reduce reliance on costly grid storage or peaking plants. Flattening demand and reducing total electricity frees up grid capacity, making it available for other uses.

Storing energy in saltwater and pure water costs roughly 10 times less than battery-based systems, providing a scalable, lower-cost way to manage cooling loads.

“Air conditioning is a top driver of peak demand and a major reason for costly grid expansion,” said Achilles Karagiozis, director of NREL’s Building Technologies and Science Center. “ESEAC stores energy when electricity is cheap and uses it during peak times—delivering energy storage benefits at a fraction of the cost of batteries.”

Installations and Early Adoption

With early backing from Breakthrough Energy Ventures, Volo Earth, 2150, Modern Niagara, and major utilities, ESEAC systems are being installed at sites across the United States, including:

• U.S. Army Fort Benning (Georgia) and Westover Air Reserve Base (Massachusetts)

• A Bank of America branch (Delaware)

• An IMAX theater at the Museum of Discovery and Science (Florida)

• Commercial locations including a restaurant (Georgia) and grocery store (California)

• Educational campuses such as Barry University and Valencia College (Florida)

• Healthcare centers such as Jackson Memorial Hospital (Florida).

“These installations provide real-world validation for ESEAC,” said Matt Tilghman, chief technology officer at Blue Frontier. “Early performance data closely match our modeling results, confirming that ESEAC achieves significant energy savings and offers clear financial benefits for commercial buildings.”

Recently named an R&D 100 Award winner, the Energy Storing and Efficient Air Conditioner is a new class of cooling technology—one that separates dehumidification from active cooling and integrates energy storage to reduce costs, support grid stability, and maintain indoor comfort with significantly less energy.

Learn more about NREL’s buildings research.