Kim Kenway, VP of Thermal Energy Storage of Maine, shows ice-based energy storage units in the Boothbay Harbor region, Maine. Photo: John Patriquin/Portland Press Herald via Getty Images
Commercial buildings account for nearly one third of U.S. total energy use. Roughly 25% of that third comes from air cooling, making it one of the main contributors to utility grid stress, especially in hot temperatures at peak times of the day.
Yes, but: Air cooling is also one of the easier electrical loads to shift to off-peak demand times. Thermal Energy Storage (TES) is an established technology that reduces grid stress by shifting cooling-energy use from high-peak periods, when demand and rates are highest, to off-peak periods, when rates are lower, and is becoming increasingly prevalent.
How it works: TES systems involve temporarily holding thermal energy in a hot or cold phase and releasing that energy for later on-demand use. Several U.S. companies use ice-based TES systems installed on rooftops: The ice is made with air conditioning equipment, integrated into the TES system at night — when demand for electricity is low — and then released to cool buildings, skyscrapers and other retail installations such as grocery stores to keep produce cold.
The benefits of TES depend on the customer and location. Commercial customers save on costly utilities rates during peak demand. For utilities, TES can alleviate the grid stress caused by air conditioning demand by shifting it to off-peak times, reducing the possibility for brown- or blackouts during heat waves.
What's new: The Massachusetts Department of Energy Resources recently awarded a contract to deploy ice-based TES capacity in Nantucket. The project is expected to deliver more than 1 megawatt of peak-demand reduction. This will enable the island to use air-cooling technology without investing in cabling to deliver power from the mainland.
What’s next: The DOE Energy Storage Database shows 114 installations in the U.S., for a total of 107,891 kilowatts of ice-based thermal energy as of 2017. By 2025, the global TES market is expected to grow to $12.5 billion.