Each night, around 280,000 litres of water are frozen at Norton Audubon Hospital in the US state of Kentucky. The hospital previously relied on a conventional air-conditioning system. Now, it uses a system of 27 ice tanks that support a network of cold-water pipes, which help maintain safe temperatures in operating rooms.
This type of thermal energy storage, commonly known as ice batteries, is being integrated into buildings across the US for its ability to provide cool air while reducing electricity consumption and alleviating pressure on the power grid.
As temperatures rise and the demand for electricity increases, ice thermal energy storage offers a more sustainable solution for cooling buildings.
Trane Technologies, a company specialising in heating and cooling equipment, has observed an increasing demand for its technology in recent years. Their ice batteries are primarily used in schools and in commercial and government buildings.
Nostromo Energy, a manufacturer of ice batteries, is targeting energy-intensive data centres with high cooling requirements. Additionally, companies like Ice Energy produce smaller systems designed for residential use.
Revolutionising energy storage solutions
Experts in sustainable energy state that ice thermal energy storage is one of the solutions that commercial buildings can implement to reduce electricity demand.
During the night, when electricity demand is low, water is frozen into ice. The next day, this ice thaws and is used to cool the building.
The ice chills the water circulating through the building’s pipes, absorbing heat from the rooms and creating a cooling effect. The cooled air is then pushed through vents to lower the temperature inside.
Ice thermal energy storage technology varies among manufacturers (see graphic). The stored ice does not require energy to thaw, reducing strain on the energy grid during peak hours and minimising electricity usage.
It is also a way to store excess energy generated by renewable sources that would otherwise go unused.
“Storing energy for further uses is where we’re going with the future of the grid,” said Ted Tiffany, senior technical lead at the Building Decarbonisation Coalition. He said access to air conditioning was a critical public health necessity, worsened by a warming planet. Ice batteries were a sustainable solution to the health risks posed by extreme heat.
Substantial cost savings
Energy costs at Norton Audubon were US$278,000 (HK$2,160,000) lower for the first year the ice battery system was in operation. The hospital estimated that the system and other energy-saving measures saved it nearly US$4 million since 2016.
“The technology has been awesome for us,” said Anthony Mathis, a Norton Healthcare executive who oversees sustainability. He said he received inquiries from other buildings about the technology and thought more facilities would adopt it.
Where are ice batteries useful?
Some commercial buildings use lithium batteries to store excess solar or wind energy that is available intermittently.
Dustin Mulvaney, an environmental studies professor at San Jose State University in the United States, said ice batteries are a sensible option for healthcare settings and senior homes because lithium batteries can pose a fire risk.
Manufacturers also see opportunities in data centres, which are increasing in number to support artificial intelligence and have high energy and cooling needs. A report from the US Department of Energy found that data centres consumed more than four per cent of the country’s electricity in 2023, and that figure could reach 12 per cent by 2028.
