Advance in Thermal Energy Storage Shows Promise

Lawrence Berkeley National Laboratory researchers recently reported a breakthrough in phase-change materials, which will improve the affordability of thermal energy storage. Phase-change materials can be added inside walls and automatically keep healthcare facilities and other institutional or commercial buildings cool or warm, depending on the ambient temperature.

Could a tank of ice or hot water be a battery? Yes. If a battery is a device for storing energy, then storing hot or cold water to power a building’s heating or air-conditioning system is a different type of energy storage. Known as thermal energy storage, the technology has been around for a long time but has often been overlooked. Now scientists at Berkeley Lab are making a concerted push to take thermal energy storage to the next level.

To overcome some of the limitations of traditional water-based thermal energy storage, Berkeley Lab scientists are looking at developing next-generation materials and systems to be used as a heating or cooling medium. They are also creating a framework to analyze costs, as well as a tool to compare cost savings. In a series of papers published this year, Berkeley Lab researchers have reported important advances in each of these areas.

“It is very challenging to decarbonize buildings, particularly for heating,” says Ravi Prasher, Berkeley Lab’s associate lab director for energy technologies. “But if you store energy in the form of the end use, which is heat, rather than in the form of the energy supply, which is electricity, the cost savings could be very compelling. And now with the framework we’ve developed, we’ll be able to weigh the costs of thermal energy storage versus electrical storage, such as with lithium batteries, which has been impossible until now.”

In the United States, buildings account for 40 percent of total energy consumption. Of that, almost one-half goes toward thermal loads, which includes space heating and cooling as well as water heating and refrigeration. In other words, one-fifth of all energy produced goes towards thermal loads in buildings. By 2050, the demand on the electricity grid from thermal loads is expected to increase dramatically as natural gas is phased out and heating is increasingly powered by electricity.

“If we use thermal energy storage, in which the raw materials are more abundant to meet the demand for thermal loads, this will relax some of the demand for electrochemical storage and free up batteries to be used where thermal energy storage cannot be used,” says Sumanjeet Kaur, lead of Berkeley Lab’s thermal energy group.