Buildings of the future could be transformed into batteries that store excess green power and backup the grid during blackouts, as scientists claimed a breakthrough in how to improve the efficiency and strength of such systems.

With the world having recently set its sights on tripling renewable energy generation by the end of the decade, the quest for new and innovative solutions to store power from wind and solar farms for when the wind isn’t blowing and sun isn’t shining has taken on a new level of urgency.

One idea being explored is storing excess green power in the fabric of buildings in the form of thermal energy storage.

A team from the University of Alabama and the National Renewable Energy Laboratory in the US claim in a new paper, published in the Journal of Energy Storage, to have made a breakthrough in developing the technology that could turn this concept into reality.

Until now, the researchers said that microcapsules used to store the phase-change materials used for thermal energy storage have typically used polymer shells that suffer from a lack of strength.

This renders them “unsuitable for applications that require high strength,” such as being incorporated into concrete or other materials used in buildings.

The US researchers have developed a “novel bioinspired method for applying a silica coating on the surface” of the microcapsules.

This coating is made of cenospheres, which are lightweight, hollow, and spherical ceramic microspheres that are a byproduct of coal-burning power plants.

This offers “several key advantages over existing methods,” they claim, including “remarkable” improvement in thermal performance of the microcapsules and enhanced fire resistance.

Crucially, it also provides “significantly” more strength than previous techniques, allowing for microcapsules that can be incorporated into building materials “without a drastic loss of strength” to the structure.

Jialai Wang, a professor at the Department of Civil, Construction, and Environmental Engineering of the University of Alabama who worked on the paper, said that a “major driving force for us to develop thermal energy storage material is to incorporate more renewable energy into the grid.”

Once the thermal energy material is integrated with building materials or heating, ventilation and air conditioning units, “we can turn buildings into distributed energy storage units.

“Surplus energy during times of high renewable generation can be stored in these buildings and be released later when demand exceeds supply or during periods of low renewable output.

“If the grid faces fluctuations or intermittent renewable generation, these distributed storage systems can provide a buffer, smoothing out variations in power supply and demand."

He added that buildings with such storage systems can even serve as “resilient power sources during grid outages or emergencies.”

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