A group of researchers at the University of Houston are developing a new device capable of capturing solar heat and storing it for long periods.

Another step forward for on-demand solar storage.

When it comes to solar storage, the first thing that comes to mind is the increasing use of batteries alongside photovoltaic systems, both large and small.

However, it’s not just the electricity that needs to be stored. One of the equally useful elements of the current energy transition is also the ability to capture and store thermal solar energy. The goal is not that simple to achieve, however, especially if you need a system that will retain heat for long periods of time. This challenge has led in recent years to the creation of a new line of research, entirely dedicated to the creation of solar accumulators on demand. The critical point of these systems remains the efficiency, but today a new work of the University of Houston could give a decisive shift in the thermal battery sector.

A research group created a small storage plant that combines latent heat accumulation with “molecular storage”, potentially capable of running 24/7.

And above all do it with a 73% efficiency in small scale operations and up to 90% in large scale operations. As Hadi Ghasemi, associate professor of mechanical engineering at the American University, explains, the high performance is due, in part, to the device’s ability to capture the full spectrum of sunlight, to collect it for a immediate use and to store excess molecules.

Indeed, this last aspect was carried out using the norbornadiene-quadricylane couple: these molecules are isomers and have a very interesting behavior for studies of solar accumulation. In detail, quadrocylan is produced by irradiating norbornadiene, in a process that requires energy. This same energy stored in the bonds of molecules is released when the reverse relationship occurs, i.e. when the quadrocyclane is converted back to norbornadiene, in the presence of suitable catalysts.

Current approaches to solar thermal energy -explain scientists in Joule’s article- They are based on expensive systems with high optical concentration, which cause significant heat loss due to hot materials and surfaces. At the same time, energy stored as thermal energy has inherently high time losses. In this case, on the other hand, the solar thermal accumulator, developed at the University of Houston, also stores energy in molecular form rather than as simple heat, and the integrated system reduces heat loss because it is not no need to transport stored energy.

During the day, solar thermal energy can be collected at temperatures of up to 120 degrees Celsius. At night, when there is no sun, the stored energy is collected by the molecular storage material, which can convert it from a lower energy molecule to a higher energy molecule. This allows the system to produce thermal energy at a higher temperature at night than during the day.

T. Randall Lee, professor of chemistry and research co-author.

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