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Scientists at the University of California, Santa Barbara have developed a molecule that can capture energy from sunlight, store it within its chemical structure, and release it later as heat. The approach could offer a new way to store solar energy without relying on conventional electrical batteries.
The material, a modified organic molecule called pyrimidone, is part of a technology known as molecular solar thermal (MOST) energy storage. It changes into a high-energy state when exposed to sunlight and can later return to its original state, releasing the stored energy as heat.
The concept works somewhat like photochromic lenses that change structure when exposed to light. In this case, however, the molecular transformation is used to store energy rather than change color. The molecule effectively traps solar energy in chemical bonds until a trigger, such as heat or a catalyst, causes it to release that energy.
The researchers drew inspiration from DNA, whose molecular components can undergo reversible structural changes when exposed to ultraviolet light. Using this principle, the team designed a compact pyrimidone-based molecule capable of storing and releasing energy repeatedly.
Computational modeling conducted with researchers including UCLA chemist K. N. Houk helped the team understand the molecule’s behavior and improve its stability. The researchers say the material can retain its stored energy over extended periods while remaining capable of being recharged.
One of the most notable results is its energy density. The material can store more than 1.6 megajoules per kilogram, compared with roughly 0.9 megajoules per kilogram for a typical lithium-ion battery. The researchers also demonstrated that energy released from the material could generate enough heat to boil water under ambient conditions.
Because the molecule is soluble, the technology could potentially be circulated through solar collectors during the day, allowing sunlight to charge the material before it is stored and used for heating later. Possible applications include residential water heating and off-grid thermal systems.
The technology is still at the research stage, and practical deployment would require further development in areas such as scalability, cost, efficiency, and long-term cycling. Still, the work demonstrates a fundamentally different approach to solar storage, in which the material itself acts as both the energy carrier and storage system.
