How sunburn inspired a new way to store energy

Chemistry professor Grace Han drew inspiration for a new energy storage method from DNA damage caused by sunburn during a move from Boston to California. While researching DNA photochemistry, she observed that UV radiation alters the shape of DNA molecules, storing energy in a strained form—a process that could be harnessed for emissions-free heat storage. Han and her team at the University of California, Santa Barbara, developed a molecular solar thermal (MOST) system using these molecules, which can store energy for extended periods. The system achieves an energy density of 1.65 megajoules per kilogram, significantly higher than lithium-ion batteries, as detailed in a February study. During experiments, the energy release caused a small vial of water to boil rapidly, demonstrating its potential. Computer modeling by collaborator Kendall Houk at UCLA played a key role in predicting the molecule’s performance. However, the system has limitations. The UV light required to trigger the shape change—300 nanometers—is rare in natural sunlight, and the energy release currently relies on hydrochloric acid, a corrosive substance that must be neutralized afterward. Despite these challenges, experts like Kasper Moth-Poulsen, who leads MOST research in Spain, praised the breakthrough, calling the 1.65 MJ/kg density 'really amazing.' Han’s team now faces the task of refining the system to use more accessible light sources and safer triggers. The research builds on decades of work in MOST technology, offering a potential low-cost, long-term energy solution if these hurdles are overcome.