Chemists at UC Santa Barbara report a modified organic molecule, pyrimidone, that captures sunlight, stores it in chemical bonds and releases the energy as heat on demand. The team, led by Associate Professor Grace Han with lead author doctoral student Han Nguyen, engineered a compact, reversible structure inspired by a DNA component that changes under UV light. They removed nonessential parts of the molecule to improve performance and used computational modelling with Ken Houk at UCLA to show why the stored energy remains stable for years.
The molecule acts like a twisted spring: sunlight drives it into a strained, high‑energy shape, and a trigger — a small amount of heat or a catalyst — returns it to a relaxed form and releases heat. The researchers describe the approach as Molecular Solar Thermal (MOST) storage and call the material a “rechargeable solar battery.” Its energy density exceeds 1.6 megajoules per kilogram, compared with around 0.9 MJ/kg for a standard lithium‑ion battery, and the released heat was strong enough to boil water under ambient conditions, a notable milestone for MOST research.
Because the material dissolves in water, it could be pumped through roof-mounted solar collectors to charge during the day and stored in tanks for use at night. Potential uses include off-grid heating for camping and residential water heating. Benjamin Baker, a coauthor and doctoral student in the Han Lab, emphasizes that the material itself stores sunlight without needing an additional battery system. The work was supported by the Moore Inventor Fellowship, which Han received in 2025 to pursue development of these “rechargeable sun batteries.”
Difficult words
- modify — change something to improve its functionmodified
- reversible — able to return to a previous state
- computational modelling — use of computers to simulate systems
- energy density — amount of energy per unit mass
- strain — tension or stress inside a materialstrained
- ambient — present in the surrounding environment
- dissolve — mix into a liquid until it becomes uniformdissolves
- catalyst — substance that speeds a chemical reaction
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- What advantages and possible limitations do you see for storing solar energy as heat in chemical bonds rather than as electricity in batteries?
- How might the ability to pump a sunlight‑storing fluid through roof collectors change how households use and store solar energy?
- What technical or practical challenges do you think researchers must solve before this material is widely used for residential heating?
Related articles
Study finds flaws in cloud password managers
Researchers at ETH Zurich tested three cloud-based password managers and found multiple attacks that could expose or change users' passwords. They followed responsible disclosure, gave companies time to fix the issues, and recommended stronger encryption and audits.
