Sunburn Inspires Breakthrough in Clean Energy Storage

When Grace Han moved from Boston to sunny California, her first sunburn sparked an idea that could change how the world stores energy.

The University of California, Santa Barbara chemistry professor wasn't just thinking about sun protection. She was reading about DNA photochemistry for fun, as scientists do, when she made a connection that had eluded researchers for decades.

DNA molecules in our skin twist into strained shapes when damaged by UV light, then repair themselves naturally. Han realized these shape-shifting molecules could be the perfect energy storage system, like setting and releasing a molecular mousetrap.

Her team created a molecular solar thermal system that stores energy as twisted molecules, holding it for months or years until needed. When triggered, the molecules snap back to their original shape, releasing stored heat on demand.

The results published in February were remarkable. The system achieved 1.65 megajoules of energy per kilogram, outperforming even lithium-ion batteries. A tiny kettle of water in their lab boiled so rapidly that Han's students rushed to show her the video.

"When I actually saw how quickly the entire solution was boiling, that was really remarkable," Han said. Fellow researcher Kasper Moth-Poulsen called the energy density "really amazing," surpassing his best systems by 60 percent.

The technology works because millions of years of evolution perfected the process in our skin. DNA repair enzymes called photolyase inspired Han's approach, creating molecules so small they can store massive amounts of energy per mass.

The Ripple Effect

This breakthrough could help solve one of climate change's toughest challenges: heating without burning fossil fuels. The world still relies heavily on oil and gas for heat, but molecular solar thermal systems operate without burning anything.

Unlike fossil fuels concentrated in specific regions, this technology could work anywhere on Earth. It stores energy far longer than traditional thermal storage, potentially for decades instead of just hours or days.

The system does face hurdles. It currently requires harsh UV light that barely reaches Earth's surface and needs hydrochloric acid to release the stored energy. Han acknowledges these aren't ideal, but she's hopeful both can be improved.

John Griffin at Lancaster University and other researchers are already working on solid versions that would be easier to use. Harry Hoster at the University of Duisberg-Essen notes challenges with thickness and liquid handling, but sees promise in the approach.

The molecules must be spread thin enough for light to penetrate, probably no thicker than 5mm. Moving liquid through the system adds cost and complexity that engineers will need to solve.

Still, the core breakthrough stands: a chemistry professor's sunburn observation led to the most powerful molecular energy storage system ever created.