Grace Han moved to California for a job at UC Santa Barbara and noticed her skin tingling after just a few hours in the sun. It’s the kind of observation most people dismiss. Han, a chemistry professor, decided to dig into why and stumbled onto something that could reshape how we store energy.
According to BBC reporting, Han began reading about DNA photochemistry during her leisure time and realized that the very molecules getting damaged by sunburn might hold the key to a long-sought scientific problem. DNA twists and contorts when hit by ultraviolet radiation, storing energy in its strained shape. For decades, scientists have chased molecules that do exactly this, hunting for ways to trigger them back to their original form on demand and release that stored energy. It’s called molecular solar thermal (Most) energy storage, and if it works at scale, it could be a game-changer for decarbonizing heat.
The challenge was always activation. You need to switch those molecules on and off reliably, repeatedly, without degradation. Then Han realized nature had already solved this problem.
How Evolution Became Her Lab Assistant
Certain plants and animals evolved to repair sun-damaged molecules using an enzyme called photolyase. Billions of years of natural selection perfected this process in living systems. Han saw the opportunity: if evolution could do it, why not harness the same mechanism for energy storage?
Working with collaborators including Kendall Houk at UCLA, Han and her team developed what they described in a February paper as the most promising Most system to date in terms of energy density. The results were startling enough that her students rushed to show her the data. When Han watched the video of their “very tiny kettle” boiling water off rapidly from the stored thermal energy, she recalls being genuinely stunned by how quickly it happened.
The numbers backed up the hype. They achieved 1.65 megajoules per kilogram of energy density. For perspective, that’s significantly higher than what lithium-ion batteries manage. Kasper Moth-Poulsen, a Most researcher at the Polytechnic University of Barcelona not involved in Han’s study, described the result as “really amazing” compared to his own lab’s best systems at one megajoule per kilogram.
The promise here is enormous. Most systems could theoretically store energy for months or even years without degradation, operating without burning anything. Unlike fossil fuels concentrated in specific regions (and subject to geopolitical leverage, as Moth-Poulsen points out regarding the Strait of Hormuz), Most technology could be deployed anywhere on Earth.
But There Are Catches
Reality, as always, intrudes. The wavelength needed to activate these molecules is 300 nanometres, which is extreme ultraviolet light. According to John Griffin at Lancaster University, this harsh UV does reach Earth from the sun, but only in tiny quantities. That’s a major limitation for practical deployment.
Then there’s the trigger mechanism. Han’s team used hydrochloric acid to reverse the molecular shape and release the energy. It works, but it’s corrosive and requires neutralization afterward. Han herself admits this isn’t ideal. She’s hopeful the team can improve responsiveness to natural light and find a less toxic trigger mechanism, but neither problem is solved yet.
There’s another wrinkle most people don’t think about. The light-sensitive molecules need to be spread thin enough for light to penetrate throughout, but not so thin they lose efficiency. Harry Hoster at the University of Duisberg-Essen estimates you could probably make a Most system about 5 millimeters thick in an optimistic scenario. And because the molecules exist in liquid form, you’ll need to pump that liquid around to store or release energy, adding complexity and failure points to the system.
The Niche Reality
Hoster remains sceptical that Most will handle all heating demands in a building. But for specialized applications like temperature-sensitive satellite components or aircraft systems, it could work. Han and others are exploring solid-state versions that might eventually become transparent window coatings, automatically warming rooms or preventing condensation. That’s elegant if it pans out.
What’s striking is how early-stage this field still is. Griffin attended a Most technology conference last year with roughly 70 attendees. That was basically the entire global research community working on this. It’s beautiful science, as Hoster acknowledges, but it’s far from mainstream.
The real question isn’t whether Most will revolutionize energy storage immediately. It’s whether the next decade of incremental breakthroughs can solve problems that still feel fundamental. A technology this promising shouldn’t stay confined to a business niche for long, but the gap between lab success and scaled deployment has buried plenty of innovations before.
