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| © NASA |
When the sun sets, traditional solar panels fall silent. Their energy production drops to zero, leaving homes and devices dependent on backup batteries or the electrical grid. But scientists may have found a clever workaround: a special molecule that can capture sunlight, store it for years, and release it as heat whenever needed.
Researchers at UC Santa Barbara have developed a new material that works like a rechargeable solar heat battery. Their findings, published in the journal Science, reveal a promising breakthrough in renewable energy storage.
A Molecule That Stores Sunshine
The research team, led by Associate Professor Grace Han, designed a modified organic molecule called pyrimidone. This molecule belongs to a technology known as Molecular Solar Thermal (MOST) energy storage. Instead of producing electricity like conventional solar panels, this molecule captures sunlight and locks that energy inside its chemical structure. When triggered later, it releases the stored energy as heat.
Lead author Han Nguyen explained the concept using a familiar example:
Photochromic sunglasses darken in sunlight and return to normal indoors. Similarly, this molecule changes its structure when exposed to sunlight, storing energy, and then reverses to release that energy when needed. The process is completely reusable, meaning the same molecule can charge and discharge repeatedly without wearing out.
Inspired by DNA’s Natural Behavior
The team took inspiration from DNA itself. Certain DNA components naturally change structure when exposed to ultraviolet light. By engineering a synthetic version of this behavior, the scientists created a molecule capable of reversible energy storage.
To understand and optimize the molecule’s performance, the team collaborated with computational chemist Ken Houk at UCLA. Computer simulations helped confirm why the molecule remains stable and can store energy for long periods without losing it. The researchers intentionally kept the molecule lightweight and compact, removing unnecessary structural elements to maximize efficiency.
Works Like a Coiled Spring
Imagine compressing a spring and locking it in place. That spring stores energy until released. This molecule behaves in a similar way. When sunlight hits it, the molecule twists into a high-energy shape and stays there. When triggered by heat or a catalyst, it snaps back to its original form, releasing the stored energy as heat. This makes it function like a rechargeable solar battery, but for heat instead of electricity.
Twice the Energy Density of Lithium Batteries
One of the most impressive achievements is its energy density. The molecule can store more than 1.6 megajoules per kilogram, which is nearly double the energy density of standard lithium-ion batteries. That level of performance places it among the most powerful molecular energy storage systems ever developed.
Powerful Enough to Boil Water
In laboratory tests, the stored energy was strong enough to boil water under normal conditions. This is a major milestone, because boiling water requires significant energy. Co-author Benjamin Baker emphasized the importance of this result. Unlike traditional solar systems that need separate batteries, this molecule stores the energy directly within itself.
Future Applications: From Camping to Homes
This technology could unlock exciting real-world uses, such as: Off-grid heating for camping and remote locations, Solar-powered residential water heating, Energy storage systems for homes without bulky batteries, Sustainable heating solutions with minimal infrastructure. Because the material dissolves in water, it could even circulate through rooftop solar collectors during the day and release heat at night.
A New Chapter in Solar Energy
This breakthrough reimagines solar energy storage. Instead of relying on heavy batteries, future systems could use lightweight molecular liquids that quietly absorb sunlight during the day and release warmth when darkness arrives. It is solar power that doesn’t sleep, even when the sun does.
