New Bio-Inspired Molecule Stores Solar Energy as Chemical Bonds, Releases Heat on Demand

A team of researchers has reported the development of a new bio-inspired molecule capable of capturing solar energy, storing it within chemical bonds, and releasing it as heat when triggered. The material, a modified organic molecule, is noted for an energy density exceeding that of standard lithium-ion batteries.

The Research and Development

The research was conducted by chemists at the University of California, Santa Barbara (UCSB). The team was led by Associate Professor Grace Han and included doctoral student Han Nguyen. Their findings were detailed in the journal Science.

Computational modeling support was provided by researchers at the University of California, Los Angeles (UCLA), including Ken Houk. The work was supported by the Moore Inventor Fellowship.

Molecular Design and Mechanism

The system is categorized as a Molecular Solar Thermal (MOST) energy storage material. It functions by converting light into chemical energy, rather than electricity.

The material is a synthetic, modified organic molecule called pyrimidone. Its design was inspired by a component of DNA that undergoes reversible structural changes when exposed to ultraviolet light.

When exposed to sunlight, the molecule twists into a strained, high-energy configuration. It can remain in this state until a specific trigger, such as a small amount of heat or a catalyst, is applied. Upon triggering, the molecule reverts to its relaxed state, releasing the stored energy as heat.

Researchers describe the concept as reusable and recyclable, drawing a functional comparison to photochromic sunglasses, which reversibly change state in response to light.

Reported Performance and Potential Applications

According to the research reports, the new molecule demonstrates an energy density exceeding 1.6 megajoules per kilogram. For comparison, a standard lithium-ion battery has an energy density of approximately 0.9 megajoules per kilogram.

In laboratory demonstrations, researchers reported that the heat released from the material was sufficient to boil water under ambient conditions.

The material is water-soluble, a property that researchers suggest could enable it to be pumped through roof-mounted solar collectors for charging and stored in tanks for later use.

Reported potential applications for the technology include:

• Off-grid heating for activities such as camping.
• Residential water heating systems.
• Providing a method for solar energy storage that does not require a separate electrical battery system.

The research is presented as addressing a challenge in renewable energy: storing solar energy for use when sunlight is not available, such as at night or during adverse weather.