UC Santa Barbara: ‘Liquid Battery’ Stores Solar Energy as Heat | Renewable Energy Breakthrough
- The challenge of storing renewable energy for use when the sun isn’t shining – or the wind isn’t blowing – has long been a significant hurdle to widespread...
- Unlike traditional solar panels that convert light into electricity requiring separate battery systems, this approach stores energy directly within chemical bonds.
- The researchers found inspiration in DNA, specifically a component that undergoes reversible structural changes when exposed to UV light.
UC Santa Barbara Researchers Develop Novel Material for Long-Duration Solar Energy Storage
The challenge of storing renewable energy for use when the sun isn’t shining – or the wind isn’t blowing – has long been a significant hurdle to widespread adoption. Researchers at UC Santa Barbara have announced a potential breakthrough: a new material capable of capturing sunlight and storing it as heat, releasing it on demand. The work, detailed in a paper published in Science, centers around a modified organic molecule called pyrimidone and falls under the umbrella of Molecular Solar Thermal (MOST) energy storage.
Unlike traditional solar panels that convert light into electricity requiring separate battery systems, this approach stores energy directly within chemical bonds. “The concept is reusable and recyclable,” explains Han Nguyen, a doctoral student in the Han Group and lead author of the study. The team draws an analogy to photochromic sunglasses, which darken in sunlight and clear indoors, demonstrating a reversible change. “Only instead of changing color, we want to use the same idea to store energy, release it when we need it, and then reuse the material over and over.”
Bio-Inspired Molecular Design
The pyrimidone structure wasn’t conceived from scratch. The researchers found inspiration in DNA, specifically a component that undergoes reversible structural changes when exposed to UV light. By synthesizing a version of this structure, they created a molecule capable of storing and releasing energy reversibly. Collaboration with Ken Houk, a distinguished research professor at UCLA, involved computational modeling to understand the molecule’s stability and energy storage capabilities over extended periods.
“We prioritized a lightweight, compact molecule design,” Nguyen said. “For this project, we cut everything we didn’t need. Anything that was unnecessary, we removed to make the molecule as compact as possible.” This focus on efficiency is crucial for maximizing energy density and minimizing material requirements.
A ‘Rechargeable Battery’ for Heat
The material functions somewhat like a mechanical spring. When exposed to sunlight, it twists into a strained, high-energy configuration. This state is maintained until triggered – by heat or a catalyst – causing it to snap back to its relaxed form, releasing the stored energy as heat. “We typically describe it as a rechargeable solar battery,” Nguyen explains. “It stores sunlight, and it can be recharged.”
The new molecule boasts an impressive energy density of 1.6 megajoules per kilogram, exceeding that of standard lithium-ion batteries (approximately 0.9 MJ/kg) and surpassing previous generations of optical switches. This high energy density is a key factor in the material’s potential for practical applications.
From Lab to Boiling Water: Demonstrating Practicality
A significant achievement for the UC Santa Barbara team was translating the high energy density into a demonstrable outcome. The researchers successfully demonstrated that the heat released from the material was sufficient to boil water – a previously challenging feat in this field. “Boiling water is an energy-intensive process,” Nguyen noted. “The fact that we can boil water under ambient conditions is a big achievement.”
This capability opens up a range of potential applications, from off-grid heating solutions for camping to residential water heating systems. Because the material is soluble in water, it could be integrated into roof-mounted solar collectors, charging during daylight hours and storing energy in tanks for nighttime use. Co-author Benjamin Baker highlights the advantage over traditional solar setups: “With solar panels, you need an additional battery system to store the energy. With molecular solar thermal energy storage, the material itself is able to store that energy from sunlight.”
Broader Context: Advances in Energy Storage
This development arrives amidst a flurry of innovation in energy storage technologies. , ScienceDaily reported advancements in bromine-based flow batteries aimed at improving long-lasting and affordable energy storage. Other recent breakthroughs, as highlighted in ScienceDaily’s coverage, include new catalysts for converting carbon dioxide into fuel, improvements to solid-state battery technology using silver and novel structural designs, and even advancements in nuclear timekeeping. Columbia Engineering is also pursuing cost-effective K-Na/S batteries to address the intermittency of renewable energy sources, as reported by SciTechDaily.
The UC Santa Barbara research is supported by the Moore Inventor Fellowship, awarded to Associate Professor Grace Han in to further develop these “rechargeable sun batteries.” This funding underscores the potential of this technology and the commitment to advancing sustainable energy solutions.