How sunburn inspired a new way to store energy

The Next Frontier: Decarbonizing the “Unreachable” Heat

For decades, the global push toward green energy has focused heavily on electricity. We have lithium-ion batteries for our phones and massive arrays of solar panels for our grids. But there is a silent giant in the energy world that remains stubbornly reliant on fossil fuels: heating.

Heating accounts for nearly half of global energy demand, with two-thirds of that met by burning natural gas, oil, and coal. While electric heat pumps are a step forward, the industry has lacked a truly efficient, long-term way to store thermal energy without losing it to the environment.

Enter Molecular Solar Thermal (MOST) energy storage. This isn’t just another battery; it is a fundamental shift in how we capture and “bottle” the sun’s power, transforming a biological quirk of human skin into a commercial energy breakthrough.

From Sunburns to Solutions: The Science of MOST

The breakthrough, led by chemistry professor Grace Han at the University of California, Santa Barbara (UCSB), mimics the photochemistry of DNA. When certain molecules are irradiated by the sun, they don’t just get hot—they change shape.

Think of it like setting a mousetrap. The molecule flexes into a strained, high-energy version of its original form. This energy remains trapped in the chemical bonds of the molecule, allowing it to be stored at room temperature without leaking heat.

When a specific trigger is applied, the “mousetrap” snaps back. The molecule reverts to its original shape, releasing the stored energy as a sudden burst of heat. In laboratory tests, this process was powerful enough to rapidly boil water in a vial, demonstrating a level of energy density that has previously eluded scientists.

Breaking the Energy Density Barrier

In the world of energy storage, density is everything. Recent data shows that Han’s team achieved an energy density of 1.65 megajoules per kilogram. To put that in perspective, this significantly outperforms previous MOST systems and rivals the energy density found in some of the most popular lithium-ion batteries used in EVs and smartphones today.

The Business Shift: Why Liquid Solar Disrupts the Market

From a business perspective, MOST technology offers several strategic advantages over traditional battery storage:

• Long-Term Stability: Unlike thermal tanks that lose heat over hours, MOST can store energy for months or even decades. This solves the “seasonal gap”—capturing summer sun to heat a home in January.
• Decentralization: Unlike fossil fuels, which are geographically concentrated in volatile regions, solar energy is available everywhere. This reduces reliance on fragile global supply chains and geopolitical choke points.
• Emissions-Free: The system operates without combustion, offering a pathway to completely decarbonize industrial and residential heating.

Future Trends: Where Will We See This Technology?

While the technology is currently niche, the trajectory suggests several high-impact applications in the coming years.

1. Smart Window Coatings

Researchers are already exploring solid-state versions of MOST. Imagine transparent window coatings that absorb UV light during the day and release it as heat at night. This could eliminate the need for traditional radiators in many office buildings, turning the building’s envelope into its own heating system.

2. Aerospace and Satellite Thermal Management

In the vacuum of space, managing temperature is a life-or-death challenge. Because MOST systems are compact and can release heat on demand without requiring a massive power draw from a battery, they are ideal for warming temperature-sensitive components on satellites or aircraft.

3. Industrial “Heat-on-Demand”

Many industrial processes require bursts of high heat. Instead of keeping boilers running 24/7, companies could use MOST-infused fluids to store solar energy and release it precisely when a process requires a temperature spike, slashing operational costs and carbon footprints.

The Roadblocks to Mass Adoption

Despite the promise, the path to market isn’t without hurdles. Currently, the system requires “harsh” UV light (around 300 nanometres) to activate, which is only available in small quantities from natural sunlight. The current trigger for releasing energy involves hydrochloric acid—a corrosive substance that isn’t ideal for home use.

The next phase of development will focus on finding non-toxic triggers and broadening the spectrum of light the molecules can absorb. Once these chemical hurdles are cleared, the transition from the lab to the living room becomes a matter of engineering, not discovery.