German Researchers Develop Breakthrough in Solar Energy Storage

October 29, 2024 – Mainz, Germany

A team of researchers from Johannes Gutenberg University Mainz (JGU) and the University of Siegen has unveiled a groundbreaking method for storing solar energy chemically, offering a revolutionary solution to one of the biggest challenges in renewable energy: efficient, long-term energy storage.

German Researchers Develop Breakthrough in Solar Energy Storage

While solar panels have come a long way in capturing sunlight—improving from converting 2% of sunlight to over 20% in recent decades—storing that energy efficiently remains a critical issue. Current methods like lithium-ion batteries and pumped hydro storage have limitations, particularly for long-term storage. The German researchers’ solution could change the game by storing solar energy in chemical bonds within specialized molecules known as photoswitches.

Storing Solar Energy in Chemical Bonds

The research, published in Angewandte Chemie, introduces a new approach where solar energy is absorbed and stored in molecular bonds, allowing it to be preserved for weeks or even months. These photoswitch molecules absorb sunlight and later release it as heat on demand, a process far more efficient than traditional thermal energy storage, which typically uses hot water for short periods.

Professor Christoph Kerzig, leading the Mainz research team, explained:

“By using a second compound called a sensitizer to absorb visible light and transfer energy to the photoswitch, we’ve drastically improved the energy storage efficiency—over tenfold compared to previous methods.”

This indirect light-harvesting method mimics the process of photosynthesis, ensuring better absorption across the solar spectrum, a significant improvement over earlier systems that relied solely on UV light.

German Researchers Develop Breakthrough in Solar Energy Storage
Converting solar power to heat.. Credit: Till Zähringer / JGU

Why This Matters

Heating accounts for nearly 50% of global energy consumption, according to the International Energy Agency. However, solar power’s role in this sector remains limited due to its intermittent availability. The German researchers’ system addresses this challenge by enabling solar energy to be stored chemically for extended periods without requiring constant heating or costly infrastructure like modified fire bricks.

Unlike existing technologies that often lose energy during multiple conversion steps, this new method stores sunlight directly in chemical bonds, reducing energy loss and improving efficiency.

Real-World Applications

The system has potential uses ranging from household heating solutions to industrial-scale energy storage, offering a sustainable path for managing energy demands. Professor Kerzig and his team validated the robustness of the process by repeatedly cycling the photoswitch molecules between energy storage and release states using solar light, demonstrating its practicality for real-world applications.

Till Zähringer, a PhD student at JGU and the study’s first author, emphasized:

“We carefully analyzed every reaction step to push the light-harvesting limits and improve the conversion efficiency of sunlight into stored chemical energy.”

A Major Step Forward for Renewable Energy

The findings position this chemical storage technology as a potential competitor to lithium-ion batteries, which currently dominate the energy storage market. Unlike batteries, photoswitches store energy as heat rather than electricity, offering a more direct solution for sectors reliant on thermal energy, such as building heating and industrial processes.

This innovation could pave the way for solar energy to play a larger role in addressing global heating needs, providing a sustainable alternative to fossil fuels.

German Researchers Develop Breakthrough in Solar Energy Storage
Credit: Electrified Thermal Solutions

Published in a Leading Scientific Journal

The research has already garnered significant attention, earning the prestigious “Hot Paper” classification in Angewandte Chemie due to exceptional reviews from leading scientific experts.

As the renewable energy sector continues to seek solutions for efficient, long-term storage, the work of these German researchers offers hope for a future where solar energy can meet more of the world’s energy demands sustainably.


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