Scientists in Germany have created a new material that can capture energy from sunlight, store it for days, and later release it as hydrogen fuel—even in the dark.
Developed by researchers at Ulm University and Friedrich Schiller University Jena, the breakthrough could help solve one of the biggest challenges of renewable energy: how to store solar power for use when the sun isn’t shining.
The findings were published in the journal Nature Communications.
Hydrogen produced using renewable energy, often called green hydrogen, is seen as a key part of the global shift away from fossil fuels.
It can power industries that are difficult to electrify, such as steelmaking, shipping, and aviation.
However, producing hydrogen directly from sunlight has a limitation: solar energy is not always available when it is needed.
The new material acts like a tiny “solar battery” at the molecular level, capturing sunlight and holding onto that energy until it is required.
The material is a special water-soluble polymer, a large molecule made from different chemical building blocks. It is designed to store energy in the form of electrons generated by sunlight.
The researchers report that the system can capture and hold more than 80 percent of the incoming solar energy and keep it stored for several days without significant loss.
When hydrogen is needed, the stored energy can be released through a simple chemical trigger. By adding an acid and a catalyst, the stored electrons combine with hydrogen ions to produce hydrogen gas.
This reaction is highly efficient, converting about 72 percent of the stored energy into hydrogen. Importantly, the process works even in complete darkness, meaning the hydrogen can be produced long after the sunlight has been captured.
Another striking feature of the system is that it can be reused multiple times. After releasing hydrogen, the solution can be neutralized by adjusting its pH level. Once reset, the material can absorb sunlight again and recharge.
The reversible chemical reactions allow repeated cycles of charging, storing, and energy release without needing to separate or replace the material.
The process also produces a visible color change, offering a simple way to tell whether the system is charged or discharged. The material turns from violet to yellow when releasing energy and returns to violet when recharged by light.
Researchers believe this technology could one day support large-scale uses of green hydrogen, especially in industries that need a reliable and steady energy supply. By storing solar energy in chemical form and releasing it on demand, the system could help balance the ups and downs of renewable power generation.
Although the technology is still in the research stage, the team says it opens new possibilities for affordable and scalable energy storage. If developed further, this “solar battery” approach could become an important tool for building a cleaner, more sustainable energy future powered by sunlight.
Source: KSR.
