Researchers from Sweden’s Chalmers University of Technology have succeeded in converting and storing solar energy directly in a chemical fluid.
Designed to be a molecular solar thermal system, the liquid chemical makes it possible to store and transport the stored solar energy and release it on demand, with full recovery of the storage medium.
According to the researchers, the process is based on the organic compound norbornadiene that upon exposure to light converts into quadricyclane.
“The technique means that that we can store the solar energy in chemical bonds and release the energy as heat whenever we need it.” says Professor Kasper Moth-Poulsen, who is leading the research team. “Combining the chemical energy storage with water heating solar panels enables a conversion of more than 80 percent of the incoming sunlight.”
The research project was initiated at Chalmers more than six years ago and the research team contributed in 2013 to a first conceptual demonstration. At the time, the solar energy conversion efficiency was 0.01 percent and the expensive element ruthenium played a major role in the compound.
Now after four years, the system stores 1.1 percent of the incoming sunlight as latent chemical energy – an improvement of a factor of 100. Also, ruthenium – a rare platinum transition metal – has been replaced by much cheaper carbon-based elements.
“We saw an opportunity to develop molecules that make the process much more efficient,” says Moth-Poulsen. “At the same time, we are demonstrating a robust system that can sustain more than 140 energy storage and release cycles with negligible degradation.”
Image illustration credits: Ella Marushchenko. Content – AlphaGalileo/Royal Society of Chemistry