Giant clams inspire breakthroughs in solar energy efficiency

In the search for efficient solar energy, scientists have turned to an unlikely source: the giant clams of the western Pacific Ocean. These fascinating creatures may boast the most advanced natural solar-power system on the planet, according to a new study led by Yale scientist Alison Sweeney.

The study, published in the journal PRX: Energy, examines how the unique physical structure of these clams allows them to maximize the absorption of solar energy. The results are promising for the future of solar technology, potentially guiding the development of more efficient solar panels and biorefineries.

At first glance, giant clams may not seem like solar power plants. But their iridescent, seemingly ordinary shells conceal a highly sophisticated photosynthetic system. The clams are characterized by intricate vertical columns of photosynthetic cells, covered with a thin layer of light-scattering iridocytes. This configuration allows the clams to efficiently capture and convert sunlight into energy, operating with quantum efficiencies that surpass existing solar panel technology.

“This is counterintuitive to many people because the clams operate in intense sunlight, but they’re actually really dark inside,” explains Alison Sweeney, an assistant professor at Yale University. “The truth is that clams are more efficient at converting solar energy than any existing solar panel technology.”

Scientists developed a model to determine this efficiency, observing quantum efficiencies of up to 67% in the mussels. This contrasts sharply with the 14% efficiency observed in typical green leaves under similar conditions. One of the most intriguing aspects of mussel functionality is their dynamic response to changes in sunlight. They “move and groove” throughout the day, stretching and contracting to optimize their photosynthetic capacity.

Beyond the mechanics of the clams, the implications of the study are enormous. It highlights the importance of biodiversity and the potential of bio-inspired design to advance sustainable technology. The rich ecosystems in which these clams live could be key to understanding and more efficiently harnessing renewable energy.

One fascinating parallel the researchers draw is between mussels and boreal spruce forests. These forests, characterized by unique, light-diffusing canopies, exhibit similar solar energy conversion efficiency because of their analogous structures. This comparison highlights how different ecosystems can offer untapped insights into efficient energy-harvesting techniques.

“One of the lessons is how important it is to consider biodiversity more broadly,” Sweeney says. “My colleagues and I continue to bounce ideas off of where else on Earth we might have this level of solar efficiency. It’s also important to recognize that we can only study biodiversity in places where it is maintained.”

Palau, in particular, stands out as a key region for this research. Local communities place significant cultural and environmental value on their reefs and clams, helping to preserve the pristine conditions needed for such research. This stewardship is crucial, Sweeney notes, to expanding our knowledge of natural systems that could inspire the next generation of solar technologies.

The potential applications for this research are manifold. For example, imagine solar panels inspired by the structure of mussels, which could be cheaper, more flexible, and more efficient. Or imagine biorefineries that harness algae growth in a way that mimics the photosynthetic processes of mussels.

The study’s promising results were made possible by the collaborative efforts of experts including Amanda Holt, a postdoctoral fellow in Sweeney’s lab, and Lincoln Rehm, a Palauan-American researcher currently with the National Oceanography and Atmospheric Administration. The project received funding from the Packard Foundation and the National Science Foundation, representing a coordinated effort to explore and exploit natural systems for technological advancement.

As research continues, the Western Pacific clams could lead the way toward a greener, more productive future. “We are so grateful to the Palauans, who place such great cultural value on their clams and reefs and work to keep them in pristine health,” Sweeney said, emphasizing the connections between culture, nature, and scientific advancement.