Giant clams inspire breakthroughs in solar energy efficiency

A recent study published in the journal PRX Energy has revealed that giant clams have crucial insights for more efficient solar energy systems. The work was done by Dr. Alison Sweeney and Dr. Amanda Holt from Yale University, and Dr. Lincoln Rehm—a former researcher at the Palau International Coral Reef Center (PICRC) and current Fisheries Resource Management Specialist at the National Oceanic and Atmospheric Administration (NOAA).

Giant clams are found in the shallow coral reefs of the Indo-Pacific region. These animals have a symbiotic relationship with algae, which live inside their tissues. Algae perform photosynthesis, providing nutrients to the clams in exchange for shelter and access to sunlight. Key to the clams’ efficiency are their iridescent cells (called iridocytes) which manipulate light. This allows clams to maximize their use of sunlight, benefiting the photosynthesis of their algal partners.

In their study, the researchers were inspired by giant clams in the shallow waters of Palau to create an analytical model to assess the maximum possible efficiency of large photosynthetic systems in intense sunlight. This model considers the geometry, movement, and light-scattering properties observed in these marine creatures. They were surprised to find that large living clams easily meet the maximum possible efficiency predicted by this model.

Algae inside giant clams are arranged in vertical columns on their surfaces – a critical adaptation that allows them to absorb sunlight optimally. This arrangement, coupled with the light manipulation by iridocytes, ensures effective utilization of scattered sunlight. Researchers also speculate that these algae columns adjust throughout the day in response to changes in sunlight intensity. This behavior enhances the clams’ ability to absorb light optimally. In fact, researchers calculated a quantum efficiency of 67% – which measures how effectively photons are converted into electrons. To put it into perspective, the typical quantum efficiencies for green plants found on land range from 2 to 4%, while those for algae used in biofuel production vary from 5 to 10%, and rooftop solar panels are around 20%. This means giant clams may be the most efficient solar energy system in the natural world!

This unique way in which giant clams manage light could inspire advancements in solar technology. Current light-harvesting technologies, such as photovoltaics and algae biofuels, often lose efficiency due to uneven light distribution, leading to energy loss. By incorporating structures that mimic the iridocytes of giant clams, solar panels could improve their ability to absorb and convert sunlight into energy.

“This research is exciting because it shows how much we can learn from nature,” remarks biophysicist Alison Sweeney of Yale University. “By understanding and applying these natural principles, we can make solar energy more efficient and accessible.”