Giant clam outperforms solar cell, converts 67 percent of sunlight

The spectacle can be observed on Palau in the Western Pacific, almost 1,000 kilometers (600 miles) east of the Philippines. In this remote island world, the natural ecosystem has largely been preserved, including a giant clam species that emits an iridescent glow.

However, this is not a type of bioluminescence like that of fireflies, but the residual shimmer of light that has been absorbed and almost completely converted. This is needed for the symbiotic algae living in the mussel.

And they only live there because the special structure of the mussel with so-called iridocytes ensures an enormous increase in usable light for these algae. These special cells are arranged in elongated channels. The light is scattered in these channels and then largely absorbed.

A logical trick further increases efficiency

A research group at Yale University has now been able to model this system and calculate the associated quantum efficiency. The value indicates the proportion of incident photons that can be converted into electrons. The replica achieved a value of 43 percent, which is three times higher than that of the leaves of tropical trees.

However, the mussel goes one step further. Depending on the prevailing light conditions, the angle of incidence, the time of day and cloud cover, it can stretch and contract the channels with iridocytes.

Taking this into account, new calculations on quantum efficiency revealed an impressive 67 percent. Two thirds of the light could be utilized. This provides a glimpse of how much potential still lies dormant in solar modules, and that solutions can be found in very unusual places - even in a threatened paradise in the Western Pacific.