Bright Solar Insights From The Deep Dark Ocean

Thousands of feet below the surface of the ocean, green sulfur bacteria somehow manage to harvest enough light to pull off one of nature’s greatest tricks, photosynthesis. And that’s where scientists from Cambridge’s Cavendish Laboratory have apparently made discoveries that could, one day, help make solar power work a whole lot better.

The scientists focused on pigment-protein complexes (PPCs), key structures in moving energy that begins as sunlight along the path from absorption to use in photosynthetic chemistry. What the researchers found was a mechanism– the bacteria’s Fenna-Matthews-Olson complex – that just doesn’t lose a single photon of energy.

Structure of Fenna-Matthews-Olson complex (image via Alex Chin/Cambridge University)

Structure of Fenna-Matthews-Olson complex (image via Alex Chin/Cambridge University)

Given that solar power as we know it today generally operates in efficiency ranges of 10 to 20 percent, the implications of gaining a better understanding of such systems – and perhaps borrowing from them – are pretty exciting.

This is a field of science the Cambridge researchers say ventures outside classical physics, merging with biology and embracing quantum concepts of coherence in photosynthesis, in which the particle-like excitons move through the molecular structure using many channels simultaneously.

“This quantum coherence is usually very fragile and quickly destroyed by random fluctuations of surrounding proteins,” the Cambridge researchers said. That’s why the researchers were surprised to find, in their simulations, long-lasting coherence in PPCs.

“Our results provide a microscopic basis for understanding how the coherence, central to these theories, is maintained in PPCs. The resulting insights provide several promising clues as to what efficiency advantages quantum coherence might provide to these systems,”  Alex Chin, from Cambridge’s Winton Programme for the Physics of Sustainability, said in a statement.

“Some of the key issues in current solar cell technologies appear to have been elegantly and rigorously solved by the molecular architecture of these PPCs – namely the rapid, lossless transfer of excitons to reaction centres.”

Now, let’s be clear here – this isn’t a new product. The research could open the door to some fascinating new innovations, but there’s no green sulfur bacteria solar cell headed to the market anytime soon that’s going to drive solar efficiency to new heights.

Meanwhile, short and medium-term advances in solar efficiency are taking places, incrementally – through improved production-line techniques at companies like Suntech; working with new materials at companies like Alta Devices; and pushing the limits of multijunction formulations at companies like Solar Junction.

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