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| Joined: | Mon Nov 21st, 2005 |
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When Ryu and colleagues shone a halogen lamp on their alga, those electrons were siphoned off by the electrode instead. Their circuit registered a current of 1.2 picoamps – which is equivalent to a yield of 0.6 milliamps per square centimetre. By increasing the light intensity that value rises to a maximum of 6 milliamps per square centimetre, Ryu says.
By contrast, some silicon solar cells have a current density of 35 milliamps per square centimetre. Despite that, Ryu thinks his algae could still find a job in power generation. "The solar cell efficiency is also related to the wavelength of light," he says. "We believe our bio-solar system may provide higher efficiency than the silicon-based solar cells at particular wavelengths." Chlorophyll, for instance, has evolved to absorb blue and red light well, but doesn't absorb much green light, hence its colour.