The Carnot efficiency and plant photosystems

The concept that the Carnot efficiency places an upper limit of 0.60–0.75 on the thermodynamic efficiency of photosynthetic primary photochemistry is examined using a PSI-LHCI preparation. The maximal quantum efficiency was determined ≈0.99 which yielded a thermodynamic efficiency of at least 0.96,...

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Bibliographic Details
Published in:Biophysics (Oxford) 2014-03, Vol.59 (2), p.230-235
Main Authors: Jennings, R. C., Santabarbara, S., Belgio, E., Zucchelli, G.
Format: Article
Language:English
Subjects:
Biological and Medical Physics
Biophysics
Cell Biophysics
Photochemistry
Photosynthesis
Physics
Physics and Astronomy
Thermodynamics
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Summary:The concept that the Carnot efficiency places an upper limit of 0.60–0.75 on the thermodynamic efficiency of photosynthetic primary photochemistry is examined using a PSI-LHCI preparation. The maximal quantum efficiency was determined ≈0.99 which yielded a thermodynamic efficiency of at least 0.96, a value far above that predicted on the basis of the Carnot efficiency. The commonly presented reasoning leading to the Carnot efficiency idea was therefore critically examined. It is concluded that the conventional assumption that the excited/ground state pigments are ergodic is incorrect, as is the assumption that the pigment system, under illumination, is in equilibrium with the incident light field, at a black body temperature of T r . It is concluded that the classical reasoning used to describe the thermodynamics of heat systems is not applicable to “photonic” systems such as plant photosystems.
ISSN:0006-3509
1555-6654
DOI:10.1134/S0006350914020080