Title: Exergy analyses of the biochemical processes of photosynthesis

Authors: S. Lems, H.J. Van Der Kooi, J. De Swaan Arons

Addresses: DelftChemTech, Delft University of Technology, Julianalaan 136, NL-2628 BL Delft, The Netherlands. ' DelftChemTech, Delft University of Technology, Julianalaan 136, NL-2628 BL Delft, The Netherlands. ' DelftChemTech, Delft University of Technology, Julianalaan 136, NL-2628 BL Delft, The Netherlands

Abstract: This paper gives the exergy analyses of the main biochemical processes of photosynthesis in green plants. In the light reactions, photosystem I, photosystem II, and ATP-synthesis are found to operate at exergy efficiencies of 50%, 68% and 81%, respectively, so that 48% of the exergy of directly utilised solar photons is converted to biochemical energy carriers. Subsequently, in the dark reactions, glucose is synthesised from CO2 at an exergy efficiency of 85%. When including the wasteful effect of photorespiration, the overall exergy efficiency of the photosynthesis of glucose is determined at 31–34%, with most of the exergy losses occurring during the initial conversion of the photon energy.

Keywords: exergy analysis; thermodynamics; second-law; exergy efficiency; biochemical processes; living cell; photosynthesis; solar photons; Calvin cycle; chloroplast; glucose; photorespiration.

DOI: 10.1504/IJEX.2010.031988

International Journal of Exergy, 2010 Vol.7 No.3, pp.333 - 351

Received: 06 Dec 2008
Accepted: 20 Jun 2009

Published online: 03 Mar 2010 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article