A Simple Thermodynamic Analysis of Photosynthesis

Abstract: In this paper we present a comparative study of nine photosynthetic pathways by means of their thermodynamic performance. The comparison is made by using the thermal efficiency of light-to-chemical energy conversion and the so-called ecological criterion arising from finite-time thermodynamics. The application of both criteria leads to photosynthesis made by metaphytes and non sulfur purple bacteria as those of best thermodynamic performance. In spite of the simplicity of our thermodynamic approach some insights over the low overall efficiency of photosynthesis is suggested. Keywords: photosynthesis, thermodynamic performance, ecological function. PACS Codes: 87.10 1. Introduction Schrodinger suggested that the maintenance of high organization of living beings is due to a continuum influx of negative entropy [1]. Photosynthesis is a process where energy-rich organic molecules emerge from simple, energy-poor molecules absorbing solar photons [2]. This photochemical reaction occurs in the photosynthetic reaction center, which is a very complicated molecular complex [3]. Many models to describe the photosynthetic center have been proposed. Van Rotterdam et. al. [3] suggested that the transduction of photons’ energy to a transmembrane electrochemical potential difference for protons operates in a simple battery-like manner. De Vos [4],

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