Title: The second-law implications of biochemical energy conversion: exergy analysis of glucose and fatty-acid breakdown in the living cell

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

Addresses: Delft Institute for Sustainable Energy, Delft University of Technology, Julianalaan 136, NL-2628, BL Delft, The Netherlands. ' Delft Institute for Sustainable Energy, Delft University of Technology, Julianalaan 136, NL-2628, BL Delft, The Netherlands. ' Delft Institute for Sustainable Energy, Delft University of Technology, Julianalaan 136, NL-2628, BL Delft, The Netherlands

Abstract: This paper gives the exergy analyses of the main stages of glucose and fatty-acid breakdown in living cells. Conversion processes like the glycolysis, the citric-acid cycle, and mitochondrial respiration consistently show exergy efficiencies of around or above 90%, while the membrane-transport processes are about 70-75% efficient. The overall efficiencies of glucose and palmitic-acid breakdown to activated phosphate groups in ATP are determined at 58% and 60%, respectively. Reasonable variations in the intracellular concentration data affect the efficiency results by no more than a few percentage points. The reported exergy analyses, thus, point at a high thermodynamic efficiency of living-cell energy conversion.

Keywords: exergy analysis; exergy efficiency; biochemical energy conversion; living cells; glycolysis; citric acid cycle; mitochondrial respiration; mitochondrion; glucose breakdown; fatty acid breakdown; palmitate; second law of thermodynamics; fatty acids; thermodynamic efficiency.

DOI: 10.1504/IJEX.2009.024000

International Journal of Exergy, 2009 Vol.6 No.2, pp.228 - 248

Available online: 22 Mar 2009 *

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