Energy conversion in isothermal nonlinear irreversible processes – struggling for higher efficiency*
1 Institute of Physics, Humboldt University, Newtonstr. 15, D-12489 Berlin, Germany
2 Leibniz Institute for Baltic Sea Research, Warnemünde, Germany
Received: 19 January 2017
Revised: 19 March 2017
Published online: 21 June 2017
First we discuss some early work of Ulrike Feudel on structure formation in nonlinear reactions including ions and the efficiency of the conversion of chemical into electrical energy. Then we give some survey about isothermal energy conversion from chemical to higher forms of energy like mechanical, electrical and ecological energy. Isothermal means here that there are no temperature gradients within the model systems. We consider examples of energy conversion in several natural processes and in some devices like fuel cells. Further, as an example, we study analytically the dynamics and efficiency of a simple “active circuit” converting chemical into electrical energy and driving currents which is roughly modeling fuel cells. Finally we investigate an analogous ecological system of Lotka-Volterra type consisting of an “active species” consuming some passive “chemical food”. We show analytically for both these models that the efficiency increases with the load, reaches values higher then 50 percent in a narrow regime of optimal load and goes beyond some maximal load abruptly to zero.
© EDP Sciences, Springer-Verlag, 2017