(287j) First Principles Modelling and Optimization of Photosynthetic Cell

First principles modelling and optimization of photosynthetic cell

Hemanth Kumar Tanneru, Raghunathan Rengaswamy*

Department of Chemical Engineering, Indian Institute of Technology – Madras, Chennai, India

*raghur@iitm.ac.in

Micro photosynthetic cell is an electrochemical device which generates electricity using photoautotrophic organisms. The photosynthetic cell consists of anode and cathode chambers separated by a Nafion membrane patterned with gold electrode. The anode chamber consists of photosynthetic microorganisms, the nutrient medium to support their growth and a mediator that transfers the electrons and protons from the cell to the anode surface. The cathode chamber consists of an electron acceptor. The electrons and protons required to generate electricity are obtained from photosynthesis and cellular respiration of the microorganisms. At the electrode surface the protons and electrons are released by the mediator. The protons have to diffuse through the Nafion membrane to the cathode chamber and the electrode surface patterns decide the available surface area for electrochemical reactions. Overall device performance is a function of the several phenomena related to the transport of the protons and other reactant species and the electrochemical reactions that occur at the electrode surfaces.

Design and optimization of these systems require reliable models. In this work we present a detailed first principles model that captures the effect of diffusion and patterning on the electrode surface. Experiments are performed where concentration profiles and the V-I characteristics are measured and the model is validated. Sensitivity analysis and optimization studies on the design and operating parameters are performed using the model. Theoretical maximum efficiency of the photosynthetic cells is also calculated.