Model Energy Conversion Efficiency of Biological Systems

Novel, highly efficient energy conversion systems based on, for example, photovoltaic and thermoelectric materials will play an important role in our nation's upcoming "Manhattan Project" for energy. Energy conversion systems that mimic biological energy conversion are of special interest for medical implants due to their inherent compatibility with the human body. Biological systems have several natural mechanisms to convert light and chemical energy into useful outputs; much can be learned by characterizing such natural systems, and in developing bio-inspired synthetic systems to benefit human enterprise.

An example of an organism that converts chemical energy into electrical energy is the electric eel. A large electric eel is able to produce 600 Volts and up to 1 Ampere of current. A Ceramics Division researcher in collaboration with a graduate student from Yale University have developed a numerical model of this organism, the first model produced for a polarized cell. The model enables study and measurement of the energy conversion process and its efficiency, and the energy density of natural cells in order to model the design for a synthetic, biologically-inspired energy conversion system. The model showed that electrocytes, the electrogenic cells in electric eels, are roughly 14.7% efficient in converting chemical energy (in the form of glucose) into electricity, comparable to the system-level efficiency of synthetic room-temperature fuel cells. 

Once the electrocyte was characterized, the model was used to design a synthetic cell that operated on the same principles. The model calculated the maximum efficiency attainable and the materials variations that maximize efficiency and power density. The design for the optimized synthetic cell system could achieve 19.2% efficiency, or a 31% improvement, over the natural cells.  The synthetic cells would be designed to contain similar materials and molecular components as a natural cell, such as a cell membrane and the accompanying proteins, but would not be a living cell. When successfully realized, such artificial cells would form a biocompatible system that can provide energy to drive implants, for example, using natural energy sources.

Created December 10, 2008, Updated August 25, 2016