Hydrazine-air fuel cells. Hydrazine-air fuel cells emerge from the laboratory.

A fuel cell is an electrochemical device that continues to generate electrical power as long as reactants are supplied and products are removed at properly controlled rates. An assembly of cells is required within which the conversion of chemical to electrical energy occurs; also required is a set of auxiliary components to supply the reactants and remove the products (including waste heat) under controlled steady-state conditions. In addition to the desired energy-conversion reactions, there are deleterious side reactions that can impair fuel economy. From knowledge of these factors influencing the possible reactions, and guided by principles of elementary chemical thermodynamics, the electrochemist can select optimum conditions for cell performance. It is then the job of the engineer to design auxiliary components and controlling devices to provide the electrochemical cells with the best possible approach to these optimum conditions.