Chapter 20 - Other electrochemical energy conversion

Abstract

This chapter describes a method of using electrochemistry in connection with energy conversion. Useful chemical energy may be defined as energy that can be released through exotermic chemical reactions. In general, chemical energy is associated with chemical bindings of electrons, atoms and molecules. The bindings may involve overlapping electron wavefunctions of two or more atoms, attraction between ionized atoms or molecules, and long-range electromagnetic fields created by the motion of charged particles. The organization of atoms or molecules in regular lattice structures represents another manifestation of chemical bindings. Some substances possess different crystalline forms, which may exist under given external conditions. In addition to the possibility of different solid phases, phase changes associated with transitions among solid, liquid and gas phases all represent different levels of latent energy. The salinity difference, such as the one existing between fresh (river) and saline (ocean) water, may be used to drive an osmotic pump, and the elevated water may in turn be used to generate electricity by an ordinary turbine. An alternative method, aiming directly at electricity production, takes advantage of the fact that the salts of saline water are ionized to a certain degree and thus may be used to derive an electrochemical cell. This electrochemical cell may be called a dialytic battery, since it is formally the same as the dialysis apparatus producing saline water with electric power input. In this case, the membrane allows one kind of ion to pass and thereby reach the corresponding electrode.