Abstract A thermoelectric generator is a unique heat engine in which charge carriers serve as the working fluid. It has no moving parts, is silent in operation and very reliable. However, its relatively low efficiency (typically around 5%) has restricted its use to specialised medical, military and space applications where cost is not a main consideration. During the past 10 years thermoelectrics has attracted increasing attention as a ‘green’ and flexible source of electricity able to meet a wide range of power requirements. Relatively recently it has been realised that in situations where the supply of heat is cheap or free, as in the case of waste heat, efficiency of the conversion system is not an overriding consideration. The use of waste heat as an energy source particularly at temperatures below 140C substantially increase the commercial competitiveness of this method of generating electrical power. The results of a recent investigation of the performance of thermoelectric generating systems powered by waste hot water indicate that, over a three year operating period, electrical power can be produced by this method and at a price which matches that of conventional utilities. This paper provides an overview of environmentally friendly applications of thermoelectric generation and assess its potential as an alternative source of electrical power.