In this publication it is given a brief overview on the state of art of green energy harvesting. Green energy harvesting aims to supply electricity to electric or electronic systems from an energy source present in the environment (e.g., thermal energy (thermoelectricity)) without grid connection or utilisation of batteries. Almost all manufacturing processes ranging from steel to food production generate heat (the so called “waste heat”), as do all machines from jet engines to microprocessors. The possibility of using a thermoelectric (TE) device to capture and to directly convert this waste heat into electric power is a very attractive and valuable approach to improve the overall energy efficiency and, thus, promotes a sustainable future.