On the improvement of electric field energy harvesting from domestic power lines

A method to improve electric field energy harvesting (EFEH) from domestic power lines by 100% is proposed in this paper. Making use of the electric field around power lines is a promising way to harvest ambient energy. One common method is to use a copper sheet to wrap on the insulator of a power line. The capacitance between the copper sheet and the live wire is utilized to extract energy. However, this parasitic capacitance would limit the output power of such a harvester as well when a full bridge rectifier is used. To deal with this problem, a new method is proposed to improve the harvested energy by using a switching circuit. By monitoring the output of a sensing circuit, the switching circuit shortens the discharging time of the parasitic capacitor and increases the output power. Compared with a conventional harvester, the proposed system can double the output power in theory. Theoretical calculations and experimental validations are presented to prove the concept. Measurement results show that the proposed harvester of a 90 cm long copper sheet wrapped on a domestic 230 V power line can harvest 367.5 μW power with 95.6 % improvement.