wikipedia

Since the late 1980s, there have been several attempts to investigate the possibility of harvesting lightning energy. A single bolt of lightning carries a relatively large amount of energy (approximately 5 gigajoules[1] or about the energy stored in 38 Imperial gallons or 172 litres of gasoline). However, this energy is concentrated in a small location and is passed during an extremely short period of time (microseconds[2]); therefore, extremely high electrical power is involved.[3] It has been proposed that the energy contained in lightning be used to generate hydrogen from water, to harness the energy from rapid heating of water due to lightning,[4] or to use a group of lightning arresters to harness a strike, either directly or by converting it to heat or mechanical energy,[citation needed] or to use inductors spaced far enough away so that a safe fraction of the energy might be captured.[5]