Sure, it’s tempting to imagine harnessing the electrical energy unleashed during a thunderstorm. After all, the average lightning bolt contains an estimated five billion joules. However, capturing and using this energy poses a raft of challenges.
The first conundrum: knowing where lightning will strike. Although lightning occursroughly100 times a second around the globe, these flashes are erratic and unpredictable, with only a small proportion reaching the ground.
The next challenge would be to convert the energy into a usable form. Objects struck by lightning can be heated to over 20,000°C, and the potential difference generated is around a hundred millionvolts. Creating equipment that could safely withstand these extreme conditions would be difficult. Any energy captured would then need to be used immediately or stored, and converting it to the low voltage, alternating current that powers our homes is extremely difficult.
Finally, the amount of energy that you could harvest from lightning may simply not justify the effort. The five billion joules in one lightning bolt amounts to about 1,400kWh – enough to power an average UK home for about four months. In reality, however, a significant proportion of this energy is dissipated into the atmosphere as heat.
All this might explain why the last organisation known to have considered the idea, a US company called Alternate Energy Holdings, gave up in 2007, declaring, “Quite frankly, we just couldn’t make it work.”
Asked by: John Awbery, Reading
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