The standard way of protecting buildings (and their occupants) from lightning is pretty simple: You stick a lightning rod on the roof, and then some kind of conducting channel that takes the huge discharge of electricity and dumps it into the ground. This is a tried and tested method that is used by most of the world’s tall buildings. In the case of something vital like lightning protection, I’m usually a firm believer in “if it ain’t broke, don’t fix it” — but that was before I read about a new lightning protection system that uses lasers to redirect the lightning, so that it ignores the building entirely, instead taking a totally new route to ground or perhaps into a futuristic energy harvesting device.
The typical bolt of lightning carries around 5 billion joules (GJ, gigajoules) of energy, or the energy stored in 145 liters of gasoline. For comparison, a ton of TNT is around 4 gigajoules — so, we’re talking about quite a lot of energy here, concentrated in a very short period of time. Despite lightning protection systems, these strikes still cause around $1 billion in structural damage annually in the US — so there’s obviously space for improvement. Enter lasers. (Read: US Navy deploys laser weapon system that’s fired with ‘video game-like controller’.)
According to researchers at the University of Arizona and University of Central Florida, high-power lasers can be used to redirect the flow of lightning. As a general rule, lightning follows the path of least resistance (impedance) to the ground. A big metal rod, with wires running into the ground, has much lower resistance than air (which has very high electrical resistance) — and so the lightning chooses the rod. High-power lasers also don’t like to travel through air — but, when they do, they strip away electrons, leaving a wake of highly conductive ionized plasma. Lightning frickin’ loves travelling through plasma.
