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Bradbury Science Museum Question Of The Month: Why Not Harness Lightning For Renewable Energy Source?

on October 6, 2017 - 8:07am

Lightning striking behind LANL's main technical area. Courtesy/BSM


Given that lightning generates so much electricity, why don’t we harness it as a renewable energy source?

While it’s true that a single lightning bolt could power the entire city of Santa Fe for about a minute, there are some issues with capturing lightning as an energy source.

First, while there are some areas of the planet (like the Sangre de Cristo mountains near Santa Fe and the Florida coast) that get a higher than average number of lightning strikes, getting lightning to exactly strike our receivers is problematic. Nature is just too erratic.

But even if we could entice lightning to routinely strike precisely where we wanted, we’d be faced with the problem of a strike’s intensity and duration. Lightning is both incredibly powerful and crazy fast. Each strike would force about 50,000 amps of current into a battery in just microseconds. No existing battery could survive this onslaught; batteries need to charge up more slowly.

Then, even if we could design a battery that would not be vaporized by the strike, all the lightning in the world would still power only a small fraction of households. It’s true that each stroke produces up to perhaps five or 10 gigajoules of energy, and a household in the U.S. needs only about five gigajoules per month—and that’s just one strike! But actually, only a fraction of that energy is in the form of electrical current—much of the energy goes to heating the air. And the process of storing the energy in a battery and then retrieving it is pretty inefficient. So, now you need a few strikes per household per month, and in the end, even if we could find a way to capture, store, and use the energy, it would power only about 0.1 percent of the world’s homes.

Tess Light, Space and Remote Sensing group, Los Alamos National Laboratory