We’re all the time trying to harvest power from various, nominally “free” sources resembling wind, water, photo voltaic, and even less-dense prospects resembling vibration and friction. Then there are lightning strikes that are potential power sources are wasted, in addition to usually being harmful. (Lighting strikes are surprisingly frequent; the European Meteosat Third Era satellite tv for pc launched in December with cameras which may observe and document lightning strikes, even the smallest and quickest ones, day and night time, over greater than 80 p.c of Earth’s floor.)
May that wasted-energy state of affairs change? Unlikely – however as we all know, it’s “by no means say by no means” with regards to know-how and advances. Again in January, a European-based crew revealed an fascinating paper in Nature Photonics with the surprisingly easy title “Laser-guided lightning.”) It detailed how they blasted repeated pulses from a high-power laser to information lightning strikes that had been so far as two miles away right down to a comparatively small, grounded rod close to their Swiss-mountain setup, Determine 1 [1].
Determine 1 a) Format of the experimental setup on high of the Säntis Mountain in Switzerland. b) Images of the experiment with the second harmonic of the laser beam used to visualise the laser path. Supply: “Laser Guided Lightning”, Nature photonics, 2023
The seemingly clarification is that the laser pulses super-heated the air, which precipitated the air to change into electrically conductive alongside the trail of the laser, Determine 2.
Determine 2 Snapshots of the lightning occasion of 24 July 2021 recorded within the presence of the laser. Supply: “Laser Guided Lightning”, Nature photonics, 2023
This skill to maybe direct a lightning strike brings up an apparent query: why not channel this power to some kind of power storage system (ESS)? In spite of everything, that power is in any other case wasted since it’s really and actually grounded. (I’ve even seen so-called “consultants” counsel this as a no/low-cost power supply.)
If solely it had been that straightforward. first query is that this: how a lot power and energy is there in a lightning strike? The reply spans a variety, however in line with Tess Gentle within the House and Distant Sensing group at Los Alamos Nationwide Laboratory, lightning is “each extremely highly effective and loopy quick” and every strike delivers about fifty thousand amps in simply microseconds, with a megavolt punch.
Moreover, whereas every strike delivers round 5 or ten gigajoules of power (one GJ = 109 joules), a lot of that power is misplaced in heating the air and so shouldn’t be “capturable” electrical power. (To offer you some sense of scale, a big EV battery has a capability of about 100 kilowatt hours, or 3.6 × 108 joules.) So though lightning does appear to have a variety of power, it’s actually not that a lot and also you’d want a variety of strikes.
Why not make it easy, and use a completely passive, easy lightning rod? The reply has to do with the lightning rod’s vary of effectiveness.
Though the precise quantity is a operate of atmospheric, floor, and different circumstances, a basic information is that an ordinary rod can appeal to lightning inside a radius equal to its peak. Thus, you’d want a big “farm” of lightning rods with some mixture of a considerable amount of land space and tall rods. The laser-based scheme will increase the seize space and reduces the rod peak necessities.
There’s one more difficulty: Is directing lightning through lasers worthwhile from an energy-balance viewpoint? Even whether it is technically viable, the laser scheme has its personal main disadvantage, because it makes use of a variety of energy itself. The researchers used a Yb:YAG laser emitting picosecond pulses at 500 MJ power with a wavelength of 1,030 nm and a 1-kHz repetition charge. In different phrases, the power value of driving the lasers was larger than that of the captured lightning.
This imbalance is considerably analogous to the latest fusion “success” report from the Nationwide Ignition Facility (NIF) in California. They targeted about 2 MJs of power from a whole bunch of lasers onto a tiny capsule of fusion gasoline, sparking an explosion that produced about 3 MJ of power. Whereas this can be a breakthrough in some ways and took years (and $) to occur, the laser-drive subsystem itself is just one% environment friendly, so about 200 MJ was wanted as the entire venture enter power—not a successful equation.
Even when the power-balance was favorable for harvesting lightning, it nonetheless doesn’t tackle one other intractable downside between captured lightning and any identified ESS. How do you get that a lot energy (the speed of power switch) into the battery? No current battery or ESS may survive that giant energy surge—and that’s what it’s.
After all, the following step in such analysis virtually all the time entails “larger” and “extra money.” The lead researcher was quoted in information experiences as saying that they wish to improve the gap that the laser can information the lightning to a whole bunch of meters. That’s theoretically attainable with an even bigger, extra highly effective laser, however the prototype laser used on this demonstration value 2 billion euros. (If that’s out of your funds, you’ll have to stay with one thing easier, resembling a four-transistor DIY lightning detector, see “Easy analog-centric circuits develop STEM views.”)
There’s an fascinating historic hyperlink to this whole lightning-capture story. Earlier than current-flow electrical energy as we use immediately existed, Benjamin Franklin really captured some lightning power in a Leyden jar (an early kind of capacitor) throughout his well-known kite-flying experiment. This isn’t delusion or legend, because it was correctly documented on the time (the Wikipedia entry “Kite experiment” has a transparent dialogue and credible reference hyperlinks).
Franklin cut up the kite’s “downlead” through the use of moist hemp string as a conductive result in the Leyden jar and an insulating silk thread on the opposite department to his son who was flying the kite, who stayed in a shed in order to not get moist. He succeeded in exhibiting the connection between static electrical energy and lightning earlier than electrical energy (static or in any other case) was understood or had any sensible makes use of.
As for harvesting lightning immediately, it appears prefer it’s the identical story: irrespective of how engaging it could appear at first, large-scale power harvesting doesn’t come straightforward, and there’s no “free lunch” on the market.
Invoice Schweber is an EE who has written three textbooks, a whole bunch of technical articles, opinion columns, and product options.
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