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We’re all the time seeking to harvest power from various, nominally “free” sources reminiscent of wind, water, photo voltaic, and even less-dense potentialities reminiscent of vibration and friction. Then there are lightning strikes that are potential power sources are wasted, in addition to typically being harmful. (Lighting strikes are surprisingly widespread; the European Meteosat Third Technology satellite tv for pc launched in December with cameras which might observe and document lightning strikes, even the smallest and quickest ones, day and night time, over greater than 80 % of Earth’s floor.)
Might that wasted-energy state of affairs change? Unlikely – however as we all know, it’s “by no means say by no means” in terms of expertise and advances. Again in January, a European-based group 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 prime 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 prompted the air to grow to be 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 means to maybe direct a lightning strike brings up an apparent query: why not channel this power to some type 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 “specialists” counsel this as a no/low-cost power supply.)
If solely it had been that simple. A great first query is that this: how a lot power and energy is there in a lightning strike? The reply spans a variety, however in keeping with Tess Mild 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 will not be “capturable” electrical power. (To present you some sense of scale, a big EV battery has a capability of about 100 kilowatt hours, or 3.6 × 108 joules.) So despite the fact that lightning does appear to have a number of power, it’s actually not that a lot and also you’d want a number of strikes.
Why not make it easy, and use a very passive, easy lightning rod? The reply has to do with the lightning rod’s vary of effectiveness.
Though the precise quantity is a perform of atmospheric, floor, and different situations, a basic information is that a normal rod can entice lightning inside a radius equal to its top. 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 top necessities.
There’s yet one more problem: Is directing lightning through lasers worthwhile from an energy-balance viewpoint? Even whether it is technically viable, the laser scheme has its personal main downside, because it makes use of a number 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 fee. In different phrases, the power price 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 lot of lasers onto a tiny capsule of fusion gas, 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 only one% environment friendly, so about 200 MJ was wanted as the entire undertaking enter power—not a profitable equation.
Even when the power-balance was favorable for harvesting lightning, it nonetheless doesn’t deal with one other intractable drawback between captured lightning and any recognized ESS. How do you get that a lot energy (the speed of power switch) into the battery? No current battery or ESS might 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 “more cash.” The lead researcher was quoted in information studies as saying that they wish to improve the gap that the laser can information the lightning to a whole lot of meters. That’s theoretically attainable with an even bigger, extra highly effective laser, however the prototype laser used on this demonstration price 2 billion euros. (If that’s out of your finances, you will have to stay with one thing less complicated, reminiscent of a four-transistor DIY lightning detector, see “Easy analog-centric circuits develop STEM views.”)
There’s an fascinating historic hyperlink to this complete 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 sort of capacitor) throughout his well-known kite-flying experiment. This isn’t fable or legend, because it was correctly documented on the time (the Wikipedia entry “Kite experiment” has a transparent dialogue and credible reference hyperlinks).
Franklin break up the kite’s “downlead” by utilizing 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 displaying 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 seems to be prefer it’s the identical story: irrespective of how enticing it might appear at first, large-scale power harvesting doesn’t come simple, and there’s no “free lunch” on the market.
Invoice Schweber is an EE who has written three textbooks, a whole lot of technical articles, opinion columns, and product options.
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