The scientific literature has almost entirely ignored this theoryThe episode (9:54) doesn't present the battery theory as conclusive fact.It is just a theory. They still need to work out how the theory could cause the lights to hang in the air. But for the time being, its the best theory they've got.

There are two facets of this that can be checked:Is this a real theory real scientists take seriously?This perspective letter published in a scientific journal reviews 3 explanations for the phenomenon. The third explanation matches the one given in the episode. A perspective letter is more like an opinion piece than a in depth scientific investigation. They typically go through an abbreviated peer review.Physicists have suggested few models to account for the HL phenomena. One possible explanation attributes the phenomena to an incompletely understood combustion process in the air involving clouds of dust from the valley floor containing scandium (Hauge, 2007, 2010). Another hypothesis suggests that HL are formed by a cluster of macroscopic Coulomb crystals in a dusty plasma produced by the ionization of air and dust by alpha particles during radon decay in the atmosphere (Paiva and Taft, 2010). The valley's shape, microclimate or unique geology might also act as a giant battery that powers the lights (Monari, 2013). Until recently, none of the hypothesis/models described above seems to account for all the observations of HL and the very high energy source generating HL remains completely unknown.

The Monar 2013 report presents the giant battery hypothesis, and presents some data that is consistent with the hypothesis. This data is far from conclusive and the report makes clear that this is just a hypothesis. It was not published in a scientific journal and I have no evidence that it went through peer review. It has gotten almost no scientific attention; According to google scholar, the perspective letter quoted earlier is the only scientific source that cites this report.I do not see any evidence that this theory is taken seriously by the wider scientific community.Is it "the best theory they've got"?The perspective paper mentioned two other theories. Hauge proposed that burning scandium causes the lights. Paiva and Taft proposed that it is caused by a dusty plasma. Hauge 2007, is a "preliminary report" that does not appear to be published in a scientific journal. It presents a little bit of evidence that supports the possibility that burning scandium dust is causing the lights. Although it has been cited by 8 other papers, none of them give it more than a cursory mention. Hauge 2010, was published in a peer reviewed journal and has been cited by two articles other than the perspective letter. I don't take either article seriously. One is short, doesn't really explain its methods or data, and is published in a probably predatory journal. The other explains that an alien "exo-civilization" built a "stealth extraterrestrial visitation probe" that is causing the lights.Paiva and Taft are two scientists who have published extensively about the Hessdalen lights. They have proposed several physical models for how the lights occur (2010,2012,2011,2012,2011). These models discuss dusty plasma, and charged particles emitted from rocks that fracture as they thaw. Most of them are published in peer reviewed scientific journals. Most of them have gotten at least 1 citation. The scientific community appears to take Paiva and Taft far more seriously than Monar or Hauge.This could be because their theory correctly explains the evidence, or it could be because they know how to write papers that will get accepted, or both. Although their work has more acceptance than the other two theories, that is a pretty low bar.Speculation about the showI personally have a good scientific background; for most scientific papers I can understand a decent amount of what is being discussed. Paiva and Taft's papers go right over my head. If the people creating the show looked at their work, they probably decided it was too complicated and arcane to try to explain to their viewers

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Can we generate enough electricity to light up street lights by means of a dynamo being rotated by car wheels?

Is it possible?Most likely yes.But:What challenges would one be facing for such an idea or design?These are what I foresee as the biggest hurdles you'd have to overcome.Hurdle 1: The laws of thermodynamics, in particular the first and second law. The first law of thermodynamics states that energy cannot be created or destroyed. There's a caveat here in that energy can be converted to and from mass using Einstein's famous equation, but there aren't any current automotive applications of Einstein's equation so we may as well assume energy and mass aren't converted to each other.So whatever energy it takes to run the lights will have to be put in by any vehicles driving on our fictional energy converter. This wouldn't be a problem except for the second law of thermodynamics which states that the entropy of the universe is at best not increasing. This leads to the concept of efficiency. Not all the energy of the gasoline your car burns goes towards "useful" work. Most of it is lost as heat. In fact so much heat is created by your engine that engines have cooling systems designed just to keep it from melting itself. Common gasoline engines have typical efficiencies of around 35%. This is before any efficiency losses created by wind resistance or efficiency losses of converting the car's motion through the converter to the street lights. Typical power plants which operate in a different fashion reach efficiencies of 50% or higher. This means we would end up wasting a lot more energy by trying to power lights off of cars instead of off the grid. Note that this hurdle applies to many different kinds of energy harvesting methods, not just Hurdle #2: The way automobiles work. Cars drive by transmitting power/torque to their wheels, getting them to spin. The wheel then spins and hopefully doesn't have significant slippage with respect to the ground, transmitting a friction force which moves your car forward. We say your car moves forward but there's no reason why we can't say the ground is moving backwards. If the ground is fixed from point A (source) to point B (destination) it really doesn't matter because either point B is getting closer to us or we're getting closer to point B.However, if the ground is rotating like a giant treadmill, the wheels can be spinning and we'd be moving with respect to a point on the treadmill, but the same reference point will also be moving away from point B. At best the car is moving faster towards point B than the reference point on the treadmill is moving away from it, at worst the reference point is moving faster away than we're moving towards it. Either way we're straining the engine more and likely arriving at our destination later, if at all.Hurdle #3: Reliability. A giant spinning dynamo is most likely not going to be reliable. This is because the system is being exposed weather, constant pounding of traffic, etc. The system would also be new and complex, the two worst enemies of reliability. Power plants and the grid used to transmit electricity are also quite complex, but these have had decades of refinement and testing to produce highly reliable systems.

Hurdle #4: Cost. The electrical grid and power plants aren't there just to power street lights. They power our homes and businesses, too. They can also use a variety of energy sources such as wind, solar, coal, natural gas, nuclear, hydroelectric, etc. Many of these energy sources are significantly cheaper or easier/cheaper to harvest in large scale. In many cases these facilities already exist. In the other cases I would argue that powering street lights are the least of your worries.

Conclusion: I'm sure it's possible someone could design a system to do what you described, but it would almost certainly be highly impractical, unreliable, and expensive

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Lighting Suggestions for Weeping Mulberry?

If you've never done any landscape lighting, I have to warn you. It is addictive. And it might be hard to find just one light. They usually come in sets for homeowners.

The trick between professional lighting and homeowner lighting is this; you never ever want to see the light bulb or fixture itself. No blinding lights. Your beautiful tree should be uplit with a spot light or two. From this position a spot light set behind the patch of Hosta? would work to hide the spot light. But if you walk to the front door? or come around on that walkway from the side of your home? More than likely to be blinded. It gets tricky to place the lights just right. Black matt spot lights with recessed bulbs is all I would use with a moon light or two.

Your landscape professionally lighted becomes alive at night. Very different than in the day light. Stunning. You should call some landscape companies to give you a bid. You want a low voltage system added to your electrical system. A box should have room to add more lighting because all the clients who started with...8 lights was the minimum, sold with an upgradeable transformer and there was a time where anyone with electrical skills was able to do this install. Not anymore. Find a landscape company that has its own licensed low voltage electrician.

Within a month, we timed it, all clients wanted more lights. Another 8 or 12 or 18...the only thing people would see are landscape features; the sweep of branches and bark, shadows, back lit, down lit or up lit. Spotting a light on the side of your home will make a black shadow of a tree in front. Moon lighting worked best for a patio situation. Let's talk about security. Those motion sensored blinding lights? The bad guy could stand outside of the circle of light and be invisible. Landscape lighting is more subtle and the ambient light off your tree, your hedge is plenty to light pathways and see bad guys sneaking around. Add gravel and barberry shrubs under windows and bad guys won't even bother.There are, 'dorky', lighting packages at home depot. Cheap. It would get you started and playing with lighting and figuring out how to hide those spot lights. Those 'fixtures' should be matt black with recessed bulbs. Low voltage will have wiring buried 6 inches deep. Make sure they bury the wiring 6 inches deep, no less than 4. Don't get tempted (best to talk to wife first) purchasing shiny brass pagodas and fixtures that look like earrings. Absolutely no pathway flying saucers. Pathway lights are for airport run ways. Can't tell I am a little opinionated? Grins. I am telling you the difference between an investment that will add to the value of your home and one that will be lost, forgotten and worse, tripped over. But when you see the power of landscape lighting, you will be smitten. Can't hurt to get some free bids. And get ideas. It will be an investment but pales with the investment you've already made in your landscape that right now gets turned off every night. People would leave their homes in the dark to go to work and it would be dark by the time they drove into their garages. Only neighbors would get a chance to see the landscapes...I wonder if they have wireless lighting now? Forget solar. Unless the lights aren't the solar absorber themselves. Like having blinding light bulbs everywhere. You want to make your landscape the light fixture.