In the biomimicry department, I'd look to the birds. Imagine an ornithopter mimic that seeks out power lines, clamps onto them, and powers itself via inductive pickups in its feet. Its battery gives it a 10-minute flying range; this gets recharged first. Then it goes into broadcast mode.
Sure, its signals could be triangulated, but if the mimicry is clever enough then it might be difficult to distinguish from a real bird. And it could be equipped with various means of monitoring its environment (such as an RF receiver which monitors the strength of nearby police-frequency broadcasts), which would allow it to rapidly bug out at the first sign of trouble. It takes to the air, circles for a few minutes, then finds another power line and starts over again.
Power distribution lines are already a major inefficiency loss to the power company. It's unclear if there would be any additional parasitic loss from the recharging bot, the efficiency of the system as a whole could in fact be greater than if the bot plugged into a metered outlet.
Kind of suits the piracy debate rather well actually. :-)
If you put a coil up to a HVAC line and draw current from that coil, that is going to increase the impedance of the line and reduce the amount of power that can be delivered at the other end.
Yes, the energy loss would probably be tiny in proportion to the energy transmitted and the resistive loss on a power line, but it is nevertheless a real loss to the power company.
It could be more efficient than plugging the bot into a metered outlet, but the power company gets paid for energy drawn from a metered outlet.
By analogy, it is more efficient for a retail shop if you steal goods from their warehouse before they are stocked on the shelves than if you buy them off the shelves, but the first case is a net loss for the retail shop, while more efficient, because they don't derive any revenues, and the second case, while less efficient, leads to an increase in profit for the shop.
This is quite different from piracy, which has no direct marginal cost - copyright was created to allow the recovery of fixed costs on certain types of work when there are low marginal costs to production.
My understanding is that at transmission line voltages, a big source of power loss is via corona discharge.
There are electrons and ions moving near the power lines. Perhaps it's possible to obtain a some of that power at a low rate without coupling back-EMF to the lines.
The electric grid loses a lot of power through inefficiencies anyway. If anyone did try this, I've no doubt the electric companies would be (rightly) very pissed off, but more about the potential risk to their power lines than the actual power lost.
I lose money through inefficiency because sometimes I drop coins on the ground and don't bother going after them, but if you start reaching into my pockets for my pennies, you and I are gonna have words, followed by fists.
It's not that they/I worry about watts/pennies, or even that they/I worry that you'll damage the powerlines/pockets, but that it's outright theft.
Human beings have the luxury of being irrational about their finances, whilst publicly traded corporations are supposed to be able to justify their financial decisions.
If a CEO says, "I hate stealing, so I'm going to spend 10 million dollars year of the company's money to stop 10 thousand dollars in power theft." then I don't think that's going to impress the company's shareholders.
Not that's an ingenious idea. It wouldn't necessarily need to fly; an operator could catapult it up and let it hook onto a line, and a lead weight in the tail would orientate it like a real bird.
You could either make it disposable (expect it to have a limited lifespan when removed by the authorities), or make it stop transmitting and drop to the ground when it thinks it could be in trouble. Birds tend to be coloured to merge into the undergrowth anyway, and if it drops before it's spotted, it could be very hard to find. An operator would then recover it at a later date.
The hight would be an advantage, and you'd get free power - the best of both worlds. You could put a transmitter (complete with inductive pickups) in place, then fly the drone back for reuse. It would also be quite hard to take down, even if they knew it was there.
I wouldn't worry too much about cloaking. The police are not going to risk their necks climbing up a power line to take out a ~$30 transmitter, unless it's to get prints or the society in question is very Orwellian (in which case, you can't make the drones anyway, because Big Brother is watching). I'd just go for transmitter which are too cheap to bother fighting against.
It's a low power device. They'd press charges if they caught you (to discourage other people doing the same thing), but it's not worth sending out counter-surveillance operatives to trace the device, then calling out a couple of linesmen to take it down simply to save power. A 60 watt device (my laptop running at full power) costs ~$70 a year. A Raspberry Pi, even with a reasonable Wifi transmitter, costs far less. And I bet the cost of power at a distribution line is less than what a consumer pays for power in their home.
As someone who lives in a society enabled by cheap, centrally generated electric power, I'd actually kind of hope the power company would seven-figures go after somebody who steals it from their distribution network, even if it's just somebody who wants to watch Game of Thrones without HBO.
The aren't going to fire a varmint rifle into the air in a populated area. They might want retrive these to get fingerprints or DNA samples, so they could chase down whoever put it there (and the MPAA / power companies might lobby for them to make this a priority), but I doubt they'll do anything dangerous simply to take down the devices.
Do you actually need an ornithopter? Why not just make it a powered glider (small pusher prop). The wing supports could be made of conductive materials, or infused with small wires, and the thing could just buzz along close to the wires. If you get it right, you could get more juice than you output, and when you get enough stored charge, just fly high and glide down, find updrafts, etc until power is low again and go buzzing some more.
Maybe I don't understand electrical engineering well enough, but wouldn't an ornithopter then also have to carry some sort of heavy duty (several hundred or thousand-pound) transformer as well?
A transformer consists of two inductors that transform electricity by - you guessed it - induction.
You don't need a transformer because you can just get the electricity in the correct voltage by using the right inductor. I haven't made any calculations but I would expect the battery to be bigger and of greater weight than a sufficient inductor.
First, since the power draw would be small, the transformer could be small too. Second, you could probably use solid-state devices like a regulator & rectifier combo instead of a transformer.
Sure, its signals could be triangulated, but if the mimicry is clever enough then it might be difficult to distinguish from a real bird. And it could be equipped with various means of monitoring its environment (such as an RF receiver which monitors the strength of nearby police-frequency broadcasts), which would allow it to rapidly bug out at the first sign of trouble. It takes to the air, circles for a few minutes, then finds another power line and starts over again.