Monday, August 20, 2018

Audacious Plan to Charge Electric Vehicles While Operating

Electric vehicles come up fairly regularly around here, and one of the weak spots of EVs is the amount of time spent in recharging, which leads to inferior performance for most buyers compared to an internal combustion vehicle.  While going through some old links ("I ought to read that..."), I stumbled across an audacious plan published in Power Electronics magazine back in February.  What if the entire infrastructure was designed to accommodate electric cars, so that they could be charged during operation?  Maybe instead of audacious, we should say "mindbogglingly expen$ive".

From a technical standpoint, it doesn't look like there's new tech that has to be completely invented; it's re-using existing ideas.  They need to be optimized for this use, but what they have to do is probably well understood.  If you have a phone or other personal electronic device that's put on a charging mat it's probably the same technology: a common electrical component called a transformer is conceptually split in half: one side is in the mat and the other in your phone.  In this case, one side of the transformer would be buried in the road and the other half mounted in the car.  The combination is called Near-Field Wireless Power Transfer.  This won't be as efficient as plugging a car in, but with dense enough placement of these transformers, the cars could have their batteries continuously topped off by the road.
Near-field WPT systems are of two types: inductive, which use magnetic field coupling between conducting coils, and capacitive, which use electric field coupling between conducting plates to transfer energy (Fig. 1). For medium-range applications (in which the distance between the transmitter and the receiver couplers is comparable to the size of the couplers, as in EV charging), inductive WPT systems have traditionally been preferred.
A simplified electrical block diagram with the transformer coils shown as green for the road and red for the car.  The concept drawing of the car shows its transformer coils in red passing over the green coils in the road.   The same figure could be redrawn with minor changes to show metal plates (capacitors).  There are profound circuit differences between the magnetic (inductive) coupling based on transformers and the electric (capacitive) coupling based on capacitors, but conceptually they're just transferring power either as an electric field or magnetic field.  The authors appear to do most of their analysis based on capacitive coupling after arguing that the transformers will depend on large hunks of ferrite (a ceramic with iron powder and other metals fired into it) while the capacitor approach will rely more on high performance electronic circuitry.  They expect the ferrites will be more expensive than the electronics approach and the electronics will get cheaper over time.

Let me break from the technical details here, and say if you want to read them head over to Power Electronics.  Honestly, they assume more familiarity with electronics than I'm doing, but not much.

What I want to address is the sheer megalomania of it, and some of the obvious problems. The article begins like this:
Consider a future in which a driverless ridesharing electric vehicle (EV) pulls over as you exit a building, takes you to your destination, and proceeds to drive passenger after passenger without ever needing to stop to recharge its battery. Instead, power generated by nearby wind and solar resources is delivered wirelessly from the roadway to the vehicle while it is in motion.

Not having to stop for recharging will make EVs truly autonomous, and, because the vehicles can thus remain in service for more hours, fewer vehicles will be needed to meet passenger demand. Furthermore, EVs with in-motion (dynamic) wireless charging can have much smaller batteries, an option that can reduce their cost and accelerate adoption.
Think of what it would cost to put electric plates with supporting electric circuitry every few feet down every road in a city; any road you don't put charging circuits on would be a back road either not-served or not well-served by electric cars, depending on how well they'd be charged and how long they could go without being charged.

Did you notice the part where it said you'd call a "driverless ridesharing electric vehicle"?  That means it's some sort of future where you're not going to be driving your own car, some entity like the city or state or some crony, er, contractor to the city or state will be renting rides to/from where you want to go.  As long as it's on a road that has the required million dollar a mile (PFA number) worth of electronic circuity.  Think back to the back road that won't get the electronic charging circuits; is that an ideal way for politicians to get "contributions" to ensure they make sure those businesses get a new road?

On this basis alone, I say it ain't happening this way.  Cities and states are far too broke to do something like this.  This is a massive, gargantuan public works job.  Only someplace as crazy as Califruitopia would spend on something this crazy, if even they would.  

Now think of the safety.  Those electric fields from the road are capable of transferring energy into pedestrians and animals, too.  The cars would need to be specifically built to shield the occupants.  The metal plates in the road would need to be able to sense when the vehicles are moving over them, pulse the power on and turn it off when the vehicle goes past.  That only adds a little cost.  The fact that the plates are in a road actually adds a little safety; after all, a stray dog or a kid will be more likely to be killed by being hit by the car than the electric field.  (That was irony - nobody would think that's a good idea).  

The cars would have to be pretty well aligned over the plates to get a good percentage of the electrical power across (i.e., good coupling).  Any placement to the side, rather than directly over/under each other would decrease the coupling.  The car couldn't be too high off the ground either: ground clearance would be a design requirement.  Any snow, or other foreign matter (like discarded hypodermics or feces, speaking of California) would make the charging less efficient.

Like most of these wild-hair design proposals that get into these magazines, this is the author's lab at the University of Colorado Boulder, showing you what they can do.  This doesn't have a snowball's chance in Florida of being adopted.  In my opinion (of course).  


  1. The solution will emerge, but as you say, it won't be this "solution".

  2. Of course, this won't be free electricity. Someone will have to pay, and that's a nice way for the benevolent government to track your movements. What a feature!

  3. The people who think of these things have no concept of what the word "infrastructure" means, or the costs of a project this big.

    The last time people thought "big" like this was when they designing Welthauptstadt Germania....

  4. Do the authors suggest any ways to make all this embedded widgetry and metal resistant to being pried up and sold for scrap?

  5. Oh dearie dearie me. This reminds me of the plan a buddy of mine and I had to harness the power of toddlers by having loose floorboards. Nikola Tesla, hear my prayer! We need you now!

    1. That's a cool idea. How did you extract energy? Magnets on the floors and coils underneath, or what?

  6. I think Hybrid is a great solution, speaking from experience.

    In 2013 I purchase a Ford Fusion Hybrid. I love it! Everytime I look down and see anywhere from 48-52 MPG. It's comfortable and rides great. Front wheel drive and in the winter I put on dedicated snows for he New England weather.

    I was commuting with my business Silverado 1500 and spending ~800.00 a month on fuel. That was the motivation for purchasing the Fusion. Now I average between 100-150 a month and I paid off the car loan in 4 years instead of 5.

    It has a 12 gallon tank and a range of 550 plus miles depending on driving. I don't run it hard when I'm on the highway. 65-70 mph with eco cruise in the right hand lane. It might take 5 extra minutes to get to my destination but the savings out weigh my time.

    I wish they would serious work on Hyrid SUV or Pick Up versions that can get great gas mileage. There should be some way to have the larger vehicles be able to switch back and forth due to weight, towing, and load. Many times you will see one person riding around here in an empty
    4x4 pick up or SUV. Granted I was one of them. Most of the 4x4s are for the winter and nowadays you really on "need" them on a few days a year.

    Anyway, if anyone ever considers a hybrid, the fusion it GREAT! excellent MPG and think of all the gas tax you are saving... until they decide to start taxing us by the mile.....

    1. I think hybrids are the peak bang per buck of what we get out of cars. I don't see electric cars as being a good compromise for much of anything. If all you want it for is to drive about 40 miles a day and have (or rent) another vehicle for driving long distances, they'll be fine. The current EVs not all that different from an electric golf cart, but have more creature comforts. I don't think most people have or want to have a commuter car and an everything else car.

      What I don't see is anyone using each technology for what it's best at. An electric motor assist for a truck/SUV used to tow a camper or boat seems like a good idea. Electric motors (well, most) have their greatest torque at stall. You need the greatest torque at lowest RPMs for pulling the boat up the ramp. Maybe use the electric motor at low speed, and once up to driving speed (25 or 35?), switch to the regular engine.

  7. Thank heavens for Adam Smith's "invisible hand":

    This Perpetual Motion Machine (literally!) would bring the cost of electric vehicles to the equivalent performance of gasoline combustion locomtion at only $87/gallon in constant 2000 dollars.

    And besides Gov. moonbeam, who wouldn't want that!

    Coupled with the fact that this is from people who think that cell phones and overhead power lines cause brain tumors, this hasn't got even as much chance of ever happening as a snowball's chance in Hell.

    They might as well try to recharge EVs on the go with wind-powered turbines mounted on the roof like a kid's whirl-a-gig, without any fundamental understanding that to work, they'd create so much resistance to movement that the car would stop, which would mean they could never work.

    This is "invention" by idiot savant Rain Men, and the kind of thing so patently obviously stupid that it's only fit for the balloons in USAToday, and the "What's Next" fapping fantasies at Popular Science, along with the ads in the back of comic books, right next to X-ray glasses and two-man cardboard SSBNs.

  8. Overhead wires like electric trains? Understreet cables like San Francisco? Refueling probes like airplanes? Or make the roads a conveyor belt like Heinlein wrote.

    Just wait until a wheelchair rolls over a near-field charging station.

    Boulder. That's all you had to say.

    How come the 'I don't want to live in the fields under a powerline' people aren't protesting?

    1. How come the 'I don't want to live in the fields under a powerline' people aren't protesting?

      They don't know about it.

      I don't think anyone is talking about it seriously. This was an industry magazine floating an idea. The author gets to put the publication on his resume.

  9. I wonder how much entertainment might ensue if a hacker were to gain control of such a system, even temporarily?

    But then surely only the Russians would even consider any such act...

  10. Busses and streetcars used to have a pole that stuck up to contact a bare overhead wire. That worked.

    Is there enough copper in the world to actually carry out this fellow's mad scheme?

  11. Assuming such a vehicle design becomes the federal standard there would have to be a less expensive method of installing the charging technology, electrostatic or electromagnetic. I forsee a mobile 3D printing machine that will lay down the conductive and magnetic plates and coils in planar fashion upon existing roadway as the Mobil printer crawls along. Other men or robotic machines will follow behind making the interconnections to the plates or coils from a main power bus. In essence the roadways would become a giant printed circuit board with asphalt or concrete substrate and printed inductors and capacitors on top. A final conformal coating would be sprayed on top to electrically insulate and mechanically protect the printed conductors.

    1. That's a better idea than anything mentioned in that article.

      Maybe the conformal coating can be the regular road black top they put down.

  12. The county I live in is struggling to repair/replace all of our bridges. There are 2 on my street within a mile of where I am right now. One has been repaired. The other needs to be. Those 2 streams join, so the bridge in the next road over (it was also repaired last year) is a little bigger. They are all on the order of 10 to 15 feet, but still too big to be a culvert. There are plenty of those that need replacing too. (Some have been.)

    In the county south of me (where I used to live) there is a bridge you could take down with a sledge hammer in a couple of hours, if a few well-placed hits didn't do it. I pushed to have it replaced when I was driving over it every day. All I was told was "it's on the list of things to do."

    2 major bridges between Cincinnati and Kentucky are in need of replacement. Funding has been an issue for a decade. (maybe more)

    But hey, I'm sure that's just an Ohio thing. Detroit will be all over rebuilding all of its roads - as soon as they figure out how to pay to fix all of their street lights. And Chicago will follow suit as soon as they can figure out how to pay for Police, Fire and Teachers' pensions. No sweat.