One of the primary issues with EVs is that you need to pull over and stop to get a charge. If there isn’t a high-speed DC charger available, this can mean waiting for hours while your battery tops up.
It’s been the major bugbear of electric vehicles since they started hitting the road in real numbers. However, a new wireless charging setup could allow you to juice up on the go.
Over the years, many proposals have been made to power or charge electric vehicles as they drive down the road. Many are similar to the way we commonly charge phones these days, using inductive power transfer via magnetic coils. The theory is simple. Power is delivered to coils in the roadway, and then picked up via induction by a coil on the moving vehicle.
Taking these ideas from concept into reality is difficult, though. When it comes to charging an electric vehicle, huge power levels are required, in the range of tens to hundreds of kilowatts. And, while a phone can sit neatly on top of a charging pad, EVs typically require a fair bit of ground clearance for safely navigating the road. Plus, since cars move at quite a rapid pace, an inductive charging system that could handle this dynamic condition would require huge numbers of coils buried repeatedly into the road bed.
Busses are the Beginning
Despite these challenges, the idea has been proven in the real world to a limited extent. The Online Electric Vehicle, or OLEV, was developed by the Korea Advanced Institute of Technology (KAIST), and used to power a shuttle bus in 2009. The system slowly expanded to four lines by 2016, with the buses charging wirelessly thanks to inductive power transmitters buried in the road along the bus’s route.
The second-generation of the system used on the buses transmits 100 kW of power wirelessly across an air gap of 17 cm at a power efficiency of 85%. This is achieved by using multiple power pickup coils mounted on a single vehicle. Much research went into finding the optimum coil geometries and electrical parameters to enable the system to run at this level. With power delivered from the road surface, the buses can rely on smaller batteries to get around, saving weight and improving efficiency. The system is buried in 5-15% of the roadway on the bus routes, and a vehicle detection system powers down the induction coils when not in use. While some of the routes have since closed, a shuttle service still operates at KAIST using the technology.
Other companies are also working in this space, too. Startup Magment is named for a portmanteau of “magnetic cement,” and is working on a special inductive road demonstration with the Indiana Department of Transport. Details are scarce, but the company is pioneering a special method of mixing ferromagnetic materials in with cement to produce a more cost-effective and efficient wireless charging road system. The company intends to use the system for non-road applications, too, like forklifts and electric scooters.
Another standout is Israel-based company Electreon operating a pilot program in Gotland, Sweden. First deployed in December 2020, the project has successfully run a 40-ton truck on a 1.65-km long test section of road. Again using copper coils buried in the road surface, it’s able to deliver around 70 kW of power to a moving vehicle at speeds up to 80 km/h. The company is also working on other pilot programs around the world, including a facility with Ford Motor Company to be installed near Detroit’s Michigan Central Terminal.
Not There Yet
The problem for such systems remains cost. For a start, burying power transmission lines and fancy coils in the road surface itself costs a lot to do in the first place. It’s expensive enough for new roads, and even worse when you need to dig up an existing road to put the hardware in afterwards. Estimates for one Swedish project indicated that a wireless system like Electreon’s would cost on the order of $2 million USD per km in a new build. This cost comes in around twice as much to install as more traditional methods of power transfer, like simple rails or overhead wires, while delivering much less power to boot. The latter are already proving their value in trucking tests in several locations around the world.
Maintenance is also a major issue. Burying anything in a roadway means that it’s a huge job to repair it if something goes wrong. At the least, it will require shutting down the road, and at worst, it will mean digging it up. Upgrading to higher-performance technology will similarly require invasive work to remove the old hardware and reinstall the new.
Finally, there’s the issue of standardization. Powering vehicles via inductive coils in the road is great, but cars and trucks will need special pickups fitted to receive this energy. The inductive pickup must be carefully tuned to the coils in the road, so there’s little chance of retrofitting a one-size-fits-all pickup that can traverse multiple electric roadway systems. Thus, in order to make such systems practical, one company’s system would have to be rolled out across broad sections of roadway, to the point where it became economically worthwhile for individual and commercial users to contemplate fitting their vehicles with pickup hardware.
It seems unlikely that we’ll be digging up our roads to fit charging coils anytime soon. After all, we’ve barely equipped our cities and towns with regular EV chargers, and they’re already a mature and established technology. However, in some applications, such as specialist bus or trucking routes, the technology may just catch on. From there, it could spread further, but only if the heavy investment makes sense.
131 thoughts on “Coils In The Road Could Charge EVs While Driving”
Am I the only one who saw coils buried along the road and thought “linear motor”? I haven’t bothered to investigate whether linear-motor-buses would be a loony idea (or at least any loonier than any other aspect of the whole scheme). But since the ultimate goal is electromagnetic traction, maybe there are efficiencies to be had by skipping the charger/battery/motor middlemen. (Obviously the bus needs to have its own motor anyway, for driving into the service garage if nothing else.)
I don’t think you could bury a coil powerful enough to overcome that initial friction required to get a bus moving over that airgap. Not sure a coil able to exert enough force just to keep it moving would be at all practical to bury either. Though with how very large a bus is energizing coils to work against magnets down its entire length probably would be just about workable, especially if the magnets are on some sort of telescopic mount so the air gap can be reduced while still able to deal with road furniture. But even then you still have the massive challenge that the movement of the bus is entirely dictated by whatever is driving the coils in the road – presumably a computer in some control centre with no real eyes on the road conditions, or its one very long ‘fly by wire’ type system with no doubt horrible latency between the driver and the road coils.
Still linear rail seems like a way smarter option than this though…
But if you want to provide electric charge on the move pantograph and overhead wires have been used for well over 100 years now, its a well developed and actually quite efficient system that just needs the wearblock replaced occasionally – think motor brushes really, same sort of concept and similarly cheap.
Yes I was totally thinking similar thoughts.
Also what about some sort of linear accelerator type of power generator?
Why not an overhead wire while we’re at it? far simpler and more efficient. And we could further improve efficiency by using metal wheels on metal tracks. May as well connect a bunch of cars together, too.
All the electric vehicle and transportation “innovation” I read about is just converging on reinventing trolleys and trains.
That last sentence says more about you than anything else.
Not that this is a good idea.
I saw an item recently celebrating the idea of wind-powered ships carrying cargo over the seas… imagine! Wind-powered ships!
What a wonderful time to be alive!
It isn’t more efficient. Whenever the distance between the coils is less than, even a small amount less than, the distance between the coils, you can get 90%+ efficiency from this type of arrangement.
This is no different than a wireless phone charging pad. It is just bigger.
With an overhead wire, the efficiency sucks, because you have a moving brush that bounces around and the resistance in practice is pretty high. It is nothing like the difference between a wireless charging pad and a plug, where the plug can be made to have low resistance at low cost.
I think you meant something different, because the following phrase is always false:
“the distance between the coils is less than, even a small amount less than, the distance between the coils”
Yeah but you can’t cut some pork for thousands of green energy sinecures with trolleys and trains. It has to be new stuff that does the same job as the old stuff but much less efficiently, therefore allocating political patronage and getting people paid off. This is why the green movement is ultimately going to pollute even more. People are missing the point.
You’re another one that “gets it”.
It’s true though. The green/environmental movement started it, and now everyone’s doing it, since it’s a tactic that works. You say it helps with the climate change, or it just appears cool and promising (e.g. hyperloop), and the public has little realistic chance of telling snake-oil from science. As long as it’s not YOUR money directly, people go “Okay, let’s subsidize it.”, and ten years later it’s still at the starting point. No issues have been solved, but the system works because they keep throwing money at it.
But it had to be tried, right?
Though, it rather goes back to the New Deal. Before: “People are being silly with the economy – but the government isn’t morally permitted to dig into other people’s pockets to save fools from themselves.” – but then people went, “But you have to do something!”. 80 years later: rampant inflation, national debt and persistent budget deficit to pay forever-expanding public spending.
“It has to be new stuff that does the same job as the old stuff”
It’s almost like this is a bunch of research and pilot programs!
Yeah, except this was already done in California in the 80’s – it’s just a rehash and will come to the same conclusions: too expensive, doesn’t work as well as the competition.
“Yeah, except this was already done in California in the 80’s”
And we all know there’s been no improvement in inductive charging/electronic control/materials science since the 1980s.
>And we all know there’s been no improvement in inductive charging/electronic control/materials science since the 1980s.
Aside from somewhat better switching devices, no. Can’t beat physics, or the price of copper and other materials and labor, which have gone up since.
The thing about trains is that they’re all the same height. For this to work, an e-type jag would need an arm holding a brush several times the height of the car so that the wire is high enough to accommodate the lorry driving behind it. Or we could all just drive lorries everywhere.
Who care’s about all the other road users – if you can make bus and lorry – all the heavy large stuff that being working vehicles likely travel vastly further in a day than most folks cars in a fortnight and certainly being heavier will need more energy per mile directly grid powered that is a huge saving. And helps the other road users too, one less thing to dig up the roads to fix, cheaper parcel deliveries etc. Overhead wires to me seem massively massively more sane, as the quality of road maintenance and number of times new holes have to get cut into the roads round here mean this system would forever be down and require huge air gaps to prevent smashing the coils into anything with the potholes…
For 95% of drivers, this is all solution looking for a problem.
I’ve recently bought an electric car. Before it arrived, we spent a pile of cash upgrading wiring to be able to put a 7.5kW charger in. This turned out to be a complete waste of money.
It does 185 miles on 51kWh, or 275Wh per mile. Plugging it into a 13A socket will charge it at 3kW. So each hour of charging gives you about 11 miles of driving. If you can leave it plugged in for 12 hours overnight, you can do 130 miles the next day. 17 hours gives you a full charge from completely flat.
For the vast, vast majority of people, 130 miles is more than they do in a day. For these people, any sort of fast charging is an irrelevance. You just plug in when you get home and unplug when you go out. You never, ever have to encounter a fast charger. For the odd occasion when you’re driving from London to Edinburgh or something, it takes eight hours of driving and you’ll have to stop to charge for an hour twice along the way. You were probably going to make those stops anyway.
Yes, there are people who drive all day for a living and no, this setup doesn’t work for them. But it would be stupid to build public infrastructure on this scale for those few percent of people who need it.
Absolutely agree. I have only used the 2kW charger that came with the car when I’m at home, and I only end up charging once a week. When travelling long distances, stopping for ten minutes at a fast charger, usually gives me more than enough power to reach destination. Also stopping three times for 20 minutes is more time efficient than stopping twice for an hour, as the charging speed drops dramatically above 60-70% charge.
> You just plug in when you get home and unplug when you go out.
2/3rds of people live in urban apartment housing with detached parking lots or leave their cars on the curbside. No park-and-charge: they have to top up at a fast charger to make it work.
I took an informal family survey and found that 12% of cars were in that category. The rest had garages with electricity.
> there are people who drive all day for a living
There’s a whole spectrum of people between “never leaves town” and “commutes 8 hours every day”. For instance, I normally bike to work, but last week I had 150 km round-trips to a remote location, twice.
Then, once or twice a year, I want to make a shopping trip to the big city where the IKEA is located. I’d have to rent a different car for that, or gamble my luck with the fast chargers along the way so I don’t have to wait an hour for someone else using it.
So basically you would be better off with a car pool / share type ownership than having your personal car.
Yes, except then I couldn’t use the car whenever I need it – I’d have to wait a day for the other guy to return it, or the rental company to bring it around, and then fetch it from somewhere – which also requires transportation to that location.
Just being able to go, now, makes the whole point.
I also drive more in the winter than in the summer, for obvious reasons. And when it rains, which would make car pooling inconvenient because everybody needs the car when it rains.
7.5kW shouldn’t have cost “a pile of money”, at least not in the US. 40A 240V NEMA 14-50 outlets are common everywhere, used for dryer and range outlets, etc, and will give you 9.6kW. there’s no real reason to install “only” a 30A outlet (7.5kW), if you’re running wire go ahead and use the 50A rated wire. Otherwise 20A x 240W is what you’ve already got everywhere in your house (though usually split into two separate 20Ax120V circuits).
A “household outlet” (12Ax120V) will give you about 4mph charging speed. Agreed that this is almost always sufficient, but there will be the odd time when you get back home from a long trip and want to leave again shortly when the extra charging speed from a 40A x240V charger (~24mph) comes in handy. If you’ve got a 3rd party fast charger nearby though that will probably serve you just as well for those unusual cases.
Trolly Busses are a great way to brigde alot of the small issues with overhead lines. “Small” Battery so it can drive without the wire for a bit (Accidents, road closed etc etc) and very high efficeny in charging
Plus, installing an overhead wire cost less than reworking all the pavement: burying stuff is costly, labor and carbon intensive.
Also, a coil requires more material than an overhead wire: additional cost, labor and carbon
Think about how the coil system can be affected by external factors, water, metal, and all kind of things that end up in the pavement
Lastly, once you have an overhead wire, you don’t need a battery.
I mean, if all of these “solutions” aim carbon reductions, then maybe start by factoring in:
– equiv carbon emissions from battery production and disposal, I believe there’s currently no way to recycle lithium batteries and lithium is obviously less abundant than oil, harder to mine, and has lower energy density
– equiv carbon emissions from infrastructure, either new or rework + its maintenance
Not sure it would be cost-competitive with electric train lines, but it is for sure far less energy efficient, lower trough-output, less safe, much higher environmental cost (tires, brakes, need for another energy source when leaving the inductive track, short-lived in comparison to trains)
Overhead power lines, just like trolleys. Collapsible and extendable booms on car top. They can be on some roads only and be sufficient. Plus some solar cells on the roof …
Solar cells on the roof of a large electric vehicle do hardly anything. A 12m bus requires about 0.9kWh/km in city conditions, so say 25kWh/hour.
A typical bus could house 12*2.4=28.8m² of solar panels, which produce 150w/m² = 4.3kW under optimal conditions (sun is directly above), which is 17% of the power budget. But during half the day it’s none, during ⅓ it’s almost nothing and the remaining ⅙ only when you’re lucky, so say closer to 4% of the power budget.
Science tells us that that kWh/hour = kW
It is, but it is not useful. kWh/hour is the consumption of energy in one hour. This might vary tremendously over seconds, from 500kW when acellerating a full bus to -100kW of usage while regenerating during braking.
>kWh/hour is the consumption of energy in one hour.
No it isn’t. It has the unit of Joules per second. Hours per hours cancels out, like saying “meters per meter” – it’s “one” by definition.
If you want to talk about average power demand, then say so. By the same point, your bus may be going an hour up a mountain in one direction, and coming down an hour later – so your “kWh/hour” is going to be different anyways.
Dude, you must be one of those people who state fuel efficiency in 1/sqin. Right?
Miles per gallon or liters per kilometer doesn’t have any unnecessary redundancy or ambiguity.
Of course it does. It’s volume divided by length, which leaves an area. This area can be visualized as the cross section of a “fuel rod” the needs to collect while driving to run its engine.
Re “fuel rod”. That’s absolutely beautiful.
(But not 100% useful when you’re trying to figure out how far you can go before the tank runs dry. Let’s see, I have 3 gallons, and the cross-section is 10 cm^2…)
True story: Friend of mine “drove faster” in high school because he didn’t want to run out of gas before making it to the gas station. If only he could have had the inutition that stepping on the accelerator widened his fuel rod!
A typical car fuel consumption over speed is a u-shaped curve that bottoms out somewhere around 50-80 kph depending on the car. Yes, you can sometimes drive faster to get further.
The engine gets more efficient as you load it up as the drag losses increase, so you get an optimum point somewhere in between.
Most cars move only for a fraction of the day (less than an hour in many cases), so can benefit significantly from solar panels. Weight of battery can be decreased too if overhead supply is used even just a portion of time while driving. This can have significant cumulative effects.
Not useful until all the roof space with good sun exposure is full. You’re carrying around weight, drag and getting less power for your trouble.
Excepting a small one to trickle charge a classic that sits. Then it’s only useful in the sense that saves you from replacing dead 12V batteries.
Electric cars have significant “vampire power” use. E.g. 15 Watts to run the onboard computers and electronics on standby is 1 mile of charge lost per day. That loss can be a significant percentage of your commute, easily 5-15% “efficiency” loss right there.
The trouble is, even if you cover the entire car with solar panels, the average charging rate would be something like 5 km per day with practically no charge in the winter time, or if you park somewhere that’s surrounded with buildings.
As others noted, first trouble with solar car is that you can’t park it anywhere and expect that it will charge itself, it has to be in the sunnny spot.
Second issue is that roof area is too small compared with energy consumption of regular car. Most cars with solar roofs are just publicity stunts.
However, with all that said, It could be done, but on microcars. Basically, on advanced golf carts. One such example is dutch Squad car, http://www.squadmobility.com
According to them, solar panels can daily get enough energy for up to 20km if parked in good conditions, which is enough for many. But this is 350kg two seater, not 3500kg SUV.
Going the other way is quite possible – if you build your ‘SUV’ light enough to lower rolling resistance and inertia with a little effort put in to reduce drag, though a large light motorhome is easier – even more surface area for very little change in drag and rolling resistance. Its actually been done.
I’d also argue its not a problem at all that you can’t ‘park it anywhere’ as long as it is somewhat often parked with some sun you gain range effort free, and with very little cost. As you needed bodywork for many other reasons anyway and the cost of your solar body panel vs the normal sheet metal isn’t a really massive difference.
It also seems to me most cars spend a great deal of time parked on the exposed road/driveway/parking lots so for many it might well be enough to never need to charge or reduce the amount of time and money spent at the fast charge etc even with only a postage stamp of surface area. Some folks don’t drive very far so the average demand over their day/week is low, not going to help the professional taxi driver much, but the school run parent and short work commute folks are gaining.
True. Saving energy in the first place by having much lighter cars is something that should be pursued maybe above everything else.
>the cost of your solar body panel vs the normal sheet metal isn’t a really massive difference.
Yes it is, because it won’t be a cheap commodity panel but some special bendable thin-film panel that costs a lot in the first place and takes a load of labor to install and paint over with special varnishes that you need to keep it from chipping from stray gravel etc. while still remaining transparent. A regular stamped steel with three coats of paint is way cheaper because it costs next to nothing and the whole process is automated.
>most cars spend a great deal of time parked on the exposed road/driveway/parking lots
The irony is that when you leave your car out in the sun, the amount of power you’d gain from the panel is offset by turning on the AC because a car covered in black solar panels is going to become painfully hot.
Dude any car in the sun can and will turn into a hotbox, doesn’t really matter what its surface, maybe the white and silver paints do not heat quite as quickly but they can all get hellish quite easily… Assuming the car is parked for a more normal span of time its going to get way way way more than the AC will need, and that AC requirement is going to be comparable no matter the bodywork…
If you are mass producing a solar body panel Dude the cost isn’t going to be stupidly high, as the production will be optimized for production costs – heck the solarPV could just be a printed surface coating or potentially a ‘vinyl wrap’! (yes that type of solar cell doesn’t yet anyway have useful lifespans in the decades, but its stupidly cheap and they do last many years now.
That argument just doesn’t work, as to make a one off reproduction body panel in sheetmetal is stupidly expensive, to make a one off solar cell arragment likewise. But if you are GM or VW group you don’t make one of the damn things, and as soon as you streamline, optimise for manufacturer and largely automate production…
>any car in the sun can and will turn into a hotbox
Which is why parking lots have trees planted around them, and people prefer to park in the shade of buildings etc.
> as the production will be optimized for production costs
That’s not proving anything, just asserting the argument. You assume it will be cheap because you assume it will be cheap.
I’d like to coin the expression “mass market fallacy” – the tendency for people to believe that once you start making lots of something, it has to become cheap because they’ve heard the term “economy of scale”.
Like electric cars: they did become cheaper once the big companies started making them – but not cheap, because the technology isn’t fundamentally cheap and suffers from marginal costs of production (e.g. demand and price of cobalt).
Like the bumper cars at the state fair.
Software-triggered 100kW induction coils buried in the road, very cool. Can’t wait until this malfunctions and incinerates a cyclist.
We literally already have software-triggered multi-kW charging systems that if the software malfunctioned, vehicles would burst into flames. Not to mention all of the other safety-critical life-threatening systems controlled by software.
My advice is to make an attempt to understand the engineering first, before coming up with doomsday scenarios.
A buried coil is… grounded. And a cyclist is floating on that. So the maximum shock they could get would be a capacitive discharge identical to the “static” shock you get when you touch a doorhandle after rubbing your feet on plastic flooring.
And with any sort of rudimentary safety features, even that would never happen, even in the case of severe malfunction.
I love being educated on electricity by someone who doesn’t know what induction is. Did you know you can heat something up without making an electrical connection to it? Wow!
If your “it is buried so it is grounded” argument made any sense, you may as well throw this entire charging road idea in the bin.
Why on earth would someone do this? It is hard to find efficiency data for wireless phone chargers, I found some test data, and energy loss is about 30% in best case, but dependent on phone position, if it wasn’t centered, it was worse. For single phone, where power is on order of 10W, this is almost acceptable. But this is for phone chargers, where distance between receiver and transmitter is less than 1cm. Clearance between road and bus is about 20cm, energy loss on that distance will be terrible. And even if it is mentioned 30%, 30% of power required for a bus is not acceptable loss.
On the other hand, we have tried and proven technology called overhead powerlines (aka trams, trolleys,…) that works cheap, efficient and reliable. But no, someone has to invent garbage like battery powered buses, wireless bus charging,…
“I found some test data, and energy loss is about 30% in best case”
Uh, yeah, this isn’t a slapdash design thrown together to cost under 2 bucks in quantity or something. Try efficiencies of more like 70%+ at 17 cm. That’s not theoretical, that’s measured. Yes, misalignment makes that worse but you’ve got smarts on both sides, that’s a manageable issue.
Yes, obviously, overhead powerlines have been around a long time but there are advantages to having systems that only require things to be installed where transportation companies already control.
Ironically efficiencies of 70% means exactly 30% energy loss. You were so excited to bash someone elses slapdash numbers, you didn’t realize your own slapdash numbers are identical.
This was in response to:
“But this is for phone chargers, where distance between receiver and transmitter is less than 1cm. Clearance between road and bus is about 20cm, energy loss on that distance will be terrible.”
not the latter point, which depends on your definition of “acceptable.”
And what about rain on the road, snow on the road, metal on the road and animals on the road, how will they affect this? Interesting idea in theory but in practice just spend the money on trolley busses.
Where are you living where there is more than 0.001% road coverage of scrap metal and dead animals? Jurassic Park after the disaster?
It doesn’t have to be more than 0.001% if all of it is under the bus, just takes one piece of aluminum siding in the busses path.
… to stop it charging for a tenth of a second?
It’s funny, because wireless only really makes sense for something that stops every once in a while, like a bus, because otherwise you have to lay waaaay too many coils. But then, since it’s stopping anyway, you might as well hook it up to wires for the time.
“Cities currently utilizing or deploying on-route opportunity charging of transit buses include New York, Portland, Salt Lake City, Vancouver, Minneapolis, and Los Angeles.”
(Edited b/c this is such a US-centric report, it breaks my head. 90-something% of all electric busses in the world are in China ATM. It’s just harder to find info on how they are charged. Anyone want to chime in?)
“But then, since it’s stopping anyway, you might as well hook it up to wires for the time.”
Eh, you can probably do the math and there might be an advantage where the connect/disconnect cycles, exposure wear, and the service life of the various connectors/mechanics becomes enough of an effect that something like this wins out. Don’t get me wrong, I agree that from my point of view it seems like you’d just want to have an automated magnetic connection or something, but it’s complicated enough that from my point of view I’d want to see both systems tested.
The pantograph charging system is already in use.
Yes, I know. But for new installations, obviously the economics depends on a lot of factors, including how large the bus route map is and how much a city’s willing to disrupt traffic.
Overhead lines scale directly with the size of the route map, charging at each stop does not. Just depends on the individual demands. Overhead lines require construction at places not just at bus stops (where the company/city may or may not be able or willing to access), charging at each stop does not.
It’s naive to think there’s a one size fits all solution. There’s a reason this is being done in conjunction with a research institution.
The system is not based on overhead lines everywhere, but simply a pantograph “socket” at certain stops along the way.
Adding an overhead charging point is cheaper than adding an underground wireless charger because it requires less materials, it’s simpler and faster to install and maintain because you don’t have to dig it up every time.
The reason this is being done is because it’s a research institution. Research is their job: doesn’t matter what or why, as long as it gets funded. They get paid for figuring out things like, “There’s still no evidence that cellphones cause cancer after trying to prove it the N-th time.”.
Not to mention the pantograph charging system is much more energy efficient.
It might not seem like an important point, but buses are not actually all that efficient in terms of energy per passenger-mile. That’s because they run mostly empty, or with fewer passengers than would be necessary to beat private cars. If you add a 20-30% penalty for charging them wireless, you negate a major point of public transportation.
“The system is not based on overhead lines everywhere, but simply a pantograph “socket” at certain stops along the way.”
While this is a good point, there are nominally still questions regarding clearances (does the area have space for it), exposed maintenance, weather, lifetime, electrical noise, etc. Let me be clear – I’m not saying that this is a *better* solution. I’m saying that you can’t dismiss the possibility that it isn’t. Which is why you do pilot programs and research, and see if you can get close to cost parity.
The simple fact that some communities bury electrical lines already tells you that there’s a lifetime advantage to not having to worry about above-ground issues.
You’re really dismissive towards research/pilot programs. The idea that you can just get funding to “disprove cancer causing for the Nth time” is practically comical.
Pure fantasy in this reality, where they can’t even fix the potholes.
Those scenes in movies where people have quiet conversations in their cars as they drive on US highways are some sort of sick joke.
The reality of driving in the US is: constant pothole avoidance, cars all over the road due to poor maintenance of lane markings, too many useless road signs, arbitrary speed limits in the name of revenue generation. Front end alignments and tire replacement constitute the majority of car repairs.
I drive a full time 4WD vehicle with high ground clearance on the street because I need it every day to drive over unfinished utility work and half constructed crosswalks that never seem to be completed. I watch the other cars scrape their undercarriages on the protruding bits of concrete. The folks who lay down the pavement have side jobs fixing the roller coaster at six flags.
Nice roads is another one of those things that humans are simply not able to do.
The Romans could pull it off, somehow. Maybe we could learn a thing or two from them.
Over on that continent, they have overhead wires that feed fast, efficient, on-time electric powered mass transportation, no batteries needed. And they don’t have to pave the roads, just use ribbons of steel, eliminating the paving material.
They also live their lives sitting in each others laps. Which makes all the difference.
If you don’t count the middle bit where nobody lives, the US has a similar population density as France.
Dude have you been to the USA?
You’re just _wrong_.
Bostiyorkadephia approaches western Europe population density. Other than that only core population centers. Doubly so west of the Mississippi.
France has it’s own political issues with HSR. After they built the ones that made sense, they had to build a bunch of money losers too.
Sure, by a bureaucrat’s definition of efficient transportation. Like number of people moved past a reference point per hour per kW. If you want to go somewhere other than the stops, it is a different matter.
Like the freeways. A crammed freeway of bumper to bumper slowness is still very efficient to moving cars. Just not very efficient at moving a particular car from A to B.
“At least under Mussolini the trains ran on time”
I don’t remember where I read that.
Do you by chance live in California? The roads around me, and in other parts of the country are silky smooth, but for some reason California can’t seem to figure it out. I will say, Portland, OR also has some nasty streets.
So, you’ve never been to Michigan.
Seriously. Why induction charging? It’s expensive and inefficient.
Busses have to stop for a minute at bus stations all the time. Just use a pantograph and some overhead wires, and top up the charge every time the bus stands still for a while.
And it has the extra benefit that you can change the bus’s route any time it’s necessary.
I have been hoping for a way to make roads more expensive.
Combine that with solar panel glass for the roadway, you have the perfect government research project.
Yes! More costly infrastructure to shift maintenance funding from!
And for a bonus it will eliminate inflation and cool the planet, which will bring a much needed boost to the wool shawl industry.
And how to make road not safe for peoples with a peacemaker!
You figure it could set off the bullets?
Let’s build some inductive coils with ten thousand times more material than needed. At any point in the system only a tiny fraction of a percent of the charging system is in use. You’d be better off recharging conventionally during the 30 minute break when you change drivers for shifts.
The bus itself doesn’t need a break! — In the driver duties I make, drivers change buses all the time (8 different vehicles on a shift is no exception) and the bus takes “a break” (i.e. charging) independent from the driver!
Recharging at endpoints is done by other companies. We just happen to prefer charging in centralized locations – I am not the one who does the financial calculations but if you have a bus charging at an endpoint, you need to give the driver a break too. I find it more efficient to send the drivers all on breaks on two central locations (the main station and the bus depot) and charge all buses on the depot. At all endpoints, the timetable is such that the bus returns within a few minutes so no paid time is lost on not transporting paying customers.
In fact, we would like to charge a few buses at the bus station as well, but we don’t have the space, and we would need extra chargers (which aren’t cheap, a rule of thumb is ½ the price of the bus) as you need a charger for each bus at the depot as well during the night.
We use plug-in chargers (like a passenger car) in my area, this hardly takes extra time for the driver compared to a roof-mounted pantograph – something on the order of 45 vs 30sec for a full plug/unplug cycle. But we have buses that charge with 87kW max. Other areas charge with up to 520kW and they use pantographs as otherwise the plugs and cables would become too heavy to handle (the 87kW charging is already done with two sockets).
Seems not the brightest, though might develop something related to the tech paradigm of thinking.
Like I’ve noted with waste from power lines from not being shielded, with I guess the best being high magnetic permeability materials to shield…, that needs to be addressed first and foremost.
However, to combine the methods… my thoughts have been written before in comments where you do some optimal shape of the shielding material that is around the power lines in the roadways so to direct the energy to the section of the receiver on the vehicle to couple some power since the losses are going to be present anyways. Why not direct the losses to be used?
My idea seems more feasible that the articles system… however I doubt the roads designs are the best for the power grid… though maybe some optimal design can be accommodated to factor in better energy and mass efficiency.
Has anybody done the WAG (Engineering Estimate) of how much copper would be required?
Should be doable, though, when room temperature superconductors are ten cents a pound.
And if that doesn’t work out, the coils could be repurposed to detect vehicle speeds, and CHARGE the vehicle’s OWNER with traffic fines!
Public transit mostly aims to solve traffic congestion, but two years ago we solved traffic problems pretty much overnight with COVID lockdowns, effectively eliminating all in-person learning and desk work, as well as the service industry that supported commuter culture.
The only infrastructure worth investing in is the planes, ships, trucks, and trains that deliver goods to the grocery stores and Amazon warehouses. Improving commuting should be the last thing we consider tackling, as it’s wasteful and makes no sense in the modern age of remote work.
>effectively eliminating all in-person learning and desk work
And as a result, a whole lot of stuff was left undone and education suffered a lot.
No kidding. He can’t even remember his username.
In Cars Land in Disney there is a ride — Luigi’s Rollickin’ Roadsters — that will recharge every car throughout the day by sharing a couple of CONTACT charging platforms when the cars are at rest.
Why not do that for a bus? Kind of like a roomba recharging.
‘Cause you just know after the first couple dozen fried pedestrians people will start to complain.
When did it become the government’s responsibility to ‘top off’ your EV as you drive?
The expense is monstrous, the issues are manifold, and the benefit is marginal.
Having not seen/been to Cars Land at Disney, I’m just making a wild guess that the cars he is referring to are a carnival type ride with vehicles resembling the characters in the movie; Cars.
Not EVs in the parking lot(s).
Yes, I still tear up watching the scene of Lightning McQueen push The King across the Finish Line.
“Why not do that for a bus? Kind of like a roomba recharging.”
Because bus stops are incredibly brief, typically less than a minute.
This is just like a wireless charging pad for a phone, which works and has decent efficiency. It is over 90% when you have good algorithms and the distance between the coils is less than about 85% of the effective coil width. However, from the picture they’re using an array that makes the effective distance smaller in one direction, so this should easily get into the high efficiency zone even without lowering the vehicle-to-ground distance.
The reason so many people are against it, and express their opposition via pejoratives, is because when they first heard the idea years ago, they said, “That’s impwossible” and instead of learning about inductive power transfer engineering, they patted themselves on the back while agreeing with a bunch of other people and having a contest for the most extreme pejorative.
So it would be constitutionally impwossible for them to even consider the engineering questions involved.
As somebody whose original response was,”That sounds wild, I don’t understand the engineering,” now that I have studied and regularly use magnetics engineering, it becomes an obviously good idea. Though mostly applicable to buses and commercial transit, because the high installation cost limits it to major routes, and there is a significant weight cost in the vehicle. So if the vehicle is designed to spend most of its time on this type of system, then the weight cost can be offset by weight savings in a battery. In a passenger car, few people would want to make that tradeoff until/unless there is a really large amount of installed support.
I wonder about charge to burn rate of a vehicle.
By this I mean the amount of charge (%/hr) vs the amount of discharge in that same hour. A car traveling, say, 60 MPH over 60 miles of continuous EV charge-enabled roadway would have a net discharge of what %?
If my EV loses net 30 miles range after driving 60 miles over EV charge-enabled roadway, that might be useful. Not sure about this ‘service’ scaling beyond the occasional EV on the roadway – if all cars are EVs equipped to charge from the roadway, that seems like a huge investment power-drain. I’m also curious about who will pay for the infrastructure and who will collect the money to fund it.
This seems like a good idea for private parking garages (residential garages/driveways, outside apartment buildings, offices, valet parking at malls, etc), not sure about its use on roadways.
Cost of a mile of charge-enabled Highway on top of roadway itself will be huge.
It would be might be more efficient to have large inductive chargers ( or why not plugs) at the highest trafficked bus stops. Not sure about how the people who are wary of EMF will react massive to electro/magnetic fields pulsing under the street though. Better to stick to the tried and true pantograph as used all around the world.
Bye the way, I think that linear induction motors seem to work well on the rapid transit here in Vancouver. But the clearance between the motor and 4th rail is very much closer.
Many US traffic light systems currently use buried coils to sense the presence and sometimes count vehicles queuing in intersections. Back about ~35-40years ago I recall USDOT put out an RFP for ways of improving the performance and reliability of vehicle sensing systems. As I recall their take was that 1/ Buried loops had very poor reliability – the pounding from heavy vehicles eventually distorts the road bed – e.g. go look at the ruts produced at busy road intersections. 2/ They were expensive to install and repair since that involves trenching into the road surface and therefore major traffic disruptions. 3/ Not directly power transfer related but they’re also lousy at sensing low magnetic mass vehicles like bicycles. We could figure some ways of improving the essential design sensitivity but shallow burial in an attempt to improve the power transfer efficiency just further trashes the reliability.
Going to be interesting to see how that idea works out.
Those are being replaced with cameras as they wear out. No brainer from a financial POV.
Plus bonus license plate readers cut down on pesky privacy.
Another system used to spin up a flywheel at every trolley stop. No batteries needed.
Loosely defined a flywheel is just a mechanical battery.
Batteries vs flywheels vs supercaps is orthogonal to issue. Will settle on it’s own.
This idea is as dumb as solar roadways or spinlaunch. Whoever thought it up deserves a kick square in the nuts.
Dedicated routes for E bikes/carts/boards et al might be an economical testing ground for proving out ideas.
No discussion about the heat created by inductive processes?
Also fry children hiding under the bus.
85% efficiency is a non-starter when it comes to higher charging rates unless you want to put some water cooling into those buried units or run them at a low duty cycle (as in – this will be fun in cities at intersections).
The easily overlooked aspect when it comes to “wireless EV charging” is that any kind of (fast) charger still needs galvanic isolation from the grid, especially when a larger number of them is directly connected to a medium voltage DC grid (MVDC), so there is no “100% efficient cable” perfection in the system as a whole anyway.
The efficiency of a stationary wireless charging system is quite something to behold though:
2018 – 97% efficiency:
2021 – 98% efficiency:
“or run them at a low duty cycle”
Say… like… bus stops? Which… is what this is intended for?
Go on, read the rest of the article and the comments, too.
Just because the other applications are silly doesn’t mean they all are.
Trolley buses are a thing too
And they don’t require batteries
Sorry this is just a waaay overcomplicated solution that’s already been solved for 140 years
The coil can be almost in the road, it can be on a arm that can follow the road with few millimeter air gap. Then the efficiency can go a lot up.
Won’t a magnetic field like this slow the car down a little?
How is any solution that consumes even more copper going to help? The limit on EVs for everyone is winnable copper reserves. As it is we can expect copper ore values to at least double. And no that isn’t investment advice, but you may want to think about it for a while, and take note of who owns the mining leases for all of the known copper reserves. Work out a way to use renewable or nuclear derived power to economically extract copper from concentrated seawater waste from desalination plants and that situation may change.
This remains an unforgivably horrible idea. We don’t need in-motion charging anymore than we need EV batteries with >400 miles of range (as an aside, stupidly-huge-range batteries also make charging take longer and make for much more expensive, heavy cars, ~300 is more than enough).
Plugging the car in for <20 minutes (or overnight, which you can't even do in a gas car) is not the grand suffering people make it out to be, especially on long road trips which you should be taking breaks on, anyways. It certainly isn't worth making roads that much more expensive and complicated, then adding efficiency losses and extra equipment to the car itself through wireless charging. Decent charging infrastructure would be drastically cheaper and easier to setup than this and render it entirely obsolete. Even for trucking, because again, drivers on long routes need to REST.
Relying on the market to determine the technological capabilities of a product will always result in something optimized for slave labor done by idiots, because that’s what most countries run on. Planning ahead and resting are luxuries for species more advanced than us.
Everybody in the comment section is talking about overhead lines versus inductive coils when the cheaper, more powerful, more efficient solution is not even brought up once: ground-level power supply rails.
At first, I wanted to say “What are you talking about, this is good only for underground, where it is protected from weather and pedestrians”, but then I found this: en.wikipedia.org/wiki/Ground-level_power_supply
It turns out that new systems are cheaper then overhead wires, and safe enough for pedestrians. But, I still fail to see how they solved weather issues, like snow, freezing or heavy rain…
There is a reason why electrified railways in the UK tend to be third rail but some places especially on the continent tends to overhead – the environment the system is in does matter as to which is ‘best’.
That said extreme levels of rain, snow and freezing weathers are not trivial for either system – nor is heat – get over 30 odd in the UK and that forces UK trains to run slower just because the tracks can’t take it, but the same doesn’t effect the places where being that hot is common, as their network was build to take that temperature – on the flip side designed and built to take hot weather and get a cold snap and you end up in trouble the other way again..
Am I the only thats going to point out that South Korea has had induction based charging electric buses for well over a decade?
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