
Wirelessly charging electric cars as they drive - hhs
https://news.stanford.edu/2020/05/04/wirelessly-charging-electric-cars-drive/
======
vikramkr
It's really interesting, but I wonder if as a society we're willing to
complicate our roads to the level of adding any sort of functionality to them.
Asphalt is wonderfully easy to work with, just pour, grind up, remelt, you can
keep reusing it. Even then maintaining our roads is a challenge. Adding
electrical infrastructure to the roads themselves to further complicate how
you would re-pave, resurface, etcetera? Even if technically feasible, I don't
know if we have the economic/political feasibility that's also required to
make that work

~~~
ashtonkem
Unclear what the benefit is, given the cost.

EVs already provide enough range for commuting. The vast majority of the
population commutes tens of miles, and EVs can regularly do hundreds of miles.
So there’s really no need to modify roads for the sake of commuters.

For longer distance travel we really should be talking less roads and more
high speed rail. They’re faster, safer, and more efficient than cars. It’s
also a less uncertain technology; there are several countries with highly
successful high speed rail systems that we could copy.

For freight we should use regular rail for similar reasons, plus the fact that
using semi trucks, diesel or EV, creates a large financial burden on the
public to undo the damage that heavy trucks do to our roads.

~~~
zamalek
> EVs already provide enough range for commuting. The vast majority of the
> population commutes tens of miles, and EVs can regularly do hundreds of
> miles. So there’s really no need to modify roads for the sake of commuters.

The 50mins I takes me to charge my Kona every ~210 miles is roughly when I
should be taking a break of roughly an hour anyway. "Technology Connections"
on YouTube has a really fantastic (and old) video on this subject: assuming
level 1 (110V) at home and at work, you'd basically never need anything more
than level 1 charging for commuting. EVs require a surprisingly small amount
of energy.

> high speed rail

I have understood the efficiencies in rail since I was maybe 12. It blows my
mind that it is such a niche mode of transport (especially for goods,
transporting humans isn't where the real savings are) in so many places around
the world. From a purely economic standpoint (forgetting environmental issues
entirely), it makes complete sense to aim to have zero semis on roads between
cities. Trains should be long-haul, semis should be last-mile.

~~~
kumarvvr
> Trains should be long-haul, semis should be last-mile

There is a reason semi's are long-haul. A fleet of semi's is tremendously
flexible, with single loading and single unloading.

The fleet can be driven in a myriad of ways and constantly re-routed for suit
the present requirement.

Trains are good for a specific types of cargo, ex. to and from ports.

~~~
redis_mlc
Also, the trains would charge monopoly prices if no long-haul trucks. You can
read about that in any US history book.

And if I'm shipping something in the form-factor of a parade float, I'd want
to load it once on a truck, not on a truck and then a train.

------
contemporary343
A few pieces of context - this builds on the insight that underlies WiTricity
- [https://witricity.com](https://witricity.com) \- near-field coupling of
designed resonators for non-radiative power transfer. Specifically, this can
enable very high efficiency wireless transfer in the near-field of resonators,
which at these wavelengths is on the order of 1-5 meters. This is
qualitatively different from other approaches to wireless power transfer and
does have some real scientific insight which originates from the
electromagnetics/ photonic community.

More specifically, this specific results builds on an insight from the same
research group which led to a Nature paper in 2017:
[https://www.nature.com/articles/nature22404/](https://www.nature.com/articles/nature22404/)
\- that using an non-linear saturable gain element in a parity-time symmetric
configuration enables robust power transfer in a range of conditions such as
moving and the presences of obstacles. There's interesting underlying science
here that shouldn't be missed for the focus on the application.

~~~
andygreenwell
Interesting development in this space this week for WiTricity (the company) is
that China is standardizing nationally on magnetic resonance technology for
wireless vehicle charging based on WiTricity’s designs and standards work. I’m
sure this was an exciting week for my former colleagues there, and
congratulations are certainly in order for them.

[https://www.greencarcongress.com/2020/05/20200508-witricity....](https://www.greencarcongress.com/2020/05/20200508-witricity.html)

There are academic connections between the group at Stanford publishing this
work and the group at MIT that founded WiTricity.

------
mNovak
I highly doubt cars are the actual killer app for wireless charging. At the
end of the day, they're usually parked a good amount of time, and are
comparably tolerant of extra weight, which makes some form of battery much
simpler.

I'd look for applications where a system cannot stop moving, otherwise isn't
in physical contact with infrastructure / cannot be accessed, or absolutely
can't tolerate additional weight.

~~~
hndamien
Exactly. Biomedical devices, electric planes/freight drones, agricultural
sensors etc.

------
samatman
It's a shame that the somewhat breathless headline is dominating the
discussion.

This is a good idea, which hasn't even been demonstrated to work with electric
cars and roads.

What it _has_ been demonstrated to work for, is robots in warehouses, and in
that context it's great: this would allow ~99% utilization and obviate laying
out warehouse space for charging docks.

------
TheSpiceIsLife
> The wireless transmission takes only a few milliseconds – a tiny fraction of
> the time it would take a car moving at 70 miles an hour to cross a four-foot
> charging zone. The only limiting factor, Fan said, will be how fast the
> car’s batteries can absorb all the power.

Well, yes, moving tens of kilowatt-hours of energy in milliseconds wirelessly
to a moving target with a lithium based rechargeable battery _is an unsolved
problem_.

Who woulda thunk.

~~~
sp332
I think you would have more than one charging strip. I mean charging your
batteries to full in four feet at highway speeds would be cool, but just
supplying four feet worth of energy every four feet would be fine.

~~~
cogman10
The problem is cost and complexity. These things need a load of copper wire to
make a loop, so if you are laying something like this down every 4 feet, it
translates into a boatload of material (think 400ft of copper per 4ft charge)
(That is being driven on... so definitely a possibility that they require
regular maintenance).

------
cogman10
IDK why there is so much focus on charging in motion.

This has a much better application for parking lots. Dedicate some percentage
of spaces as charging spaces and power vehicles at rest. It doesn't need to
deliver a high power charge to be useful.

Heck, this even makes sense for loading docks/semi. Put these induction
chargers at every loading bay and let the electric semis charge while they
load and unload.

~~~
toast0
For fixed vehicles, using one of the two to seven standardish plugs makes a
lot more sense. Giving up 8% efficiency to save 30 seconds over usually
20-30/minutes of dwell time isn't worth it.

As mentioned elsewhere in the thread, charging forklifts or something in a
warehouse in motion, or while briefly stopped drives up how long you can use
an electric powered device, and the added utility pays for efficency loss.

Of course, it's easier to add this to cover enough of a warehouse than to
cover enough of a highway system.

------
ChuckMcM
And your mechanical watch stops working every time you pass over one of the
recharging grid squares :-)

I love the idea of using magnetic inductance to charge at a distance but with
all that flux even small loops of conductors might be in danger of generating
a serious voltage potential across them.

------
jrlocke
This article presents the functionality as new, but wirelessly charged
electric vehicles have been in use at small scale for many years:
[https://en.wikipedia.org/wiki/Online_electric_vehicle](https://en.wikipedia.org/wiki/Online_electric_vehicle)

~~~
thegagne
Or smaller - bumper cars.

Or smaller yet - slot cars.

(Not technically wireless or battery powered, but still)

------
Hortinstein
One step closer to F-Zero. On a more serious note, This is really exciting. I
would be interested to see how they would bill for this type of charging.

[https://en.wikipedia.org/wiki/F-Zero](https://en.wikipedia.org/wiki/F-Zero)

~~~
dogma1138
Many countries would have to replace the money lost to fuel duty with
something fuel duties are a huge portion of the tax revenue in most of Europe
and many other countries.

So adding a road tax for EVs eventually would have to happen to offset the
loss of revenue.

------
peter_d_sherman
_" Wireless chargers transmit electricity by creating a magnetic field that
oscillates at a frequency that creates a resonating vibration in magnetic
coils on the receiving device. The problem is that the resonant frequency
changes if the distance between the source and receiver changes by even a
small amount.

In their first breakthrough three years ago, the researchers developed a
wireless charger that could transmit electricity even as the distance to the
receiver changes. They did this by incorporating an amplifier and feedback
resistor that allowed the system to automatically adjusts its operating
frequency as the distance between the charger and the moving object changed.
But that initial system wasn’t efficient enough to be practical. The amplifier
uses so much electricity internally to produce the required amplification
effect that the system only transmitted 10% of the power flowing through the
system.

In their new paper, the researchers show how to boosts the system’s wireless-
transmission efficiency to 92%. The key, Assawaworrarit explained, was to
replace the original amplifier with a far more efficient “switch mode”
amplifier. Such amplifiers aren’t new but they are finicky and will only
produce high-efficiency amplification under very precise conditions. It took
years of tinkering, and additional theoretical work, to design a circuit
configuration that worked."_

A resonant structure (AKA "antenna") can be thought of as Star Trek's
Transporter, version 0.0000001...

A resonant coil, 0.0000002...

A resonant coil to transport electricity, 0.0000003...

Then of course there's this:

[https://www.youtube.com/watch?v=NB_hF_K_7cc](https://www.youtube.com/watch?v=NB_hF_K_7cc)

2:28:

Montgomery Scott: "What's that?"

Alternate Universe Mr. Spock: "Your equation for achieving transwarp
beaming..."

[He shows Mr. Scott the equation on screen...]

Montgomery Scott: "Imagine that! _It never occurred to me to think of space as
the thing that was moving!_ "

------
Animats
Here's the author's web page at Stanford.[1] Not much there. He published a
very similar paper in 2017.[2] The actual papers are paywalled. So we don't
get to see how big a coil, or whatever, is needed to get 10W at 1 meter.

It's straightforward to do that with a split transformer. Berkeley used to
have an electric bus which recharged at bus stops that way. More trouble that
it was worth, but it worked. There's an old patent from, I think, GE, for a
scheme for long transformers below highway lanes to do the same thing. The
practical question is whether this new thing is substantially better.

Parity–time symmetry is a concept from quantum optics. The author, from his
papers, used to do optical work. There's been work on this in the magnetic
domain, but at very small scales, like nanometers.[3] Doing this on a scale of
meters is new.

No idea whether this makes any sense. None of the non-paywalled papers have
anything useful to read. Anybody enough into quantum magnetics to make sense
of this?

[1] [https://web.stanford.edu/~sca/](https://web.stanford.edu/~sca/)

[2] [https://www.livescience.com/59487-wireless-power-systems-
cha...](https://www.livescience.com/59487-wireless-power-systems-charge-
electric-cars.html)

[3]
[https://www.osti.gov/pages/servlets/purl/1356846](https://www.osti.gov/pages/servlets/purl/1356846)

------
foxyv
An interesting thought would be if EVs carried capacitors that had about a
quarter mile of range that could be charged instantly then slowly dumped into
a battery as the car travels. Then every quarter mile have a fast charge strip
that the car pulls from like a light rail into the super capacitor.

------
stickydink
I visited Monterey and noticed some odd markings on the roads. Monterey has
induction charging built into the roads along some bus routes. I'm not sure if
they're charging along the way, or just at the bus stops?

Either way, it's an interesting application. I'm not sure how wild you could
go with this right now, given all the roads that exist already, and the cost
that would come along with it. Or maybe the traffic implications of people
climbing to get on those free charging roads?

But public transit seems like a smart use for this kind of thing. Takes a
predictable path, for a (somewhat) predictable about of time, on a loop all
day. If you designed it right, perhaps you could drive that bus along that
route until it breaks down?

~~~
paypalcust83
_wireless power transfer (WPT) technology_

[https://mst.org/news_items/media-invitation-cord-cutting-
for...](https://mst.org/news_items/media-invitation-cord-cutting-for-msts-
wirelessly-charged-electric-trolley-june-8/)

------
sandworm101
So they need to transmit enough enegy to power a moving car, through the road
surface, using a reciever small enough to fit on/under a moving car. Ok.
That's a huge amount of energy. I hope nobody is trying to use a compass
anywhere near these roads. And I would seriously think twice about getting out
of your car if you have a pacemaker, hip or other impanted metal device.

There is aleady a decades-old system in widespread use for delivering
electrical energy to moving vehicles. It isn't rocket science. It's called a
"wire".

[https://en.wikipedia.org/wiki/Trolley_buses_in_Vancouver](https://en.wikipedia.org/wiki/Trolley_buses_in_Vancouver)

------
battery_cowboy
This will be used for some niche use, like a closed road for dump trucks to
run full time, or on train tracks for electric trains. This is too complex
even compared to putting a cable in every parking space that currently exists.

------
nickpinkston
Does the below quote really mean that there's only 8% power drop from the
charger to the battery? That too good to be true with a wireless system, even
with directional antennae.

"In their new paper, the researchers show how to boosts the system’s wireless-
transmission efficiency to 92%. The key, Assawaworrarit explained, was to
replace the original amplifier with a far more efficient “switch mode”
amplifier."

~~~
kube-system
Yeah, 8% at what distance? The inverse square law is a bitch.

------
mpolichette
Hmm, I wonder if there could be an interesting incentive alignment with the
transaction of charging cars as they drive along a highway and collecting a
tax for improving it.

There are other comments about political feasibility, but what if the same
system became a way to re-produce the tax for use we originally built into
gasoline.

Obviously theres a bunch of tax evasion / self charge cases that would need to
be considered.

------
lazyjones
This sounds like a waste of energy to me. My favourite highway concept is
autonomous electric vehicles connecting to each other physically and forming
"trains", where the large factor of air resistance is reduced greatly and cars
would negotiate with each other who's expending and who's recouperating energy
depending on each car's distance to its target.

------
xnx
Rentable portable removable gas generators that attach to you tow hitch are
also a decent solution for charging on the go.

~~~
berbec
Small point - why not just but an ICE car then?

~~~
CrazyStat
Because the electric car is better than an ICE car for the 98% of the time
that you don't need the extra range.

------
kumarvvr
Any tech that aims to improve something by re-designing roads is bound to
fail. It's simply not cost effective.

How about truck by-lanes across the country are equipped with electric cables
on poles, and trucks have those train type extenders to get charged. Or even
charging stations in truck stops.

And wireless charging is in-efficient.

~~~
Semaphor
This is currently in an extended trial in a few places in Germany. Several
kilometers of highway have those overhead lines for electric trucks.

------
6510
[Large] wind tubines by the side of the road can produce a lot of unreliable
power efficiently. Transporting it to urban areas adds inefficiency to the
unreliable. You need a fair bit of wind to get anything out at the other end.

Solar voltaic has its own weird reliability issues but the panel does produce
unusable amounts of power most of the day. (if your plan is to transport it)

Good weight/kwh ratio batteries are expensive.

If you can have the batteries roll along the power source for free the wind
and sun could be offered very cheaply.

Wireless I dunno, overhead cables or contact rails in the road seem fine.
Still costly but reasonable.

Pondering this it struck me how wonderful this ancient tech is.

[https://www.rac-info.nl/lv/images/lvtrekschuitenpaard.jpg](https://www.rac-
info.nl/lv/images/lvtrekschuitenpaard.jpg)

Its A horse pulling a boat!

We could put rails by the side of the road with drones on them (mechanical
horses) hook up any old clunker by its towing ring, cut dramatically into fuel
consumption, reduce tire wear and get rid of much of the driving idiocy.

It gets more spectacular where you can dump mechanical energy into vehicles
while it is available.

I have no idea at what speed conventional cars are still usable but I see far
less need for a speed limit if everyone drives in formation. If someone hits
the breaks the drone can detect it and slow down the car behind it. Perhaps 2
cables, one at the front and one at the back.

Charging the battery over cables gets pretty obvious at this point. (there is
regenerative breaking too!)

To add a final bit of hilarity: If we stop gluing batteries into appliances
(ffs?) fit them to the bottom and make them easy to swap by driving over a
swapping station... then the fully charged battery is more valuable than the
empty one.

This can drive the cost per km down below zero.

~~~
6510
Thanks for the unexplained downvote. Reminds me, we could chain people to
rails too! That way we can prevent them from going where they have no
business. People like me, or like you! It will revolutionize training
schedules. You will be on time for work every day.

------
mothsonasloth
Why not Scalextrics on a real life size scale?

------
el_don_almighty
Isn't this just a miles-long induction stove top? What keeps the rest of the
metal from heating?

------
davedx
“Indeed, the magnetic fields can transmit electricity through people without
them feeling a thing.”

Pretty glib considering the current 5g controversy

~~~
berbec
Pretty glib considering the non-factual current 5g conspiracy theory

~~~
hawski
Whether it is factual or not is irrelevant for the public outcry over the next
conspiracy theory. I'm not defending it, but we currently have a crisis of
science authority. I'm not sure what to do about it though.

I wonder if putting the system before lights at intersections would help to
buy, so to say, people. If it would be cheaper and more convenient for them
directly. I think the problem with 5g is that it is not entirely clear how
better is it. Also there are probably more people driving, then using mobile
Internet. Or at least more people that would protest such undertaking.

~~~
akira2501
> but we currently have a crisis of science authority

Did science ever carry any authority on it's own? In the last few decades I've
been living in the United States, I honestly don't think it has.

> I'm not sure what to do about it though.

I think what we're seeing now is really organized emotional manipulation on a
massive scale. I seriously doubt that any of these conspiracies are truly
organic, or if they are, that their current scale is organic.

Worse still is it's impossible to determine who is doing the pumping. Is it
"activist" groups looking for funding? Is it "corporate" groups looking for
legal leeway? Is it bored kids on the internet looking for entertainment?

As to what to do about it, I think the answer basically starts with a lot more
investigative journalism. We don't do that anymore. It creates a vacuum that
allows these groups to thrive.

