
Highway Will Recharge Your Batteries as You Drive - SQL2219
http://spectrum.ieee.org/cars-that-think/transportation/advanced-cars/british-highway-will-recharge-your-batteries-as-you-drive
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elsewhen
The article suggests that mitigating range anxiety is the primary benefit. But
such systems could allow EVs to have much smaller batteries which would lower
their cost and increase their efficiency (due to lower weight).

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jtchang
It's wireless charging just like in the old snes game fzero!

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codyb
I'm very much looking forward to the future of transportation. Here in NYC
traffic can be awful. And of course the smell of the gas, vehicle fatalities,
lack of parking, and the emissions which cause increased rates of cancer near
toll free bridges and heavily trafficked roads are ever present.

Autonomous electric vehicles can offer a solution to all of those issues and
they can also allow this city to reclaim a tremendous amount of the space
currently used to park vehicles which are just sitting and doing nothing. I
like to imagine more bike lanes, more trees, wider sidewalks, and trash piles
farther from pedestrians. Ahh, and with air so clean, it shall be a wonderful
new beginning for the city if it is executed properly and implemented well
with a focus on improving pedestrian life.

A technology like this could mean that autonomous cars would rarely have to
leave the road, making them even more useful. Perhaps here in NYC it could
just be main drags which can wirelessly recharge the vehicles as they drive
over.

As a side note, if they kept the roads green like in the concept picture,
that'd be awesome too.

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jsprogrammer
Is there really a measurable increase in cancer rates at toll free bridges
versus tolled bridges?

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codyb
I've heard it before (with a map). I'm having trouble locating that same map
but I suppose it'd be possible to come to a conclusion based on a map of high
traffic areas in NYC and the rates of cancer using the cancer maps provided by
NYS [0].

Unfortunately, I'm at work so that 30 minutes isn't readily available at the
moment.

[0] -
[https://apps.health.ny.gov/statistics/cancer/environmental_f...](https://apps.health.ny.gov/statistics/cancer/environmental_facilities/mapping/map/)

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Roodgorf
A concern about a rapid increase in EV usage that I see a lot is of having the
infrastructure to cope with the increased electricity usage. To that end,
wouldn't this be creating even more of a problem?

While 75% efficiency (I assume that's only under optimal conditions) sounds
pretty good, that's still a lot of wasted energy. And wouldn't there be some
overhead for running these roads while no EV vehicles are on it? Seems like a
lot of wasted energy to promote use of something that is supposed to be more
environment/energy conscious.

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rurban
This would only work for bus lanes, but normal cars driving to work are best
loaded either at home or better at work, where the energy company can extract
energy during the peak times. These charging lanes are way too expensive, and
the charger too heavy.

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baldfat
I feel like the next big thing is creating energy out of things we use
everyday. Like stairs, doors, floors (especially rooms with children) and
overns. We waste energy but this won't happen till we get the efficiency
percentages higher and higher.

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VLM
Carnot had a lot to say about theoretical efficiency WRT input and output
temps.

For example if I did the math in my head correctly, the peak Carnot heat
engine efficiency of an oven cooling down would be 30%, dropping to 0% as it
hit room temp. Only way to boost the theoretical Carnot limit would be to
boost the temp... sear more steak, bake less bread, etc.

So if pessimistically it took a tenth of a kilowatt hour to heat up a kitchen
oven, you'd get maybe a hundredth of a KWH out of a cooling engine (the rest
goes to waste heat). Its going to be hard to environmentally amortize the cost
of the heat engine. Spending the resources on better insulation would have a
much higher payoff. Similar problem with the structure, you could collect
energy off the hydraulic door closer, but it would be way better for the
environment overall to dial up the weather stripping and door insulation than
to gather a watt or two.

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Retra
And then the things you are trying to get energy out of need to be used
frequently enough to recoup the cost and energy demands of refining and
building a more efficient device.

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JoshTriplett
This mentions 75% efficiency, but doesn't say anything about energy transfer
rate. How quickly could this charge a vehicle?

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Dylan16807
One of the linked articles talks about a prototype delivering 100kW to a bus,
so it should be in the feasible range.

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VLM
So that would imply thirty or so KW of heat at 75% efficiency and a hundred
delivered. I suppose road icing and snow accumulation would not be much of an
issue at those levels.

On hot summer days, during traffic jams, a slowly rolling 30 KW heat source
might cause road softness issues, something to think about.

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mikeash
If it's rolling slowly then it won't need anywhere near 30kW, though. Power
consumption varies roughly by the third power of speed.

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JoshTriplett
Unless the vehicle is already fully charged, I'd expect it to draw as much
power as it can for charging, regardless of its current power consumption.

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mikeash
Even if it does that (and if this is a problem then you could simply design
the system to only deliver enough power to sustain travel) then the car won't
be charging for very long before it becomes full.

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JoshTriplett
> Even if it does that (and if this is a problem then you could simply design
> the system to only deliver enough power to sustain travel)

That seems far less useful; "your charge won't go down in this lane" means the
lanes would need to go everywhere, while "your charge will slowly go up in
this lane" would mean the lanes could sustain travel over a wide area even if
they only appear on major highways.

Also, different EVs require different amounts of power to sustain travel.

> then the car won't be charging for very long before it becomes full.

Depends heavily on the charging rate. Considering that many EVs can take hours
to charge with a _wired_ charger...

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mikeash
Right now, EVs are fine for short-distance travel but most EVs have trouble
with long-distance travel. An EV's battery will be fine with getting you to
and from the highway, and you'll charge wherever you park as well.

Your emphasis on "wired" is kind of out of place here. These wireless chargers
will necessarily be able to provide substantially more power than a typical
wired charger. A typical wired charger is 10kW or less, while highway
inductive charging will need to provide 20-30kW just to sustain highway
speeds.

Let's say you draw 30kW no matter what until the battery is full. If you're in
a traffic jam, you might be consuming 2kW or so on average, leaving 28kW
available to charge the battery. If you're in a LEAF and your battery is
completely empty, your battery will be full in less than an hour. And your
battery is likely to be well above empty.

