Oslo Will Build Wireless Chargers For Electric Taxis in Zero-Emissions Push (cnet.com) 110
Norway is helping lead the charge toward complete electrification, and it will soon have a whole network of wireless chargers for its capital city's fleet of taxis. From a report: The city of Oslo, in conjunction with Finnish utility company Fortum and American manufacturer Momentum Dynamics, announced last week that the three will work together to create a wireless-charging infrastructure for Oslo's growing zero-emission taxi fleet. The charging plates will be installed at places where taxis park and wait for fares.
The city will use Momentum Dynamics' wireless charging technology, which is claimed to work at speeds up to 75 kilowatts, which is in the neighborhood of most current DC Fast Charge stations. Taxis will have the requisite hardware installed, so all they need to do is park over a charging station and accumulate electrons before shuffling off somewhere else. "We believe this project will provide the world with the model it needs for keeping electric taxis in continuous 24/7 operation," said Andrew Daga, CEO of Momentum Dynamics, in a statement. "It will build on the success we have demonstrated with electric buses, which also need to be automatically charged throughout the day in order to stay in operation. Momentum is very excited to be working with the people of Oslo and with our partner Fortum."
The city will use Momentum Dynamics' wireless charging technology, which is claimed to work at speeds up to 75 kilowatts, which is in the neighborhood of most current DC Fast Charge stations. Taxis will have the requisite hardware installed, so all they need to do is park over a charging station and accumulate electrons before shuffling off somewhere else. "We believe this project will provide the world with the model it needs for keeping electric taxis in continuous 24/7 operation," said Andrew Daga, CEO of Momentum Dynamics, in a statement. "It will build on the success we have demonstrated with electric buses, which also need to be automatically charged throughout the day in order to stay in operation. Momentum is very excited to be working with the people of Oslo and with our partner Fortum."
Smart government (Score:4, Insightful)
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Re:Smart government (Score:4, Insightful)
I would love to see this as well. Of course, the first reply is "it doesn't benefit me, so why should my taxes pay for it?" This ends the discussion right there.
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The total tax on 850,000NKR (around 100,000 USD) is 30.8%
Please focus.
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The total tax on 850,000NKR (around 100,000 USD) is 30.8% Please focus.
It's slightly more than that... 31.8%. The marginal tax rate caps at 46.6%. Also, note that in addition to this there is VAT (25% on pretty much everything you buy) and extra taxes for things like gas, tobacco or alcohol. And cars, unless you buy electric ones. Plus taxes on your income which you don't see, but is paid by your employer.
On the very positive side: health care is free, education up to and including university level is free and kindergartens are heavily subsidized - so that people can work,
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Credit and debt (Score:3)
as soon as you're willing to pay a 75% income tax.
...which surely beats setting aside 75% of your revenues to pay off various debts (mortgages, other credits, etc.) that you got your self into to pay things that we tax-paying "evil euro-communists" get for free (e.g.: student loans vs. nearly free education).
Oh, yeah, I get it. You don't like that taxes are imposed on you, you'd prefere chosing yourself, where you're going to lose 75% of your income.
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Let Norway try it first. If passersby have their laptop HDD wiped by the strong nearby EM field, and people with pacemakers die, then you'll be glad you didn't build it.
2019 (Score:3)
If passersby have their laptop HDD wiped by the strong nearby EM field,
Hello, what is this weird object that you call "HDD"?
And how can I connect it to my laptop's M.2 NVMe connector?
Also Risky (Score:2)
Okay, I've seen a number of similar "smart build outs" through history, and the problem that you can run into is that you can miss the direction technology is actually moving in and the infrastructure ends up wasted, never used. Or you end up with a sub-optimal beta solution that needs custom engineering for anything new, because you're literally the only install.
Guess right and it's glorious. Guess wrong and it's an expensive boondoggle.
It's like companies and governments coming together to design univer
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Not sure about Tesla, but as I understand it they rolled out their charging network in Europe with the same proprietary connector as
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So you start small, local, in a setting where a small scale rollout can stand on its own. Like wirelessly charging taxis in a single city. Even if a different wireless EV charging standard emerges a few years down the line, those taxis can either adopt the new system or continue to use the existing infrastructure, neither of which should incur large costs or inconvenience.
Indeed, which is why I mentioned it being risky, not that it is universally stupid. If a new standard becomes standard, one could install the new standard next to the old ones, then as taxis age out and are replaced with ones with new style chargers(whatever that is), you hold the occasional minor construction project to swap out old chargers with new. Assuming that you can't make chargers compatible with both, of course.
I just wanted to counter the "extremely smart" idea that it is a universally good mov
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Wireless charging efficiency (Score:5, Informative)
I'd be careful with presuming that there's extra inefficiency with inductive charging.
For example, Cleantechnia [cleantechnica.com]
says,
Wireless EV charging is just as efficient — or more efficient — than plugging in. Most people think they have to plug in an electric car to get the most efficient charging possible, but that’s not true. No charging method is 100% efficient. Conventional chargers are typically 88% to 95% efficient. Wireless charging is right in the middle of that range at 90% to 93% efficiency. That means it does as good a job of transferring electricity from the charger to a car’s battery as most conventional charging equipment that uses a cord.
This is largely because a wired charging system still needs to use a transformer to match voltage to the battery, while with a wireless charger, the inductive loop IS the transformer.
Even wikipedia [wikipedia.org] notes that inefficiency is primarily a problem for systems under 100W, and becomes inapplicable over 5 kW. Which is interesting that it is more efficient to plug our small devices - IE smartphones and such, in, but better to charge our huge devices (electric vehicles) wirelessly.
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What I want to know is what happens to the pennies, tinfoil, and the ferromagnetic hair barrette someone dropped on the charge plate.
But hey if it works and is efficient, more power to them. Pun intended.
Personally, once I get my Level 2 charger installed at home I'll probably only rarely give a crap what's going on at the public stations, and (un)plugging in before/after parking is not something I view as onerous. Literally takes just ten seconds.
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Right off the bat, ignore the Cleantechnica site. ANYONE who claims inductive charging can be more efficient is simply ignoring the laws of physics. There is ALWAYS loss in an inductive system. It manifests as heat. It will never be as efficient as a direct wire connection (provided the direct wire is large enough to actually handle the current). The best you can get is a transformer with a common core - and that is not a wireless system, and usually are in the 95% range themselves (note - this is NOT
You gotta pay attention to the whole system (Score:2)
Right off the bat, ignore LynnwoodRooster. Otherwise known as an Ad Hominem fallacy. The rest of your argument suffers from problems as well, such as strawman. For example, "There is ALWAYS loss in an inductive system". Well, duh. I never said inductive charging doesn't have losses. For example, I said "extra inefficiency", the Cleantech article mentions "No charging method is 100%", and I follow up mentioning that while low power systems ( < 100W) have major problems with inefficiency, high power
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Wireless EV charging is just as efficient — or more efficient — than plugging in.
When you start off with a physical lie, just quit...
Physical lies (Score:2)
Then why haven't you quit?
You haven't proven it to be a lie. It's been outright stated that physically connected chargers are in the 90% range, efficiency wise, and I've posted plenty of links showing that inductive chargers can reach those ranges as well.
Wired EV chargers aren't just a cable either, remember? They're a lot like computer power supplies, AC-DC transformers. Except instead of spitting out 12V, they spit out something like 400VDC. 90% is good efficiency for that.
Hell, I save money on runni
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Wireless EV charging is just as efficient — or more efficient — than plugging in.
More efficient? That's a lie. Flat out. They are not even as efficient. Even your own numbers say so. Why do you insist otherwise? And I don't think you realize that the losses of the inductive charging portion is in addition to the losses of the charger in the first place. It's an additional loss...
Let me guess, you're not an electrical engineer, are you? Because if you were, you wouldn't even have this discussion to start with, you'd realize the fallacy of their claim, and y
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More efficient? That's a lie. Flat out. They are not even as efficient. Even your own numbers say so.
Then cite them. Prove your assertion with evidence. At this point you're committing the fallacy of "proof by assertion". IE that you'll prove your argument right if you merely say it enough times.
Meanwhile, well:
https://www.energy.gov/eere/vi... [energy.gov]
https://www.sciencedirect.com/... [sciencedirect.com]
https://insideevs.com/momentum... [insideevs.com]
https://www.businesswire.com/n... [businesswire.com]
And I don't think you realize that the losses of the inductive charging portion is in addition to the losses of the charger in the first place. It's an additional loss...
Prove it. Everything I've seen shows that they're looking at "wall to battery" efficiency. Wired chargers have losses as well. It could very well be that inducti
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Actually, I am an electrical engineer, I've designed many power systems, and it's quite obvious. for anyone with first year EE or physics.
First, start with a primer on air core transformers [electrical4u.com].
Then check a simple model and experiment [www.psi.ch] (which confirms the model) to see what kind of coupling you can get. See slide 5 about the coupling factor.
Now learn about how coupling factor - leakage inductance - affects efficiency [wikipedia.org].
Lastly, add in the permeability of the core material - steel versus air - and it is quite
Careful about proving my point? (Score:2)
Well, I'm glad that you're finally trying. However, you still have problems of non-applicability, and have introduced spherical cow problems. To be blunt, in theory, there's no difference between theory and reality. In reality there is. Oh, and I'm quite up on my physics, and they don't say that I'm wrong. I may not be an EE, but I'm still STEM. So you can drop the credentials fallacy.
Next, I'll point out that you're strawmanning my(and my cited article)on the actual efficiency. The article, and I, h
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All I've been arguing is "as efficient".
And that right there is the fail. Show me for a transformer how you can get a K value (coupling factor) of 1. You can't - unless there is no secondary (which means - it's not a transformer). Thus there is ALWAYS a loss in a transformer. Apply the low permeability of air (1, versus 1000+ for steel) and you have even more loss. It doesn't have to go beyond that..
If there is a transformer, it WILL be lossy. If there is resistance, it WILL be lossy. It will never be as efficient - laws of physics and suc
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Show me for a transformer how you can get a K value (coupling factor) of 1.
Why would I need to? I've never asserted that. I suggest that you stop strawmanning me and keep to arguments that I have actually made. I cited, from your source mind you, a maximum k factor a bit above 0.95. I'll thus remind you. Page 8 of the pdf you cited.
You need to go back to your books, apparently. Permeability is a factor of electric field strength, not transformer efficiency. The primary use of iron cores, from my boning up on the subject for this conversation, is to make transformers more c
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Why would I need to? I've never asserted that. I suggest that you stop strawmanning me and keep to arguments that I have actually made.
Because the original article that I said was wrong - that you too offense of - made that very claim. That it was more efficient than a connector. And that is flat out wrong.
True or False. Measured from wall to battery, modern inductive chargers for electric battery vehicles are in the same efficiency range as modern wired chargers.
The claim was more efficient. Nice goal-post move... And it is false. Take any charger, add a wireless transformer system to the output - and you've made it quite a bit less efficient. Provably so.
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Because the original article that I said was wrong - that you too offense of - made that very claim. That it was more efficient than a connector. And that is flat out wrong.
You're strawmanning the original article and taking the quote out of context.
You quoted the "just as efficient" part frequently as well, so it looked like you were arguing that they had to be less efficient, thus my arguing against you, as my position is that they can be AS efficient, IE equal. At least within manufacturing tolerances.
Let me repeat the original quote:
Wireless EV charging is just as efficient — or more efficient — than plugging in. Most people think they have to plug in an electric car to get the most efficient charging possible, but that’s not true. No charging method is 100% efficient. Conventional chargers are typically 88% to 95% efficient. Wireless charging is right in the middle of that range at 90% to 93% efficiency. That means it does as good a job of transferring electricity from the charger to a car’s battery as most conventional charging equipment that uses a cord.
You're claiming that the article, using this quote, claimed that wireless charging is more efficient than wired.
"Just as or more" is a statem
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The charging system for an EV starts with electricity at the wall and includes components from there all the way to components inside the car connected to the battery. All have impacts on efficiency.
Yes, and changing that last link from a connector to an air-core transformer is necessarily more lossy. I don't know why you have an issue with this. The math is right above - coupling factor. You will never be as efficient when you terminate your charging system with a transformer (air core or iron core, although iron is more efficient) as compared to a hard-wired connector. Just not going to happen.
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I don't know why you have an issue with this.
I have an issues with this because, by all my research, you are wrong on this. You have failed to provide a citation proving this, I have failed to find a citation proving this. The math is NOT "right above". You have posted no math that I can see. Indeed, I keep encountering statements [quora.com] in documents that air core transformers can sometimes be preferred in order to prevent Hysteresis and Eddy loses, otherwise known as "iron losses". Air core works better at higher frequencies [sayedsaad.com], Hmm.. I wonder what EV ind
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How is an inductive loop wireless?
It uses a lot of wire.
inductive loop wireless? (Score:2)
It's because there isn't a wire connecting the charger directly to the car. Instead you do indeed have lots of loops of wire that aren't actually touching each other, like in the transformer that would otherwise be present.
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produce a ton of CO2 during manufacture
We actually measure CO2 emissions in tons, so using it as a superlative here is dicey.
I would not sweat the battery production footprint. It will shrink over time and use more renewable process energy as well. Approximately half of a battery’s emissions come from electricity used in the manufacturing process." [theicct.org] By the time a battery gets to 8 years old, much has improved. Currently the battery production footprint is nulled out about 2-3 years in, for average driving needs.
Meanwhile, upstream liquid
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Well, for most of the US, the land and people are just TOO large and spread out for mass transit to really work.
> If you live in a highly congested, crowded Urban area like NYC, etc, sure you can have workable mass transit.
But as I understand it, NYC is having more and more problems with their aging subway systems, and the coming bill and time to overhaul is will prove to likely be very troublesome for the city citizen
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"the land and people are just TOO large and spread out for mass transit to really work." = Bullshit from a fountain of it.
" NYC is having more and more problems with their aging subway systems," Built in 1869, most things require maintenance and reinvestment. Your education may vary. [wikipedia.org]
"I"d rather have my own modes of transport" = Unrelated disjointed non sequitur.
You don't get a say, this is representative government, we elect people to speak for us. Don't like it? Move back to Moscow and bribe your wa
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Well, for most of the US, the land and people are just TOO large and spread out for mass transit to really work.
>
If you live in a highly congested, crowded Urban area like NYC, etc, sure you can have workable mass transit.
Norway have about the same population density as Wyoming but whatever.
The only thing that makes it harder to do in the us is that Americans lacks the attitude needed to get things like this done.
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Well, ok...for attitude....let's make it simple.
How would tearing everything up we have now, and setting up mass transit around me, make my life better directly?
Will it be better than what I have now, with ability to go door-to-door in a rapid and direct manner better?
Will it make things easier for me to buy m
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Cheaper alternative? (Score:3)
Towing a trailer is complicated (Score:3)
Probably not, because then you'd have to train all the drivers on how to move with a trailer behind them.
On the other hand, if you're buying hundreds of electric buses, have the battery pack be modular, between the wheels on the bottom where it enhances stability, then swap using a dedicated swap station, or even a forklift. Some electronics in the bus and you could even have the bus itself unhook the battery and rehook the new one.
https://www.tesla.com/videos/b... [tesla.com] - showing that an in-chassis batt
Re:Towing a trailer is complicated (Score:5, Informative)
Busses are even easier than taxis because you can just plug in at the terminal while they change drivers and get cleaned. Most new busses in China have been electric for years now, with high power chargers for their up to 450kWh battery packs.
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Towing a trailer is trivial so long as you don't need to back it up, and there's no reason to have an urban bus back up. The drivers wouldn't know or care that it's back there. I've towed trailers dozens of times for hundreds of miles, have you ever towed one?
And yes, I understand that swappable battery packs seem like they would be easy, but I also observe that it isn't being done so there's probably far more to it than the self-proclaimed experts here are assuming.
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I've towed trailers dozens of times for hundreds of miles, have you ever towed one?
Around the same as you, I've towed for over 2.5k miles. And I'm sure there'd be plenty of edge cases that they WOULD need to be trained for. Buses are already big enough without adding even more.
As for swappable battery packs, the answer thus far has been more "swappable buses". I'm sure that bus lines would go towards swapping battery packs before they start towing trailers.
It even makes some sense. Have a problem with a bus? Park it, do the minimal amount of paperwork necessary to tell the station wh
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I have actually seen a bus with a passenger trailwin Tallinn, a decade or so ago. I think it was a Scania.
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A trailer has additional drag and problems associated. There's no reason internal batteries can't be quickly and easily swapped out in modular designs. Most people making actual engineering suggestions understand this already. Not you.
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Wouldn't it be cheaper/easier to have the buses tow a trailer with their battery pack? That way they can swap out the drained one in a couple of minutes.
This initiative is for taxis. There are other initiatives to get electric buses [unibuss.no] (sorry, Norwegian only).
Great way to waste energy (Score:1)
Would it be just too damn hard to make a robot arm that attaches and detaches a cable to charge? I don't think so.
Robot battery charge connecter (Score:3)
It's not that it's too hard, it's that it's too creepy for most people.
Tesla built one. [youtube.com]
That said, consider the matching prices, and maintenance. With a robot arm, you have to maintain the robot arm. An inductive charger is at least solid state. You need some sensors for both the robot and the inductive charger, but the sensors for the robot arm are going to be more complicated, sensitive, and subject to breakage. With the inductive charger, you can build it INTO the road, build it so that it can be run
Why not in-flight charging? (Score:5, Interesting)
To me it makes more sense long term, to try and figure out how to do on-road charging of vehicles in motion - some kind of heavy support van with massive electrical storage, that drives alongside or behind an electric vehicle and charges it as it goes about the day delivering people. Then you don't have the problem of vehicles having dead time to charge, which would seem to get worse using a wireless charging solution which is bound to be a lot slower than a cabled charge.
A second vehicle to hold the batteries? (Score:5, Informative)
First up, you're operating under a misconception. A properly designed wireless charging solution can be every bit as fast as a cabled charge. In many cases, faster, if you're, for example, comparing a 110V@15A cable compared to a induction system designed for 10kW.
It's actually very interesting. At the sizes and power levels we're looking at for induction charging EVs, the 6" or so between the wires doesn't give you much loss. Indeed, if designed properly, the system can act as a voltage changing transformer, eliminating the need to have one elsewhere. So they're actually efficient as well.
As for your van solution -
Problem 1 I see with a "heavy support van" is that you've just doubled the number of vehicles you need to drive around, you can fit fewer buses and battery vans into an area than just buses, etc...
Problem 2 Is that you're doubling the number of vehicles you drive around, which doubles the number of drivers you need(for now) or if self-driving, you're still doubling the number of vehicles and drivetrains you need to maintain.
Problem 3 is that it is currently entirely possible to fit an entire day's worth of energy into batteries that fit within a standard bus frame, at least for buses that spend most of their day stopped or at low speeds. IE downtown loops more than greyhound between town. This eliminates the need for the battery van completely.
Problem 4 is that the van will probably end up costing as much as a bus, so just buying twice as many buses actually gives you more flexibility. Have a problem? Swap the bus.
Most cities/towns run fewer buses at night, so you can charge most of them then. Even at the most severe use scenarios, you need to haul a bus in occasionally just for cleaning and other maintenance, so if the need is great enough you can simply swap out with a fresh bus, giving them 8 hours while on a charging station while they also clean/disinfect the bus, perform any repairs needed, etc... Or they can build a battery swap station, swap the batteries out, and be good for another 12 hours without charging at all.
Then, depending on route and all that, you can put charging pads under the bus stop spots, and depending upon the ratios, never really need to come in due to running out of energy, if the use tends to be 5 minutes of charging for every 10 minutes of driving.
If you want to get really, really, fancy, it's also possible to put a series of induction loops into the road surface and use electronics to charge the vehicle from the road even as it moves down the road at speeds in excess of 60 mph. You could have a system where, over the course of a mile, every EV running over the road gains a mile of charge. Though I'll admit that spots where the average speed is less or stops are expected can give you more charge ability with fewer loops, and are therefore cheaper. So, first you put it where the buses are stopping to load/unload. Then you put them in at redlights and such. Then you start building what I'd call 'runways' where the bus can accelerate using power from induction loops rather than its battery packs, preserving them. This is more useful than trying to give the bus power when it's stopping due to regenerative braking.
All this stuff is possible, of course, but the question is whether it's cheaper than just adding more batteries, cutting some weight from the bus, swapping out buses more frequently, or putting in a more efficient electric motor?
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Re:A second vehicle to hold the batteries? (Score:4, Informative)
For a bus, instead of using a road to charge, they could use a troley like system. Something like this here
From what I've read, trolly type overhead wires involve a surprising amount of maintenance and expense because the wires have to be out in the weather and you're constantly rubbing your contacts on them, so the contacts have to be replaced frequently.
Induction systems don't have traditional wear points, and can be completely sealed.
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They use a narrow focus beam when transmitting, to increase efficiency. In fact they claim that at 75kW they get 96% efficiency, compared to 93% over a cable.
For a moving target the system would be a lot less efficient as the beam could not be as focused, or would have to somehow track a moving object.
Taxis spend a long time sat still anyway, as they line up at the taxi rank. Might as well take advantage of that.
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Electric everything does not mean zero emissions if your electrical production facilities are pumping our emissions like crazy. Nuclear is the only current answer for this that is consistent and sustainable
Norway's electricity production [energifaktanorge.no] is dominated by hydro power, with a little bit of wind - 98% renewable.
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Inductive charging - wasteful low, efficient high (Score:3)
Actually, I was just checking up on this, it seems that inductive charging [wikipedia.org] tends to be most wasteful at under 100W, and more efficient above around 5kW. EV charging being closer to 5kW than 100W....
That said, you have the problem that universal standards themselves tend to be cludges and thus slightly less efficient, but a wired charger might not encourage people to use them as much as wireless as they'd require the driver to not only get out to hook them up, but they'd have to remember to get out and unho
Drops the energy efficiency of EVs below ICEs (Score:1)
The EPA lists the Nissan Leaf [fueleconomy.gov] at 30 kWh per 100 miles. This is energy stored in the battery. Getting the energy into the battery involves a charging efficiency of about 80% [mynissanleaf.com] (i.e. only 80% of the electricity coming out the wall socket makes it into the battery, the other 20% becomes waste heat). Transmission over power lines is about 95% efficient. And electricity generated from coal plants is about 37% efficient, about 58% efficient [wikipedia.org] for natur
Efficiency levels (Score:2)
I think you made a couple mistakes though. First up, the inductive charger would REPLACE the 80% charging efficiency of the leaf's charger, not be in addition to it. In short, a wash. This is what I've found when I researched it myself, for EVs wireless and wired charging are effectively equal in efficiency.
Second, you make absolutely no adjustment for the energy costs involved in extracting, refining, shipping, and pumping gasoline.
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The 80% wireless induction efficiency is for energy transfer over the wireless link. Basically you're switching from a 100% efficient cable to 80% efficient wireless. The 80% battery charging efficienc
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Basically you're switching from a 100% efficient cable to 80% efficient wireless.
Problem:
1. As LynnwoodRooster identified, cables aren't 100% efficient themselves.
2. The 80% efficiency is for the entire charging circuit, and is a false number. I'm seeing [energy.gov] numerous [sciencedirect.com] examples [wikipedia.org] around [insideevs.com] 90%. [businesswire.com]
Of course, the ideal isn't to just look at the "wireless link" and assume all other parts are still present and the same loss. It's better to look at the loss from the input on the charging 'station' to what the vehicle receives. Most charging stations have extensive electronics, after all. Inductive c
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A hypothetical efficiency model, that doesn't even account for varied driving where EV gains efficiency from regenerative braking?
EV efficiency calculated under the base assumption that all electricity generated comes only from an even 50/50 split of coal/natgas? Is there one example of this situation, anywhere?
Plus the inductive chargers related to this article use charged coupling, and are demonstrated to be %90+ efficient.
But it would result in EVs generating more CO2 per mile than ICE vehicles, defeating much of the purpose of switching to EVs.
Only if you want to create a worst case scenario in order to work backwards from a
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A hypothetical efficiency model, that doesn't even account for varied driving where EV gains efficiency from regenerative braking?
That's actually accounted for in the EPA mileage estimate. What isn't said is that Solandri is doubling up a lot of the inefficiencies. For example, the EPA mileage estimate ALSO takes charger inefficiency into account. They're not measuring the kWh used inside the car, they're measuring how many kWh were fed to the charger. IE how much it will actually cost you. When looking at inductive charging, they're ignoring that charging efficiency is ~90% whether it's a wired or wireless charger. Wireless cha
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That's actually accounted for in the EPA mileage estimate. What isn't said is that Solandri is doubling up a lot of the inefficiencies.
That was an informative post, but no, Solandi is also making inefficiencies up out of thin air. I guess factoring in power produced only from burning tar sands oil was a bit too much, when an even split of only coal/nat gas might seem plausible to the average reader.
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The EPA lists the Nissan Leaf [fueleconomy.gov] at 30 kWh per 100 miles. This is energy stored in the battery. Getting the energy into the battery involves a charging efficiency of about 80% [mynissanleaf.com] (i.e. only 80% of the electricity coming out the wall socket makes it into the battery, the other 20% becomes waste heat).
First, your charging efficiency of 80% is too low. 90% is a better estimate. More importantly for your calculations though, the EPA fuel economy estimates already include the charging losses: "The recharge energy includes any losses due to inefficiencies of the manufacturer’s charger." (Source [fueleconomy.gov])
This means that you need to remove the first step of your efficiency calculation.
Furthermore, Momentum Dynamics claim that their losses are lower than with a wired charger (only 4% compared to 7%). If that
Re:zero emissions? 20-30% wireless charging loss. (Score:5, Informative)