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Can electric cars on the highway emulate plane-to-plane refueling?

47 points| jonbaer | 5 years ago |spectrum.ieee.org | reply

128 comments

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[+] jccc|5 years ago|reply
Asking sincerely: Why should we not simply pull over to do this? Planes obviously are a different situation, but cars can easily just stop.

While cool to imagine, it seems unnecessarily complicated and unsafe to do this in motion on the road.

[Edit: The prof and his team are quite serious about it, so I assume there must be a reason and I'm actually curious what it might be.]

[+] willis936|5 years ago|reply
It seems like a valuable proposition if we threw out the existing paradigms of road transport.

If we throw out concepts such as ownership of vehicles and fuel and treat all road vehicles as one system of controlled individual elements, you could envision is a more efficient solution. Traffic jams would be lessened, trip times would be shortened, total fuel usage would go down, etc. On road-fueling would be one element in a world like this: road based freight delivery could run without stopping by using vehicles expected to have short journies to refuel the trucks along the way.

This is all to define a hypothetical new paradigm in road transport and to quantify its potential consequences (good and bad). I had not thought about on-road refueling before and I think there is good value in pointing it out. We're not at the point where we're seriously charting a course to world like this, but we need to know what the world looks like before we can start to do that.

[+] baltimore|5 years ago|reply
Because charging takes much longer than filling up with gas. If someone is willing to pay a premium for charging while driving to reduce total trip time, that's a business opportunity.
[+] irishcoffee|5 years ago|reply
This is the correct question. Planes did it because they had to. Highly trained pilots execute in-air refueling. Not kids with their folks teslas.
[+] valuearb|5 years ago|reply
Commercial planes don’t even do midair refueling, because it’s expensive and dangerous.
[+] ashtonkem|5 years ago|reply
Why bother? With top line EV ranges reaching close to 400 miles, after that amount of time I need to get out of the car. If you want people to be able travel huge distances cleanly without stopping, then what you’re actually looking for is a train.
[+] root_axis|5 years ago|reply
400 miles is possible but there isn't a 100% EV that achieves a 400 mile range under typical circumstances. Realistically you get about half that if you're doing highway driving and live in a place where you need to have the HVAC running all the time. Though, I think it'll probably get there within the next 10 years.
[+] willis936|5 years ago|reply
What about an autonomous semitruck that could run 24 hours a day except for unloading/reloading cargo, refueling, and maintenance?
[+] ntsplnkv2|5 years ago|reply
Not everyone wants to take an hour long break every 400 miles.

On a 2000 mile trip, that's an extra 5 hours of travel time. I'd much rather be at the beach than at Rest Stop X in the middle of nowhere for an hour.

[+] ppod|5 years ago|reply
Maybe special powerful cars that are constantly charged could drag others along a fixed line in a kind of "train".
[+] patall|5 years ago|reply
Can anyone explain what happened to battery swapping. A few years ago there was this Tesla show where they swapped three cars in the time it took to refuel a normal ICE automotive. But after that nothing happened.

I know it is difficult to handle when you do not own the battery but I would guess 90% of private long distance trips are return trips, so you could swap batteries at your trusted former gas station every 200 miles and then on the way back home do the same and get your old battery back at your last stop and keep that pack for all your short day to day trips. But somehow, this idea seems to be 100% abandoned.

Edit: Follow up conspiracy: Could it actually be because the battery is the one component of an EV that degrades the fastest and thus cars would last much longer (and no manufacturer would want that) if you could just swap the main battery every 100.000 miles or so?

[+] NickM|5 years ago|reply
It was abandoned because fast charging stations keep improving, and are much simpler and cheaper to operate than battery swap stations. It's already at the point where you can take a 400-500 mile road trip in a Model 3 with maybe a single twenty minute charging stop, which is just not that much extra time, and most people like to take a short break every few hours anyway.

I suspect Tesla knew this would probably happen, but IIRC there was a rule for a while with the California ZEV credit program where manufacturers qualified for extra credits if a vehicle could be "refueled" in under five minutes. Tesla set up a single swapping station to prove it could be done and therefore qualify for the extra credits, but it was always kind of inconvenient and expensive and very few people actually used it.

[+] leetcrew|5 years ago|reply
unless manufacturers implement some sort of standardized battery pack, it seems like this would be a logistical headache. simple enough to store and charge your original battery for when you return, but how do they have the correct battery for you to pick up on the outgoing leg? is the "gas" station supposed to keep a stock of charged batteries for every type of EV?
[+] yingw787|5 years ago|reply
Immediate concern for me would be safety. My impression is the battery pack provides a lot of the rigidity necessary to keep the car in one piece, and swapping the battery out introduces new hazards.

There's also the concern about liability, whether the battery pack you're getting is as good as the one you're trading in (what if it's older and has a lower overall capacity), and how that might impact resale value.

Third would be logistics, keeping the flow of batteries through the stations and having enough batteries on hand to swap on demand, and keeping compatibility with different makes and models, is a challenge.

[+] m463|5 years ago|reply
Nobody who actually owns a car wanted to swap batteries.

There are many reasons: ownership of the battery, logistics of the swap and swap back, required payment for convenience, need to stop anyway, range of vehicle, etc.

[+] ztakeo|5 years ago|reply
Well if you want to see one way the battery swapping model can fail work, check out the book Totaled, which is about the Israeli EV startup Better Place that tried battery swapping before Tesla was a thing. Granted there were a lot of complicating factors that may not apply in the Tesla case (securing battery swapping locations in Israel came with specific challenges), but it may provide some insight.
[+] jdofaz|5 years ago|reply
Increased capacity and high speed charging have made it not worth the cost/complexity.

I've read the Rivian truck can have an additional battery dropped in the truck bed but I don't think it is something you can buy yet.

[+] matz1|5 years ago|reply
Probably the same reason why smartphone battery is not swappable. For various reason we don't have swappable smartphone battery even though it is technically much easier problem to solve.
[+] dumbfounder|5 years ago|reply
I am imagining a scenario where an autonomous vehicle zooms toward the car at high speed and then from underneath the car swaps out the batteries then zooms away.
[+] ravenstine|5 years ago|reply
That's because it's not "cool". We wanted our flying cars, so if we aren't getting those, we at least want our cars to do wild and unbelievable things like flock together and fuel each other like jet planes. Who's going to invest in battery swapping technology? It's effectively a solved problem and not exciting.
[+] nullsmack|5 years ago|reply
Why not just have overhead lines that you can attach to when you need a charge? Do it like the street cars. Or have something like a railroad you can drive up onto and then it charges you while you're traveling over it.
[+] munsters|5 years ago|reply
This seems like it would only work if you're able to stay bumper to bumper with the charging car for 30+ minutes. You'd have to be traveling a very long distance along the same route (and, the charging car's destination MUST be before it runs out of power after transferring its power). What are the odds of that happening, on a reliable basis? At that scenario, it seems more sensible to install overhead wires (or underground) along freeways for long distance travel.
[+] zackkatz|5 years ago|reply
This reminds me of old Popular Science magazines promising a future of unrealized technology.

I do not think this is the future. But it’s something I’d like to see in a sci-fi movie.

[+] viburnum|5 years ago|reply
Replacing highways with trains for most trips is more sustainable.
[+] bob33212|5 years ago|reply
The only good options are:

1. Make much more rapid charging possible on the cars much closer to the interstate. 2. Add a electrified metal rail to the road so that the cars can charge like a subway car.

[+] letitbeirie|5 years ago|reply
Emulating plane-to-plane refueling entails all sorts of system dynamics problems because of the untrained human driver in the mix.

Wouldn't it be a lot easier (and likely cheaper in the long run) to emulate overhead line-to-train power transfer?

Seems like "transfer of electricity into an (ideally) land-bound vehicle from its infrastructure" would be a more closely related problem than "transfer of fluid from one airborne aircraft to another."

[+] Someone|5 years ago|reply
I think http://eptender.com/en/battery-tender-2-2 (renting a battery in a small trailer to extend a car’s range, potentially dropping it off at a different place from the one you picked it up) has more chance of succeeding In the market.
[+] toss1|5 years ago|reply
I've been thinking for years that fully-automated platooning / drafting should be a good option for self-driving cars. Run it via an app, cars make themselves available for drafting, others nearby sign up, they all line up and save energy. Could be a nice feature for Tesla, or a competitor, to augment the value of being in their network.

Obviously, this would rely on both self-driving and car-to-car communications to ensure simultaneous braking, acceleration, etc. to avoid accordion effect and chain-reaction collisions.

Charge-sharing as in this article could be a nice addition too. Also seems most plausible to automatically pay for shared charge in credits of some sort, or cash through the app. My biggest question is whether the shared charge would be sufficiently useful in comparison to the cost/maintenance of the extra moving parts. Seems like induction power&charging in sections of road could be more effective.

[+] pjkundert|5 years ago|reply
One of the next obvious steps for self-driving vehicles is “flocking” or drafting; this is an almost trivial problem once two or more vehicles are autonomously locked within a few inches of each other.
[+] jstanley|5 years ago|reply
If you have a car only a few inches behind you and you spot a problem and need to emergency brake, you can't actually start braking until the car behind has started braking, otherwise the car behind will crash into the back of you.

If you have 3 cars in a row, and the first car spots a problem, it can't start braking until after the 2nd car has started, but the 2nd car can't start braking until after the 3rd car has started.

It gets linearly more dangerous as more cars are added.

Not saying it can't be done, but the problem is more subtle than just working out how to stop the cars from crashing into each other at speed: they also need to be able to brake in emergencies without crashing into each other.

Possibly the way to do it would be to mechanically couple the cars like a train, so that it is safe for the one in front to start braking earlier than the one behind, albeit with reduced performance.

[+] ashtonkem|5 years ago|reply
Just build high speed rail. It’s available today, rather than in some hypothetical future once autonomous cars work.
[+] kevin_thibedeau|5 years ago|reply
> two or more vehicles are autonomously locked within a few inches of each other.

Never going to happen so long as potholes and poorly patched roads exist.

[+] grecy|5 years ago|reply
Tesla have talked extensively about "Convoy Mode" for the upcoming Semi Truck where they will do exactly that. Maybe the gap will be more than inches, but the idea is they draft together.

I think the plan for early autonomous driving is the first one in the line will have a human driver, and the others will follow autonomously in convoy.

[+] Tade0|5 years ago|reply
Too close for comfort I think. Brakes are still hydraulic and they react when they react - with a different delay for each vehicle.
[+] infecto|5 years ago|reply
Once we solve autonomous driving. Decades out.
[+] jsjohnst|5 years ago|reply
I see no problems at all with being magnetically coupled via an extended probe to another car transferring high voltage and/or current while driving at highway speeds, none what so ever...
[+] nicoburns|5 years ago|reply
Wouldn't it make more sense to build the charging into the road?
[+] umvi|5 years ago|reply
We could make the road out of interlocking hexagonal solar panels
[+] simonblack|5 years ago|reply
Why do that?

Incorporate a charging loop into the road.

Better still, throw away those heavy and toxic batteries and just collect the car's power directly from the road.

[+] PhantomGremlin|5 years ago|reply
What's the efficiency on something like that?

What's the cost of tearing up every single highway in existence to add a charging loop?

[+] mmaunder|5 years ago|reply
I’m assuming very high power transmission in short period of time. Thus moderate amps and very high voltage or you’ll need thick cables.
[+] lmilcin|5 years ago|reply
Seriously doubt fast charging a battery of running car from battery of another running car.