[mehrdadn]

I'll point out that although it's indeed atrocious compared to a train ride, flying is still more efficient than driving a car. So if traveling is required and you're debating between driving vs. flying (say SF <-> LA), you should prefer flying unless you can carpool. I don't know the exact numbers since it depends on where you're going and what plane/airline you fly, but I would expect around 50-75 MPG for a reasonably full airplane [1], whereas your car might be more like 25-30 MPG on the highway, so you'd want at least 2-3 (ideally 4) people in the car to make it more efficient.

However the thing about flying is of course that it burns fuel at a much, much faster rate, so if it means the difference between you driving to workplace A vs. flying to workplace B regularly, then you'll be burning one hell of a lot more fuel by flying.

[1] https://en.wikipedia.org/wiki/Fuel_economy_in_aircraft#Airli...

[mmt]

Interestingly, the efficiency ratio you suggest appears to be reflected in the ratio between the overall cost (including ground transportation at the other end) of flying SFBA-SoCal and driving.

Whenever I've spot-checked, the break-even is at 2 people, which tends to make flying more attractive for time/fatigue reasons (only barely, at some points in history) even for 2, and sometimes worth the cost premium for 3. For a family of 4 or more, even with the increased fuel cost (but generally not other operating costs) of something like a minivan, driving saves too much money to pass up.

[mehrdadn]

That's interesting, thanks for mentioning this!

[Reason077]

That’s true today. But in the coming years and decades, ground transport will be largely electrified and it’s per-mile emissions greatly reduced.

Hopefully, aviation can be electrified too one day (or it’s emissions reduced with hybrid technology), but unlike ground transport, the technology is not quite here yet.

[smolder]

Hybrid tech doesn't help at all with with planes. There is no braking energy to be regained and batteries are too heavy. It has no place there until battery energy density approaches that of fuel, which would require a huuge breakthrough of some kind.

[Reason077]

The idea behind a hybrid aircraft is that eFans (electric fans) are more energy efficient than a turbofan, so you can burn less fuel for a given journey.

Companies including Airbus, Siemens, and Rolls Royce are actively working on this technology with a view to have working prototypes in the early 2020s.

Besides that, there is some "braking" energy to be recaptured during descent or when slowing the aircraft. This technology already exists today: The Pipistrel Electro can regen it's battery during descent. This is similar in principle to the ram air turbine (RAT) in conventional aircraft.

[smolder]

Well thanks for the pertinent info. I was pretty sure of myself that the cost benefit ratio wasn't there but if there are engineering efforts towards it there's at least potentially some merit.

I wonder, does the efficiency gain from efans and a generator apply to a single engine setup as well as it does to multi engine setups?

[mehrdadn]

With battery capacities being what they are you'll also have to hang tight for the moment when they stretch long enough to allow you to even have the choice of driving to the same place you can fly. (Or swap batteries on the way somehow... not sure how well that would work.)

[Reason077]

This is already solved in technology terms. Battery capacities and charging speeds are already good enough for almost all long-distance travel scenarios.

It’s now just a case of getting costs down and infrastructure built out. But that’s the easy part.

[mehrdadn]

> his is already solved in technology terms. Battery capacities and charging speeds are already good enough for almost all long-distance travel scenarios.

Really? It seems to me that decent EV ranges are around 150mi right now, with the best ones going to 300mi... meaning they generally might get you halfway from (say) SF to LA, and you can bet that none of them will get you all the way. And that's not even that long of a distance, depending on what your standards are. Now charging times run into multiple hours, right? How is that even remotely close to gasoline?

[Reason077]

Charging times are around 45 minutes today for 250-300 miles of travel. Most people want to take a break after 4-5 hours of driving anyway, so it’s just a case of having chargers in the right locations.

The new generation of 350kW / 800V chargers will bring that down into the 15-20 minute range.

[mmt]

> Most people want to take a break after 4-5 hours of driving anyway

I realize I'm not most people (I love to drive), but this seems like it's bordering on extraordinary-claim territory. I don't actually expect evidence, since this would be the kind that's particularly difficult to gather (you could ask people, but what people say doesn't necessarily translate to what they do).

Regardless, it seems unlikely to me that anyone would want to be forced to take a break at the 4 hour mark rather than waiting for their destination at the 5 hours mark (e.g. SJ-LA).

I realize, of course, that it's just a matter of (not that great a) degree between 20 minutes every 300 miles for charging versus 10 minutes every 400 miles for fueling. However, because we're not even there yet for a comparably-priced/affordable electric car, it may be premature to think that way.

[mehrdadn]

Interesting, I didn't realize that, thanks. But these must be the best cars, right? Not typical?