It's much easier, IMHO, to switch over these short haul flights to electric aircraft than to High Speed Rail in the US. By the time even one major new HSR route will be finished, we'll have certified and be flying electric passenger aircraft with just as much speed and just as long of a route (500 miles) BUT with ability to go anywhere in the country by hopping.
I kinda doubt it will go that quickly. See how many problems Boeing had with their lithium batteries in the 787. And those were just auxiliary power. This will take a hundred times that many batteries with the scale bringing many engineering challenges. And then the totally different engines.. I think it'll take a long time to have a battery powered airliner built, in mass production and as reliable and safe as current airliners. There's a lot of stuff to be built from scratch without half a century of trial and error to learn from.
I think biofuels might be a better option for aviation until the tech has time to catch up.
I'd love for that to be true, but I am quite dubious. Flight technology tends to be very weight sensitive, and our battery densities are just nowhere close to the density that flight needs.
Current batteries have an energy density of 90-190 Wh/kg, depending on the specific chemistry. Jet fuel on the other hand has an energy density around 12,000 Wh/kg. Obviously some amount of that will be made back up with the relative light weight and high efficiency of electric motors, but that is a very step energy difference to overcome.
A quick bit of Googling says that turbofan engines are about 40% efficient, while triple phase electric motors are roughly 85% efficient. Given the 3,000 nautical mile range of a 737NG, some back of the envelope math says that an EV equivalent would have a range of about 100 miles at best[0]. Forget LAX -> SFO, this isn't even enough to get you from LA to Bakersfield. And even 100 is optimistic, given that the FAA requires that all planes have extra fuel for diversions, weather, holding, etc.
At this point, I suspect it might be easier to refine kerosene out of capture CO2 using excess renewable energy than it would be to make an EV 737 replacement.
0 - I'm obviously not accounting for weight and aerodynamic differences, which are beyond my capability to estimate, but I doubt that would make a significant difference. I'm also assuming that we're using Li-Ion Cobalt batteries, which have the highest density. The more common Phosphate chemistry makes these numbers even more bleak.
The best lithium ion batteries have 300-400Wh/kg (some cells do up to 650Wh/kg with sulfur), electric motors can have up to 95% efficiency. Long range jets can fly 20,000 km with passengers. Easily enough to do 500 miles. But if you improve aerodynamics, can go much further.
Source on 400-650Wh/kg? That’s significantly higher than what’s even reported in Tesla EVs, and I’m curious if that’s lab or production figures. Even going up to 400Wh/kg and 95% efficiency only yields 237 miles for a 737 equivalent, which isn’t enough.
The top spec 777 would give you 677 miles on batteries, assuming 400Wh/kg. Enough to serve the LAX to SFO route, but a fairly limited vehicle all things considered, especially for the price and size.
> Long range jets can fly 20,000 km with passengers.
Sure, but economics begins to dominate here. There’s a reason I chose the 737 as a reference benchmark; it’s the gold standard of short to medium range airliner, and absolutely the vehicle that we should be aiming to minimize. If you have to pull out a 777 sized aircraft to service LAX -> SFO, then the price of tickets is going to begin rising significantly to cover the higher vehicle cost. I’m also genuinely quite doubtful that many airports can handle 100% of their jets switching over to wide body aircraft, which this would require, without significant improvements to the terminals and other facilities. If governments are forced to upgrade airports to save money on rail, I’d argue that that’s penny wise and pound foolish.
All of this can be done, of course, but it really begins to erode all of the supposed cost savings over HSR.