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Startups are exploring how electric planes could clean up air travel, which accounts for about 3% of worldwide greenhouse-gas emissions. The problem is that today’s electric aircraft could safely carry you and about a dozen fellow passengers only around 30 miles, according to a recent analysis.
The limiting factor is the battery, in particular the amount of energy that can be stored in a small space. If you’ve folded your legs into a cramped window seat or been charged extra for overweight luggage, you’re probably familiar with the intense space and weight constraints on planes.
[...] Batteries have been packing more power into smaller spaces for about 30 years, and continuing improvements could help electric planes become a more feasible option for flying. But they’re not there yet, and ultimately, the future of electric planes may depend on the future of progress in battery technology.
The prospect of electric flight is appealing in many ways. Aviation contributes a growing share of the global greenhouse-gas emissions that cause climate change, and battery-powered planes could help speed decarbonization in a growing sector.
The emissions reductions could be significant. A battery-powered plane charged with renewable energy could produce nearly 90% less in emissions than today’s planes that run on jet fuel, says Jayant Mukhopadhaya, a transportation analyst at the International Council on Clean Transportation (ICCT). (Remaining emissions are largely from producing the battery, which likely would need to be replaced each year for most planes.)
Batteries are also an efficient way of using electricity. In an electric plane, about 70% of the energy used to charge up a battery would actually power the plane. There are some losses in the battery and in the motor, but this efficiency is high compared with other options being considered to decarbonize flight. With hydrogen and synthetic fuel, for example, efficiencies could be as low as 20 to 30%.
[...] Reserve requirements could severely limit the true range of electric planes. A plane needs extra capacity to circle the airport for 30 minutes in case it can’t land right away, and it must also be able to reach an alternative airport 100 km (60 miles) away in an emergency.
When you take all that into account, the usable range of a 19-seat plane goes from about 160 miles to about 30 miles. For a larger aircraft like the 100-seat planes that Wright is building, it’s less than six miles.
“That reserve requirement is ultimately the killer,” says Andreas Schafer, director of the air transportation systems lab at University College London.
Ultimately, Schafer says, the future of electric planes depends on the future of battery improvements.
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Electric planes might seem futuristic, but they aren't that far off, at least for short hops:
Two-seater Velis Electros are already quietly buzzing around Europe, electric sea planes are being tested in British Columbia, and larger planes are coming. Air Canada announced on Sept. 15, 2022, that it would buy 30 electric-hybrid regional aircraft from Sweden's Heart Aerospace, which expects to have its 30-seat plane in service by 2028. Analysts at the U.S. National Renewable Energy Lab note that the first hybrid electric 50- to 70-seat commuter plane could be ready not long after that. In the 2030s, they say, electric aviation could really take off.
[...] Aircraft are some of the most complex vehicles out there, but the biggest problem for electrifying them is the battery weight.
[...] Jet fuel can hold about 50 times more energy compared to batteries per unit mass. So, you can have 1 pound of jet fuel or 50 pounds of batteries. To close that gap, we need to either make lithium-ion batteries lighter or develop new batteries that hold more energy. New batteries are being developed, but they aren't yet ready for aircraft.
An electric alternative is hybrids.
(Score: 2) by drussell on Thursday August 18 2022, @05:46PM (11 children)
Concentrating on good ways to store the input "energy store" for fuel cell powered aircraft seems like a better investment of time and effort than trying to make batteries that are energy dense enough for the task, at least in the short-to-medium term... right?
(Score: 5, Informative) by Anonymous Coward on Thursday August 18 2022, @06:07PM
According to Sadoway, https://www.youtube.com/watch?v=FYuVoSqj1OE [youtube.com] (discussed in another topic here recently), there isn't much going on in battery basic science and innovation. From what I've seen in the press, the next step after Lithium ion (various chemistries in use now), the next step could be solid lithium metal which might give a 2:1 increase in energy_storage:weight. This would go a long way in making electric cars better, but it is not nearly enough to make electric aircraft generally useful.
In addition to the battery weight, which is a killer for aircraft performance, there is a related issue which is that the weight stays constant for the length of the flight. Some healthy portion of aircraft range is a function of the reduced load from fuel burn during the flight. The lighter weight on landing also means you can land at a lower speed and also use a lighter landing gear.
(Score: 5, Funny) by JoeMerchant on Thursday August 18 2022, @08:25PM (9 children)
Solar panels on the top surfaces, and intense light capable photo-electric converters on the underside. Have enough battery for a safe landing, but fry that sucker with a high intensity laser from the ground (IR: to better not freak out the citizens, and also penetrate water vapor better). People shouldn't be up and flying on extreme weather days, anyway.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 4, Insightful) by SomeRandomGeek on Thursday August 18 2022, @08:57PM (5 children)
It is probably a totally unworkable idea, but I keep coming back to detachable flying batteries. Drone electric aircraft with lots of excess battery capacity. When the parent aircraft needs energy, one flies up from a recharging station and docks on it's wing. When the battery is mostly discharged, it undocks and flies back down to a recharging station. Mid-air refueling for electric aircraft. It is no more unwieldy than refueling a normal plane mid-flight.
(Score: 2) by JoeMerchant on Thursday August 18 2022, @10:08PM (4 children)
Battery exchange, upon docking the mostly discharged battery transfers from plane to drone, and the mostly charged battery transfers from drone to plane, then the drone flies / glides back to the same charging station it lifted off from.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 0) by Anonymous Coward on Thursday August 18 2022, @10:59PM (3 children)
> Battery exchange, .....
And all this gadgetry and effort is somehow better or "greener" than current jets?
...or were you going for a +1 funny?
(Score: 3, Insightful) by SomeRandomGeek on Friday August 19 2022, @03:49PM (2 children)
Yes. Much.
Fossil fuel based engines all work on the principal of turning fuel into heat, and then turning the heat into motion. This process has a theoretical maximum efficiency of 50%. But in practice it is only 20 to 30% efficient. Most of the fuel energy is lost as waste heat. In contrast, converting electrical energy to motion has a theoretical efficiency limit of 100%. In practice it is more than 90% efficient. There are, however, some losses turning chemical energy into electrical energy. So, in practice you're looking at more like 70% efficiency for a battery electric system. All of this is to say that, in addition to being cleaner, battery electric systems use a third to a half the energy of fossil fuel systems. So there is the potential for cost savings.
Also, consider the gadgetry and effort associated with fossil fuels. Teams of explorers drill hundreds of test holes miles beneath the ocean to discover new oil deposits. Once they find one they like, they sink a pipe miles into the sea floor, attach a pump to it, and start pumping out crude oil. The crude oil is then carried by ship to land, where it is then shipped to a refinery via a pipeline. At the refinery the crude oil is processed into av gas using some really complex machinery. The av gas is then put on a truck and driven to an airport, where it is pumped into a storage tank until it is needed. Finally, it is pumped into an aircraft to be used.
By contrast, solar panel to drone battery to aircraft battery is completely straightforward.
(Score: 3, Insightful) by maxwell demon on Friday August 19 2022, @04:59PM (1 child)
Fossil fuels are not the only fuel option. And the only efficiency figure that really counts is energy per mile. And for planes, more weight translates directly into less efficiency. I don't know whether that compensates the lesser efficiency from making and using synthetic fuels, but what I know is that looking at the energy conversion alone is definitely not sufficient for planes. And of course nothing you wrote in the second large paragraph applies to synthetic fuels.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 3, Insightful) by SomeRandomGeek on Friday August 19 2022, @05:29PM
I was trying to make the point that battery powered aircraft with midair refueling does have advantages, at least in the abstract. And that although such a system seems quite complex, it is not any more complex than any of our other energy production, transmission, and distribution options. None of which is to say that such a system is actually viable. The costs of fuel, batteries, and solar panels are changing all the time. And to build a system like this one would need to make a huge upfront capital investment based on predictions of what they will be years from now. But in a world where batteries, solar panels, and computers are cheap, while fuel is expensive, midair refueling is one way to compensate for the problem of battery weight in electric aircraft. That's not the world we live in, but batteries, solar panels, and computers are getting cheaper all the time while fuel is just getting more expensive.
(Score: 0) by Anonymous Coward on Thursday August 18 2022, @08:57PM
Just build it strong enough to keep the rain out.. Never fly into a thunderstorm during peacetime.
(Score: 4, Interesting) by deimtee on Friday August 19 2022, @01:28AM (1 child)
One of the proposed uses of SPS (solar power satellites) was to beam microwave power down to collectors mounted on top of electric planes. It would require some pretty good tracking, and an onboard safety reserve but would give you unlimited range. Since you are doing active tracking anyway, you could do it with satellites in much lower orbits, less than few thousand km high. Put up several and have them hand over planes as they get out of range.
The proposal was for a wavelength that would be absorbed by the lower atmosphere, so it couldn't hit the ground. The plane needs enough onboard charge to get to sufficient altitude, then the receiver takes over. It could even re-charge the on-board battery so the plane had a reserve for landing.
...
Cool. Somebody in Japan built a ground-based model Study of Electric Aircraft Charged by Beamed Microwave Power(PDF) [ihi.co.jp]. It's something that should scale up well.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 2) by JoeMerchant on Friday August 19 2022, @01:20PM
>beam microwave power down to collectors mounted on top of electric planes
That sounds like a firearms training class of firing angles NOT to use... miss the plane and cook Aunt Bessie's poodle on the porch.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 4, Interesting) by oumuamua on Thursday August 18 2022, @06:02PM (11 children)
A lot of solutions to the energy crisis involve looking to the past. Windmills were revived as wind turbines. Early aviation also had blimps. Yeah they are slow but just go for a steampunk look and people will clamour to buy tickets.
(Score: 1, Interesting) by Anonymous Coward on Thursday August 18 2022, @06:17PM (8 children)
I had a blimp ride once, we knew someone that got us on one of the Goodyear blimps and flew around over LA. Lots of fun, but the crew recognized that they were a marginal technology. While we were faster than some of the notorious LA traffic jams, the cruising speed of 35 mph means that you can usually get somewhere faster by car than blimp.
Interesting aside: Since the blimp is neutrally buoyant, the cruising speed of 35 mph barely changed in a steep climb, or in a steep dive. It just keeps on trundling along at 35 mph.
(Score: 4, Informative) by istartedi on Thursday August 18 2022, @06:21PM (6 children)
Googling around, the Hindenburg allegedly once obtained 180 mph over the ground with a tailwind, and could do about 75 mph over the ground through still air.
So a blimp could compete with the bus or Amtrak, but not planes.
Appended to the end of comments you post. Max: 120 chars.
(Score: 0) by Anonymous Coward on Thursday August 18 2022, @06:23PM (2 children)
"Blimp" is not the same as "rigid airship"...
(Score: 0) by Anonymous Coward on Thursday August 18 2022, @06:48PM
Thanks for that great-grandpa.
(Score: 2) by istartedi on Thursday August 18 2022, @07:15PM
True, and it may make a difference here since the flexing of a gas-bag might create more aerodynamic losses vs. the tight skin stretched over the frame of a dirigible.
Appended to the end of comments you post. Max: 120 chars.
(Score: 0) by Anonymous Coward on Thursday August 18 2022, @06:29PM (2 children)
> the Hindenburg allegedly once obtained 180 mph over the ground with a tailwind, and could do about 75 mph over the ground through still air.
Looks to me like that is a one way ride, the return trip can't be done? If the downwind speed is 180 mph - the still-air-speed of 75 mph means the tail wind was 105 mph. 75 mph into a 105 mph headwind means going backwards (relative to the ground) at 30 mph.
There is some wiggle room, you can change altitude to find different wind speeds, but, on some routes in some wind conditions, the trip won't be feasible.
(Score: 3, Interesting) by istartedi on Thursday August 18 2022, @07:10PM (1 child)
Yes, definitely one-way and the source I read indicates that it was indeed a 100 mph tailwind. AFAIK they didn't really understand the jet-stream back then. The Hindenberg didn't have a pressurized compartment so there's no way they could have gotten that high anyway. It must have been a fluke weather system that allowed them to do that safely.
With what we know now, it might be possible to take advantage of the circulations around pressure centers and use winds at various altitudes to find favorable winds.
Balloonists have been doing this intuitively for centuries, often navigating back to their launch point with only buoyancy the knowledge of winds blowing in different directions at different altitudes.
Appended to the end of comments you post. Max: 120 chars.
(Score: 2) by JoeMerchant on Thursday August 18 2022, @08:29PM
>allowed them to do that safely.
That would be Hindenberg levels of safely? No telling how wild that ride was in the gondola.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 3, Insightful) by maxwell demon on Friday August 19 2022, @07:45AM
Well, if your destination can be reached by car, what is wrong with going there by car? Or by "multi-passenger car" aka bus? If your destination cannot be reached by car, the comparison to cars does not matter.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 3, Funny) by richtopia on Friday August 19 2022, @03:37PM
We first need to unlock fusion, which will give us helium for blimps. I hear it is 10 years out.
(Score: 2) by turgid on Saturday August 20 2022, @07:30PM
So for flying we should have magic carpets?
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 4, Funny) by krishnoid on Thursday August 18 2022, @08:45PM (3 children)
With drone capability, you just need to make it 5 miles, then trapdoor the passengers into the plane right below it, have that plane dip just a little to accommodate a soft landing in their new seats, and voila! Old plane lands and taxis to the Air-X supercharger powered by our new ignition-powered Fusion-X plant, little robot arm plugs the charging cable into the plane, and you're done.
With that kind of range, they could be literal puddle-jumpers. You'll probably want to swap out the seats to speed up cleaning the airsick out of the interior, but that's a minor issue.
(Score: 3, Insightful) by JoeMerchant on Thursday August 18 2022, @08:59PM
You're thinking big drone, try smaller ones that attach to the passenger plane to provide propulsion, and as the drone runs low on energy it detaches, flies down to a charger and is replaced by another that just flew up with a fresh charge. Maybe 10 or 20 drones per plane in a constant dance replacing each other one per minute... 4 hour flight? 240 drone exchange operations, but compared with a turbine they're cheap! You might even keep a minimal compliment of propulsion and battery permanently on board and let the fly-up drones just do "in-air refueling". Bonus points for charging stations in the sky, maybe blimp based....
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 0) by Anonymous Coward on Thursday August 18 2022, @09:04PM (1 child)
Better yet, just dehydrate the passengers before loading, and rehydrate them after landing. Problem solved.
(Score: 2) by maxwell demon on Friday August 19 2022, @07:48AM
I didn't know we have readers from Trisolaris here.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by tekk on Thursday August 18 2022, @09:14PM
That jet fuel'd go a lot farther if we saved it for transoceanic flights, wouldn't it?
(Score: 1) by MonkeypoxBugChaser on Thursday August 18 2022, @11:22PM (4 children)
And double so not at afordable prices. Electric planes are already here, they are called quadcopters and you can order them on ebay. You can maybe pull off a foamer. That's what the technology supports.
Same thing for heavy equipment. It doesn't matter how efficient you are, the amount of pixies you need to hold won't fit in the box.
(Score: 0) by Anonymous Coward on Friday August 19 2022, @02:57AM (1 child)
Correct. Even the battery electric cars with the largest batteries only have the equivalent of a few gallons of gas when fully charged. Here's an overview from 10 years ago that is still mostly correct,
https://www.aps.org/publications/apsnews/201208/backpage.cfm [aps.org]
One paragraph from the link,
I guess electric motors and inverters have gotten better, are they up to 90% or better now? ICE have also gotten better, I believe 20% overall thermal efficiency is now common. The turbocharged hybrid power units used in Formula 1 racing are right around 50%, so there is plenty of room for better ICE efficiency--of course these are hugely expensive now, but the lessons learned will be used in high volume production eventually.
Turbofan engines in jet aircraft are almost to 50% now as well, see https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node84.html [mit.edu] for a plot.
(Score: 2) by ChrisMaple on Friday August 19 2022, @04:57AM
Uranium 500,000 MJ/kg (minimum).
(Score: 2) by maxwell demon on Friday August 19 2022, @07:55AM (1 child)
I'm sure reactor grade uranium has much higher energy density. However I don't advocate its use in planes. :-)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 1) by MonkeypoxBugChaser on Sunday August 21 2022, @10:23PM
Turns out all the shielding you need outweighs that.
I long wanted an RTG until I found out the size to wattage ratio.
(Score: 3, Interesting) by darkfeline on Friday August 19 2022, @03:55AM (3 children)
Physics is stopping battery powered planes. I'm going to hypothesize that it's physically impossible to store enough energy via batteries (that is, via electron charge differential) to make battery planes practical. You have to use some other form of energy, with the obvious option being chemical energy.
I don't get this fixation on batteries. Batteries are horrendous for the environment, considering you have to make the batteries. There are ways of utilizing chemical energy from fuels that don't involve releasing tons of waste chemical into the environment, including but not limited to fuel cells or waste capture/scrubbing.
Join the SDF Public Access UNIX System today!
(Score: 2) by Username on Friday August 19 2022, @12:44PM (1 child)
Flying nuclear reactor.
Longest lasting battery ever, but is every terrorist wet dream.
(Score: 2) by turgid on Saturday August 20 2022, @07:34PM
You could make a nuclear powered airship/hot air balloon. It would be enormous. It would need to be large and heavy enough to have shielding for the reactor, but the reactor is effectively an infinite source of heat. People would be scared of it though.
I refuse to engage in a battle of wits with an unarmed opponent [wikipedia.org].
(Score: 2) by choose another one on Friday August 19 2022, @05:55PM
Yep, unless battery tech improves more then order of magnitude electric planes are a cannae - as in "cannae change the laws of physics".
Bjorn over at Leeham did a very good series on this a couple of years ago:
https://leehamnews.com/2019/12/13/bjorns-corner-why-e-in-eplane-shall-stand-for-environment-not-electric-part-1/ [leehamnews.com]
It is not just raw energy density compared to liquid fuel, it's the fact that liquid fuel gets used up, saving weight as you go - batteries don't. The weight penalty is therefore multiplied. Causes other issues too - most big jets cannot land safely at max takeoff weight, because they don't have to (hence circling to burn, or dumping fuel in emergency), battery versions would therefore need far stronger gear adding even more weight.
There will be niche markets such as inter-island hops in small planes where the journey times actually are a handful of minutes, but for anything long distance they are a pipe dream for now.
Making a substitute for JetA1 from atmospheric CO2 and renewable electricity... now _that_ will be a big time success for whoever cracks it.
(Score: 3, Informative) by SomeGuy on Friday August 19 2022, @12:06PM
Your mom is so fat....
(Score: 2) by choose another one on Friday August 19 2022, @05:57PM (1 child)
I think a bit of research into aviation accident history will show that _lack_ of reserve requirement is actually the killer...
(Score: 0) by Anonymous Coward on Sunday August 21 2022, @08:08AM
With our current tech level I think fuel cells are the path to go for electric planes. Could have capacitors or even batteries for when you need bursts of power.