We already have a fantastic dense energy battery called kerosene. All we need to do is make it carbon neutral and our existing aviation tech won't even need to change.

Here is a good overview of the plan: https://cleantechnica.com/2019/10/30/no-you-dont-have-to-wor...

I believe his exact quote was:

""" Sometimes I get criticism for, ‘why are you using combustion in rockets and you have electric cars’. There isn’t some way to make an electric rocket. I wish there was. But in the long-term, you can use solar power to extract CO2 from the atmosphere, combine it with water, and produce fuel and oxygen for the rocket. """

That Musk is no Tom Swift. Tom even had an electric rifle, not just a flamethrower.

which he used to great advantage in colonizing Africa

The difference is in the timeframes for capture and replacement - with coal it is millions of years, and with wood it is years. That means burning coal releases carbon which was trapped millions of years ago, and it would take millions of years to trap equivalent amounts of carbon with the formation of new replacement coal deposits. Burning wood on the other hand releases carbon that has been trapped within our lifetime, and it is easy to replace with new trees grown in our lifetime. Bear in mind that if we reverse millions of years of carbon capture we would revert the atmosphere to what it was like millions of years ago, and time travellers visiting that era are likely to need breathing equipment.

Our biology and our biosphere are not adapted to the atmospheric CO2 levels we would have if we burned all the fossil fuels.

Nope. You're emitting exactly the same CO2.

Want to be green? Burn less. Changing your point of view won't lessen CO2 emissions. Burning less carbon will.

It’s also fine to burn fossil fuels if you can make long-term carbon sinks from other processes, hence people caring about making carbon-rich rocks or whether dead plankton floats our sinks.

It’s a question of being responsible for the consequences of actions, not outright banning those actions before the alternatives have been deployed at scale.

Nobody is worrying about CO2 on geological timescales. It is simply not relevant to any discussion anyone is having, or any problem anyone is trying to solve.

This isn't complicated? How are you managing to miss the point with such vigour?

I could ask the same of you - how are you helping matters at all by chopping down a tree and burning it over digging up a tree and burning it? You're emitting the same amount of CO2.

Want to reduce global warming?

1. plant a tree

2. burn less

If you're wondering what to do with the tree after it grows, you can:

1. use it for lumber

2. bury it

Neither makes the situation BETTER. But one makes it WORSE.

If it's nearly suitable for cars I suspect it's even more nearly suitable for aviation on account of the lower volumes and higher margins.

Almost there https://en.wikipedia.org/wiki/Wood_gas

"Flight attendants will resume service in just a moment, after they throw another tree trunk into the wood gas generator"

[1]: https://www.alaskaair.com/content/about-us/sustainability-re...

I.e. burning coal.

The total amount of carbon in circulation is what matters because that part can end up in the atmosphere as carbon dioxide where it shows its heat capturing effects. Trees fix carbon while growing and emit it while decomposing but do not change the total amount of carbon in circulation in the long term.

Digging up carbon that has been locked away for aeons is what is so damaging. There would be nothing bad about burning oil IF that oil were produced by capturing carbon dioxide. We do not do that. We dig up loads of fossil resources and add them to the cycle.

If that explanation was too complicted, here is an easier one: fill a bucket to the brim with water, take a cup and start scooping and pouring back to the bucket. Everything is fine. Now get a second bucket full of water and start pouring into the first (material so far not in circulation is added to it). You see the problem?

If you still insist on your view with burning coal and trees being equivalent, then I challenge you to conduct the water-bucket experiment in the middle of your living room. I mean it wouldn't do no harm, right?

1. chopping down a tree and burning it

2. digging up a tree and burning it

Both are the same. Calling (1) "green energy" is outright wrong. Want to be green? Burn less carbon. The source of the carbon you're burning is irrelevant.

(The only reason the industrial revolution switched to coal was because the landscape was denuded of trees. The Jamestown colony in America was tasked with making glass, glass needs lots of fuel, and England ran out of trees. "Connections" by James Burke)

I highly recommend a visit to Plimouth Plantation to anyone interested in 1700's era technology: https://www.plimoth.org/

Or Old Sturbridge Village for 1800's era technology: https://www.osv.org/

Another topic of research is very rapid sub-orbital passenger flight. Are there any numbers on proposed fuel efficiency for that? I'd expect you gain a lot by removing hours and hours of wind resistance, but getting up to speed and out of the atmosphere probably (gut feel) uses more.

Except making it carbon neutral will require enormous amounts of energy, shift the price up, and make aviation available only to the richest among us.

Aviation industry may keep existing, but will need to scale down.

Also, we have a huge amount of free nuclear energy, daily delivered from Sun, about 1 kW / m². It is nit stable enough for electric baseload, but, depending on the process, may be adequate for fuel synthesis.

North of Sahara may become a primary source of jet fuel, given its vast amounts of insolation, cheapness of the land, and access to seawater. Not exactly tomorrow, though.

Anyways, this is the way France is going.

A step in the right direction, but I hope this doesn't get used as an excuse to fly more.

Scaling up an electric motor is not particularly hard. Some of the largest machines in existence are electric.

Power is not a challenge for electric. In fact, this electrified seaplane has much more power (560kW) than the original radial piston engine one (336kW), and even more than the turboprop conversion (510kW).

A LOT of very confident people on the Internet post lots of very wrong and/or outdated misinformation about electric aircraft (and electric vehicles in general).

Energy is a challenge, but the answer there is to increase efficiency and increase the mass of the vehicle which is battery. Both of those together give you a usable range of about 1000km. The same motor provider, Magnix, is also providing the motors for the 1000km range Eviation Alice.

Just because a conventional aircraft maker thinks something isn't possible, doesn't mean someone can't make it work. It most certainly doesn't require 30 times the energy density. For the same exact reason why electric cars don't require batteries with 30 times the energy density to compete with gasoline cars.

You say "just increase mass of the vehicle which is battery". If you read about this airplane you find that since they are using batteries with an appropriate safety rating for aviation, they've used all the space and mass already:

"this eBeaver isn’t carrying passengers — there isn’t room — and will only have a 15-minute endurance with a 25-minute reserve."

https://www.skiesmag.com/news/harbour-air-makes-history-with...

I tried finding concrete info about the Eviation Alice, but the best I could find was a photo of an unpowered full-scale model. They've been saying the first flight test is a couple of months away for more than one year it seems.

>> the plane’s four-bladed Hartzell composite propeller generated all of the remarkably quiet takeoff sound — a fraction of the thunder from the legacy Beaver’s radial piston

Maybe they’ll get a special class to be able to launch closer to cities without the noise complaints. Although I’d imagine it’s still pretty loud.

Also the bit after the paragraph about the batteries filling up the back mentions they didn’t use fully efficient batteries... they purposefully chose very safe but underpowered batteries previously used and flight tested by NASA for their own testing purposes instead of the higher end batteries used today in EV cars.

I don't think you're right from an engineering point of view. Just multiply the aircraft size and battery number by some amount. For example:

>In September 2017, U.K. budget carrier EasyJet announced it was developing with Wright Electric an electric 180-seater aircraft to be developed by 2027. https://www.nextbigfuture.com/2018/09/easyjet-and-wright-ele...

Though all battery aircraft whether micro drones or A380 size will have a limited time they can stay up. Electrics currently seem limited to an hour or so whereas jets can do 16 hours now.

There seems quite a lot of potential on short routes <300 miles though using present batteries. (eg. London Paris or LA San Diego).

And small general aviation aircraft like these usually only have a small portion of their takeoff weight as fuel, maybe 20-25%. But passenger aircraft may have 50% of their takeoff weight be fuel (for instance, 777 on long haul flights). Electric aircraft like Eviation will need to go further (55%). This is something you can do with a cleansheet design like Alice, but can't with a mere conversion designed literally over 70 years with manufacturing and materials from 70 years ago.

And you can apply the same principle of increasing take-off weight fraction for kerosene-powered aircraft as well. The Virgin GlobalFlyer was 82% fuel on takeoff. It flew around the world and then some. Kerosene is much better than it needs to be to enable modern flight.

You're absolutely right about Alice being late, but the design concept is a good example of what is possible. You combine state of the art but existing lithium ion chemistry (which needs some work for aviation certification but IS used on the ground already) with state of the art lift to drag ratio (and perhaps additional innovations, like wingtip propulsion to reduce losses from wingtip vortices) with efficient enough structural mass to enable 55% of the takeoff weight (as well as landing weight, of course) to be battery.

These things multiply together to enable long range.

With airplanes, you have to lift that weight using the same energy stored within. In that case, energy density is the absolute issue. Nothing else matters.

There's no magical solution, a high-school physics class will teach you how to calculate the potential energy requirement to lift up a certain amount of weight, and dividing by energy density and volume of current battery tech does not lead to a working jet any time soon.

E=mgh

E=(1kg * 9.81m/s^2 * 10.000m) / 3600s = 27.25Wh.

Tesla currently is at around 260Wh/kg thus roughly ten times the amount of potential energy needed to get to 10.000m altitude.

I'd assume that till 2030 we get to ~500Wh/kg by improving current technology. And maybe some quantum leap to 1500-2000Wh/kg within 20 years.

An A320 or A380 will likely always need a fuel cell but a 15 seater with 1000km range is only a question of time.

That's the energy - assuming 100% efficient conversion of battery power to altitude - to lift _only_ the battery to altitude (and then immediately fall back down).

Actual engines are nowhere near that efficient and you'll presumably want to lift the rest of the airplane too. Then you have to keep using power to keep the plane aloft and land it safely.

Your hypothetical 2000Wh/kg future batteries still have a specific energy less than 1/5 that of aviation fuel (Jet A = 11950Wh / kg). A 15-seater electric with 1000km range based on those magic (7.5x better than state-of-the-art) batteries would instantly upgrade to a 5000km range if you tore out the batteries and replaced them with a gas tank of equal weight.

Batteries need a ~40x improvement in their specific energy density to make sense as an energy source for aircraft that depend on thrust for lift.

Tragically, physics doesn't care that battery powered planes would be cool.

I don't know how I can say "no" strongly enough.

If you only need 500km of range, it does not matter a single bit that jet fuel would increase your range from 1000km to 5000km. (Or 100km/180km/5000km respectively, if you want to talk about more contemporary batteries.)

Two things matter. Is the range good enough? How much does it cost? Jet fuel should not even be considered when answering the first question.

Drag increases the square of the velocity. That means going at 500knots (as an airliner does) uses a lot more power than going at the 150knots this seaplane might fly at.

You can calculate an approximate power requirement for the aircraft based on its glide ratio [1] or look at the power based on engine thrust [2]. In all cases you get figures in the 14-80MW range (engines don't tend to be full throttle during cruise)

That means your 260Wh/kg battery would need to weigh somewhere between 54 and 308 tonnes to sustain an hour of flight. That doesn't include takeoff, which is only a few minutes but might reach towards 200MW.

For reference, the 737 (low end power calculation) max takeoff weight is 62 tons and the 747-400 max takeoff weight is 397 tons. So in both cases you're looking at basically 30 minutes of useful cruise with current battery tech.

The range loss is additionally confounded by the fact that current aircraft lose fuel, so lose weight, during the flight. This accounts for a not-insignificant portion of the range.

[1]: http://large.stanford.edu/courses/2013/ph240/eller1/ [2]: https://aviation.stackexchange.com/questions/19569/how-many-...

So basically for electric passenger aircraft with even remotely comparable performance, we need a battery revolution. It definitely won't be by 2030.

But if you want to go as fast as a chemical engine and sustain that for as long as a chemical engine, you either need at least the energy density of a chemical fuel or some way to refuel in-flight.

Fuel efficient often means “slow”. Great for cargo, not so much for passengers.

Edit:

Just to add, I’m looking forward to a future of short-range electric personal aircraft, I’m just not expecting pure electric intercontinental for anyone other than hobbyists — unless there’s a big breakthrough in density or wireless power transmission.

Fuel efficient for aircraft doesn't necessarily mean slow, however (unlike ships). What matters is cruise lift to drag ratio. As long as you can adjust cruise altitude for peak efficiency and as long as all the flow is fully subsonic, then lift to drag ratio is mostly independent of speed (as you can increase altitude where the air is thinner to compensate).

So yeah, electric aircraft might stay at Mach 0.5 or so, but they don't need to be slow. Mach 0.5 is still much faster than any passenger high speed rail service and MUCH faster than car or bus or boat.

Pure electric intercontinental may be feasible for near-term chemistries like lithium-sulfur if you continue to push efficiencies (both structural and aerodynamic). Very long haul, like LA to Tokyo, will need lithium-air technology which is a few decades off.

Not even that. I believe an 86 nmi range is what they are hoping to achieve by 2025. Current range is a fraction of that. The technology demonstrator has a theoretical flight time of 15 minutes and no ability to carry passengers because all the room/weight is taken up by batteries.

   -- "Skunk Works" by Ben Rich

There's plenty of room for passengers in this concept. Where are you getting this false information?

From the article:

> What certainly hasn’t been done before is to fill a Beaver’s cabin with lithium-ion batteries, taking the plane to its gross weight. As a technology demonstrator, this eBeaver isn’t carrying passengers — there isn’t room — and will only have a 15-minute endurance with a 25-minute reserve.

> These are batteries that NASA is using, but they’re not batteries that we’d use if we were going to try and make it economical to fly today, because they’re very low in watt-hours per kilogram

And then the other much harder problem which is achieving sufficient Wh per kg energy density in batteries, and Wh per litre of volume. For which they are dependent on global factors for r&d of batteries and improvement in density.

They rely on the plane being lighter from fuel burn and therefore more efficient to extend their possible flight time, but not for safety.

Needing to land before getting under weight usually means a crash landing. In modern times, very few things like fire or an engine self-destructing will require immediately getting out of the air. It is usually better to fly in a straight line, figure out what is going on, figure out where to land, then land. This lets you get underweight, lets you communicate with air traffic control, lets emergency services prepare, etc.

Airliners will dump fuel or keep flying to get below maximum landing weight if possible. If they're still overweight and manage to land without issue, the plane will need to be inspected and repaired before it can fly again.

Contained vapor creates an explosion, while liquid must evaporate first.

If we could make progress targeting just short hops targeted by DASH-8s or CRJs or whatever, we could still make significant progress, even if it meant leaving the longer-haul flights alone, or targeting their emissions with different technologies (synthetic fuels from carbon capture, maybe).

It's pretty much a smooth curve, with the breakeven point depending primarily on energy density of your batteries. Until very recently, the electric aircraft weren't possible at all. We're now at the point where two seat trainers with short (but long enough for a typical lesson) endurance are possible and in production. If you look at where battery tech is going, we can probably push that up to 8ish seats and a somewhat longer endurance within a few decades. When you look at the size of even a small regional jet, it doesn't seem likely that current battery tech is ever going to get us to the energy density necessary to make it work.

The round trip efficiency would be similar to diesel (since you are re-smelting rather than recharging), but the effective energy density on the plane could actually be much better than jet fuel.

First of all: citation needed.

Secondly: it's a disengenious argument to say "you can't scale it up", then give the largest passenger aircraft in operation as your first scale up target.

What about scaling up to the size of the propellor aircraft regularly carrying people between Amsterdam and many cities in the United Kingdom every day, or thousands of the other short haul routes? Indonesia is another example.

I actually think the future may be a lot more simple than we're making it out to be. With some slight modifications to design, we could run existing turbofans on liquid hydrogen fuel. The biggest objection that most people have is the storage of hydrogen...but liquid hydrogen doesn't actually need to be stored in cryo tanks as long as the fuel is being used at faster rates than it evaporates. That's not a problem with jet engine consumption rates...low tech insulation may be sufficient.

Electrical motors would solve this; if we'd be able to avoid dispersing water from fuel cells up high, that could work.

LH2 has storage - and safety - issues still not solved. Toyota Mirai approaches it from a different angle, with some other shortcomings.

[0] https://en.wikipedia.org/wiki/Airship

[1] https://www.sciencealert.com/this-gigantic-chinese-airship-f...

I think hybrid would be a great compromise. Short range jets spend a lot of kerosene just during taxi and takeoff. If you could just do launch and climb on batteries and then replenish the batteries from a jet powered generator during cruise, that would already be huge in terms of not just CO2 but also ops cost.

1. DHC-2 takes 6 people 86 miles ~= 500person/miles

2. 747 potential battery payload ~= 200,000kg (fuel capacity)

3. Power capacity of 200,000kg lithium-in ~= 25MW hours

4. Power required to take off, assuming 2.5 minutes to reach cruising altitude ~= 90MW * 2.5 / 60 ~= 4MWh

5. Power to cruise at about 600mph ~= 1/4 power to take off = 22MW (waves hand)

6. Time available to cruise ~= 1hr

7. Distance cruised ~= 600miles

8. Electric 747 takes 600 people 600 miles = 360,000person/miles

Maybe the power to cruise is 1/2 of power to take off, they'd still get 120,000person/miles.

Also, the weight on landing is critical not on takeoff, and you can't exactly shed battery weight because empty batteries weigh roughly the same as full ones do, so you will need to take maximum landing weight into account.

Finally, you need to take reserve fuel into account, alternates and headwinds.

I think you should re-do these numbers with more realistic inputs.

Fuel is a major expense for commercial airlines, they don't burn it just for shits and giggles. Airplanes use fuel when landing because destroyed aircraft and piles of corpses will quickly cost more than any fuel they'd save by trying to glide every plane to the ground.

What electrical flight will do initially is enable the 5$ hamburger flight and create that market. Same distance, same speed, fraction of the cost. GA is currently prohibitively expensive mainly because of fuel. Operating that kind of flights commercially offers similar advantages though you still have to account for the pilots.

And while pilot cost is a factor, their availability is a much bigger problem. There simply aren't enough of them to operate the tens of thousands of mass produced electrical planes that on paper could out compete commuter jets on cost, scale, noise, flexibility, ability to land just about anywhere, etc.

The solution to that is self flying planes, aka. drones. This will likely happen long before we train up hundreds of thousands of new pilots. Like self driving cars there are challenges for this and like self driving cars those challenges are increasingly of a legal rather than a technical nature. It's technically feasible but getting permission to actually start doing this will take time and is happening very slowly despite e.g. Waymo 'drivers' actually needing to touch their controls is now becoming a once every few tens of thousands of miles kind of thing.

The list price for the Eviation Alice (projected to hit the market in 3-5 years) is around 3M and flies 9 passengers. The list price for an A319 is around 90M and flies about up to 160 passengers. So, ballpark it's not unthinkable to fly similar amounts of people using 20-30 mass produced self flying electrical planes competing on most 1-2 hour hops that these jets are typically used for. That will take decades to happen but it is entirely feasible with today's level of technology.

Small planes are not fundamentally hard. Cessna nailed mass production decades ago and electrical planes are vastly simpler (way less moving or combustible parts) And as Tesla and other battery manufacturers are showing, there's nothing fundamentally hard about producing a few hundred kwh of battery at a reasonable weight. A small plane with 500-1000khwh of battery will have a very usable range. With increasing energy densities, that will eventually extend into longer ranges as well. The Eviation Alice manages close to 600 miles on 900 kwh of what is essentially similar to the current energy density of mass produced EVs i.e. hardly the state of the art in battery tech. They are holding back here to get this thing certified ASAP instead of opting for already existing newer battery tech.

The impressive thing about this particular announcement is that it is a cost effective conversion for planes that are 60+ years old with a very well understood mission, which is very short hops. The reason that is economical is because combustion engine economics for that are so spectacularly bad and always have been. Electric flight is going to kill that market first and very soon because it hardly was a market to begin with. Small electrical planes crossing the Atlantic is going to happen at some point in the next decade or so. From there to that becoming a routine thing will take more time. But once that happens, it's likely to challenge the economics of dong the same in a 747. There's no fundamental need to scale electrical planes to that size even though that will probably eventually actually happen as well; but that will indeed require decades of improvements in energy density in batteries.

The only questions around electrical flight is when, not if.

Like High speed rail

Assuming you mean turbofan vs. turboprop here, since both of these are turbine-driven.

In either case, my understanding is that turboprops don't present a substantial gain in efficiency, as turbofans allow for higher and faster cruising altitude, which reduces drag on the airframe.

I just read your message as, “Can’t be done yet, will most likely be done somehow in the near future”.

Scaling up on range is different, but just scaling size/passenger count I would think would be easier.