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It’s just a question of the energy density of batteries vs. fuel. We need a couple more battery breakthroughs before we get a fully electric commercial airliner

It’s just a question of the energy density of batteries vs. fuel. We need a couple more battery breakthroughs before we get a fully electric commercial airliner.

Shivetya 9y ago
pretty much what many in motorcycling are waiting to see happen. a hundred and at most hundred fifty but that requires judicious use of acceleration and speed. cars and trucks can carry the mass but if anything screams "this tech isn't there yet" it is the weight to range ratio we have now in cars. yeah we can build them but looking back twenty years from now should be really interesting
- mattnewton 9y ago
  We’re getting there with motorcycles too- they are expensive but starting to get useable ranges with today’s battery tech: http://www.zeromotorcycles.com/range/ http://www.zeromotorcycles.com/range/ Plus, they sound like pod racers from the future.
mpweiher 9y ago
> energy density of batteries vs. fuel For short-haul flights, this matters a lot less.
knolan 9y ago
You also expel all that burnt fuel reducing weight was you fly. Some aircraft even redistribute fuel between tanks to control stability and performance. [0] [0] https://www.amevoice.com/blog/1058/airbus-a340-fuel-system-distribution-briefing/ https://www.amevoice.com/blog/1058/airbus-a340-fuel-system-d...
- skookumchuck 9y ago
  > Some aircraft even redistribute fuel between tanks to control stability and performance. Aircraft have been doing that forever. Carefully managing the fuel flow from which tank has always been a task for the pilot.
- skookumchuck 9y ago
  A large gas tank was added behind the pilot's seat in the P-51 to extend its range. But it unbalanced the airplane, and made it difficult to fly. Pilots always drained it first. The Luftwaffe never figured out that they could have trashed the P-51s if they caught them early enough. These days, that tank has been replaced by a passenger seat so you can get a joyride on a P51.
  - Merad 9y ago
    Actually the aux tank wasn't added to the Mustang purely for range. A big factor was helping to balance out the heavier Merlin engine. Pilots would typically leave about 1/3 of the tank to keep ideal balance and have an emergency fuel reserve. Typically by the time they had taken off and made the climb to altitude they had burned enough fuel from the aux tank (about half) to be in reasonable "fighting trim". Would've been pretty audacious for the Luftwaffe to try intercepting them that early in the mission, well within the range of every other USAAF and RAF fighter.
    - skookumchuck 9y ago
      Interesting. I was told this by a former P51 pilot. He also said sometimes lone Ju-88s would sneak in at low altitude and pick off B-17s taking off or landing when they thought they were safe.
      - Merad 9y ago
        I’m sure the Ju-88 thing probably happened. IIRC there were at least a couple instances of caputured B-17s trying to slip into formations and shoot at damaged bombers, and there were definitely a few cases of captured allied fighters being used on bombers.
GuB-42 9y ago
There is more than that. Planes become lighter as they burn fuel, batteries don't become lighter as they drain. Lighter planes are more efficient, and most airliners are not designed to land with their tanks full. They have a option to jettison their fuel in case of emergency. It means that just matching the energy density of fuel is not enough, batteries must exceed it. Jet engines are also quite efficient: around 40% now, and it may reach up to 60% in the future. It means that the more efficient electric engine is less of an advantage compared to cars for example. The only battery technology that seems viable in order to replace fuel would be lithium-air. Petrol is just too good at storing energy. Right now, I'd say the only chance for a "zero-emission" plane would be using biofuels.
- dragonwriter 9y ago
  > There is more than that. Planes become lighter as they burn fuel, batteries don't become lighter as they drain. Flow batteries can and open cycle fuel cells do; electric isn't just the kind of batteries that retain reaction products.
  - hcknwscommenter 9y ago
    I get the fuel cell concept: fuel (H2) and oxygen combine to make water, which is thrown overboard. But, I don't see how this pertains to flow batteries. Generally, the flow battery material (e.g. vanadium oxide) is highly toxic and/or reactive. Do you propose sending that type of material overboard?
- skookumchuck 9y ago
  > batteries don't become lighter as they drain. Right, but they can be thrown overboard :-)
  - dotancohen 9y ago
    > Right, but they can be thrown overboard That might work for disposable rockets launched from the south Pacific, but it does not work for a reusable aircraft flying over populated continents.
rsynnott 9y ago
Short high-traffic routes might be viable sooner. For instance, the Dublin-London route has 14,500 flights per year (highest in Europe), crossing about 400km. Mostly 737-sized planes, flying a tiny fraction of their full range. There are a number of similarly short/frequent routes in Asia. A specialized electric plane for this type of route would save a lot of CO2 emissions, and could come long before p, say, viable transatlantic electric planes.
greglindahl 9y ago
So you're boldly predicting that you can't even build a short-range electric plane. Which is what everyone's trying to do. Your criticism is similar to what many people said about electric cars and electric trucks. Well, surprise, commercial short-range cars and trucks became viable before longer-range cars and trucks.

It’s just a question of the energy density of batteries vs. fuel. We need a couple more battery breakthroughs before we get a fully electric commercial airliner.

Shivetya 9y ago

pretty much what many in motorcycling are waiting to see happen. a hundred and at most hundred fifty but that requires judicious use of acceleration and speed. cars and trucks can carry the mass but if anything screams "this tech isn't there yet" it is the weight to range ratio we have now in cars. yeah we can build them but looking back twenty years from now should be really interesting

mattnewton 9y ago
We’re getting there with motorcycles too- they are expensive but starting to get useable ranges with today’s battery tech: http://www.zeromotorcycles.com/range/ http://www.zeromotorcycles.com/range/ Plus, they sound like pod racers from the future.

mpweiher 9y ago

> energy density of batteries vs. fuel For short-haul flights, this matters a lot less.

knolan 9y ago

You also expel all that burnt fuel reducing weight was you fly. Some aircraft even redistribute fuel between tanks to control stability and performance. [0] [0] https://www.amevoice.com/blog/1058/airbus-a340-fuel-system-distribution-briefing/ https://www.amevoice.com/blog/1058/airbus-a340-fuel-system-d...

skookumchuck 9y ago
> Some aircraft even redistribute fuel between tanks to control stability and performance. Aircraft have been doing that forever. Carefully managing the fuel flow from which tank has always been a task for the pilot.
skookumchuck 9y ago
A large gas tank was added behind the pilot's seat in the P-51 to extend its range. But it unbalanced the airplane, and made it difficult to fly. Pilots always drained it first. The Luftwaffe never figured out that they could have trashed the P-51s if they caught them early enough. These days, that tank has been replaced by a passenger seat so you can get a joyride on a P51.
- Merad 9y ago
  Actually the aux tank wasn't added to the Mustang purely for range. A big factor was helping to balance out the heavier Merlin engine. Pilots would typically leave about 1/3 of the tank to keep ideal balance and have an emergency fuel reserve. Typically by the time they had taken off and made the climb to altitude they had burned enough fuel from the aux tank (about half) to be in reasonable "fighting trim". Would've been pretty audacious for the Luftwaffe to try intercepting them that early in the mission, well within the range of every other USAAF and RAF fighter.
  - skookumchuck 9y ago
    Interesting. I was told this by a former P51 pilot. He also said sometimes lone Ju-88s would sneak in at low altitude and pick off B-17s taking off or landing when they thought they were safe.
    - Merad 9y ago
      I’m sure the Ju-88 thing probably happened. IIRC there were at least a couple instances of caputured B-17s trying to slip into formations and shoot at damaged bombers, and there were definitely a few cases of captured allied fighters being used on bombers.

GuB-42 9y ago

There is more than that. Planes become lighter as they burn fuel, batteries don't become lighter as they drain. Lighter planes are more efficient, and most airliners are not designed to land with their tanks full. They have a option to jettison their fuel in case of emergency. It means that just matching the energy density of fuel is not enough, batteries must exceed it. Jet engines are also quite efficient: around 40% now, and it may reach up to 60% in the future. It means that the more efficient electric engine is less of an advantage compared to cars for example. The only battery technology that seems viable in order to replace fuel would be lithium-air. Petrol is just too good at storing energy. Right now, I'd say the only chance for a "zero-emission" plane would be using biofuels.

dragonwriter 9y ago
> There is more than that. Planes become lighter as they burn fuel, batteries don't become lighter as they drain. Flow batteries can and open cycle fuel cells do; electric isn't just the kind of batteries that retain reaction products.
- hcknwscommenter 9y ago
  I get the fuel cell concept: fuel (H2) and oxygen combine to make water, which is thrown overboard. But, I don't see how this pertains to flow batteries. Generally, the flow battery material (e.g. vanadium oxide) is highly toxic and/or reactive. Do you propose sending that type of material overboard?
skookumchuck 9y ago
> batteries don't become lighter as they drain. Right, but they can be thrown overboard :-)
- dotancohen 9y ago
  > Right, but they can be thrown overboard That might work for disposable rockets launched from the south Pacific, but it does not work for a reusable aircraft flying over populated continents.

rsynnott 9y ago

Short high-traffic routes might be viable sooner. For instance, the Dublin-London route has 14,500 flights per year (highest in Europe), crossing about 400km. Mostly 737-sized planes, flying a tiny fraction of their full range. There are a number of similarly short/frequent routes in Asia. A specialized electric plane for this type of route would save a lot of CO2 emissions, and could come long before p, say, viable transatlantic electric planes.

greglindahl 9y ago

So you're boldly predicting that you can't even build a short-range electric plane. Which is what everyone's trying to do. Your criticism is similar to what many people said about electric cars and electric trucks. Well, surprise, commercial short-range cars and trucks became viable before longer-range cars and trucks.