6 ms·

If this really represents (in general) the weight and efficiency you're going to get, then electric planes of this size will have to remain a specialized niche

If this really represents (in general) the weight and efficiency you're going to get, then electric planes of this size will have to remain a specialized niche for only certain kinds of rare flights. At 100 miles max range, the people would be better off driving, unless you're talking about mountainous or water-crossing flights where there is no alternative. (plus think about the added overhead of getting to/from airports, etc) You have to wonder why they chose a 208B -- when you would generally try for the smallest and lightest plane to start with. Answer: because they can't fit enough batteries in a smaller Cessna to get it to perform on a reasonable flight. The ideas elsewhere in the thread about having electric planes lower the cost of training flights, etc. won't work if you need a bus sized plane to hold the batteries. The plane has to be half empty, and even then can only eke out 100 miles. That's like a half hour of flight. A $2-3M plane can only handle a 1 hour ~50% duty cycle, max? That's not gonna...fly. I'm not intending to sound discouraging, and it's an interesting demonstration, but fundamental energy density of battery chemistry is a bitch. Edit: why, for the love of god, would they include that ear-destroying audio with the showcase video clip?

arcticbull 6y ago
IMO this comment is pretty short-sighted. Gravimetric energy density of batteries tripled between 2010 and 2020 and in the same time period cost went down 87% [1]. By 2030, this plane could easily have a range of 300mi. [1] https://cleantechnica.com/2020/02/19/bloombergnef-lithium-ion-battery-cell-densities-have-almost-tripled-since-2010/ https://cleantechnica.com/2020/02/19/bloombergnef-lithium-io...
- jcampbell1 6y ago
  There is a physics problem with carrying both fuel and oxidizer and not dumping spent fuel into the atmosphere. I suppose one could use lithium air batteries and then land heavier than takeoff. The reason petroleum fuel works so well is because you scavenge 2/3 of the fuel from the air.
  - CrazyStat 6y ago
    This is an underappreciated factor, particularly for long-haul flights. For transatlantic/transpacific flights the fuel can be over a third of the total takeoff weight of a modern airliner. Burning that mass off as you go means you get more efficient the longer you've been flying. Even if/when batteries match the energy density of aviation fuel (appropriately adjusted for motor/engine efficiency), they will still be at a substantial disadvantage for long flights.
    - deleted 6y ago
      [deleted]
    - arcticbull 6y ago
      The efficiency is worse the further you go, because you have to burn extra fuel just to carry extra fuel the whole way, so that it be used for the incremental distance travelled. It's why the A340-500 flying gascan is such a disaster from a unit economics perspective. It's also why Emirates, Etihad and Qatar did such good business for so many years connecting east and west with a stop in the Gulf as compared to eastern and western carriers who had to go the whole distance without stopping.
      - CrazyStat 6y ago
        That's a different efficiency comparison. You are correct that for a given type of plane, efficiency is worse for father distances. When comparing battery vs. hydrocarbon-fueled planes, however, hydrocarbon does relatively better the longer the distance, for the reasons discussed above. Battery-powered planes may soon be practical for regional short-haul flights but they're not going to be competing on transatlantic routes anytime soon.
  - arcticbull 6y ago
    It's not a problem per se, but it is of course a factor. On the other hand, the thermal efficiency of driving an electric motor from a battery is ~99%. The thermal efficiency of jet and propeller planes is in the mid-30s.
- owenversteeg 6y ago
  I seem to remember being referred to as "that battery guy" here on HN, so here I am I guess. Unfortunately that is complete bullshit. (No offense intended to the Bloomberg suit.) Energy densities have absolutely -not- tripled since 2010, in fact they have barely changed. Costs have gone down, yes, but not by 87%. Cost-wise: a simple counterexample is to look at any smartphone BOM from 2010. Phone batteries around 10-12 Wh cost around $5. That's somewhere around $416-$500 per kWh. And that's for a phone battery, AKA not exactly the cheapest batteries out there, and not at massive scale (phone batteries are tiny in capacity and almost all 2010 smartphones sold in the single-digit millions max.) Currently, as Bloomberg claims, cheap batteries are around $160/kWh. So that'd be a change of around 61% cheaper. Around 0.4x the 2010 price instead of the outlandish claim of 0.13x the price. Keep in mind that this I'm just basing this off mobile phone BOMs cause I can't be bothered to find anything cheaper - there certainly were cheaper batteries then. Energy density wise, it's even more bullshit. TRIPLED? No, energy density has sat around 200 Wh/kg for approximately forever. (Off the top of my head, since at least 2009.) 200 Wh/kg batteries have been available to the -consumer- at not-insane prices for over a decade. In 2013, anyone - business or consumer - could purchase Panasonic cells at 224 Wh/kg. Today, the highest energy density anyone claims is around 240 Wh/kg from Tesla's 2170. Let's take that at face value and assume it is 240.0 Wh/kg; that's a 7% increase from 2013, and at best somewhere around a 15% increase from 2010. The sad reality is that batteries are extremely hard, and few things have changed aside from price. Hell, even the form factor, the 18650, was invented about three decades ago! Pretty much the only thing that has changed recently is that volumes have gone up massively, driving down costs with at-scale manufacturing. But that has happened in the vast majority of industries, and was entirely predictable. Furthermore, the cost decrease for batteries specifically hasn't been as fast as nearly everyone predicted. All the other magical headlines, about energy densities skyrocketing, or fancy new chemistries, or swappable packs, have been pure bullshit.
  - owenversteeg 6y ago
    I'm glad the above comment got some attention even buried here :) Another comment I'd like to make: Even with that increase, say 200 Wh/kg in 2010 to 240 in 2020, a lot of these higher-energy-density batteries are more expensive/easier to damage/have bigger heat management problems/etc. Keep in mind that is the raw cell weight. At 240 Wh/kg, you do not have any cooling, casing, wiring, BMS, safety systems - that is a plain cell in a vacuum. Once you've got all those goodies around the battery, even if you're best-in-class like Tesla your total energy density is around 150-160 Wh/kg. If you aren't making a luxury vehicle, you might end up around 80-90 Wh/kg (24kWh Nissan Leaf battery is in total 82 Wh/kg), and even if you do aim for something light and use fancy engineering you might end up around the 130 Wh/kg mark (2019 Audi e-Tron: 134 Wh/kg.) Batteries are hard.
baybal2 6y ago
Above all, the plane, and especially something like Caravan needs to be cheaaaap. Planes like DHC-3, C208, PC-12, An-2 are all utility aircraft above all. They are sold, and resold until they can't fly, and then they get cannibalised, rebuilt, and made to fly again, and when nothing would really be left of the plane, it will be sold to places like Africa, or Latin America. One of the biggest problem for makers of such aircrafts is the second hand market getting too big. There is zero demand for brand new An-2s, but the second hand market is surreally big. Same for DHC-3, Caravans, and Pilatuses seem to be joining that category too soon.
- redis_mlc 6y ago
  > Above all, the plane, and especially something like Caravan needs to be cheaaaap. Sorry, commercial aviation is an expensive game with no cheap options. - Cessna Caravan new $2.3 million - DC-3 Reman (Basler Turbine) $8 million, used (piston) $300-000 to $1 million (bargain in the cargo business) - C-130/L-100 new $70 million https://en.wikipedia.org/wiki/Basler_BT-67 https://en.wikipedia.org/wiki/Basler_BT-67 https://en.wikipedia.org/wiki/Cessna_208_Caravan https://en.wikipedia.org/wiki/Cessna_208_Caravan One derelict DC-3 was repaired from a hull to flyable using $85,000 in donations by Plane Savers using donated labor from a school, so that's about the price floor: https://www.youtube.com/watch?v=8haGfVvcS0I https://www.youtube.com/watch?v=8haGfVvcS0I The Basler Turbine DC-3 is a from-the-sheet-metal up reman, and the airframe is expected to last a total of 150 years. (Since the DC-3 is not pressurized, it has not lifetime age limit.)
coredog64 6y ago
I could see this working out for the skydiving niche market. They do lots of very short trips, and the space required to move around for the jump means the smaller seating capacity isn’t horrible.

arcticbull 6y ago

IMO this comment is pretty short-sighted. Gravimetric energy density of batteries tripled between 2010 and 2020 and in the same time period cost went down 87% [1]. By 2030, this plane could easily have a range of 300mi. [1] https://cleantechnica.com/2020/02/19/bloombergnef-lithium-ion-battery-cell-densities-have-almost-tripled-since-2010/ https://cleantechnica.com/2020/02/19/bloombergnef-lithium-io...

jcampbell1 6y ago
There is a physics problem with carrying both fuel and oxidizer and not dumping spent fuel into the atmosphere. I suppose one could use lithium air batteries and then land heavier than takeoff. The reason petroleum fuel works so well is because you scavenge 2/3 of the fuel from the air.
- CrazyStat 6y ago
  This is an underappreciated factor, particularly for long-haul flights. For transatlantic/transpacific flights the fuel can be over a third of the total takeoff weight of a modern airliner. Burning that mass off as you go means you get more efficient the longer you've been flying. Even if/when batteries match the energy density of aviation fuel (appropriately adjusted for motor/engine efficiency), they will still be at a substantial disadvantage for long flights.
  - deleted 6y ago
    [deleted]
  - arcticbull 6y ago
    The efficiency is worse the further you go, because you have to burn extra fuel just to carry extra fuel the whole way, so that it be used for the incremental distance travelled. It's why the A340-500 flying gascan is such a disaster from a unit economics perspective. It's also why Emirates, Etihad and Qatar did such good business for so many years connecting east and west with a stop in the Gulf as compared to eastern and western carriers who had to go the whole distance without stopping.
    - CrazyStat 6y ago
      That's a different efficiency comparison. You are correct that for a given type of plane, efficiency is worse for father distances. When comparing battery vs. hydrocarbon-fueled planes, however, hydrocarbon does relatively better the longer the distance, for the reasons discussed above. Battery-powered planes may soon be practical for regional short-haul flights but they're not going to be competing on transatlantic routes anytime soon.
- arcticbull 6y ago
  It's not a problem per se, but it is of course a factor. On the other hand, the thermal efficiency of driving an electric motor from a battery is ~99%. The thermal efficiency of jet and propeller planes is in the mid-30s.
owenversteeg 6y ago
I seem to remember being referred to as "that battery guy" here on HN, so here I am I guess. Unfortunately that is complete bullshit. (No offense intended to the Bloomberg suit.) Energy densities have absolutely -not- tripled since 2010, in fact they have barely changed. Costs have gone down, yes, but not by 87%. Cost-wise: a simple counterexample is to look at any smartphone BOM from 2010. Phone batteries around 10-12 Wh cost around $5. That's somewhere around $416-$500 per kWh. And that's for a phone battery, AKA not exactly the cheapest batteries out there, and not at massive scale (phone batteries are tiny in capacity and almost all 2010 smartphones sold in the single-digit millions max.) Currently, as Bloomberg claims, cheap batteries are around $160/kWh. So that'd be a change of around 61% cheaper. Around 0.4x the 2010 price instead of the outlandish claim of 0.13x the price. Keep in mind that this I'm just basing this off mobile phone BOMs cause I can't be bothered to find anything cheaper - there certainly were cheaper batteries then. Energy density wise, it's even more bullshit. TRIPLED? No, energy density has sat around 200 Wh/kg for approximately forever. (Off the top of my head, since at least 2009.) 200 Wh/kg batteries have been available to the -consumer- at not-insane prices for over a decade. In 2013, anyone - business or consumer - could purchase Panasonic cells at 224 Wh/kg. Today, the highest energy density anyone claims is around 240 Wh/kg from Tesla's 2170. Let's take that at face value and assume it is 240.0 Wh/kg; that's a 7% increase from 2013, and at best somewhere around a 15% increase from 2010. The sad reality is that batteries are extremely hard, and few things have changed aside from price. Hell, even the form factor, the 18650, was invented about three decades ago! Pretty much the only thing that has changed recently is that volumes have gone up massively, driving down costs with at-scale manufacturing. But that has happened in the vast majority of industries, and was entirely predictable. Furthermore, the cost decrease for batteries specifically hasn't been as fast as nearly everyone predicted. All the other magical headlines, about energy densities skyrocketing, or fancy new chemistries, or swappable packs, have been pure bullshit.
- owenversteeg 6y ago
  I'm glad the above comment got some attention even buried here :) Another comment I'd like to make: Even with that increase, say 200 Wh/kg in 2010 to 240 in 2020, a lot of these higher-energy-density batteries are more expensive/easier to damage/have bigger heat management problems/etc. Keep in mind that is the raw cell weight. At 240 Wh/kg, you do not have any cooling, casing, wiring, BMS, safety systems - that is a plain cell in a vacuum. Once you've got all those goodies around the battery, even if you're best-in-class like Tesla your total energy density is around 150-160 Wh/kg. If you aren't making a luxury vehicle, you might end up around 80-90 Wh/kg (24kWh Nissan Leaf battery is in total 82 Wh/kg), and even if you do aim for something light and use fancy engineering you might end up around the 130 Wh/kg mark (2019 Audi e-Tron: 134 Wh/kg.) Batteries are hard.

baybal2 6y ago

Above all, the plane, and especially something like Caravan needs to be cheaaaap. Planes like DHC-3, C208, PC-12, An-2 are all utility aircraft above all. They are sold, and resold until they can't fly, and then they get cannibalised, rebuilt, and made to fly again, and when nothing would really be left of the plane, it will be sold to places like Africa, or Latin America. One of the biggest problem for makers of such aircrafts is the second hand market getting too big. There is zero demand for brand new An-2s, but the second hand market is surreally big. Same for DHC-3, Caravans, and Pilatuses seem to be joining that category too soon.

redis_mlc 6y ago
> Above all, the plane, and especially something like Caravan needs to be cheaaaap. Sorry, commercial aviation is an expensive game with no cheap options. - Cessna Caravan new $2.3 million - DC-3 Reman (Basler Turbine) $8 million, used (piston) $300-000 to $1 million (bargain in the cargo business) - C-130/L-100 new $70 million https://en.wikipedia.org/wiki/Basler_BT-67 https://en.wikipedia.org/wiki/Basler_BT-67 https://en.wikipedia.org/wiki/Cessna_208_Caravan https://en.wikipedia.org/wiki/Cessna_208_Caravan One derelict DC-3 was repaired from a hull to flyable using $85,000 in donations by Plane Savers using donated labor from a school, so that's about the price floor: https://www.youtube.com/watch?v=8haGfVvcS0I https://www.youtube.com/watch?v=8haGfVvcS0I The Basler Turbine DC-3 is a from-the-sheet-metal up reman, and the airframe is expected to last a total of 150 years. (Since the DC-3 is not pressurized, it has not lifetime age limit.)

coredog64 6y ago

I could see this working out for the skydiving niche market. They do lots of very short trips, and the space required to move around for the jump means the smaller seating capacity isn’t horrible.