7 ms·

This is a great set of charts and analysis, although I have two problems with it. 1. On the chart of energy density, I'd like to see the the energy density of

This is a great set of charts and analysis, although I have two problems with it. 1. On the chart of energy density, I'd like to see the the energy density of petrol for comparison. It's much higher, and even though extrapolation is dangerous, I'd like to see how long it could take to reach parity given some of the different forecasting models they mention. Specifically regarding their mention of air travel, I'd like to know what the minimum viable energy density would be for a vessel's fuel source, because my current understanding is that commercial air travel powered by electricity is not feasible. 2. They mention S-curve adoption, but that reaches a horizontal asymptote eventually, it doesn't go up forever. I'd like to see more analysis on where we think we're at on the S-curve, and why. I'd like to see a guess on where it levels out displayed on that chart, instead of the arrow simply pointing at the sky. If nothing else, show where the chemical limit might be based on current battery technology. I want to displace fossil fuels and reduce pollution and slow the greenhouse effect as much as possible. I think transparency and realistic expectations need to be part of the transition. The more information available to markets, the more efficiently they can work towards the goal. I find it very difficult to get answers to these types of questions when discussing renewable energy generation and storage. I'm sure part of it is my own ignorance on where to look, which is why I ask: especially here, hopefully an expert can see this and quickly point me in the right direction.

thelastgallon 3y ago
> I'd like to see the the energy density of petrol for comparison. Petrol's higher energy density doesn't matter as much as people think. Electric vehicles are around four times as efficient as petrol. In a petrol car, only 20% of the energy is converted to motion. In electric cars, this is around 80% (with some variation dependent on regenerative braking). I wrote about this extensively in a previous article: https://www.sustainabilitybynumbers.com/p/electrification-energy-efficiency https://www.sustainabilitybynumbers.com/p/electrification-en...
- BobaFloutist 3y ago
  Ok, how about "effective energy density"?
- treflop 3y ago
  Batteries aren’t just used in cars man. Really hard to beat propane or diesel for heat in the wilderness right now.
  - vvern 3y ago
    “Heat in the wilderness” must be so small in terms of global emissions footprint to be almost irrelevant, no? The wilderness implies ultra low density sort of by definition.
  - crote 3y ago
    We don't have billions of people living in the wilderness. And technology has reached a price level where off-grid solar is actually an affordable and superior alternative to propane and diesel for household use in rural Africa.
    - amluto 3y ago
      Heat pump heat, in the wilderness or otherwise, is about 4x as efficient as resistance or fire. This is somewhat silly, since a gas-fired heat pump can be very efficient, but gas-fired heat pumps are quite rare. (California has a pricing/policy problem here, IMO. Electricity is absurdly expensive, gas is somewhat reasonable, and the result is that electric heating is not nearly as economical as it should be.)
      - semi-extrinsic 3y ago
        Gas-fired heat pumps are neither economical nor efficient for single-apartment or single-house systems. Internal combustion engines with shaft power output of 1-2 kW are inefficient, loud and maintenance intensive. They can start to make sense from around 50 kW heating/cooling capacity and upwards, so the smallest units are suitable for 8-15 apartments depending on size.
    - treflop 3y ago
      Yeah but the article is just about batteries and someone asked to see a graph about energy density. Plus they asked about airplanes and somehow you made it about cars.
- Veserv 3y ago
  That is not even comparing apples to oranges, that is comparing apples to steel. You are correct in that energy density does not matter very much for weight-insensitive generation such as grid-scale generation, but energy density matters for weight-constrained applications such as airplanes and rockets as the poster mentioned. However, assuming that the renewable generation cost curve continues to improve exponentially then the most likely outcome for a carbon-neutral or carbon-negative future will be using electricity to manufacture high density combustible fuels out of atmospheric carbon, effectively using it as a high density "battery" for use cases that demand high energy density. To the extent that your analysis is relevant to the concerns of the poster, all it means is that batterys are actually ~4x better than the raw energy density would indicate. As to the specifics, Wikipedia claims petrol is ~12,888 W*h/kg or ~24x the battery energy density in the article, so ~6x better with respect to car motion. Note that the current curve has only gone from ~100 W*h/kg to ~500 W*h/kg, so we would need to see density growth comparable to the last 30 years to happen again.
  - aswanson 3y ago
    What are the theoretical limits of electrical energy density?
    - alted 3y ago
      Excellent question! A sufficiently advanced battery can theoretically beat gasoline. Any given energy storage technology can store a maximum amount of energy in a fixed volume or mass. Behold one of my favorite plots: [1] From lowest to highest energy density: - springs, which use mechanical elastic potential energy, are kinda horrible - capacitors, which use electric permittivity, aren't great - next are both batteries and combusted fuels, which both use chemical reactions. - nuclear gets us another few orders of magnitude - finally, antimatter (E=mc^2) is a ways beyond that Both batteries and fuels rely on the energy difference between unreacted molecules, so their theoretical energy density is the same. Well, actually, fuels are burnt to create heat which is converted to energy, and this heat->energy conversion is fundamentally thermodynamically inefficient (only ~tens of percent), whereas batteries are the same sorts of reaction but much more controlled. A sufficiently clever battery, which moves atoms around to react in the right places at the right time, is thus more efficient and thus energy-dense than fuel. However, moving atoms around like this to make a more efficient battery is much more advanced nanotech than what we currently have. But it's theoretically possible. This is what biology does: us humans are powered by chemical storage (sugar/fat/glucose), which is used more efficiently than current batteries but without combustion. (lithium-ion is ~0.8 MJ/kg, glucose is ~16 MJ/kg, gasoline ~46 MJ/kg) [1] https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density
- slingnow 3y ago
  "Doesn't matter as much as people think" Doesn't matter for WHAT? You start out talking about energy density, and then cite some numbers regarding efficiency. What does one have to do with the other? You've done nothing to support your opening claim here.
  - _aavaa_ 3y ago
    "Energy" value of gasoline and "energy" value of a battery pack are measuring two very different things even though they are both units of energy. When you burn gas in an engine, the engine has a theoretical upper limit on its efficiency which is FAR below 100%, and electric vehicle does not. So saying that gasoline has an energy content of 115,000 BTU/gal doesn't mean much since you'll be lucky to see 30% of that be turned into useful work.
    - goodSteveramos 3y ago
      Well, acording to wikipedia gasoline has an energy density of 46.4 MJ/Kg and LiPo batteries have an energy density of 0.36–0.875 MJ/Kg. So if your electric drivetrain has a 100% efficiency and your gas drivetrain has a 30% efficiency then the gasoline car would be able to do 16 times more work per unit of fuel.
      - _aavaa_ 3y ago
        And yet, electric cars you can by today don’t have 1/16th the range of a gasoline car. So energy density is not enough.
        goodSteveramos 3y ago
        Not enough for what? The energy densities of both LiPo batteries and gasoline are enough to make a passenger vehicle with an acceptable range. For gasoline it is more than enough and for LiPo it’s barely enough.
        3y ago
- nerdbert 3y ago
  > In a petrol car, only 20% of the energy is converted to motion. In electric cars, this is around 80% How does it settle out when you take into account the significantly higher weight of EVs?
  - vel0city 3y ago
    By "significantly heavier" it is often a difference of a few hundred pounds on a few thousand pound vehicle. A 2L engine is about 400lbs, an automatic transmission is another 220lbs, 20 gallons of gas is 120 lbs, add another 100ish pounds for a much larger cooling system. So sure, the battery is like 1,000lbs but you traded 840 pounds for 200 pounds of EV motors (assuming two of them!) so in reality you're up like 360lbs. Combined with regenerative braking, it doesn't make that big of difference in total energy usage. A massive chunk of the energy used in an EV is aero drag which makes little difference about weight. Weight makes a bigger impact with stop and go traffic on non-regen cars as slowing down that extra mass turns more energy into heat. An object in motion wants to stay in motion and all, once you're up to speed you're using about the same energy. This is why a lot of the EV trucks have close to the same range if the bed is full or not assuming it has the cover on the bed, but towing even a small trailer becomes a massive range hit. I get on average 3.5mi/kWh in my EV, ~1MJ/mi. A gallon of gas is like 120 MJ, an average hybrid will get like 40mpg, so 3 MJ/mi being burned. You'd need to get like 120mpg to match my average efficiency of energy usage, and my EV isn't even that incredibly efficient of an EV.
- deleted 3y ago
  [deleted]
- drtgh 3y ago
  >Petrol's higher energy density doesn't matter as much as people think. When vehicles uphill, ramp, and fight with the increasing wind resistance due speed, it is needed a high torque for to motion. The petrol's energy density is translated in high torque, that the gearbox latter transforms progressively. In electric vehicles, generating high torque and cooling the overheated coils for to obtain such high torque drains the battery quickly, the range drops quickly. And for to increase the range, more weight is added (more batteries), that requires higher torque for motion, that requires more energy again, and so on. This is why the energy density it is important, in batteries are the watts hour per kilogram. As also it is important the number of cycles before such batteries start to drop energy density until to fail (to note the weight keeps being the same along all of this degradation). With the current technology, due the magnetic fields strength generated in the coils, and the energy density of the batteries, EVs just can not compete with petrol vehicles. It is about torque, among other things. What is needed? batteries with bigger energy density ( higher Wh/Kg with higher number of recharge cycles), and/or higher efficiency generating magnetic fields of high strength (ambient superconductivity, also stronger magnets would help some coil's topologies).
  - deleted 3y ago
    [deleted]
  - XorNot 3y ago
    This is completely wrong: an ICE has 20-25% of the energy of petrol to use to do all those things. The rest is lost as heat.
    - drtgh 3y ago
      Regardless of theorical efficiency or not of the energy, in practice the ICE gets the torque needed by the vehicle for driving on all types of slopes (and speed, by transforming part of that high torque with the gearbox). This is why electric and combustion vehicles have such different ranges at even the same weight. Nowadays. Such high torque is needed at the same moment the vehicle doesn't circulate on a flat terrain, or when have to reach highway speeds. For to get at least the same ranges, the electric vehicle must reduce the energy consumption for the generation of the required torque (and speed), or needs to increase the energy density of the battery in companion of increasing the recharge cycles. will be possible to achieve this? of course. (The losses cooling or heating the battery and avoid the self-discharge should get the same advances, as it's counted as stored energy but it's not used for motion)
malfist 3y ago
Comparing energy density between batteries and oil is not "transparency and realistic expectations" Once the oil is used it's gone. Batteries can be recharged
- Spivak 3y ago
  That's not really their point, it's do we have any reasonable hope of applications that require the energy density of fossil fuels (flight) to be powered by electricity.
  - jeffbee 3y ago
    Flight will never be powered by electricity, so you can stop checking. Using synthetic liquid fuels for flight is the only currently-foreseeable path to carbon-neutral, long-haul passenger flight.
    - stcredzero 3y ago
      Flight will never be powered by electricity, so you can stop checking. Fuel cells could well enable 30X better power densities. That would count to me as flight powered by electricity. There's also beamed power. Perhaps this wouldn't be practical, but it's a thought experiment that shows there's nothing impossible from first principles for electrical powered flight.
    - PaulHoule 3y ago
      Long haul yes, but it's a little known story that regional airlines are on the edge of disaster because: (1) they can't find pilots, (2) manufacturers have stopped making the 50-seat jets that are the mainstay of that business. Airports like ITH are already at the top of the "regional development problems" in third-tier cities and it is not so clear they're going to be able to have service in 20 years the way things are going. Given that the status quo is "go out of business when old planes can't be maintained anymore" the possibility of some radical change like electrification or a change in the scope rules is increasingly likely.
Spinnaker_ 3y ago
The mention of air travel was strange. I wasn't aware of anyone who thought long range flight would ever be electrified. At least not without some fundamental breakthrough. S-curves are hard to predict. Basically every time someone attempts to do it, they are way off. This [0] is a neat paper that addresses the question. We've blown past every single prediction. [0] https://www.inet.ox.ac.uk/files/energy_transition_paper-INET-working-paper.pdf https://www.inet.ox.ac.uk/files/energy_transition_paper-INET...
- NotSammyHagar 3y ago
  There are some very early stage tests, there is some kind of island hopper electric airplane that flys regular service, and it's only like 5 or 10 miles across water. Batteries will get more energy dense, the range will increase a bit. But yeah, it's hard to see it getting to a few 100 miles.
  - KolmogorovComp 3y ago
    Hello, do you have a link or name?
    - schiffern 3y ago
      Here's the link, but the range isn't as bad as they said. https://www.prnewswire.com/news-releases/eviation-announces-first-commercial-customer-cape-air-for-its-all-electric-airplane-alice-300870249.html https://www.prnewswire.com/news-releases/eviation-announces-... https://en.wikipedia.org/wiki/Eviation_Alice https://en.wikipedia.org/wiki/Eviation_Alice https://en.wikipedia.org/wiki/Cape_Air https://en.wikipedia.org/wiki/Cape_Air
    - kccqzy 3y ago
      There's also an electric "flying water taxi" https://sfstandard.com/2024/01/18/san-francisco-navier-electric-water-taxi-sfo/ https://sfstandard.com/2024/01/18/san-francisco-navier-elect...
  - pramsey 3y ago
Phenomenit 3y ago
2. If batteries are growing exponentially right now then we are in the beginning of the S curve.
simonebrunozzi 3y ago
#1: certainly decades. Probably several, not few, decades. Unless a BIG breakthrough happens.
tonymet 3y ago
Lithium Battery 0.5 kWh/kg Diesel 12.7 kWh/kg
- api 3y ago
  Diesel is more like 3.175 (25%) due to the inefficiencies of small heat engines. You're throwing away like 3/4 of the energy as waste heat. Electric motors are >95% efficient and lithium batteries are in the high-90s percent efficient. Electricity is already low-entropy, whereas energy from burning petrol is high entropy and thus contains less useful work.
  - wizardwes 3y ago
    Also, a kilo of diesel can emit that energy once. A kilo of battery can emit that energy hundreds or even thousands of times
  - tonymet 3y ago
    it's not waste half the year
    - api 3y ago
      True if you are cogenerating, but few people do that. Only a miniscule fraction of waste heat from a car engine is required to heat a car. Tangent but: I've always wondered why home cogeneration never took off. Too bad we don't have gas water heaters and gas furnaces that generate electricity and dump the excess onto the grid and heat with the waste heat. Even a low-efficiency thermoelectric generator would recover some useful energy that is otherwise kind of wasted.
    - nerdbert 3y ago
      It's still waste, because if you're in a fixed location (which you'd have to be in order to benefit from much of the heat) you'd be better off running a heat pump.
  - pkolaczk 3y ago
    Diesel has efficiency of 40% not 25%.

thelastgallon 3y ago

> I'd like to see the the energy density of petrol for comparison. Petrol's higher energy density doesn't matter as much as people think. Electric vehicles are around four times as efficient as petrol. In a petrol car, only 20% of the energy is converted to motion. In electric cars, this is around 80% (with some variation dependent on regenerative braking). I wrote about this extensively in a previous article: https://www.sustainabilitybynumbers.com/p/electrification-energy-efficiency https://www.sustainabilitybynumbers.com/p/electrification-en...

BobaFloutist 3y ago
Ok, how about "effective energy density"?
treflop 3y ago
Batteries aren’t just used in cars man. Really hard to beat propane or diesel for heat in the wilderness right now.
- vvern 3y ago
  “Heat in the wilderness” must be so small in terms of global emissions footprint to be almost irrelevant, no? The wilderness implies ultra low density sort of by definition.
- crote 3y ago
  We don't have billions of people living in the wilderness. And technology has reached a price level where off-grid solar is actually an affordable and superior alternative to propane and diesel for household use in rural Africa.
  - amluto 3y ago
    Heat pump heat, in the wilderness or otherwise, is about 4x as efficient as resistance or fire. This is somewhat silly, since a gas-fired heat pump can be very efficient, but gas-fired heat pumps are quite rare. (California has a pricing/policy problem here, IMO. Electricity is absurdly expensive, gas is somewhat reasonable, and the result is that electric heating is not nearly as economical as it should be.)
    - semi-extrinsic 3y ago
      Gas-fired heat pumps are neither economical nor efficient for single-apartment or single-house systems. Internal combustion engines with shaft power output of 1-2 kW are inefficient, loud and maintenance intensive. They can start to make sense from around 50 kW heating/cooling capacity and upwards, so the smallest units are suitable for 8-15 apartments depending on size.
  - treflop 3y ago
    Yeah but the article is just about batteries and someone asked to see a graph about energy density. Plus they asked about airplanes and somehow you made it about cars.
Veserv 3y ago
That is not even comparing apples to oranges, that is comparing apples to steel. You are correct in that energy density does not matter very much for weight-insensitive generation such as grid-scale generation, but energy density matters for weight-constrained applications such as airplanes and rockets as the poster mentioned. However, assuming that the renewable generation cost curve continues to improve exponentially then the most likely outcome for a carbon-neutral or carbon-negative future will be using electricity to manufacture high density combustible fuels out of atmospheric carbon, effectively using it as a high density "battery" for use cases that demand high energy density. To the extent that your analysis is relevant to the concerns of the poster, all it means is that batterys are actually ~4x better than the raw energy density would indicate. As to the specifics, Wikipedia claims petrol is ~12,888 W*h/kg or ~24x the battery energy density in the article, so ~6x better with respect to car motion. Note that the current curve has only gone from ~100 W*h/kg to ~500 W*h/kg, so we would need to see density growth comparable to the last 30 years to happen again.
- aswanson 3y ago
  What are the theoretical limits of electrical energy density?
  - alted 3y ago
    Excellent question! A sufficiently advanced battery can theoretically beat gasoline. Any given energy storage technology can store a maximum amount of energy in a fixed volume or mass. Behold one of my favorite plots: [1] From lowest to highest energy density: - springs, which use mechanical elastic potential energy, are kinda horrible - capacitors, which use electric permittivity, aren't great - next are both batteries and combusted fuels, which both use chemical reactions. - nuclear gets us another few orders of magnitude - finally, antimatter (E=mc^2) is a ways beyond that Both batteries and fuels rely on the energy difference between unreacted molecules, so their theoretical energy density is the same. Well, actually, fuels are burnt to create heat which is converted to energy, and this heat->energy conversion is fundamentally thermodynamically inefficient (only ~tens of percent), whereas batteries are the same sorts of reaction but much more controlled. A sufficiently clever battery, which moves atoms around to react in the right places at the right time, is thus more efficient and thus energy-dense than fuel. However, moving atoms around like this to make a more efficient battery is much more advanced nanotech than what we currently have. But it's theoretically possible. This is what biology does: us humans are powered by chemical storage (sugar/fat/glucose), which is used more efficiently than current batteries but without combustion. (lithium-ion is ~0.8 MJ/kg, glucose is ~16 MJ/kg, gasoline ~46 MJ/kg) [1] https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density
slingnow 3y ago
"Doesn't matter as much as people think" Doesn't matter for WHAT? You start out talking about energy density, and then cite some numbers regarding efficiency. What does one have to do with the other? You've done nothing to support your opening claim here.
- _aavaa_ 3y ago
  "Energy" value of gasoline and "energy" value of a battery pack are measuring two very different things even though they are both units of energy. When you burn gas in an engine, the engine has a theoretical upper limit on its efficiency which is FAR below 100%, and electric vehicle does not. So saying that gasoline has an energy content of 115,000 BTU/gal doesn't mean much since you'll be lucky to see 30% of that be turned into useful work.
  - goodSteveramos 3y ago
    Well, acording to wikipedia gasoline has an energy density of 46.4 MJ/Kg and LiPo batteries have an energy density of 0.36–0.875 MJ/Kg. So if your electric drivetrain has a 100% efficiency and your gas drivetrain has a 30% efficiency then the gasoline car would be able to do 16 times more work per unit of fuel.
    - _aavaa_ 3y ago
      And yet, electric cars you can by today don’t have 1/16th the range of a gasoline car. So energy density is not enough.
      - goodSteveramos 3y ago
        Not enough for what? The energy densities of both LiPo batteries and gasoline are enough to make a passenger vehicle with an acceptable range. For gasoline it is more than enough and for LiPo it’s barely enough.
        3y ago
nerdbert 3y ago
> In a petrol car, only 20% of the energy is converted to motion. In electric cars, this is around 80% How does it settle out when you take into account the significantly higher weight of EVs?
- vel0city 3y ago
  By "significantly heavier" it is often a difference of a few hundred pounds on a few thousand pound vehicle. A 2L engine is about 400lbs, an automatic transmission is another 220lbs, 20 gallons of gas is 120 lbs, add another 100ish pounds for a much larger cooling system. So sure, the battery is like 1,000lbs but you traded 840 pounds for 200 pounds of EV motors (assuming two of them!) so in reality you're up like 360lbs. Combined with regenerative braking, it doesn't make that big of difference in total energy usage. A massive chunk of the energy used in an EV is aero drag which makes little difference about weight. Weight makes a bigger impact with stop and go traffic on non-regen cars as slowing down that extra mass turns more energy into heat. An object in motion wants to stay in motion and all, once you're up to speed you're using about the same energy. This is why a lot of the EV trucks have close to the same range if the bed is full or not assuming it has the cover on the bed, but towing even a small trailer becomes a massive range hit. I get on average 3.5mi/kWh in my EV, ~1MJ/mi. A gallon of gas is like 120 MJ, an average hybrid will get like 40mpg, so 3 MJ/mi being burned. You'd need to get like 120mpg to match my average efficiency of energy usage, and my EV isn't even that incredibly efficient of an EV.
deleted 3y ago
[deleted]
drtgh 3y ago
>Petrol's higher energy density doesn't matter as much as people think. When vehicles uphill, ramp, and fight with the increasing wind resistance due speed, it is needed a high torque for to motion. The petrol's energy density is translated in high torque, that the gearbox latter transforms progressively. In electric vehicles, generating high torque and cooling the overheated coils for to obtain such high torque drains the battery quickly, the range drops quickly. And for to increase the range, more weight is added (more batteries), that requires higher torque for motion, that requires more energy again, and so on. This is why the energy density it is important, in batteries are the watts hour per kilogram. As also it is important the number of cycles before such batteries start to drop energy density until to fail (to note the weight keeps being the same along all of this degradation). With the current technology, due the magnetic fields strength generated in the coils, and the energy density of the batteries, EVs just can not compete with petrol vehicles. It is about torque, among other things. What is needed? batteries with bigger energy density ( higher Wh/Kg with higher number of recharge cycles), and/or higher efficiency generating magnetic fields of high strength (ambient superconductivity, also stronger magnets would help some coil's topologies).
- deleted 3y ago
  [deleted]
- XorNot 3y ago
  This is completely wrong: an ICE has 20-25% of the energy of petrol to use to do all those things. The rest is lost as heat.
  - drtgh 3y ago
    Regardless of theorical efficiency or not of the energy, in practice the ICE gets the torque needed by the vehicle for driving on all types of slopes (and speed, by transforming part of that high torque with the gearbox). This is why electric and combustion vehicles have such different ranges at even the same weight. Nowadays. Such high torque is needed at the same moment the vehicle doesn't circulate on a flat terrain, or when have to reach highway speeds. For to get at least the same ranges, the electric vehicle must reduce the energy consumption for the generation of the required torque (and speed), or needs to increase the energy density of the battery in companion of increasing the recharge cycles. will be possible to achieve this? of course. (The losses cooling or heating the battery and avoid the self-discharge should get the same advances, as it's counted as stored energy but it's not used for motion)

malfist 3y ago

Comparing energy density between batteries and oil is not "transparency and realistic expectations" Once the oil is used it's gone. Batteries can be recharged

Spivak 3y ago
That's not really their point, it's do we have any reasonable hope of applications that require the energy density of fossil fuels (flight) to be powered by electricity.
- jeffbee 3y ago
  Flight will never be powered by electricity, so you can stop checking. Using synthetic liquid fuels for flight is the only currently-foreseeable path to carbon-neutral, long-haul passenger flight.
  - stcredzero 3y ago
    Flight will never be powered by electricity, so you can stop checking. Fuel cells could well enable 30X better power densities. That would count to me as flight powered by electricity. There's also beamed power. Perhaps this wouldn't be practical, but it's a thought experiment that shows there's nothing impossible from first principles for electrical powered flight.
  - PaulHoule 3y ago
    Long haul yes, but it's a little known story that regional airlines are on the edge of disaster because: (1) they can't find pilots, (2) manufacturers have stopped making the 50-seat jets that are the mainstay of that business. Airports like ITH are already at the top of the "regional development problems" in third-tier cities and it is not so clear they're going to be able to have service in 20 years the way things are going. Given that the status quo is "go out of business when old planes can't be maintained anymore" the possibility of some radical change like electrification or a change in the scope rules is increasingly likely.

Spinnaker_ 3y ago

The mention of air travel was strange. I wasn't aware of anyone who thought long range flight would ever be electrified. At least not without some fundamental breakthrough. S-curves are hard to predict. Basically every time someone attempts to do it, they are way off. This [0] is a neat paper that addresses the question. We've blown past every single prediction. [0] https://www.inet.ox.ac.uk/files/energy_transition_paper-INET-working-paper.pdf https://www.inet.ox.ac.uk/files/energy_transition_paper-INET...

NotSammyHagar 3y ago
There are some very early stage tests, there is some kind of island hopper electric airplane that flys regular service, and it's only like 5 or 10 miles across water. Batteries will get more energy dense, the range will increase a bit. But yeah, it's hard to see it getting to a few 100 miles.
- KolmogorovComp 3y ago
  Hello, do you have a link or name?
  - schiffern 3y ago
    Here's the link, but the range isn't as bad as they said. https://www.prnewswire.com/news-releases/eviation-announces-first-commercial-customer-cape-air-for-its-all-electric-airplane-alice-300870249.html https://www.prnewswire.com/news-releases/eviation-announces-... https://en.wikipedia.org/wiki/Eviation_Alice https://en.wikipedia.org/wiki/Eviation_Alice https://en.wikipedia.org/wiki/Cape_Air https://en.wikipedia.org/wiki/Cape_Air
  - kccqzy 3y ago
    There's also an electric "flying water taxi" https://sfstandard.com/2024/01/18/san-francisco-navier-electric-water-taxi-sfo/ https://sfstandard.com/2024/01/18/san-francisco-navier-elect...
- pramsey 3y ago

Phenomenit 3y ago

2. If batteries are growing exponentially right now then we are in the beginning of the S curve.

simonebrunozzi 3y ago

#1: certainly decades. Probably several, not few, decades. Unless a BIG breakthrough happens.

tonymet 3y ago

Lithium Battery 0.5 kWh/kg Diesel 12.7 kWh/kg

api 3y ago
Diesel is more like 3.175 (25%) due to the inefficiencies of small heat engines. You're throwing away like 3/4 of the energy as waste heat. Electric motors are >95% efficient and lithium batteries are in the high-90s percent efficient. Electricity is already low-entropy, whereas energy from burning petrol is high entropy and thus contains less useful work.
- wizardwes 3y ago
  Also, a kilo of diesel can emit that energy once. A kilo of battery can emit that energy hundreds or even thousands of times
- tonymet 3y ago
  it's not waste half the year
  - api 3y ago
    True if you are cogenerating, but few people do that. Only a miniscule fraction of waste heat from a car engine is required to heat a car. Tangent but: I've always wondered why home cogeneration never took off. Too bad we don't have gas water heaters and gas furnaces that generate electricity and dump the excess onto the grid and heat with the waste heat. Even a low-efficiency thermoelectric generator would recover some useful energy that is otherwise kind of wasted.
  - nerdbert 3y ago
    It's still waste, because if you're in a fixed location (which you'd have to be in order to benefit from much of the heat) you'd be better off running a heat pump.
- pkolaczk 3y ago
  Diesel has efficiency of 40% not 25%.