12 ms·

> Oxis recently developed a prototype lithium-sulfur pouch cell that proved capable of 470 Wh/kg, and we expect to reach 500 Wh/kg within a year. Meanwhile, ga

> Oxis recently developed a prototype lithium-sulfur pouch cell that proved capable of 470 Wh/kg, and we expect to reach 500 Wh/kg within a year. Meanwhile, gasoline / petrol / benzin (wherever you are in the world) has an energy density of 12200 Wh/kg. In other words, even in a world where all petroleum is perfectly depleted, we would still be producing synthetic gasoline for high-demand applications and capturing 100% of the emissions for recycling — essentially using gasoline as a battery. It’s just too good an energy storage to ignore. I’ve been looking at cars and geeking out on internal combustion engines for the past few weeks since I had to buy a car, and for the usual Silicon Valley guy such as yours truly whose standpoint on cars hadn’t been much more than ‘I want a Tesla’, it was an outright revelation. ICEs are real technology — and for a software guy it is easy to understand because the complexity is bounded by physical dimensions of parts (i.e they don’t work past a certain small size) so you literally see human-size machinery with human size movements. It’s been a refreshing change from potentially unbounded complexity of software.

jmercouris 6y ago
While energy density as an important measure when talking about a fuel source, we can not forget about the other part of the equation. Energy efficiency, of those units of energy in jet fuel, how much of it can we effectively utilize? In other words, what is the distance travelled for a given weight of jet fuel vs the distance travelled for a given weight of batteries.
tenuousemphasis 6y ago
>Meanwhile, gasoline / petrol / benzin (wherever your are in the world) has an energy density of 12200 Wh/kg. Electric motors are 90% efficient, ICE are less than 20%. So in reality gasoline is 2-3x as energy dense, when you look at how much of the fuel's energy can be used to do useful work.
- tengbretson 6y ago
  You also have to factor in the weight reduction as petroleum fuel is consumed vs the fixed weight of a battery.
  - Tuna-Fish 6y ago
    True, but the effect of this is less than it sounds like, as while the fuel is consumed, in an ICE car the engine is the heavy part and that isn't consumed.
    - klyrs 6y ago
      Don't discount this so easily. You can't land a jumbo jet immediately after takeoff because its maximum allowed landing weight is much less than its maximum allowed takeoff weight. So you'll need a stronger fuselage and landing gear for electric plans, which means even more weight
  - tenuousemphasis 6y ago
    Yes, that's true. And the cost of electricity vs. fuel. Safety is another factor. The point is there's a lot more to it than Wh/kg of the energy source.
  - outworlder 6y ago
    This is a huge deal for aircraft. Not much for cars, as EVs are not carrying a lot of extra baggage that ICE cars require. When was the last time you saw an ICE with both a trunk and a frunk? :)
    - throwaway189262 6y ago
      Modern gasoline engines are not as heavy as you may think. I once transported 2 liter car engine in the back seat of my civic. Only ~150 lb and quite manageable. Even monster SUV motors are only ~350 lbs. That doesn't include cooling, oil, accessories, or transmission but EV's have those too.
    - ScottBurson 6y ago
      > When was the last time you saw an ICE with both a trunk and a frunk? Seconds ago -- there's one in my carport :-) (A 1993 Toyota MR2; it's mid-engine. The frunk is small, and completely filled by the spare tire and aftermarket stereo amp.)
- throwaway189262 6y ago
  Electric vehicles have range problems in cold climates because you don't have waste heat. On a very cold day 60% of that waste heat might be used to warm the cabin. This translates to up to 50% range reduction in electric vehicles.
  - DarmokJalad1701 6y ago
    This is a myth. It is not nearly that bad. I own a Model 3 in a place where it is frequently below 30F in the winter. My last road trip when it was 17F throughout I consistently got around ~250-270 miles out of 310 rated range. The new hybrid heat-pump based system in the newer models makes it even more efficient.
    - throwaway189262 6y ago
      Isn't the range penalty a lot worse on short trips? When I was researching Leaf I noped out of buying one because range penalty in the cold for daily commutes was almost 50%
      - DarmokJalad1701 6y ago
        Depends on the generation of Leaf. The older ones had a big problem with thermal management. Teslas on the other hand has a cooling loop that takes in excess heat from the motor (in some cases, intentionally running the motor inefficiently to generate more heat), to "condition" the battery to the ideal temp. Ideally this is done while plugged in if for short trips. The car essentially stalls the motor with just enough current to generate heat. On long trips, the heat generated during the drive is enough to take care of this and the battery stays at the optimum temperature even if it is extremely cold outside.
    - hansvm 6y ago
      I'm not sure how much it would matter, but it's probably worth pointing out that 17F is nearly shorts weather in the middle of the brutally cold winters a lot of places experience.
phonon 6y ago
Electric motors are simpler, more reliable, smaller, lighter, almost perfectly efficient, and have better torque characteristics than ICE. You can't compare the energy storage density in isolation. Engines are heavy...Model S's motor generates 362 horsepower (according to the official specs), and only weighs 70 pounds...the equivalent ICE would be 500+ :-) (Yes, the inverter weighs something, but the transmission is much simpler as well for electric...overall you save a few hundred pounds easily...A Model 3 battery pack is between 600 and 1000 pounds--so pretty close to the crossover point.)
- outworlder 6y ago
  Forgot about that on my longer reply. EV engines are _tiny_ and incredibly efficient.
- Shivetya 6y ago
  However you are ignoring that while you can spin the blades more efficiently, however scaling an electric motor to that size may end up with even more weight, you also have to replace the turbojet portion of these motors. So you will need even more engine. That turbo jet is more efficient at speed while the fan is better at lower speed. In the end we would have slower planes but we will eventually reach a point where we can do it. Someone can probably explain it better and my understanding is rough and not current; jets were cool when I was kid
  - hwillis 6y ago
    Your speculation about motors is incorrect; motors are actually more efficient the larger you build them. It's a property of the goodness factor: https://en.wikipedia.org/wiki/Goodness_factor https://en.wikipedia.org/wiki/Goodness_factor It is profoundly foolish to compare motors and heat engines on first principles like this, obviously. Still, here's a turbine that handles 30x the power of a jet engine, running a generator that is about the same size as a jet engine: https://www.ge.com/news/sites/default/files/Reports/uploads/2019/01/25132345/P1000089.jpg https://www.ge.com/news/sites/default/files/Reports/uploads/... generator is in the upper left. Obviously not at all optimized for size or weight- there aren't even any magnets in that thing.
outworlder 6y ago
> Meanwhile, gasoline / petrol / benzin (wherever your are in the world) has an energy density of 12200 Wh/kg. Yeah, and yet, if you are talking about cars, you are bound by the Carnot efficiency, which is at most 35% no matter what(in reality more like 20% or so). Now gasoline goes to 4270 Wh/kg even assuming the best possible engine. That's without accounting for extraction, refining, transportation losses. Yes, still 10x more. However, you don't really need 10x, as electric motors are way more efficient (85 - 90%). The long range Tesla Model 3 only requires a 75kWh (72.5 usable) battery for a 450km (~279 miles). In other words, it uses 161 Wh/km . > ICEs are real technology So are EVs. For all the tech they tend to have, it boils down to: Battery and electric motor. There are some pretty reliable solid state electronics to monitor and deliver power, but that's all you really need(even the 'charger' is optional - and for quick charging, it's located outside the vehicle). You could theoretically use decades old technology to control the amount of power delivered to the motors - so you could see with your naked eye. And, in fact, we have done that! The first cars ever designed were electric, battery tech just wasn't there. It doesn't make sense to do that in this day and age, electronics driven by software work better. We would replace ICE engines with solid state components if it was possible. Now, for an ICE car, you have valves. You have a crankshaft, controlling said valves (and tied to pistons) - hundreds of moving parts right there. You have spark plugs (and a coil to generate the voltage). Air filters. You have an alternator (usually driven by a belt). You have water pumps (optional on EVs - and for the battery only, when they are used). You need fuel pumps. Fuel filters. Radiators (because of all the engine inefficiency). You need oil - and replace said oil, as well as the oil filter. You have an exhaust with a catalytic converter. Each one of those things may break and some are even consumables. So much crap EVs don't have. And you still have software and the tiny electronics you can't see with your eyes ! Unless, of course, you still use carburetors (which add a few hundred more parts each). EVs are much, much simpler. And more reliable, less parts and most of them don't move. The only thing that degrades is the battery. For now. I drive a Leaf, which is notorious for having no battery thermal management, and degradation is minimal.
- zkms 6y ago
  > you are bound by the Carnot efficiency, which is at most 35% no matter what(in reality more like 20% or so) Internal-combustion engines are not limited by the Carnot efficiency; see page 4 of these slides. In fact, latest-generation Priuses gets almost 40% thermal efficiency on the gasoline engine, and large diesel engines -- thanks to lean combustion (favorable ratio of specific heats for the gases that push on the piston), no throttling losses, higher compression ratio -- do even better. https://www.energy.gov/sites/prod/files/2014/03/f8/deer11_edwards.pdf https://www.energy.gov/sites/prod/files/2014/03/f8/deer11_ed...
petre 6y ago
True but gas turbines (not ICEs, those are mainly used on small aircraft) can reach a theoretical efficiency of 30% while electric motor efficiency of 92…93% is quite common. So you can multiply that number by 1/3 since 2/3 becomes heat.
- microcolonel 6y ago
  With turbofans and turbojets it gets a little harder as well, since unlike stationary turbine generators, not all "waste heat" is actually wasted, when considering thrust-specific fuel consumption.
DarmokJalad1701 6y ago
Sure. The average car gets 25 mpg, consuming ~1400 Wh/mi. A Tesla Model 3 uses ~240 Wh/mi. Thats almost a factor of 6 difference. You don't need quite as much energy when you are significantly more efficient and it is only getting more efficient as time goes on. Also add in the factor of recovering energy using regenerative braking which is impossible with ICE. With a car, unless you have a specific use-case where you are driving 200+ miles a day, an EV is a no-brainer when it comes to efficiency in operating cost as well as emissions and overall energy use.
- asdfadsfgfdda 6y ago
  A Model 3 is smaller than the average car, it should be compared to something like a Honda Accord hybrid. Both have a similar cabin volume of ~100 ft^3. The fuel economy for a hybrid Accord is 48 mpg, or 760 Wh/mile. The Accord is also $10k cheaper, presumably that is because the Model 3 requires more materials and more embodied energy.
  - mulmen 6y ago
    > The Accord is also $10k cheaper, presumably that is because the Model 3 requires more materials and more embodied energy. Do economies of scale and manufacturing expertise factor in to "embodied energy"?
- dmos62 6y ago
  What are the energy requirements and emissions for just building the vehicle? I've heard rumours that it's non-negligible when considering total emissions that a car will have caused.
  - 1958325146 6y ago
    Page 9 of https://www.tesla.com/ns_videos/2019-tesla-impact-report.pdf https://www.tesla.com/ns_videos/2019-tesla-impact-report.pdf has a chart for that (Average Lifecycle Emissions in New York State (gCO2e/mi)). Electric: 54 in manufacturing, 74 in use Gas: 45 in manufacturing, 420 in use
pixelbash 6y ago
> ICEs are real technology They are real technology, in the sense that this is where over 100 years of optimising every aspect of ICE has got us to. Fascinatingly complex, extremely well engineered, and depending on the brand still relatively likely to break down within the first few years. The engines are also longer designed to be maintained without special processes, and are increasingly designed around emission regulations. To the point where a lot of the complexity is in emission systems and the cars are choked by their own extremely lean fuel maps. Electric motors on the other hand are still relatively unoptimised and the potential in things like torque vectoring is amazing. I'll miss driving manual, but it's getting just about impossible to buy those now anyway.
- justapassenger 6y ago
  > Electric motors on the other hand are still relatively unoptimised Electric motors have huge applications across most industries for longer than combustion engines. Calling them unoptimized is quite a stretch. There're some car specific optimizations to be done, sure, but it's very mature technology, with little potential for breakthroughs.
  - pixelbash 6y ago
    Those applications generally haven't been focused on putting ridiculous horsepower in a tiny format and then running a highly variable load while dissipating heat. For example Axial flux motors are still very much being developed with a steady flow of breakthroughs (Magnax, Emrax), and have mind bending power to weight ratios. A lot of the current issues seem to be around heat dissipation, which is where I am hoping some of the next big wins are. I'm a bit sad that currently easily available motors are currently not in the same league as Tesla (I have a 50kw Me1616 and Sevcon 4 sitting on my bench) but it looks like that is slowly changing.
speedgoose 6y ago
I drive both ICE cars and electric cars and there is something about ICE engines in cars : they are very unresponsive compared to electric engines. They are fine at high RPMs, but you don't want to and shouldn't drive at high RPM. They have things such as turbo lag or really shitty torque curves. The gearboxes do not help as well. It's weird to wait half a second to get full power when you are used to the instant torque. You should test drive a random eletric car and a random ICE car.
- ramses0 6y ago
  If you have the opportunity, try comparing your ICE experience with a manual transmission ICE. Many modern ICE cars are effectively fly-by-wire with eco-junk-softwware in between the accelerator and engine. Manual transmissions would likely not have the lag that you're experiencing, but I definitely recognize what you're saying w.r.t. torque curves. I'm not challenging ICE v. Electric, but instead attempting to clarify that there is quite a wide variation in ICE-behavior that is less present in a manual transmission ICE car.
  - reubenswartz 6y ago
    Moving from a manual ICE to electric, it's still night and day. And the manual felt like night and day compared to a lot of automatics...
  - speedgoose 6y ago
    I own a ICE car with a manual gearbox. The lag is there. The engine needs time to find his torque at low RPM so you need to drop one or two gears if you want some power. Mine doesn't have a turbo, but when I drive manual cars with Turbo, the turbo lag is huge. A manual gearbox doesn't fix this problem. You may drop gears before you need the power, to overtake someone for example, because you plan ahead and want the full power, but that's slow. And even when I do it fast, I'm much much slower to manipulate the clutch and change gears compared to a modern automatic gearbox.
  - adrianN 6y ago
    I doubt that most people can operate a manual transmission significantly better than the "eco-junk software" that controls a modern automatic. Almost nobody is a race driver, but everybody can feel the nicer behavior of an electric engine.
woodandsteel 6y ago
Top-level ev's like the Model 3 are already superior for most drivers. The only problem is cost, and that is being fixed in the coming years through steadily falling battery prices. Other use cases like aviation and ocean boats are more difficult. It may well be that synfuels made with renewable energy will be the solution there.
nine_k 6y ago
ICEs are way heavy for their power. I agree that we will produce and burn synthetic fuel for flight long into the future. But this is going to burn in turbines for flying in atmosphere, and in rocket engines for getting to orbit.
jillesvangurp 6y ago
The only metric with planes that matters is $/mile. A soon as something flies far enough with enough payload, energy density stops being an issue. It doesn't matter that the plane is going to be four times the weight if it gets from A to B at a fraction of the cost. Think 100$ hamburgers turning into 5$ coffee runs because of vastly reduced fuel cost and maintenance cost. You see the same pattern with EVs. All of the cool ones are really heavy compared to the ICE cars they compete with. But they still go really fast and pretty far. So, you see much heavier Tesla's making formerly cool ICE sports cars look sluggish and outdated. And lets be honest, those never had any kind of fuel economy (or range) worth talking about because they burn fuel at obscene rates to get that speed. Being obscenely noisy and inefficient was kind of the point of owning one.
kumarvvr 6y ago
> 12200 Wh/kg Most ICE engines have efficiencies from 20 to 35%. Taking an average of 25% effciency, batteries have to essentially aim at about 3000 Wh / kg Most battery motor systems have a round trip efficiencies of about 80%, so to compete with ICE engines, EV systems have a target of about 4000 Wh/kg. edit : I also forgot to add about regenerative braking. For on road EV vehicles, regenerative braking can capture about 70% of the energy lost in braking. So, while a battery can store just 450 Wh/kg, averaged total energy, expended from the battery terminals, averaged over time, would have to be higher. It also makes sense to calculate the average total energy stored in the vehicle, rather than the energy densities of the fuels. For a 300 mile range, assuming an average 30 mpg fuel efficiency, you would need about 10 gallons, about 38 kg. So total stored energy in the vehicle in form of fuel, is 12200 * 38 = ~ 465 kWh. But, of this energy, only 25 % is converted to usable movement, i.e, about 118 kWh. However on a Model 3 LR, which has a range of 300 miles per charge, the battery capacity is 80 kWh (Tesla claims 75 kWh). So there is no basis to compare energy densities of various fuels directly.

jmercouris 6y ago

While energy density as an important measure when talking about a fuel source, we can not forget about the other part of the equation. Energy efficiency, of those units of energy in jet fuel, how much of it can we effectively utilize? In other words, what is the distance travelled for a given weight of jet fuel vs the distance travelled for a given weight of batteries.

tenuousemphasis 6y ago

>Meanwhile, gasoline / petrol / benzin (wherever your are in the world) has an energy density of 12200 Wh/kg. Electric motors are 90% efficient, ICE are less than 20%. So in reality gasoline is 2-3x as energy dense, when you look at how much of the fuel's energy can be used to do useful work.

tengbretson 6y ago
You also have to factor in the weight reduction as petroleum fuel is consumed vs the fixed weight of a battery.
- Tuna-Fish 6y ago
  True, but the effect of this is less than it sounds like, as while the fuel is consumed, in an ICE car the engine is the heavy part and that isn't consumed.
  - klyrs 6y ago
    Don't discount this so easily. You can't land a jumbo jet immediately after takeoff because its maximum allowed landing weight is much less than its maximum allowed takeoff weight. So you'll need a stronger fuselage and landing gear for electric plans, which means even more weight
- tenuousemphasis 6y ago
  Yes, that's true. And the cost of electricity vs. fuel. Safety is another factor. The point is there's a lot more to it than Wh/kg of the energy source.
- outworlder 6y ago
  This is a huge deal for aircraft. Not much for cars, as EVs are not carrying a lot of extra baggage that ICE cars require. When was the last time you saw an ICE with both a trunk and a frunk? :)
  - throwaway189262 6y ago
    Modern gasoline engines are not as heavy as you may think. I once transported 2 liter car engine in the back seat of my civic. Only ~150 lb and quite manageable. Even monster SUV motors are only ~350 lbs. That doesn't include cooling, oil, accessories, or transmission but EV's have those too.
  - ScottBurson 6y ago
    > When was the last time you saw an ICE with both a trunk and a frunk? Seconds ago -- there's one in my carport :-) (A 1993 Toyota MR2; it's mid-engine. The frunk is small, and completely filled by the spare tire and aftermarket stereo amp.)
throwaway189262 6y ago
Electric vehicles have range problems in cold climates because you don't have waste heat. On a very cold day 60% of that waste heat might be used to warm the cabin. This translates to up to 50% range reduction in electric vehicles.
- DarmokJalad1701 6y ago
  This is a myth. It is not nearly that bad. I own a Model 3 in a place where it is frequently below 30F in the winter. My last road trip when it was 17F throughout I consistently got around ~250-270 miles out of 310 rated range. The new hybrid heat-pump based system in the newer models makes it even more efficient.
  - throwaway189262 6y ago
    Isn't the range penalty a lot worse on short trips? When I was researching Leaf I noped out of buying one because range penalty in the cold for daily commutes was almost 50%
    - DarmokJalad1701 6y ago
      Depends on the generation of Leaf. The older ones had a big problem with thermal management. Teslas on the other hand has a cooling loop that takes in excess heat from the motor (in some cases, intentionally running the motor inefficiently to generate more heat), to "condition" the battery to the ideal temp. Ideally this is done while plugged in if for short trips. The car essentially stalls the motor with just enough current to generate heat. On long trips, the heat generated during the drive is enough to take care of this and the battery stays at the optimum temperature even if it is extremely cold outside.
  - hansvm 6y ago
    I'm not sure how much it would matter, but it's probably worth pointing out that 17F is nearly shorts weather in the middle of the brutally cold winters a lot of places experience.

phonon 6y ago

Electric motors are simpler, more reliable, smaller, lighter, almost perfectly efficient, and have better torque characteristics than ICE. You can't compare the energy storage density in isolation. Engines are heavy...Model S's motor generates 362 horsepower (according to the official specs), and only weighs 70 pounds...the equivalent ICE would be 500+ :-) (Yes, the inverter weighs something, but the transmission is much simpler as well for electric...overall you save a few hundred pounds easily...A Model 3 battery pack is between 600 and 1000 pounds--so pretty close to the crossover point.)

outworlder 6y ago
Forgot about that on my longer reply. EV engines are _tiny_ and incredibly efficient.
Shivetya 6y ago
However you are ignoring that while you can spin the blades more efficiently, however scaling an electric motor to that size may end up with even more weight, you also have to replace the turbojet portion of these motors. So you will need even more engine. That turbo jet is more efficient at speed while the fan is better at lower speed. In the end we would have slower planes but we will eventually reach a point where we can do it. Someone can probably explain it better and my understanding is rough and not current; jets were cool when I was kid
- hwillis 6y ago
  Your speculation about motors is incorrect; motors are actually more efficient the larger you build them. It's a property of the goodness factor: https://en.wikipedia.org/wiki/Goodness_factor https://en.wikipedia.org/wiki/Goodness_factor It is profoundly foolish to compare motors and heat engines on first principles like this, obviously. Still, here's a turbine that handles 30x the power of a jet engine, running a generator that is about the same size as a jet engine: https://www.ge.com/news/sites/default/files/Reports/uploads/2019/01/25132345/P1000089.jpg https://www.ge.com/news/sites/default/files/Reports/uploads/... generator is in the upper left. Obviously not at all optimized for size or weight- there aren't even any magnets in that thing.

outworlder 6y ago

> Meanwhile, gasoline / petrol / benzin (wherever your are in the world) has an energy density of 12200 Wh/kg. Yeah, and yet, if you are talking about cars, you are bound by the Carnot efficiency, which is at most 35% no matter what(in reality more like 20% or so). Now gasoline goes to 4270 Wh/kg even assuming the best possible engine. That's without accounting for extraction, refining, transportation losses. Yes, still 10x more. However, you don't really need 10x, as electric motors are way more efficient (85 - 90%). The long range Tesla Model 3 only requires a 75kWh (72.5 usable) battery for a 450km (~279 miles). In other words, it uses 161 Wh/km . > ICEs are real technology So are EVs. For all the tech they tend to have, it boils down to: Battery and electric motor. There are some pretty reliable solid state electronics to monitor and deliver power, but that's all you really need(even the 'charger' is optional - and for quick charging, it's located outside the vehicle). You could theoretically use decades old technology to control the amount of power delivered to the motors - so you could see with your naked eye. And, in fact, we have done that! The first cars ever designed were electric, battery tech just wasn't there. It doesn't make sense to do that in this day and age, electronics driven by software work better. We would replace ICE engines with solid state components if it was possible. Now, for an ICE car, you have valves. You have a crankshaft, controlling said valves (and tied to pistons) - hundreds of moving parts right there. You have spark plugs (and a coil to generate the voltage). Air filters. You have an alternator (usually driven by a belt). You have water pumps (optional on EVs - and for the battery only, when they are used). You need fuel pumps. Fuel filters. Radiators (because of all the engine inefficiency). You need oil - and replace said oil, as well as the oil filter. You have an exhaust with a catalytic converter. Each one of those things may break and some are even consumables. So much crap EVs don't have. And you still have software and the tiny electronics you can't see with your eyes ! Unless, of course, you still use carburetors (which add a few hundred more parts each). EVs are much, much simpler. And more reliable, less parts and most of them don't move. The only thing that degrades is the battery. For now. I drive a Leaf, which is notorious for having no battery thermal management, and degradation is minimal.

zkms 6y ago
> you are bound by the Carnot efficiency, which is at most 35% no matter what(in reality more like 20% or so) Internal-combustion engines are not limited by the Carnot efficiency; see page 4 of these slides. In fact, latest-generation Priuses gets almost 40% thermal efficiency on the gasoline engine, and large diesel engines -- thanks to lean combustion (favorable ratio of specific heats for the gases that push on the piston), no throttling losses, higher compression ratio -- do even better. https://www.energy.gov/sites/prod/files/2014/03/f8/deer11_edwards.pdf https://www.energy.gov/sites/prod/files/2014/03/f8/deer11_ed...

petre 6y ago

True but gas turbines (not ICEs, those are mainly used on small aircraft) can reach a theoretical efficiency of 30% while electric motor efficiency of 92…93% is quite common. So you can multiply that number by 1/3 since 2/3 becomes heat.

microcolonel 6y ago
With turbofans and turbojets it gets a little harder as well, since unlike stationary turbine generators, not all "waste heat" is actually wasted, when considering thrust-specific fuel consumption.

DarmokJalad1701 6y ago

Sure. The average car gets 25 mpg, consuming ~1400 Wh/mi. A Tesla Model 3 uses ~240 Wh/mi. Thats almost a factor of 6 difference. You don't need quite as much energy when you are significantly more efficient and it is only getting more efficient as time goes on. Also add in the factor of recovering energy using regenerative braking which is impossible with ICE. With a car, unless you have a specific use-case where you are driving 200+ miles a day, an EV is a no-brainer when it comes to efficiency in operating cost as well as emissions and overall energy use.

asdfadsfgfdda 6y ago
A Model 3 is smaller than the average car, it should be compared to something like a Honda Accord hybrid. Both have a similar cabin volume of ~100 ft^3. The fuel economy for a hybrid Accord is 48 mpg, or 760 Wh/mile. The Accord is also $10k cheaper, presumably that is because the Model 3 requires more materials and more embodied energy.
- mulmen 6y ago
  > The Accord is also $10k cheaper, presumably that is because the Model 3 requires more materials and more embodied energy. Do economies of scale and manufacturing expertise factor in to "embodied energy"?
dmos62 6y ago
What are the energy requirements and emissions for just building the vehicle? I've heard rumours that it's non-negligible when considering total emissions that a car will have caused.
- 1958325146 6y ago
  Page 9 of https://www.tesla.com/ns_videos/2019-tesla-impact-report.pdf https://www.tesla.com/ns_videos/2019-tesla-impact-report.pdf has a chart for that (Average Lifecycle Emissions in New York State (gCO2e/mi)). Electric: 54 in manufacturing, 74 in use Gas: 45 in manufacturing, 420 in use

pixelbash 6y ago

> ICEs are real technology They are real technology, in the sense that this is where over 100 years of optimising every aspect of ICE has got us to. Fascinatingly complex, extremely well engineered, and depending on the brand still relatively likely to break down within the first few years. The engines are also longer designed to be maintained without special processes, and are increasingly designed around emission regulations. To the point where a lot of the complexity is in emission systems and the cars are choked by their own extremely lean fuel maps. Electric motors on the other hand are still relatively unoptimised and the potential in things like torque vectoring is amazing. I'll miss driving manual, but it's getting just about impossible to buy those now anyway.

justapassenger 6y ago
> Electric motors on the other hand are still relatively unoptimised Electric motors have huge applications across most industries for longer than combustion engines. Calling them unoptimized is quite a stretch. There're some car specific optimizations to be done, sure, but it's very mature technology, with little potential for breakthroughs.
- pixelbash 6y ago
  Those applications generally haven't been focused on putting ridiculous horsepower in a tiny format and then running a highly variable load while dissipating heat. For example Axial flux motors are still very much being developed with a steady flow of breakthroughs (Magnax, Emrax), and have mind bending power to weight ratios. A lot of the current issues seem to be around heat dissipation, which is where I am hoping some of the next big wins are. I'm a bit sad that currently easily available motors are currently not in the same league as Tesla (I have a 50kw Me1616 and Sevcon 4 sitting on my bench) but it looks like that is slowly changing.

speedgoose 6y ago

I drive both ICE cars and electric cars and there is something about ICE engines in cars : they are very unresponsive compared to electric engines. They are fine at high RPMs, but you don't want to and shouldn't drive at high RPM. They have things such as turbo lag or really shitty torque curves. The gearboxes do not help as well. It's weird to wait half a second to get full power when you are used to the instant torque. You should test drive a random eletric car and a random ICE car.

ramses0 6y ago
If you have the opportunity, try comparing your ICE experience with a manual transmission ICE. Many modern ICE cars are effectively fly-by-wire with eco-junk-softwware in between the accelerator and engine. Manual transmissions would likely not have the lag that you're experiencing, but I definitely recognize what you're saying w.r.t. torque curves. I'm not challenging ICE v. Electric, but instead attempting to clarify that there is quite a wide variation in ICE-behavior that is less present in a manual transmission ICE car.
- reubenswartz 6y ago
  Moving from a manual ICE to electric, it's still night and day. And the manual felt like night and day compared to a lot of automatics...
- speedgoose 6y ago
  I own a ICE car with a manual gearbox. The lag is there. The engine needs time to find his torque at low RPM so you need to drop one or two gears if you want some power. Mine doesn't have a turbo, but when I drive manual cars with Turbo, the turbo lag is huge. A manual gearbox doesn't fix this problem. You may drop gears before you need the power, to overtake someone for example, because you plan ahead and want the full power, but that's slow. And even when I do it fast, I'm much much slower to manipulate the clutch and change gears compared to a modern automatic gearbox.
- adrianN 6y ago
  I doubt that most people can operate a manual transmission significantly better than the "eco-junk software" that controls a modern automatic. Almost nobody is a race driver, but everybody can feel the nicer behavior of an electric engine.

woodandsteel 6y ago

Top-level ev's like the Model 3 are already superior for most drivers. The only problem is cost, and that is being fixed in the coming years through steadily falling battery prices. Other use cases like aviation and ocean boats are more difficult. It may well be that synfuels made with renewable energy will be the solution there.

nine_k 6y ago

ICEs are way heavy for their power. I agree that we will produce and burn synthetic fuel for flight long into the future. But this is going to burn in turbines for flying in atmosphere, and in rocket engines for getting to orbit.

jillesvangurp 6y ago

The only metric with planes that matters is $/mile. A soon as something flies far enough with enough payload, energy density stops being an issue. It doesn't matter that the plane is going to be four times the weight if it gets from A to B at a fraction of the cost. Think 100$ hamburgers turning into 5$ coffee runs because of vastly reduced fuel cost and maintenance cost. You see the same pattern with EVs. All of the cool ones are really heavy compared to the ICE cars they compete with. But they still go really fast and pretty far. So, you see much heavier Tesla's making formerly cool ICE sports cars look sluggish and outdated. And lets be honest, those never had any kind of fuel economy (or range) worth talking about because they burn fuel at obscene rates to get that speed. Being obscenely noisy and inefficient was kind of the point of owning one.

kumarvvr 6y ago

> 12200 Wh/kg Most ICE engines have efficiencies from 20 to 35%. Taking an average of 25% effciency, batteries have to essentially aim at about 3000 Wh / kg Most battery motor systems have a round trip efficiencies of about 80%, so to compete with ICE engines, EV systems have a target of about 4000 Wh/kg. edit : I also forgot to add about regenerative braking. For on road EV vehicles, regenerative braking can capture about 70% of the energy lost in braking. So, while a battery can store just 450 Wh/kg, averaged total energy, expended from the battery terminals, averaged over time, would have to be higher. It also makes sense to calculate the average total energy stored in the vehicle, rather than the energy densities of the fuels. For a 300 mile range, assuming an average 30 mpg fuel efficiency, you would need about 10 gallons, about 38 kg. So total stored energy in the vehicle in form of fuel, is 12200 * 38 = ~ 465 kWh. But, of this energy, only 25 % is converted to usable movement, i.e, about 118 kWh. However on a Model 3 LR, which has a range of 300 miles per charge, the battery capacity is 80 kWh (Tesla claims 75 kWh). So there is no basis to compare energy densities of various fuels directly.