Here's a fun bit: in the article they say that lithium-sulfur is hard to measure charge level for due to the voltage properties of charging and discharging.
"The upshot is that voltage is not a good proxy for the state of charge and, to make things even more complicated, the voltage curve is asymmetrical for charge and for discharge."
Since it would be bad if your battery suddenly died and you dropped out of the sky, they had to develop complex statistical and neural network algorithms to accurately determine state of charge to within a few percent. One black box for staying in the sky and another in case you end up on the ground!
Or you could do what they did on Apollo (forget if it was the CM or LM). They had the problem of measuring how much was in a tank, but the tank was in 0G, so a float is no good. The proposed solution was some sophisticated radiation based thing where they measured the attenuation of some radioactive source through the tank. This wound up being highly complex, and the solution was simply to have a reserve tank. When the main tank ran out, you knew you had exactly the amount in the reserve tank.
State of charge tracking is tricky even for lithium ion batteries. I worked on it for a bit as part of a solar car competition. Usually it involves a mix of coulomb counting and voltage measurements. IIRC, a handful of laptops and consumer electronics have trained neural networks to assist in estimating SOC.
As far as aircraft goes, it's sufficient to put a lower bound on the remaining charge. Realistically, the poor (abysmal, really) energy density of batteries pretty much precludes their usage in any serious aircraft. For sustainable air flight I'm more optimistic about syngas or hydrogen.
This makes me wonder how accurate float bulb based fuel level sensors really are. This sounds like a major problem and the solutions are interesting but potentially even better than what we are used to.
My 1990 Toyota never read full. The buffer on the fuel sender was so extreme that by the time the needle made it to the "F" I had already burned 1/8 of a tank! My current car warns me when I have about 50 miles of fuel left, I wonder how much historical data it uses in that calculation.
None of my motorcycles even have fuel gauges. I just keep an eye on the odometer and when I stop to stretch my legs I give the tank a shake or a peek.
> 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.
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.)
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.
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.
> 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.
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.
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.
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.
>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.
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.
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.
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.
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.
Higher energy density makes electric planes a little bit more reasonable, but they'd still be quite range-limited compared to gas. For some use cases, that might be okay.
I'm more interested in how this affects cars. Getting four or five hundred miles out of a battery pack that's lighter than what's in a typical Tesla would be a great thing, especially if it's cheap.
I'm currently working on an electric conversion of a Mazda RX-8. I just bought about 450 pounds of lithium iron phosphate batteries. They're the most expensive component, and provide about 27kwh; maybe enough for 100 miles if I'm lucky. I sort of assumed that in about ten years or so I'll probably replace the whole pack with whatever great new technology can provide more range with less weight, and probably cost less too. It would be wonderful if we had awesome batteries now.
(I considered used tesla modules; they have much better energy density, but they're more dangerous and they wouldn't have fit well in the odd-shaped places I wanted to put them.)
Any range you can achieve with batteries in a plane it's basically going to decimate operational cost and be unbeatable from that point of view for missions falling into that range. There are a number of products in development that have interesting enough range that they are pre-selling well because there are companies out there that can fit that in their missions. Double the range, and there are going to be more such companies.
There are a number of battery companies looking to improve energy densities by a factor of 2x to 7x. It's increasingly looking like a matter of when; not if we hit 2x-3x. Five years seems reasonable; even quite long given the constant barrage of announcements from various companies and research groups. These improved batteries will likely be expensive initially and not produced in mass volumes right away. But could be perfect for niche markets where volume and cost are less of a concern; i.e. aviation.
Tesla's battery day next month is going to be interesting as well. Rumors are currently flying about longevity and energy density of that particular battery. It's clearly going to be better than what they are currently shipping and some insiders seem to hint it's quite close to the magical 400 wh/kg that e.g. Elon Musk has been citing as a minimum viable battery for electric flight.
Another thing to consider is that a lot of already announced electrical airplanes are equipped with what are now already obsolete batteries. That's not because the companies behind them are stupid but because certifying planes just takes a very long time and does not allow for massive technical overhauls in between. So, there are some gains to be had by simply updating existing designs with newer off the shelf technology as it becomes available. Second and third generations of a lot of the products that are close to production ready are going to be interesting in the next few years and in some cases, manufacturers are already planning such products. Doubling or tripling ranges is going to be very disruptive in that market.
Sweet project! How much did the batteries cost? I see this works out to ~130 Wh/kg--did you avoid batteries with higher energy density for cost reasons, or are they just difficult to get?
Everyone is talking energy density but nobody is talking about Urban Air Mobility.
Electric is the name of the game for a VTOL plane that will take you from SFO to downtown or Santa Cruz. They don't have to have all the performance in the world, they just need to have enough performance to do their job.
Also, pilots will appreciate the operating costs and simplicity of these aircraft. Student pilots will love a plane that costs $10/hr instead of $100/hr in the Bay Area. 90 minutes of flight time (1 hour lesson + 30 minute VFR 'fuel' reserve) is all it needs.
Neighbors will appreciate higher torque motors that turn modern props at 1500 RPM instead of 2200 for the noise reduction.
With every lithium-sulfur battery I've come across you need to have a lot of steel clamping plates together because they expand so much when charging, and will otherwise delaminate. So ultimately they become the same mass.
This includes the oxis energy battery mentioned here.
This might sound crazy but is it possible to do that in some way such that the clamping plates etc. are only there during the charging process? Prevent the delamination during charging and then remove the prevention mechanism?
Or just charge really really slowly? Airports etc. could just have terminals full of trickle-charged batteries to swap in and out.
Is there some way to embrace this in the design of the plane? Could the wing structure be built in such a way that an expanding battery actually adds strength?
For speculative (near future) fiction, that uses a lightweight electrically-powered aircraft as a linking device, "News From Gardenia" by Robert Llewellyn, is a good read.
He also identified a couple of sweet spots where electric flight would make sense factoring in engine efficiency & cost of fuel etc. bottom line is that the picture is more complex than just comparing energy density of jet-fuel & batteries. with batteries becoming much lighter IMO it should open up many more use cases for short haul frequent flights without the need of big central hub airports. which is good. an more importantly give the trajectory of battery energy density it should provide enough justification for heavy investment into research into electric planes so i wouldn't dismiss it out of hand.
Yes but presumably electricity is order(s) of magnitude cheaper than jet fuel. And also order(s) of magnitude more available than jet fuel. And also order(s) of magnitude cleaner than jet fuel (depending on the source).
To be fair, you need to compare a complete workflow including the renewable production of the jet fuel.
If the overhead of heavy batteries does not annihilate the benefit of the carbon-neutral production rendered possible by using electricity (and associated carbon-neutral sources like photovoltaic etc... heck, even nuclear fission), then batteries are still the path to go.
If there are carbon-neutral ways to produce the jet-fuel, and to have a completely carbon-neutral(or even negative) cycle production+consumption, then why not. If it could be done without turning the Earth into a giant bio-fuel crop, that would be nice.
>> Still orders of magnitude less energy-dense than jet fuel.
Does that matter, if other aspects of the system compensate with lighter weight? For example, lighter weight electric engines versus heavier fuel-burning engines along with exhaust and cooling systems.
[+] [-] dougmwne|5 years ago|reply
"The upshot is that voltage is not a good proxy for the state of charge and, to make things even more complicated, the voltage curve is asymmetrical for charge and for discharge."
Since it would be bad if your battery suddenly died and you dropped out of the sky, they had to develop complex statistical and neural network algorithms to accurately determine state of charge to within a few percent. One black box for staying in the sky and another in case you end up on the ground!
[+] [-] cameldrv|5 years ago|reply
[+] [-] manfredo|5 years ago|reply
As far as aircraft goes, it's sufficient to put a lower bound on the remaining charge. Realistically, the poor (abysmal, really) energy density of batteries pretty much precludes their usage in any serious aircraft. For sustainable air flight I'm more optimistic about syngas or hydrogen.
[+] [-] BurningFrog|5 years ago|reply
Have 10 small batteries, that you go through one by one, instead of the single big one. You only need to start worrying on the 10th one.
[+] [-] mrfusion|5 years ago|reply
[+] [-] mulmen|5 years ago|reply
My 1990 Toyota never read full. The buffer on the fuel sender was so extreme that by the time the needle made it to the "F" I had already burned 1/8 of a tank! My current car warns me when I have about 50 miles of fuel left, I wonder how much historical data it uses in that calculation.
None of my motorcycles even have fuel gauges. I just keep an eye on the odometer and when I stop to stretch my legs I give the tank a shake or a peek.
[+] [-] unknown|5 years ago|reply
[deleted]
[+] [-] monadic2|5 years ago|reply
[+] [-] rolleiflex|5 years ago|reply
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.
[+] [-] phonon|5 years ago|reply
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.)
[+] [-] DarmokJalad1701|5 years ago|reply
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.
[+] [-] jmercouris|5 years ago|reply
[+] [-] outworlder|5 years ago|reply
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.
[+] [-] pixelbash|5 years ago|reply
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.
[+] [-] speedgoose|5 years ago|reply
You should test drive a random eletric car and a random ICE car.
[+] [-] kumarvvr|5 years ago|reply
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.
[+] [-] tenuousemphasis|5 years ago|reply
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.
[+] [-] woodandsteel|5 years ago|reply
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.
[+] [-] petre|5 years ago|reply
[+] [-] nine_k|5 years ago|reply
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|5 years ago|reply
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.
[+] [-] elihu|5 years ago|reply
I'm more interested in how this affects cars. Getting four or five hundred miles out of a battery pack that's lighter than what's in a typical Tesla would be a great thing, especially if it's cheap.
I'm currently working on an electric conversion of a Mazda RX-8. I just bought about 450 pounds of lithium iron phosphate batteries. They're the most expensive component, and provide about 27kwh; maybe enough for 100 miles if I'm lucky. I sort of assumed that in about ten years or so I'll probably replace the whole pack with whatever great new technology can provide more range with less weight, and probably cost less too. It would be wonderful if we had awesome batteries now.
(I considered used tesla modules; they have much better energy density, but they're more dangerous and they wouldn't have fit well in the odd-shaped places I wanted to put them.)
[+] [-] jillesvangurp|5 years ago|reply
There are a number of battery companies looking to improve energy densities by a factor of 2x to 7x. It's increasingly looking like a matter of when; not if we hit 2x-3x. Five years seems reasonable; even quite long given the constant barrage of announcements from various companies and research groups. These improved batteries will likely be expensive initially and not produced in mass volumes right away. But could be perfect for niche markets where volume and cost are less of a concern; i.e. aviation.
Tesla's battery day next month is going to be interesting as well. Rumors are currently flying about longevity and energy density of that particular battery. It's clearly going to be better than what they are currently shipping and some insiders seem to hint it's quite close to the magical 400 wh/kg that e.g. Elon Musk has been citing as a minimum viable battery for electric flight.
Another thing to consider is that a lot of already announced electrical airplanes are equipped with what are now already obsolete batteries. That's not because the companies behind them are stupid but because certifying planes just takes a very long time and does not allow for massive technical overhauls in between. So, there are some gains to be had by simply updating existing designs with newer off the shelf technology as it becomes available. Second and third generations of a lot of the products that are close to production ready are going to be interesting in the next few years and in some cases, manufacturers are already planning such products. Doubling or tripling ranges is going to be very disruptive in that market.
[+] [-] highfrequency|5 years ago|reply
[+] [-] inamberclad|5 years ago|reply
Electric is the name of the game for a VTOL plane that will take you from SFO to downtown or Santa Cruz. They don't have to have all the performance in the world, they just need to have enough performance to do their job.
Also, pilots will appreciate the operating costs and simplicity of these aircraft. Student pilots will love a plane that costs $10/hr instead of $100/hr in the Bay Area. 90 minutes of flight time (1 hour lesson + 30 minute VFR 'fuel' reserve) is all it needs.
Neighbors will appreciate higher torque motors that turn modern props at 1500 RPM instead of 2200 for the noise reduction.
[+] [-] the8472|5 years ago|reply
Because flying cars have always been just behind fusion.
[+] [-] Antipode|5 years ago|reply
[+] [-] adammunich|5 years ago|reply
This includes the oxis energy battery mentioned here.
[+] [-] cmrdporcupine|5 years ago|reply
Or just charge really really slowly? Airports etc. could just have terminals full of trickle-charged batteries to swap in and out.
[+] [-] mulmen|5 years ago|reply
[+] [-] ncmncm|5 years ago|reply
[+] [-] zzedd|5 years ago|reply
[+] [-] tuatoru|5 years ago|reply
Impressed with the persistence here.
[+] [-] akrymski|5 years ago|reply
[+] [-] foxylad|5 years ago|reply
Big oil has done an amazing job making the subject unmentionable.
[+] [-] msaroff|5 years ago|reply
[deleted]
[+] [-] ddoice|5 years ago|reply
[+] [-] DesiLurker|5 years ago|reply
He also identified a couple of sweet spots where electric flight would make sense factoring in engine efficiency & cost of fuel etc. bottom line is that the picture is more complex than just comparing energy density of jet-fuel & batteries. with batteries becoming much lighter IMO it should open up many more use cases for short haul frequent flights without the need of big central hub airports. which is good. an more importantly give the trajectory of battery energy density it should provide enough justification for heavy investment into research into electric planes so i wouldn't dismiss it out of hand.
[+] [-] umvi|5 years ago|reply
[+] [-] henearkr|5 years ago|reply
If the overhead of heavy batteries does not annihilate the benefit of the carbon-neutral production rendered possible by using electricity (and associated carbon-neutral sources like photovoltaic etc... heck, even nuclear fission), then batteries are still the path to go.
If there are carbon-neutral ways to produce the jet-fuel, and to have a completely carbon-neutral(or even negative) cycle production+consumption, then why not. If it could be done without turning the Earth into a giant bio-fuel crop, that would be nice.
[+] [-] blisterpeanuts|5 years ago|reply
Does that matter, if other aspects of the system compensate with lighter weight? For example, lighter weight electric engines versus heavier fuel-burning engines along with exhaust and cooling systems.
[+] [-] unknown|5 years ago|reply
[deleted]