I swear I've been reading this headline for last 15 years.
CATL has announced a new “condensed” battery with 500 Wh/kg
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Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#72Key numbers: They doubled Wh/kg from about 280 to about 500. I assume that thinking about battery capacity form first principles, the theoretical limit is reached when the charged battery consists of 50% matter and 50% antimatter, right? Then during discharge, the reaction between the two would turn the matter/antimatter into energy. How would that stack up against the 500Wh/kg stated here? Update: Did a bit of googl…
No. That wouldn’t be a battery by any meaningful definition, nor have any similarities in implementation or enabling technology or physics.
But it would deliver 24 trillion wh/kg… so by that metric at least we’ve room to progress :-)
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#73Why does 500wh/kg make electric aircraft possible? 6x less than kerosene. Is that the break even on cost if you can source very cheap electricity? Seems like it would still annihilate the payload/range.
I don’t think Musk has given a writeup of his reasons for thinking 400wh/kg is the magic number, but a lot of research has been done that says similar numbers. This paper https://www.sciencedirect.com/science/article/pii/S2666691X2... is a good review; it cites researchers saying 800wh/kg for an electric Airbus A320, NASA saying 400Wh/kg for general aviation and 750Wh/kg for regional aviation, and other researchers saying 600Wh/kg for commercial regional aircraft and 820Wh/kg for commercial narrow-body aircraft.
That paper also sketches out the argument for electric flight at close to current battery densities rather than close to kerosene energy densities. It goes:
Jet fuel gets roughly 28% final efficiency while electric gets roughly 90%, so divide jet fuel by 3 to get 4,000 effective Wh/kg.
Alternate aerodynamic designs and especially distributed propulsion are much more achievable with electric engines. Imagine the difficulty of making a 14-, 24-, or even 36-turbine aircraft, yet all of those have been built and flown with electric engines already (https://en.m.wikipedia.org/wiki/NASA_X-57_Maxwell, https://en.m.wikipedia.org/wiki/Aurora_XV-24_LightningStrike, and https://en.m.wikipedia.org/wiki/Lilium_Jet respectively). Gains of 3-5x have been observed here and higher is predicted, the conservative mean is 4x, so divide again by 4 to get jet fuel to 1,000 effective Wh/kg.
That is getting close to current energy densities of batteries. You only need to find one more ~2x improvement that electric flight can obtain over jet fuel to bring it into the range of 500Wh/kg, which CATL is saying they have in production right now.
(Presumably Musk’s magic 400Wh/kg number involved another 2.5x improvement, though I don’t know where specifically he thought it would come from. The internet seems to think he said you can go higher because you don’t need oxidizer from the air to burn jet fuel, but that doesn’t sound right since you still need to push on the air with your fans and you’ll run out of that at high altitude before you run out of oxygen, so it must be coming from somewhere else. Regardless, the point is that jet fuel imposes design constraints that trap you in a local maximum of aircraft efficiency, and electric engines allow you to explore a wider space which may have much much higher maximums.)
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#74Earlier quoted context omitted.
Let's consider Cessna-172S ([4]). Its characteristics: - 130 kW engine, Lycoming_O-360 that weighs 117 kg. For comparison, an electric motor of this range would weigh 11-13 kg (at 10-12 kW/kg, [2]). That saves 100+ kg weight immediately and we can put 50+ kWh batteries instead. - It carries up to 200 liters of kerosene ([3]), which weighs 164 kg. We can place 82 kWh of batteries instead. - The engine consumes around…
> quite practical for recreation and short flights Perfectly agree with everything, but 1.5hr may be very short if you need to have 30 minutes of reserve at landing. On the saving side, you don’t have to have an alternator to transform ICE energy into energy for the dashboard instruments. On the downside, you now need to heat the cabin manually, rather than reusing the ICE heat.
> you now need to heat the cabin manually, rather than reusing the ICE heat.
Interestingly, the Boeing 787 has already dispensed with bleed air. It uses compressors for heat and electric pumps for hydraulics.
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#75Earlier quoted context omitted.
You may not have a choice in the matter as more and more countries are thinking of/implementing ICE bans in the near future.
They're unlikely to succeed because if the massive tax on poor people (ICE bans) actually gets implemented, all of the poor people who are forced to buy an unaffordable EV will vote for populists promising to unwind the bans.
Not all countries are car-centric as USA
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#76Earlier quoted context omitted.
Electric planes could recharge using solar or wind. As efficiency increases with these technologies, it would mean planes wouldn't require carrying the same watt-for-watt energy as fuel.
Recharging a small plane with solar power would either take ages or hectares. Pick your poison. Recharging multiple airliners will take a nuclear reactor at the airport.
Why does it have to be poison? Wouldn't having an airport nearby be a blessing for anyone with solar panels on their roof? Just like an industrial zone, it'd be a nonstop load ready to buy from anyone, anytime. (Yes I understand the infrastructure would need to change a lot.)
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#77Earlier quoted context omitted.
Let's consider Cessna-172S ([4]). Its characteristics: - 130 kW engine, Lycoming_O-360 that weighs 117 kg. For comparison, an electric motor of this range would weigh 11-13 kg (at 10-12 kW/kg, [2]). That saves 100+ kg weight immediately and we can put 50+ kWh batteries instead. - It carries up to 200 liters of kerosene ([3]), which weighs 164 kg. We can place 82 kWh of batteries instead. - The engine consumes around…
> quite practical for recreation and short flights Perfectly agree with everything, but 1.5hr may be very short if you need to have 30 minutes of reserve at landing. On the saving side, you don’t have to have an alternator to transform ICE energy into energy for the dashboard instruments. On the downside, you now need to heat the cabin manually, rather than reusing the ICE heat.
No alternator, but some dc-dc to get the voltage of the main battery down to 14/28 V for the avionics, lights, etc.
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#78Cool! What didn’t occur to me until I learnt it was that you get a multiplicative benefit with energy density when weight is a major factor (air transport, especially) because you need to spend less energy accelerating mass used by the battery itself.
Same with jet fuel on a plane. They calculate the amount to fuel carefully to be efficient but safe. Too much and the plane is heavier and uses more fuel. Too little and you might run out if put into a holding then diverted. Obviously jet fuel is what it is it wont get more dense but a more efficient engine means less fuel needed means even more efficiency and so on.
Not only that but too much might also cause you to have to dump fuel in order for the plane to be able to land.
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#79Nice this would mean potentially cheaper electrical cars with same or longer range than today or more expensive cars with much longer range than today.
Re: CATL has announced a new “condensed” battery with 500 Wh/kg
#80Earlier quoted context omitted.
> quite practical for recreation and short flights Perfectly agree with everything, but 1.5hr may be very short if you need to have 30 minutes of reserve at landing. On the saving side, you don’t have to have an alternator to transform ICE energy into energy for the dashboard instruments. On the downside, you now need to heat the cabin manually, rather than reusing the ICE heat.
> you now need to heat the cabin manually, rather than reusing the ICE heat. Interestingly, the Boeing 787 has already dispensed with bleed air. It uses compressors for heat and electric pumps for hydraulics.
That's probably less of an efficiency concern, but more likely to avoid future legal cost for supplying contaminated air to the cabin.