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Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

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Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#181

Post by class3shock »

hedora wrote: post #166
class3shock wrote: post #161

Earlier quoted context omitted.

"Additionally, that 60x claim is getting old by the minute. We are getting to 300+ with advancements coming in so fast they are hard to keep track of. That 60x could drop to 10x or lower in just a few years" What was a Tesla Model S power density 10 years ago? Today? Hardware moves slower than you think. All your points have some basis of consideration but the potential performance improvements they represent are tin…

Battery density doubled in the last ten years: https://www.westchestercleanenergy.com/post/lithium-battery-... Density is going up exponentially in the graph because it has been improving 18% for every doubling of the number shipped. Global EV market share is projected to cross 25% this year, so we should expect two more 18% improvements as it approaches 100%. That should improve density 39%. Then (ignoring batteries…

And that's great, lets assume that continues, which there is no guarantee of, when would batteries be in the same ballpark as jet fuel?

Lets call current batteries 300 Wh/kg and jet fuel 12,000 Wh/kg, that means, according to you, development would look something like:

Battery Density: 2035 - 600 Wh/kg 2045 - 1200 Wh/kg 2055 - 2400 Wh/kg 2065 - 4800 Wh/kg 2075 - 9600 Wh/kg

So in half a century we may see batteries approaching the power density needed.

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#182

Post by derriz »

numpad0 wrote: post #141
derriz wrote: post #125

Earlier quoted context omitted.

> The technology hadn't improved not much more than a quarter's worth so far in my lifetime as far as EV is concerned. Average EV range has increased 2.7 fold in the years 2010 to 2021[1] and has continued to increase - by 40% since then. Neary a 4-fold improvement in 15 years. Charging tech has improved from the initial Level 1 (1kW) and Level 2 (13kW) technology to fast charging (150kW) or 350kW (current fastest co…

> Average EV range has increased 2.7 fold Don't dodge the question like that. I said efficiency hasn't improved. You basically said, the car got 2.7 fold bigger. Consider that Gen1 Nissan Leaf already had 24kWh battery and 200km(125mi) rated range. Today's EV with 100kWh battery packs has at most 500mi - literally zero improvement. CHAdeMO supported up to 62.5kW since 2009 or so. It can do 400kW now, that's still not…

> Don't dodge the question like that. I said efficiency hasn't improved.

That's not what you said and to avoid confusion, as usual, I provided an exact quote of what you claimed before providing my response.

To repeat, your actual exact words:

> The technology hadn't improved not much more than a quarter's worth so far in my lifetime as far as EV is concerned.

Your attempt to twist away from your original claim while suggesting that I've acted in a shameful manner does not suggest that you're making any attempt to engage honestly or with good faith.

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#183

Post by wkat4242 »

asn007 wrote: post #104
wkat4242 wrote: post #90

Earlier quoted context omitted.

> but putting a reactor on each plane would probably have negative externalities. Probably? It would be a disaster every time one crashes, would carry a huge proliferation and terrorism risk. Oof. In the 50's some countries were that crazy and they even put reactors in space. Two of which crashed and one contaminated a huge area in Canada. Luckily common sense prevailed and these things don't happen anymore. Though n…

Correct me if I'm wrong, but I thought we still use RTGs in space on some satellites? Not counting extraterrestrial research, since those are definitely still powered by RTGs

The ones I speak of had actual reactors with moving parts. Most of them were Soviet, one was American (a research one, the soviet ones were active radar sats with a shelf life of only a few months). https://en.wikipedia.org/wiki/US-A (The soviets called them US-A for some weird reason, lol). There were 33 of them, 3 of which have already crashed to earth.

But yeah RTGs are very nasty stuff too. They are much easier to secure against breaking apart on re-entry though (although dropping a concentrated plutonium source into a random place is not a great idea either obviously).

I don't think any are used on current earth-orbiting sats though: https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#184

Post by ndsipa_pomu »

RetroTechie wrote: post #163
ChuckMcM wrote: post #63

Earlier quoted context omitted.

Was going to post something similar. I love me a screed where the author rails against some group saying they don't know what they are talking about, and then goes on to demonstrate that they don't know what they are talking about. :-) For a long time I didn't understand what 'talking past each other' meant but this article is a good example of that. Mostly it's bad form to make sweeping generalizations. But let's be…

"Lithium propulsion for aircraft and boats is fundamentally unprofitable (..)" It's annoying (and ignorant) author lumps aircraft & boats into 1 category. Jumbo jets won't be electrified anytime soon. Weight (and thus, energy density/kg) is everything. But synthetic fuels, hydrogen etc might be good options. But there's also short-haul flights. Routes with say, 15..20min between take-off & landing. For such flights,…

> Jumbo jets won't be electrified anytime soon. Weight (and thus, energy density/kg) is everything. But synthetic fuels, hydrogen etc might be good options.

That's making me think that hydrogen-filled airships (Zeppelins/dirigibles) might be practical with some kind of electric propulsion. That way, the weight is no longer so much of an issue, though the trade-off is that they'll need to be bigger. Their speed (or slowness) could be an advantage in that they should be much easier to fly and collisions would hopefully be infrequent and not so catastrophic (I'm picturing more of a bounce than a collision).

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#185

Post by throw-qqqqq »

kumarski wrote: post #112
mangecoeur wrote: post #41

Finance bro decides tweets are better evidence than physics… nothing to see here

former engineer, but w/e.

I found it funny that you felt a need to comment on the “finance bro”-label while simultaneously labeling HN-users as “programmers”:

> I'm getting roasted by programmers, I'll survive.

… often chosen as a sufficiently insulting label to dismiss software engineers.

I may be interpreting your choice of words beyond what is reasonable - as you said: you’ll survive ;)

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#186

Post by throw-qqqqq »

numpad0 wrote: post #85
api wrote: post #48

I remember seeing loads and loads of analyses like this back in the 2000s on a site called The Oil Drum about why electric cars would never work at scale. (Spoiler: My family has two EVs.) They always assume that the technology will never get better, that industrial economies of scale don't exist and therefore that prices don't decrease with scale, that currently developed reserves of resources like lithium equal tot…

> They always assume that the technology will never get better, that industrial economies of scale don't exist The technology hadn't improved not much more than a quarter's worth so far in my lifetime as far as EV is concerned. Wh/kg figures hasn't changed, even fusion seems closer than solid state batteries, mileage figures for EVs is same 4mi/kWh, battery recycling still hasn't been figured out. They can't even rec…

> Wh/kg figures hasn't changed

Maybe I misunderstand you, but taken at face value, this assertion is incorrect.

Battery density (Wh/kg) has more than quadrupled since the 90s. See e.g. https://rmi.org/the-rise-of-batteries-in-six-charts-and-not-...

Price is also dropping fast!

The learning rate for Li-ion batteries right now, is around a 35% price reduction for every doubling in installed capacity.

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#187

Post by sitkack »

RetroTechie wrote: post #163
ChuckMcM wrote: post #63

Earlier quoted context omitted.

Was going to post something similar. I love me a screed where the author rails against some group saying they don't know what they are talking about, and then goes on to demonstrate that they don't know what they are talking about. :-) For a long time I didn't understand what 'talking past each other' meant but this article is a good example of that. Mostly it's bad form to make sweeping generalizations. But let's be…

"Lithium propulsion for aircraft and boats is fundamentally unprofitable (..)" It's annoying (and ignorant) author lumps aircraft & boats into 1 category. Jumbo jets won't be electrified anytime soon. Weight (and thus, energy density/kg) is everything. But synthetic fuels, hydrogen etc might be good options. But there's also short-haul flights. Routes with say, 15..20min between take-off & landing. For such flights,…

Clearly the whole article is wasting hundreds if not thousands of peoples time.

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#188

Post by Retric »

svnt wrote: post #176
Retric wrote: post #136

Earlier quoted context omitted.

You can always scale design to fit reduced demand. Also, loss of efficiency is more than made up for with vastly lower energy demand. “Lowering speed reduces fuel consumption because the force of drag imparted by a fluid increases quadratically with increase in speed. Thus traveling twice as fast requires four times as much energy and therefore fuel for a given distance.” https://en.wikipedia.org/wiki/Slow_steaming “…

Sure, but what does this have to do with what I said? You need design and operating margin, and the engine is always running.

Reducing the load is always going to save fuel. There’s no difference between energy used to move a boat and energy used to run the lights.

Put another way if there was excess torque being generated it would go somewhere such as increasing the engine RPM.

Re: Electric Propulsion's Dirty Secret: Why Lithium Can't Fly (Or Float) Profitably

#189

Post by jmward01 »

perilunar wrote: post #178
cryptonector wrote: post #173

Earlier quoted context omitted.

Airplanes don't get to do regenerative braking except briefly upon landing, but you're not going to put generators in the wheels just for that, and you need active thrust reversers, so really there is simply no room for regenerating power in electric planes.

There’s no reason why you couldn’t do regen when descending with an electric-powered prop plane. It would give a steeper descent than normal, and may not be more efficient overall than cutting power earlier and descending more gradually, but it could be done.

Electric will start smaller and build up to big just like everything else. The single and twin engine world is pretty dominated by structure so the gains are easy to see there. As new capabilities and designs are prooven out things will grow or, and this is what I really hope for, we will find that we don't need the massive aircraft to be profitable anymore and we will just get more smaller electric aircraft providing the service in a more point to point nature. One of the biggest efficiency gains we could have is not forcing people into a hub and spoke mega airport model, something that isn't practical with the current massive aircraft tech.
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