In the chart from the article I see that capacitors are shown as having high specific power. Would it not work to use a hybrid approach of capacitors for takeoff and then Li-ion for most of the flight? I know it would make the system more complicated and therefore more expensive up front, but I wonder if it's an option or if it's out of the question for one reason or another. I've read that supercapacitors are being used for busses and other applications. https://en.wikipedia.org/wiki/Supercapacitor
Battery supply problems faced by electric air taxis
31–40 of 46 posts
Re: Battery supply problems faced by electric air taxis
#32Earlier quoted context omitted.
Sodium is very clearly a contender for stationary batteries. It may even be competitive for surface mobile applications like cars... But there is just no way it can compete on air transport.
I keep being intrigued by vanadium redox flow batteries, and I've seen some in the real world in stationary applications. And the prospect of instant charging by spit-swapping in a mobile application is pretty wild. How scarce is vanadium, though?
It’s like 2 percent by mass of spent iron slag.
Re: Battery supply problems faced by electric air taxis
#33Earlier quoted context omitted.
I keep being intrigued by vanadium redox flow batteries, and I've seen some in the real world in stationary applications. And the prospect of instant charging by spit-swapping in a mobile application is pretty wild. How scarce is vanadium, though?
It’s like 2 percent by mass of spent iron slag.
Now now, no need to be rude.
/
Re: Battery supply problems faced by electric air taxis
#34The Achilles heel of electric aviation is that batteries don’t shed weight as they discharge. A fundamental aspect of Aerospace engineering is that rockets/planes shed a lot of weight during flight by by burning fuel. Many big jets take off at weights far too heavy to land and long ranges are only possible because of all the weight shed in flight.
Until that issue can be addressed with electric aviation, electric planes will be a concept limited to very short range flying.
Rockets solve this problem by dumping the dead weight overboard but not sure a bunch of dead airplane batteries parachuting back to earth is a viable approach.
Re: Battery supply problems faced by electric air taxis
#35Earlier quoted context omitted.
What exactly do they mean by "seawater"? Not all seawater is exactly the same, chemically speaking. I have actually measured "seawater" before, and the chemistry of the water at a single location can vary wildly from day to day. I just want to know under what conditions they tested their prototype! THIS IS NOT BAD FAITH FAUX IGNORANCE. I AM ACTUALLY CURIOUS ABOUT THIS.
Lithium content varies as much as salt content, but one thing is certain: the open seas are consistently salty.
That's only if you take the average of all the measurements collected across the entire ocean for decades. In one spot, salinity is not consistent. Patterns of evaporation and rainfall affect not only salinity but also the presence of organic matter and other random contaminants. Such fluctuations are most pronounced at the surface, where this device is meant to operate.
Re: Battery supply problems faced by electric air taxis
#36In the chart from the article I see that capacitors are shown as having high specific power. Would it not work to use a hybrid approach of capacitors for takeoff and then Li-ion for most of the flight? I know it would make the system more complicated and therefore more expensive up front, but I wonder if it's an option or if it's out of the question for one reason or another. I've read that supercapacitors are being…
Capacitors are great for high load requirements but not great as an energy storage device. i.e. if you wanted to draw several hundred amps for a second or two with relatively low heat waste, an ultra-capacitor arrangement would be the way to go, but for energy storage, a battery wins hands down. There's huge research going into expanding the capacity of capacitors.
Check out this video about capacitors: https://www.youtube.com/watch?v=EoWMF3VkI6U
Re: Battery supply problems faced by electric air taxis
#37Earlier quoted context omitted.
Why tax the income side when you could just tax the consumption side?
Taxing consumption is regressive; Bill Gates can't eat that many more hamburgers than the average person.
Write everyone a cheque.
Taxing income is quite regressive too: it’s how people with nothing can survive.
Re: Battery supply problems faced by electric air taxis
#38Earlier quoted context omitted.
Sodium is very clearly a contender for stationary batteries. It may even be competitive for surface mobile applications like cars... But there is just no way it can compete on air transport.
I keep being intrigued by vanadium redox flow batteries, and I've seen some in the real world in stationary applications. And the prospect of instant charging by spit-swapping in a mobile application is pretty wild. How scarce is vanadium, though?
Vanadium has an horrible weigh/charge ratio. That's why it's used in stationary applications.
Sodium redox flow batteries are all the hype nowadays, because sodium is much cheaper, sulfur for the oxydizer is also very cheap, weight/charge is very high, and volume/charge (important for stationary applications) is also much higher. But I think it's stuck in a patent minefield.
Re: Battery supply problems faced by electric air taxis
#39Earlier quoted context omitted.
Best way to do it I've ever seen is the automated transactions tax, whereby you replace most taxes with a small percentage taken on every financial transaction (plus a larger one when converting to/from cash to account for the black economy). It's progressive because poor people will only pay twice (once on their salary/benefits, once when buying stuff), whereas rich people will pay several times when moving money ar…
Expect a new class of companies to spring up overnight that are dedicated to bundling transactions to avoid this new tax. For instance, I could make a single transaction to my broker that covered all of my expected expenditures for the month, and that broker would then disburse it to my payees, bundling it with funds from other payers to avoid the tax on the other end. I am strongly in favor of a tax on all stock mar…
Wouldn't work. Tax law can tell the difference between an individual transaction and bundled transactions. It's also the only area of law that allows for ex post facto changes to the criminality of acts.
Re: Battery supply problems faced by electric air taxis
#40The Achilles heel of electric aviation is that batteries don’t shed weight as they discharge. A fundamental aspect of Aerospace engineering is that rockets/planes shed a lot of weight during flight by by burning fuel. Many big jets take off at weights far too heavy to land and long ranges are only possible because of all the weight shed in flight. Until that issue can be addressed with electric aviation, electric pla…
Don’t conflate rockets and airplanes. Most of the energy an airplane uses is to overcome parasitic drag – to overcome the air resistance caused by moving forward through the air mass. While some of the energy is used to keep the plane in the air, that is not dominant. Yes, planes have a higher maximum takeoff weight then maximum landing weight, but that has to do with the design of the landing gear, in some hypothetical world where jet fuel did not shed weight, planes would only have slightly worse range.
The real problem with electric aviation is that batteries have terrible weight to energy ratios compared to fossil fuels.