Australia's first electric aircraft has begun test flights • Hacker News Board

Re: Australia's first electric aircraft has begun test flights

#41

Post by Hasz » Sat, Jan 06, 2018, 6:03 PM UTC

kevincox wrote: post #27

TillE wrote: post #25

Are there denser ways to store electrical energy? Hydrogen fuel cells maybe? Seems like you need something much lighter than lithium-ion batteries to even begin to fill the role of passenger planes.

Hydrogen fuel cells would also make refuelling much faster. In the video they claimed an hour recharge time for the small plane. While you can get more parallelism as you add more batteries it still seems like making it much faster would be beneficial.

It seems like battery swapping would be a viable alternative here. The packs are only ~17kWh

Re: Australia's first electric aircraft has begun test flights

#42

Post by wallace_f » Sat, Jan 06, 2018, 6:04 PM UTC

pkolaczk wrote: post #21

jfoucher wrote: post #14

Earlier quoted context omitted.

Coal power plants are roughly as efficient as an internal combustion engine (around 40%) and considering the power transmission losses, charging losses, electric engine inefficiencies and so on, any electric vehicle has worse overall efficiency than the equivalent gas vehicle. Electric vehicles only make sense from a pollution reduction point of view if the power is generated from renewable sources.

Typical coal power plants have practical electric efficiency 40% but total energy efficiency is 60-70%, because they produce electricity and useful heat . Also 40% is a theoretical (lab) value for a non turbocharged diesel engine - in practice most engines are operated out of their optimal range, they are turbocharged (a turbo increases power output at the cost of decreasing compression ratio and thermal efficiency),…

Are you sure about your statement on turbos reducing efficiency? Some of the most economical consumer engines are turbocharged--in fact auto makers commonly cite mpgs as a reason to use turbos; so I am confused.

Re: Australia's first electric aircraft has begun test flights

#43

Post by dang » Sat, Jan 06, 2018, 6:21 PM UTC

gus_massa wrote: post #29

pedrocr wrote: post #28

Earlier quoted context omitted.

This is local news so what they mean is that this is the first plane in the country with those characteristics. The internet makes local news sites global and it probably never even crossed their minds that someone not local would naturally make that interpretation from the headline.

What about "First electric passenger plane takes to the skies in Australia"?

That's better, except someone would then complain that "first" implies that it's the world's first and happens to be in Australia. We used your suggestion but reordered the phrases above.

Edit: actually, I think we can get around all this by just using the first sentence of the article.

Re: Australia's first electric aircraft has begun test flights

#44

Post by [deleted] » Sat, Jan 06, 2018, 6:22 PM UTC

mey wrote: post #3

aphextron wrote: post #2

The plane is a Pipistrel Alpha Electro [0]. Designed and built entirely in Slovenia. Kind of a weird/misleading article as it presents the plane as Australian. [0] http://www.pipistrel.si/plane/alpha-electro/overview

Additionally I'm not sure I would call a 2 seater, a "passenger plane".

[deleted]

Re: Australia's first electric aircraft has begun test flights

#45

Post by goodcanadian » Sat, Jan 06, 2018, 6:34 PM UTC

chrismorgan wrote: post #38

scoggs wrote: post #19

Earlier quoted context omitted.

Very cool, right? I had a brain fart when I read the title on the front page thinking it was a self-driving electric plane, for some odd reason, and my heart skipped a beat. >It costs about $3 an hour to run the plane's engine, one-tenth the cost of a fuel engine. This sounds really great and at only €65,000 ($78196.30USD) it sounds like a steal that will scale nicely once it can carry the 5+ passengers it intends to…

Where’s the €65,000 number coming from? I found http://www.flypipistrel.com/price-lists/PIPISTREL-ALPHA-ELEC... which suggests €159,000. That datasheet also says 700 cycles to 75% battery capacity, rather than the “about 1,000” of this article. The $3/hour figure doesn’t seem to me to match the other numbers, either: 60kW for takeoff and 20kW for cruising; let’s ignore takeoff (it’s rounding error) and just call it 2…

Price of electricity varies greatly depending on where you are. My residential rate is about $0.13/kWh, so completely consistent with the article.

Re: Australia's first electric aircraft has begun test flights

#46

Post by olfox » Sat, Jan 06, 2018, 6:42 PM UTC

jfoucher wrote: post #33

olfox wrote: post #20

Earlier quoted context omitted.

You would find it very hard, if not impossible, to run an ICE car at 40% efficient for normal driving. The same can not be said for a coal plant. So if the coal plant averages 35% and the ICE car averages 25%, that leaves some room for a coal-driven electric car to be more efficient. The conversion from grid power to mechanical power only needs to be over 70% efficient. If anything, that sounds easy to beat. Any coun…

I we say all three of: charging, motor controller and motor are about 90% efficient, that's already 72% efficiency from grid power to mechanical. So maybe not that easy.

While a 90% efficient motor is quite good, a 90% controller and a 90% charger is not. I would expect them to be closer to 95%. But I have to back down from easy, according to [1], some Tesla owners charge their vehicles at 80% efficiency and not the ideal 92-98%. I imagined that would be a problem at those energy levels, apparently not! Anyhow, there is nothing inherently worse about fueling a central ICE to pump out electricity to EVs than directly fueling an ICE car. Larger ICEs tend to be more efficient, especially so for diesels. If you add the savings by the regenerative charging enabled by electric motors, it becomes even more favorable to electrify cars. We need a lot of batteries though!

[1] https://forums.tesla.com/forum/forums/charging-efficiency-0

Re: Australia's first electric aircraft has begun test flights

#47

Post by seanmcdirmid » Sat, Jan 06, 2018, 6:50 PM UTC

pkolaczk wrote: post #21

jfoucher wrote: post #14

Earlier quoted context omitted.

Coal power plants are roughly as efficient as an internal combustion engine (around 40%) and considering the power transmission losses, charging losses, electric engine inefficiencies and so on, any electric vehicle has worse overall efficiency than the equivalent gas vehicle. Electric vehicles only make sense from a pollution reduction point of view if the power is generated from renewable sources.

Typical coal power plants have practical electric efficiency 40% but total energy efficiency is 60-70%, because they produce electricity and useful heat . Also 40% is a theoretical (lab) value for a non turbocharged diesel engine - in practice most engines are operated out of their optimal range, they are turbocharged (a turbo increases power output at the cost of decreasing compression ratio and thermal efficiency),…

How is the useful heat used? I know some places have central heating, so the hot water is just piped throughout the city, but if not that, what would they do with it?

Re: Australia's first electric aircraft has begun test flights

#48

Post by seanmcdirmid » Sat, Jan 06, 2018, 6:53 PM UTC

olfox wrote: post #20

jfoucher wrote: post #14

Earlier quoted context omitted.

Coal power plants are roughly as efficient as an internal combustion engine (around 40%) and considering the power transmission losses, charging losses, electric engine inefficiencies and so on, any electric vehicle has worse overall efficiency than the equivalent gas vehicle. Electric vehicles only make sense from a pollution reduction point of view if the power is generated from renewable sources.

You would find it very hard, if not impossible, to run an ICE car at 40% efficient for normal driving. The same can not be said for a coal plant. So if the coal plant averages 35% and the ICE car averages 25%, that leaves some room for a coal-driven electric car to be more efficient. The conversion from grid power to mechanical power only needs to be over 70% efficient. If anything, that sounds easy to beat. Any coun…

What about refinement costs to turn oil into gasoline in the first place? That takes energy as well, and creates pollution. So we have a loss before we even get to the ICE.

Re: Australia's first electric aircraft has begun test flights

#49

Post by labcomputer » Sat, Jan 06, 2018, 6:55 PM UTC

kevincox wrote: post #27

TillE wrote: post #25

Are there denser ways to store electrical energy? Hydrogen fuel cells maybe? Seems like you need something much lighter than lithium-ion batteries to even begin to fill the role of passenger planes.

Hydrogen fuel cells would also make refuelling much faster. In the video they claimed an hour recharge time for the small plane. While you can get more parallelism as you add more batteries it still seems like making it much faster would be beneficial.

Probably not as much as you'd think, though.

Cars powered by compressed natural gas take longer to fill than gasoline-powered ones[1]. I can't find it right now, but Edmunds did a long-term test of a natural gas Honda Civic. One of the persistent complaints was long fill times at public high-pressure stations. Natural gas has about 4x the energy density of Hydrogen, so the problem becomes even worse.

Re: Australia's first electric aircraft has begun test flights

#50

Post by ajkjk » Sat, Jan 06, 2018, 6:59 PM UTC

jfoucher wrote: post #34

icebraining wrote: post #22

Earlier quoted context omitted.

What's the power transmission loss from carrying crude to a refinery and then to Australia? The country is a net importer of oil, which means tankers burning foul stuff to carry it there.

Very true. Considering the whole supply chain for accurate comparison is complicated. Although I think my main point still stands : from an environmental perspective it's rather ineffective to have an electric car in a place where electricity comes from fossil fuels.

While electric cars might be worse for the environment, they're probably much better for people, because the pollution generation can be moved well away from dense urban areas. I imagine most people don't even remember what a city without gasoline pollution, like, smells like.

I imagine it will be similar to those before-after photos of cleaning smoker's apartments.