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Channex757
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Electric planes: the state of the art

Thu Dec 20, 2018 10:16 am

https://thedriven.io/2018/11/12/this-ch ... ne-travel/

Progress in this field is nothing short of amazing. In just a couple of years manufacturers have gone from small 2 seat demonstrators to this latest design; a 9 seat small business or commuter type plane with 1000 km range and maintenance costs a third of an equivalent hydrocarbon fuelled aircraft.

At this rate, could the next absolute killer application be even closer than we think? A 100 seat shorthauler with half a megawatt charging facilities and a few thousand miles of range? There is a Chinese battery company working with Nissan who plan to breach the $100 per killowatt/hour cost next year, with a target of half that. At those prices batteries are even more feasible.
 
leghorn
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 10:42 am

https://www.upinthesky.nl/2018/12/17/ai ... che-motor/

airbus announced buying an old ARJ100 for testing a few days ago.
one of the four motors will be replaced with an electric motor

This is where we need the testing done so that short hop commercial aviation can be done between cities like Dublin and Manchester/Liverpool/Newcastle/Cardiff/Glasgow.

I hope Elon Musk sell out of Tesla and works it out of his system because he has always said he wants to get electric planes working. We only have a short window of opportunity here before he kills himself trying to become the first Martian.

BTW I'm taking my first ride in an electric intercity bus tomorrow to the airport which is about 80km away, my Renault Zoe arrives in February and I read yesterday that the Irish Government expect to be levying CO2 taxes of about 100 euro per tonne by 2050.
 
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JannEejit
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 10:50 am

Loganair have embarked upon a research project with Cranfield University aimed at electrically powering their Britten Norman Islanders, used for extremely short hops between the various Orkney Islands.
 
TSS
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 11:18 am

Channex757 wrote:
https://thedriven.io/2018/11/12/this-cheap-clean-electric-airplane-could-reshape-australian-regional-air-plane-travel/

Progress in this field is nothing short of amazing. In just a couple of years manufacturers have gone from small 2 seat demonstrators to this latest design; a 9 seat small business or commuter type plane with 1000 km range and maintenance costs a third of an equivalent hydrocarbon fuelled aircraft.

As a paper/cyber concept it's great, but my cynical self will want to see a life-size working prototype in action rather than a very slick but oddly-proportioned computer-generated picture before I'll take the company's claims seriously. The wingtip-mounted motors along with another motor at the tip of the tail seem more high school study hall doodle than a serious aircraft proposal in which rotation without damaging the aft propeller and asymmetric thrust from engine-out scenarios are real considerations.

The comments section underneath the linked article is most entertaining.
Able to kill active threads stone dead with a single post!
 
dtw2hyd
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 11:31 am

I think the electric hybrid is probably a better option than all battery powered.

Batteries have a major disadvantage over kerosine in aviation, its weight stays the same even after juice runs out. Al least kerosine burns up making the plane lighter.
All posts are just opinions.
 
parapente
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 11:45 am

Present liquid electrolyte lithium batteries do not have the required energy density, they function terribly in cold conditions and as we know can catch fire/explode.Oh and then there is the 'dendrite' growth issue that lowers performance over time.So no not ready yet.
But
The whole of the automotive world is working on solid state metal/lithium batteries.These have roughly double the energy density ( still far far lower than hydrocarbon fuels). But it's a start-when it comes - 5/10 years best estimate.

As above hybrid is another matter.An aircraft that could take off and land primarily on electric power would obviously be a game changer.

Note aircaft are 'point to point' vehicles to limited destinations ( airports).So hydrogen fuel stacks/cells are a very real possibility with the right ( hydrogen) infrastructure .Now this system does have a decent energy density.Automotive esp' BMW has done a lot of work on this technology.
But still way off.
We are getting closer and it's a good time to be testing technologies but not ready for commercial use yet sadly.
 
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hippogryphe
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 11:54 am

Someone did a back-of-the-envelope calculation here once on energy density of lithium ion battery vs. kerosene, something like 1:12 if I recall. Adding to that the above mentioned issue of the weight not burning off in flight and it's clear this tech is a non-starter except for small, short range toys at this stage. Down the road, who knows? I'm not an engineer but the even bigger issue to me seems like thrust output. An electric dynamo can spin up a propellor just fine but no combustion=no turbine as far as I know. Hydrogen revolution when?
 
WIederling
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 12:13 pm

dtw2hyd wrote:
I think the electric hybrid is probably a better option than all battery powered.


Helicopters and other vertical lift vehicles : that is where hybrid will be an attractive option.
efficient IC sustainer engine, short term high power electric overlay
providing twin engine savety on a single IC engine platform.
Murphy is an optimist
 
planecane
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 12:15 pm

parapente wrote:
Present liquid electrolyte lithium batteries do not have the required energy density, they function terribly in cold conditions and as we know can catch fire/explode.Oh and then there is the 'dendrite' growth issue that lowers performance over time.So no not ready yet.
But
The whole of the automotive world is working on solid state metal/lithium batteries.These have roughly double the energy density ( still far far lower than hydrocarbon fuels). But it's a start-when it comes - 5/10 years best estimate.

As above hybrid is another matter.An aircraft that could take off and land primarily on electric power would obviously be a game changer.

Note aircaft are 'point to point' vehicles to limited destinations ( airports).So hydrogen fuel stacks/cells are a very real possibility with the right ( hydrogen) infrastructure .Now this system does have a decent energy density.Automotive esp' BMW has done a lot of work on this technology.
But still way off.
We are getting closer and it's a good time to be testing technologies but not ready for commercial use yet sadly.


The issue with hydrogen is the volume not the weight. Look at the size of the space shuttle/SLS fuel tank vs something like the falcon 9 heavy that uses kerosene. With the latter it would be really apparent if it was a single tank instead of 3.

Besides the weight of the tank, it would add drag. This is much less of an issue with a rocket that is mostly flying in very low density atmosphere.

A hybrid using electric boost for take off has some potential but I'd imagine it only makes sense for long haul where the extra efficiency can be realized over a very long cruise to offset the battery and motor weight that must be carried around. Also, batteries will need to have excess capacity to allow for multiple go arounds.
 
planecane
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 12:16 pm

parapente wrote:
Present liquid electrolyte lithium batteries do not have the required energy density, they function terribly in cold conditions and as we know can catch fire/explode.Oh and then there is the 'dendrite' growth issue that lowers performance over time.So no not ready yet.
But
The whole of the automotive world is working on solid state metal/lithium batteries.These have roughly double the energy density ( still far far lower than hydrocarbon fuels). But it's a start-when it comes - 5/10 years best estimate.

As above hybrid is another matter.An aircraft that could take off and land primarily on electric power would obviously be a game changer.

Note aircaft are 'point to point' vehicles to limited destinations ( airports).So hydrogen fuel stacks/cells are a very real possibility with the right ( hydrogen) infrastructure .Now this system does have a decent energy density.Automotive esp' BMW has done a lot of work on this technology.
But still way off.
We are getting closer and it's a good time to be testing technologies but not ready for commercial use yet sadly.


The issue with hydrogen is the volume not the weight. Look at the size of the space shuttle/SLS fuel tank vs something like the falcon 9 heavy that uses kerosene. With the latter it would be really apparent if it was a single tank instead of 3.

Besides the weight of the tank, it would add drag. This is much less of an issue with a rocket that is mostly flying in very low density atmosphere.

A hybrid using electric boost for take off has some potential but I'd imagine it only makes sense for long haul where the extra efficiency can be realized over a very long cruise to offset the battery and motor weight that must be carried around. Also, batteries will need to have excess capacity to allow for multiple go arounds.
 
peterinlisbon
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 12:31 pm

Maybe this would work well for short routes where airlines are currently using Turboprops. They can swap out the batteries on the ground. It would probably make short flights a lot cheaper and it would also cut noise. It might even make very small airports viable that are not currently used because these small airports could connect small towns to the larger airports in each state or country.
 
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PW100
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 1:06 pm

A lot of wishful thinking there.

Anybody noticed that he airframe not pressurized (to save weight)? This thing does not even compare to a 50 year old Piper Navajo.

Electric 100 seater, able to fly above the weather, with meaningful real world range (1500 nm) is at least 40 years away. But probably much longer.
Immigration officer: "What's the purpose of your visit to the USA?" Spotter: "Shooting airliners with my Canon!"
 
parapente
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 1:23 pm

Norway is ( I believe) funding development for a regional (500 miles?) aircaft which is something ( I believe) EasyJet are also working on ( with partners no doubt).It mY be possible -just to achieve this with solid state batteries,but that's just a guess really ( although clearly the above mentioned feel it's possible or wouldn't be looking at it).
Sitting where I do - in London 500nm would actually allow you to reach a hoast of v important locations.Having said that.Even if it were possible,the economics of regional transport is all about fast turn around and in air utilisation.
Can't see how you do that if you have to recharge a huge amount of batteries each time.
Re energy density.I read similar with a 10:1 ratio for hydrocarbon fuel.Its a massive difference.
 
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Francoflier
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 1:27 pm

Aviation will likely be the last transport industry to switch to electric propulsion.
The energy density required, especially associated with the weight requirements of anything that flies, won't be available for a looong time.

I would rather advocate for the use of carbon neutral liquid hydrocarbons. The transition can be done quite easily, progressively and using current technology.
In fact, it has already started. The eventual taxation of CO2 production should pressure the industry towards accelerating that transition... hopefully.
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
Newbiepilot
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 1:38 pm

PW100 wrote:
A lot of wishful thinking there.

Anybody noticed that he airframe not pressurized (to save weight)? This thing does not even compare to a 50 year old Piper Navajo.

Electric 100 seater, able to fly above the weather, with meaningful real world range (1500 nm) is at least 40 years away. But probably much longer.


I would expect many sacrifices to save weight. It takes a lot of energy to travel 1000km. Storing that energy in liquid form such as kerosene is much lighter than a battery. The auto industry can reach us


Stored energy in fuel is considerable: gasoline is the champion at 47.5 MJ/kg and 34.6 MJ/liter; the gasoline in a fully fueled car has the same energy content as a thousand sticks of dynamite. A lithium-ion battery pack has about 0.3 MJ/kg and about 0.4 MJ/liter (Chevy VOLT). Gasoline thus has about 100 times the energy density of a lithium-ion battery. This difference in energy density is partially mitigated by the very high efficiency of an electric motor in converting energy stored in the battery to making the car move: it is typically 60-80 percent efficient. The efficiency of an internal combustion engine in converting the energy stored in gasoline to making the car move is typically 15 percent (EPA 2012). With the ratio about 5, a battery with an energy storage density 1/5 of that of gasoline would have the same range as a gasoline-powered car. We are not even close to this at present.


https://www.aps.org/publications/apsnew ... ckpage.cfm
 
WIederling
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 2:37 pm

Newbiepilot wrote:
PW100 wrote:
A lot of wishful thinking there.

Anybody noticed that he airframe not pressurized (to save weight)? This thing does not even compare to a 50 year old Piper Navajo.

Electric 100 seater, able to fly above the weather, with meaningful real world range (1500 nm) is at least 40 years away. But probably much longer.


I would expect many sacrifices to save weight. It takes a lot of energy to travel 1000km. Storing that energy in liquid form such as kerosene is much lighter than a battery. The auto industry can reach us

[i]
Stored energy in fuel is considerable: gasoline is the champion at 47.5 MJ/kg and 34.6 MJ/liter; the gasoline in a fully fueled car has the same energy content as a thousand sticks of dynamite. A lithium-ion battery pack has about 0.3 MJ/kg and about 0.4 MJ/liter (Chevy VOLT).


Thermodynamics.
You are making the error of counting all thermal energy as "workable" energy.
first order estimation allows for about 1/3 of thermal to be turned into "workable" energy.

(bigger) electric machines today tend to have conversion efficiency in the 94..98% range.
your cited energy density of 0.3 MJ/kg is today on the lowish side of things.

In the common path remains propulsion efficiency.
Murphy is an optimist
 
frmrCapCadet
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 2:43 pm

A pressurized fuselage likely will not appear until there is a real production model, nor is there a need at this time. I expect the first few commercial models will be for far less than 500 miles. And the cheaper they are the better. There is a great need for a one and two hundred mile transportation. Pressurized models with greater range will follow. And those early models outfitted with later technology batteries may be flying for 50 years. Or more!
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frmrCapCadet
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 3:46 pm

Let me ask some of our technical people.

For a plane going less than 200 miles, and less than 500 miles:
How fast does it have to fly to make things work well?
How high does it have to fly?
How long a runway will it need?

A modern jet is pressurized to 7 or 8000 feet. A small regional plane might not have to go over that. Would it kill the economic case that it couldn't fly over a high mountain range?
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YIMBY
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 3:52 pm

Francoflier wrote:
Aviation will likely be the last transport industry to switch to electric propulsion.
The energy density required, especially associated with the weight requirements of anything that flies, won't be available for a looong time.

I would rather advocate for the use of carbon neutral liquid hydrocarbons. The transition can be done quite easily, progressively and using current technology.
In fact, it has already started. The eventual taxation of CO2 production should pressure the industry towards accelerating that transition... hopefully.


Yes.

When all trains, cars and ships use electric propulsion, we can start thinking it in commercial aviation. (And military ... it would be nice to have an international treaty to use only electric war planes, tanks etc, but i would not hold my breath for such an agreement.)

If there is excess electricity, that could be used to make synthetic fuel for aviation. It could be cleaner than natural kerosene, to minimize the problems of pollution.
Biofuels are other possibility, though they are and will be rather scarce, and their ecology must be carefully analyzed.

Otherwise, best we can do to resist the climate change is to avoid flying :hissyfit: or plant trees in Sahara.
 
PPVRA
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 4:06 pm

There’s no great need for 1-200 mile transportation in an airplane, especially given all the complexities of flight operations. Just drive/take a train.

A pressurized fuselage will me MUCH heavier. Probably leave no payload.
"If goods do not cross borders, soldiers will" - Frederic Bastiat
 
airzona11
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 4:53 pm

YIMBY wrote:
Francoflier wrote:
Aviation will likely be the last transport industry to switch to electric propulsion.
The energy density required, especially associated with the weight requirements of anything that flies, won't be available for a looong time.

I would rather advocate for the use of carbon neutral liquid hydrocarbons. The transition can be done quite easily, progressively and using current technology.
In fact, it has already started. The eventual taxation of CO2 production should pressure the industry towards accelerating that transition... hopefully.


Yes.

When all trains, cars and ships use electric propulsion, we can start thinking it in commercial aviation. (And military ... it would be nice to have an international treaty to use only electric war planes, tanks etc, but i would not hold my breath for such an agreement.)

If there is excess electricity, that could be used to make synthetic fuel for aviation. It could be cleaner than natural kerosene, to minimize the problems of pollution.
Biofuels are other possibility, though they are and will be rather scarce, and their ecology must be carefully analyzed.

Otherwise, best we can do to resist the climate change is to avoid flying :hissyfit: or plant trees in Sahara.



Question is, how do you charge those batteries? How do you make those batteries? There is nothing "green" about the batteries themselves. Batteries have so long to go before they have a positive environmental impact.
 
AirFiero
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 5:34 pm

planecane wrote:
parapente wrote:
Present liquid electrolyte lithium batteries do not have the required energy density, they function terribly in cold conditions and as we know can catch fire/explode.Oh and then there is the 'dendrite' growth issue that lowers performance over time.So no not ready yet.
But
The whole of the automotive world is working on solid state metal/lithium batteries.These have roughly double the energy density ( still far far lower than hydrocarbon fuels). But it's a start-when it comes - 5/10 years best estimate.

As above hybrid is another matter.An aircraft that could take off and land primarily on electric power would obviously be a game changer.

Note aircaft are 'point to point' vehicles to limited destinations ( airports).So hydrogen fuel stacks/cells are a very real possibility with the right ( hydrogen) infrastructure .Now this system does have a decent energy density.Automotive esp' BMW has done a lot of work on this technology.
But still way off.
We are getting closer and it's a good time to be testing technologies but not ready for commercial use yet sadly.


The issue with hydrogen is the volume not the weight. Look at the size of the space shuttle/SLS fuel tank vs something like the falcon 9 heavy that uses kerosene. With the latter it would be really apparent if it was a single tank instead of 3.

Besides the weight of the tank, it would add drag. This is much less of an issue with a rocket that is mostly flying in very low density atmosphere.

A hybrid using electric boost for take off has some potential but I'd imagine it only makes sense for long haul where the extra efficiency can be realized over a very long cruise to offset the battery and motor weight that must be carried around. Also, batteries will need to have excess capacity to allow for multiple go arounds.


Actually, it is both. Obviously you can’t use the large volume of hydrogen like the space shuttle. Using hydrogen in airplanes would be more like the proposed hydrogen burning cars, which use very heavy tanks with the gas under tremendous pressure. Think welding tanks. Ever had to lift or move one? Better eat your Wheaties, they are HEAVY. What does all that added weight do to an airplane? Reduce useful payload, which is EVERYTHING in aviation.
 
PSAatSAN4Ever
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 6:12 pm

PPVRA wrote:
There’s no great need for 1-200 mile transportation in an airplane, especially given all the complexities of flight operations. Just drive/take a train.

A pressurized fuselage will me MUCH heavier. Probably leave no payload.


While I agree with this for the vast amount of the world, inter-island Hawai'i and other scattered island nations full of short hops might be the next logical step in this engine technology department.

In our discussions about the future of inter-island Hawai'ian travel, modern jet engines don't have the cool-down time between sets to operate the 11-14 cycles per day that Hawai'i needs. Something like this concept, while inefficient possibly for longer routes, might be what Hawai'i needs.
 
TSS
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 7:48 pm

PSAatSAN4Ever wrote:
PPVRA wrote:
There’s no great need for 1-200 mile transportation in an airplane, especially given all the complexities of flight operations. Just drive/take a train.

A pressurized fuselage will me MUCH heavier. Probably leave no payload.


While I agree with this for the vast amount of the world, inter-island Hawai'i and other scattered island nations full of short hops might be the next logical step in this engine technology department.

In our discussions about the future of inter-island Hawai'ian travel, modern jet engines don't have the cool-down time between sets to operate the 11-14 cycles per day that Hawai'i needs. Something like this concept, while inefficient possibly for longer routes, might be what Hawai'i needs.

Agreed. With current battery technology being what it is, electric aircraft using quick-change battery packs a la cordless drills might be a workable solution in that scenario. Aircraft lands, techs come out and swap the depleted battery pack for a freshly charged one while pax exit, techs then place the depleted battery on a charger so it'll be ready for the next flight.

More pics of the aircraft concept:

Expanded view of the pic in the article showing motor placement-
Image

3/4 side view from the other side-
Image

Head-on view-
Image

Even the proof-of-concept scale model needs extra tail support-
Image

Other issues aside, where are the batteries in the aircraft? From a weight & balance perspective, just ahead of the main landing gear and underneath the cabin floor would seem to be the optimum location, but in the large pic (assuming the seats are rendered to scale in the illustration) there doesn't appear to be enough room between the cabin floor and the bottom of the fuselage to accommodate the landing gear, let alone a large battery pack. Inside the wings where liquid fuel is stored in conventional aircraft might be a good location as well, but those are rather thin wings and I've got to wonder what access would be provided for inspection and replacement purposes.
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WIederling
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 10:15 pm

Propulsion on the wingtips. Best lever ever for asymmetric thrust.

Would that ever be certifiable as a passenger carrying plane?
It is ok as a drone : you can lose it with a shrug.
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RJMAZ
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Re: Electric planes: the state of the art

Thu Dec 20, 2018 11:07 pm

Newbiepilot wrote:
With the ratio about 5, a battery with an energy storage density 1/5 of that of gasoline would have the same range as a gasoline-powered car. We are not even close to this at present.[/i]

https://www.aps.org/publications/apsnew ... ckpage.cfm

Based on those numbers we're already there with battery tech. 1/5 is more than good enough.

A 787-8 sized airliner would have 1500nm range with 250 passengers

A G650ER would also fly 1500nm with 19 passengers.

A A321XLR would be close to 1000nm range.

A 777-8 or A350ULR would be pushing 2000nm range with 300 passengers.

All this means is electric aircraft will have to be sized and shaped like an ultralonghaul aircraft to do shorthaul. To do medium haul you would need an aircraft shaped like fitting a 767-200 size and width fuselage to a 777x wing and landing gear. This aircraft electric powered might be able to reach 3000nm on electric power. Hopefully the electricity is cheap because the electric aircraft will have a MTOW 3-4 times higher to fly the same payload equal distance.
 
AirFiero
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 12:44 am

RJMAZ wrote:
Newbiepilot wrote:
With the ratio about 5, a battery with an energy storage density 1/5 of that of gasoline would have the same range as a gasoline-powered car. We are not even close to this at present.[/i]

https://www.aps.org/publications/apsnew ... ckpage.cfm

Based on those numbers we're already there with battery tech. 1/5 is more than good enough.

A 787-8 sized airliner would have 1500nm range with 250 passengers

A G650ER would also fly 1500nm with 19 passengers.

A A321XLR would be close to 1000nm range.

A 777-8 or A350ULR would be pushing 2000nm range with 300 passengers.

All this means is electric aircraft will have to be sized and shaped like an ultralonghaul aircraft to do shorthaul. To do medium haul you would need an aircraft shaped like fitting a 767-200 size and width fuselage to a 777x wing and landing gear. This aircraft electric powered might be able to reach 3000nm on electric power. Hopefully the electricity is cheap because the electric aircraft will have a MTOW 3-4 times higher to fly the same payload equal distance.


In other words, you’d need more aircraft to haul less. That doesn’t sound like it would be a commercial success.
 
rbretas
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 2:11 am

Hydrogen is a moot point. The only way it can be cost effectively produced at the moment is through steam reformation of hydrocarbons, which is still much more expensive than kerosene while also generating CO2.
 
ewt340
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 3:10 am

Why do we need 2 doors on this tiny aircraft? could they just got away with a single door. The second one seems unnecessary unless it's for an extremely tight regulations. And the second stair surely add extra weight. The placement of the engines is a bit weird too.

Image
 
ScottB
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 4:30 am

PSAatSAN4Ever wrote:
While I agree with this for the vast amount of the world, inter-island Hawai'i and other scattered island nations full of short hops might be the next logical step in this engine technology department.

In our discussions about the future of inter-island Hawai'ian travel, modern jet engines don't have the cool-down time between sets to operate the 11-14 cycles per day that Hawai'i needs. Something like this concept, while inefficient possibly for longer routes, might be what Hawai'i needs.


Unfortunately, the total global market size for inter-island travel within archipelagos probably doesn't meet the necessary scale to support a commercial aircraft development program, especially with modern safety requirements. Moreover, the requirements are quite different for different regions; i.e. Hawai'i needs 100-to-150-seat aircraft for trunk routes while this would be far too large for Tahiti, Fiji, Vanuatu, etc.

Recharging the aircraft batteries is unlikely to be fast enough to support short turnarounds, and IMO it would be challenging to safely swap what would almost certainly be heavy power packs during a quick turn. I also expect that an aircraft dependent on batteries would require redundant power packs to deal with potential failures, and large battery packs with the necessary safety features to prevent/contain thermal runaway are likely to be even heavier than what we're seeing in these prototypes; c.f. the 787's Li-ion battery issues and the heavy armor retroactively fashioned around those batteries.
 
JayinKitsap
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 4:45 am

Hydrogen filled blimps, the fuel for the main engine with fuel cells for power, electric thrusters. Should work great



https://www.airships.net/hindenburg/disaster/
 
TSS
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 5:56 am

ewt340 wrote:
Why do we need 2 doors on this tiny aircraft? could they just got away with a single door. The second one seems unnecessary unless it's for an extremely tight regulations. And the second stair surely add extra weight.

Current evacuation regs may require two exits on all commercial passenger aircraft, I don't know for sure. Often there is one on either side. Much more so than the number of doors I have a problem with the door's design- Two sections that each open in entirely different ways with what might be the world's flimsiest staircases attached to the bottom section of each one? Why not just go with one-piece doors hinged at the bottom with steps molded on to the inside of each door, as has been used on private jets, instead?
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Waterbomber
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Joined: Sat Jul 09, 2016 11:51 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 9:24 am

While on paper this would seem comparable to a Cessna Caravan that has a 500kW engine and 9 seats, one has to realise that the fuel load for a C208 would be about 450kg for a 1000 hour journey.
A 900kWh battery pack would weigh about 5000kg, which is about 150% of the C208's gross weight.

So is it possible at all?
Let's imagine that they fit an A321 fuselage on an A380 wing, how far would it be able to fly?
Supposing lighter electric engines, a lighter structure, the machine without battery pack would weigh a bit more than half the empty weight of the A380 at about 180 tons.
Now we have 300 tons of useful weight left to play with, of which 20 tons goes to payload.
Remain 180 tons of weight for the batteries.
The current state of the art Lithium-based batteries are getting to 200 Wh per kg or 200kWh per ton..
280 tons would give you 56000kWh or 56MWh worth of capacity.
In comparison, a single A380 engine, a single T900 will develop 56MW of power at full power. Even if electric engines can develop the same power more efficiently, they will need to develop the same power.
So basically, a 280 ton battery pack fitted to an A380 with an A321 fuselage would have enough capacity to power a single A380 engine for an hour if the engines can operate at 100% efficiency.
For all 4 engines, only 15 minutes...

As you can see from this example, the problem is that batteries need to reach a certain turning point in weight density.
At current, the energy density is insufficient even for a wing shaped battery pack to sustain flight without added power input as with the Solar Impulse.

No matter how big the wing, each time you make the wing bigger to get a better L/D ratio or fit in more batteries, the weight of the batteries is going to drag you down.

In scientific terms, if today's commercial designs are designed for a lift to drag ratio of 20, the battery technology only having 1/6th the energy density of aviation fuel at best, even if electric engines can double the conversion efficiency, you would need a lift to drag ratio of about 60.
This is sailplane territory.

So we're getting there, but if you see paper projects that look nothing like a sailplane, you can already dismiss them as non plausible.

As for hybrids, this was already covered in another thread a few months ago, I believe the Norway electric-only plane legal requirement by 2030 or 2040 thread.
Hybrid cars convert waste from braking back into potential energy, they don't produce energy more efficiently. There is hence no merit to a hybrid aircraft.

Adding to the above, the safety concerns are insurmountable, as is the cost of batteries.
Furthermore, at a global scale, 75% of electricity is produced today from non-renewable sources, which makes it an illusion that this would save global warming.
When even land-based energy needs are not being met by renewable sources despite the possibility and viability of it, it's a bit too much to expect airborne transportation to become a pioneer in the field.
This is like mankind trying to go from walking on four feet to walking on their hands... It is absurd.
 
2175301
Posts: 1909
Joined: Wed May 16, 2007 11:19 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 10:10 am

Waterbomber wrote:
Furthermore, at a global scale, 75% of electricity is produced today from non-renewable sources, which makes it an illusion that this would save global warming.
When even land-based energy needs are not being met by renewable sources despite the possibility and viability of it, it's a bit too much to expect airborne transportation to become a pioneer in the field.
This is like mankind trying to go from walking on four feet to walking on their hands... It is absurd.


It's actually worse than most people think as far as efficiency. Yes, electric motors can achieve 95% efficiency. The question is where does the electricity come from that is put in those batteries.

The bulk of that 75% of the electrical power production is via steam cycle thermal plants with efficiencies in the range of 30 - 35%. The latest natural gas or refined oil fired combustion turbine & steam cycle plants are in the 50-60% efficiency range (and natural gas and refined oil tends to be a costly fuel compared to other fuel sources).

Here's the kicker that most people never heard of: The amount of electricity delivered to small factories, households, small business, etc. for most cities and rural areas is only about 50% of what is generated. The other 50% is transmission and distribution line losses. Very large factories and users can push the delivered up to in the 80-90% range if they can take a direct feed of a 115KV or higher voltage line to their transformer yard.

Last I looked (about a decade ago) modern developments and communities are building local distribution in the 30-40 KV range which increases the delivered to about 75% of what is produced by the power plant.

A lot of the USA and Europe (and other countries) have legacy distribution systems that are typically in the 2-14 KV range. It is not economical to replace and upgrade local distribution systems to higher voltages just on the savings. However, when they have to be replaced anyway due to age that are typically upgraded to at least 6 KV (which fits into the same footprint and clearance of the older lines), and within the US more common to 13.2 or 13.8 KV. If they have the line clearance room and the substation room they may go for mid 20s to 40 KV. Underground lines are exponentially costly to upgrade beyond 13.8 KV - and often are installed at 6.9 KV or less In the USA.

So take a 33% power plant, deliver half of the power to a battery charger, assume no changing or battery losses (not realistic), run that though a 95% motor - and you have an overall fuel efficiency of about 15.7%. Now add the massive batteries needed.

I really don't think jet engines or turbo props are really going to be challenged by electrical aircraft any time soon as a cost effective means of transportation - on any large scale. Small scale where they ignore the efficiencies of generation and delivery of electricity and the existing grid can easily support... may exist. But, not on a large energy use scale.

As for Hydrogen: It can be produced using nuclear power plants doing a several process plant with most of it from electrical disassociation from water (and some from "waste heat" steam fracking of natural gas and other products). That has been extensively modeled and the cost and efficiencies are fairly well known.

But, for aviation the hydrogen would be recombined with carbon to make jet fuel due to the energy density and ease of use. Thus jets will fly for a long time...

Of course; should their be a breakthrough of a totally new energy source (or production method) - that could all change.

Have a great day,
 
RJMAZ
Posts: 2081
Joined: Sat Jul 09, 2016 2:54 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 11:00 am

Waterbomber wrote:
In comparison, a single A380 engine, a single T900 will develop 56MW of power at full power. Even if electric engines can develop the same power more efficiently, they will need to develop the same power.
So basically, a 280 ton battery pack fitted to an A380 with an A321 fuselage would have enough capacity to power a single A380 engine for an hour if the engines can operate at 100% efficiency.
For all 4 engines, only 15 minutes...

All your calculations are wrong. As you missed one very important thing.

Engine thrust decreases with altitude. A T900 puts out a fraction of that power at 40,000ft. This also means an aircraft needs a fraction of the power to maintain cruise at high altitude.

Taking this into account that 15 minutes would easily exceed 2 hours. 1000+nm easy with current battery tech.

An A380 wing with a A321 fuselage would have such an amazing lift to drag ratio it would probably only need two T900 engines to takeoff.

Electric engines also dont reduce thrust with altitude, so the engines would throttle right back at 40,000ft while cruising.
 
frmrCapCadet
Posts: 4423
Joined: Thu May 29, 2008 8:24 pm

Re: Electric planes: the state of the art

Fri Dec 21, 2018 1:00 pm

An electric or hybrid plane carrying ten to a hundred passengers up to 400 miles could destroy the need for Greyhound and Amtrak. Quiet takeoffs and landings would obviate noise problems near cities. Lower flying non-pressurized planes would be a little more affected by weather, but here in Washington state we have had two major wind storms and a tornado in the last several days which did ae job on our state and local ferry schedules, but we have the means to cope with it. There are few places in the state farther than 30 miles to the nearest airstrip or airport, and better weather forecasting makes them viable for safe flying.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
frmrCapCadet
Posts: 4423
Joined: Thu May 29, 2008 8:24 pm

Re: Electric planes: the state of the art

Fri Dec 21, 2018 1:00 pm

An electric or hybrid plane carrying ten to a hundred passengers up to 400 miles could destroy the need for Greyhound and Amtrak. Quiet takeoffs and landings would obviate noise problems near cities. Lower flying non-pressurized planes would be a little more affected by weather, but here in Washington state we have had two major wind storms and a tornado in the last several days which did a job on our state and local ferry schedules, but we have the means to cope with it. There are few places in the state farther than 30 miles to the nearest airstrip or airport, and better weather forecasting makes them viable for safe flying.
Buffet: the airline business...has eaten up capital...like..no other (business)
 
parapente
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 1:10 pm

https://www.mirror.co.uk/travel/news/ea ... s-13500358

This is the latest on the EasyJet electric powered development.Clearly a serious venture.But sadly I remain sceptical.500 km.300miles or less.Amsterdam the target -and no doubt anywhere in U.K.
But you can take an electric train to any of these places.So no environmental saving there.Frankly at the present rate of development in the US and China ( some in Europe).Very soon there will be ( maybe there are already) electric coaches with a 300 mile range.So no environmental saving there either.
Ok the plane is a bit faster than a high speed train and obviously a coach.But they go city centre to centre so perhaps no time saving.But a lot more electricity used.
What am I missing?
 
leghorn
Posts: 1297
Joined: Sun Jan 22, 2017 9:13 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 1:33 pm

how many changes of train from Newcastle to Amsterdam?
No trains to Ireland. That's about 33million passengers for Ireland mainly going to near Europe.
 
hitower3
Posts: 188
Joined: Fri Oct 21, 2016 9:55 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 2:45 pm

Dear a-netters,

Let me try to calculate the possibility and capability of a A320-sized electrical aircraft.

For information I am a material engineer working in the electrical industry, specializing in high temperature insulation optimization.

So, let's see the energy requirements for a 2h / 800nm flight:
A current A320NEO would likely require a fuel tankage (including reserves) of 6 tons. At 46.2 MJ/kg, this is equivalent to 277.2 GJ of chemical energy "on board". Assuming an average conversion efficiency from chemical energy to thrust of 33% of the engines, the amount of energy the plane will require in the form of thrust is about 91,5GJ.

Now let's go electric.We can assume a much higher efficiency for the conversion of electrical energy to thrust, I will use a figure of 80% here. This would define my electrical energy requirement for the flight of 114,3 GJ. Convert it to MWh (1 MWh = 3,6GJ): 31,8 MWh of required battery capacity.
The energy density of current cells is around 250kWh/ton, but upcoming solid state cells promise roughly double of that, i.e. 500kWh/ton. Assuming that, by the time an electrical plane is developed, such solid state batteries are available in industrial quantities, the weight of such a battery would be 63,5 ton.

In practice, the A320 is obviously not capable to lift such a heavy battery, as this would require to bump the MTOW from 78t to something around 125t. Basically, you would have to fit a 757 wing under the Bus.

But this is the state of the technology of today or just a few years ahead. Looking some 15 to 20 years into the future, the energy density of the batteries will likely increase further, while their cost will diminish and the practical limitations (charging time, lifetime, temperature ranges) will progressively go away. All in all, electrical technology progresses much faster than traditional combustion engine technology. It is therefore not a question IF electrical will prevail, but WHEN!

Wishing all of you a merry Christmas and my best wishes for 2019!
Hendric
 
UpNAWAy
Posts: 700
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 2:50 pm

If we are going to all electric everything why are we not also starting a massive worldwide (Especially in the 3rd world) Nuclear Energy push to produce all this electricity?
 
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smithbs
Posts: 519
Joined: Wed May 17, 2017 6:09 pm

Re: Electric planes: the state of the art

Fri Dec 21, 2018 3:00 pm

RJMAZ wrote:
Waterbomber wrote:
In comparison, a single A380 engine, a single T900 will develop 56MW of power at full power. Even if electric engines can develop the same power more efficiently, they will need to develop the same power.
So basically, a 280 ton battery pack fitted to an A380 with an A321 fuselage would have enough capacity to power a single A380 engine for an hour if the engines can operate at 100% efficiency.
For all 4 engines, only 15 minutes...

All your calculations are wrong.


Could you please show your own math? In engineering discussions, it doesn't count if someone says "you're wrong" without a detailed response. If this great debate of electric aircraft hinges on the math and physics, we need to see well-explained figures.
 
hitower3
Posts: 188
Joined: Fri Oct 21, 2016 9:55 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 3:01 pm

UpNAWAy wrote:
If we are going to all electric everything why are we not also starting a massive worldwide (Especially in the 3rd world) Nuclear Energy push to produce all this electricity?


Hello,

Nuclear is dead. At least from an economic perspective. You can produce electricity at rates as low as 50USD/MWh from PV or wind farms (this is taking into account the cost for transformation into 110kV lines. New built nuclear plants would easily reach twice that cost, without even accruing for waste storage and possible nuclear disasters.
I would speculate that if someone builds a nuclear plant today, he is either under political misguidance, or he needs the plant for (hidden) military purposes.

We don't need no nukes! :-)
Hendric
 
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flyingturtle
Posts: 5909
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 3:20 pm

JayinKitsap wrote:
Hydrogen filled blimps, the fuel for the main engine with fuel cells for power, electric thrusters. Should work great

https://www.airships.net/hindenburg/disaster/


And yet, before Hindenburg, no airship ever had a problem with its hydrogen filling. They had deadly accidents where airships crashed in wind gusts. Airships were ripped open. But no fire.

---

Regarding the wingtip engines: Aren't electrical engines eeeeextreeemely reliable? An electric engine does away with most failure modes of jet/turboprop engines.


David
Reading accident reports is what calms me down
 
Waterbomber
Posts: 849
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Re: Electric planes: the state of the art

Fri Dec 21, 2018 3:26 pm

RJMAZ wrote:
Waterbomber wrote:
In comparison, a single A380 engine, a single T900 will develop 56MW of power at full power. Even if electric engines can develop the same power more efficiently, they will need to develop the same power.
So basically, a 280 ton battery pack fitted to an A380 with an A321 fuselage would have enough capacity to power a single A380 engine for an hour if the engines can operate at 100% efficiency.
For all 4 engines, only 15 minutes...

All your calculations are wrong. As you missed one very important thing.

Engine thrust decreases with altitude. A T900 puts out a fraction of that power at 40,000ft. This also means an aircraft needs a fraction of the power to maintain cruise at high altitude.

Taking this into account that 15 minutes would easily exceed 2 hours. 1000+nm easy with current battery tech.

An A380 wing with a A321 fuselage would have such an amazing lift to drag ratio it would probably only need two T900 engines to takeoff.

Electric engines also dont reduce thrust with altitude, so the engines would throttle right back at 40,000ft while cruising.


First of all, thank you for reading the content that I wrote.
Sure, at cruise altitude turbofans burn less fuel per unit of distance travelled and if aircraft were battery-powered they would consume less electricity per unit of distance travelled, so you are right that range-wise, we shall not assume that the engines would always be sucking power from the batteries at 100%.

In this particular case though, I'm not wrong and I'll explain why. As calculated above with some assumed parameters, an electric lithium battery powered A380 that would have its fuselage replaced by an A321 fuselage to maximise the weight available to the batteries, would not be able to fly at full power for more than 15 minutes.
To that you responded that the power requirements are different at 40.000ft, which is irrelevant as it would not be able to reach that altitude in the first place, not with the current energy density of batteries. In fact, taking into account safety regulations, the aircraft would not be allowed to take-off given that it wouldn't be able to meet final reserve requirements. The final reserve is an operational parameter that would apply to any aircraft in the interest of safety.

The lift to drag ratio of an A380 with an A321 fuselage would not improve by enough to make a difference. The wing stays the same, the tailplane may need to be made bigger due to the shorter fuselage and torque arm length.
The narrower fuselage would be the only improvement so at best, profile drag could be reduced by 25%, increasing the lift to drag ratio by 33%. If it was 18, it would become 24.
The assumed aircraft would be able to stay airborne 1/3rd longer, ie 20 minutes at 100% power instead of 15 minutes. We're still not clearing safety requirements.

Also, we are ignoring battery heating requirements. LIthium ion batteries would lose 40% of their retentive capacity at - 20 degrees Celsius.
Also, operating at below - 40 degrees Celsius is out of the question, while discharge rates will be reduced strongly at anything close to these temperatures. The batteries would need heating, friction heating from ram air will not be sufficient.

Poster 2175301 exposes some other major loss issues that strongly impact the feasibility of an electrical aviation infrastructure or in fact, any electricity-centered transportation infrastructure.
Efficiency gains of the electric motors can get lost at the distribution level as transportation of carbohydrates from source to fuel tank is quite energy efficient, at levels comparable to distribution losses from locally produced renewable electricity.
 
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SomebodyInTLS
Posts: 1868
Joined: Wed Jun 15, 2016 12:31 pm

Re: Electric planes: the state of the art

Fri Dec 21, 2018 3:37 pm

UpNAWAy wrote:
If we are going to all electric everything why are we not also starting a massive worldwide (Especially in the 3rd world) Nuclear Energy push to produce all this electricity?


Because despite what people think renewables are already the most cost-effective form of energy generation and their deployment is increasing at an exponential rate.

Nuclear (fission) - even before taking decommisioning into account - has proven to be the LEAST effective way of generating electricity. That's why there's been almost nothing new built in the last couple of decades - and the handful currently under construction (and way over time and budget) are the result of lobbying and subsidies.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
TSS
Posts: 3672
Joined: Fri Dec 29, 2006 3:52 pm

Re: Electric planes: the state of the art

Fri Dec 21, 2018 4:41 pm

flyingturtle wrote:
Regarding the wingtip engines: Aren't electrical engines eeeeextreeemely reliable? An electric engine does away with most failure modes of jet/turboprop engines.

Yes, electric motors are extremely reliable. They do still occasionally stop working without warning, though, whether it be from a purely electrical issue like a short or a failed control component, or a mechanical issue like a bearing gone bad. Plus these motors will be turning conventional propellors and they have been known to fail as well, particularly after having scimitared their way through the bodies of birds.
Able to kill active threads stone dead with a single post!
 
leghorn
Posts: 1297
Joined: Sun Jan 22, 2017 9:13 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 4:41 pm

Posting from a byd electric long distance bus. I am living the dream! :)
 
leghorn
Posts: 1297
Joined: Sun Jan 22, 2017 9:13 am

Re: Electric planes: the state of the art

Fri Dec 21, 2018 4:50 pm

I think to increase the reliability while aiding simplicity they are proposing double props and motors on the same shaft so that if one fails the other still provides thrust on that side of the plane.
 
WIederling
Posts: 9448
Joined: Sun Sep 13, 2015 2:15 pm

Re: Electric planes: the state of the art

Fri Dec 21, 2018 4:55 pm

2175301 wrote:
Here's the kicker that most people never heard of: The amount of electricity delivered to small factories, households, small business, etc. for most cities and rural areas is only about 50% of what is generated. The other 50% is transmission and distribution line losses. Very large factories and users can push the delivered up to in the 80-90% range if they can take a direct feed of a 115KV or higher voltage line to their transformer yard.


No idea in what kind of 3rd world country you live in.

For Germany overall grid losses are below 5% (4.4%@2013).
Murphy is an optimist

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