What will power our vehicles in the future?

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#2975750 1-Oct-2022 11:05

tweake:

frankv:

I see that Eviation has flown their Alice for the first time. https://airwaysmag.com/first-flight-eviations-alice/

This is a 9-passenger aircraft, so a competitor for the likes of the Cessna Caravan. The big differences are the weight (Alice max gross is 16,500lb of which 8300lb is batteries, payload 5,000lb, Caravan max gross 8,000lb, payload 3,300lb) range (440nm vs 1000nm), cruise speed (250 vs 186 knots), and price (US$4M vs US$2.5M). Battery recharge time is 70 minutes (30 minutes for a 1-hour flight). So for short-haul flights from paved runways the Alice will out-perform the Caravan handsomely, and if electricity is cheap enough relative the Jet A1, perhaps well enough to recoup the price. Certainly several short-haul airlines think so, with somewhere around 140 aircraft already ordered.

its not really a competitor to the Cessna Caravan as the caravan carries far more load.

The figures I have (highlighted above) say the Alice carries far more load than the Caravan.

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#2975767 1-Oct-2022 12:23

A couple of articles I read say 2500 lbs for the Alice. Wiki also says 2500 lbs (1100 kg) https://en.m.wikipedia.org/wiki/Eviation_Alice

The speed you quoted for the Caravan was a TAS though not sure at what altitude. Wonder what altitude was used for the Alice figures. So the Alice is faster, though at what energy consumption penalty.

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#2975776 1-Oct-2022 12:47

frankv:

..This is a 9-passenger aircraft, so a competitor for the likes of the Cessna Caravan. The big differences are the weight (Alice max gross is 16,500lb of which 8300lb is batteries, payload 5,000lb, Caravan max gross 8,000lb, payload 3,300lb) ........

The figures I have (highlighted above) say the Alice carries far more load than the Caravan.

https://www.eviation.com/aircraft/#Alice-Specifications

WEIGHTS
MTOW18,400 lbs
Useful Payload (Commuter)2,500 lbs

its actually heavier than you mention and half the payload. which makes sense as its only 9 passengers compared to 14 for the caravan. the critical thing is bums on seats is what pays for the flight. the flights cost is split 9 ways instead of 14. that makes it an expensive flight. hence why i don't see it becoming a caravan replacement.

however i would expect specs to change a bit before they get into production. after all its only a prototype.

it will be interesting to see what real world range they get and also the effects of temperature are on the batteries during flight.

Technofreak

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#2975781 1-Oct-2022 13:10

tweake:

https://www.eviation.com/aircraft/#Alice-Specifications

WEIGHTS
MTOW18,400 lbs
Useful Payload (Commuter)2,500 lbs

its actually heavier than you mention and half the payload. which makes sense as its only 9 passengers compared to 14 for the caravan. the critical thing is bums on seats is what pays for the flight. the flights cost is split 9 ways instead of 14. that makes it an expensive flight. hence why i don't see it becoming a caravan replacement.

however i would expect specs to change a bit before they get into production. after all its only a prototype.

it will be interesting to see what real world range they get and also the effects of temperature are on the batteries during flight.

Usually change for the worse. Reality tempers the optimistic goals of the initial concept.

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#2977019 3-Oct-2022 23:04

Hydrogen electric for the Cessna Caravan.

https://www.avweb.com/aviation-news/hydrogen-electric-caravan-proposed/

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tweake

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#2977375 4-Oct-2022 16:31

Technofreak:

Hydrogen electric for the Cessna Caravan.

https://www.avweb.com/aviation-news/hydrogen-electric-caravan-proposed/

that will be interesting to see. i wonder if they will have to beef up the wing to handle the tanks. also what size battery would they need as fuel cells are not fast in changing output.

of course is hydrogen fuel cell better than just burning the hydrogen in an engine ??

johno1234

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#2977379 4-Oct-2022 16:41

tweake:

frankv:

..This is a 9-passenger aircraft, so a competitor for the likes of the Cessna Caravan. The big differences are the weight (Alice max gross is 16,500lb of which 8300lb is batteries, payload 5,000lb, Caravan max gross 8,000lb, payload 3,300lb) ........

The figures I have (highlighted above) say the Alice carries far more load than the Caravan.

https://www.eviation.com/aircraft/#Alice-Specifications

WEIGHTS
MTOW18,400 lbs
Useful Payload (Commuter)2,500 lbs

its actually heavier than you mention and half the payload. which makes sense as its only 9 passengers compared to 14 for the caravan. the critical thing is bums on seats is what pays for the flight. the flights cost is split 9 ways instead of 14. that makes it an expensive flight. hence why i don't see it becoming a caravan replacement.

however i would expect specs to change a bit before they get into production. after all its only a prototype.

it will be interesting to see what real world range they get and also the effects of temperature are on the batteries during flight.

For the electric plane, payload is all payload. For a traditional plane, payload depends on amount of weight allowance left over after fuel, IOW payload is variable with distance, altitude and temperature.

Is the Cessna payload with full fuel?

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johno1234

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#2977380 4-Oct-2022 16:46

tweake:

Technofreak:

Hydrogen electric for the Cessna Caravan.

https://www.avweb.com/aviation-news/hydrogen-electric-caravan-proposed/

that will be interesting to see. i wonder if they will have to beef up the wing to handle the tanks. also what size battery would they need as fuel cells are not fast in changing output.

of course is hydrogen fuel cell better than just burning the hydrogen in an engine ??

The logistics for hydrogen are really bad - it is hard to distribute and store. If you needed one tanker of JetA1 you might need 18 tankers for equivalent energy in hydrogen. I don't believe it will ever play out with anything resembling current technology. This is a very interesting listen: How Clean is Hydrogen, Actually? With Prof. David Cebon — The PLUS Podcast by The Fully Charged Show — Overcast

PolicyGuy

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#2977381 4-Oct-2022 16:48

tweake:

of course is hydrogen fuel cell better than just burning the hydrogen in an engine ??

A today's technology fuel cell is about 60% efficient in converting chemical energy into electricity, a gas turbine (i.e. jet) engine is about half as energy efficient (30 - 35%). Fuel cells are, relatively speaking, at the beginning of their development and refinement whereas the gas turbine has been under intensive development for more than three quarters of a century.

Burning hydrogen in an engine is relatively quick and inexpensive to develop, and is certainly less polluting than burning a hydrocarbon fuel. For really large-scale applications, it may be the only way to go - we don't really know how to build 10MW electric motors that don't weigh tens of tonnes

Technofreak

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#2977488 4-Oct-2022 21:41

tweake:

Technofreak:

Hydrogen electric for the Cessna Caravan.

https://www.avweb.com/aviation-news/hydrogen-electric-caravan-proposed/

that will be interesting to see. i wonder if they will have to beef up the wing to handle the tanks. also what size battery would they need as fuel cells are not fast in changing output.

of course is hydrogen fuel cell better than just burning the hydrogen in an engine ??

Other than beefing up the attachment area to physically attach the tanks I wouldn't expect there would be any need to beef the wing up. I say that for two reasons. The wing is where the fuel tanks are in a normal Caravan so basically replacing one item of weight with another. Secondly weight attached to the wing reduces in flight loading on the wings.

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Technofreak

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#2977492 4-Oct-2022 21:54

johno1234:

For the electric plane, payload is all payload. For a traditional plane, payload depends on amount of weight allowance left over after fuel, IOW payload is variable with distance, altitude and temperature.

Is the Cessna payload with full fuel?

Payload is usually quoted with no fuel. In the case of the Caravan the 800 lbs difference in payload give about 2 hours 30 minutes endurance. I doubt the Alice has a 2 hour 30 endurance.

While what you say is true about all the payload of an electric aircraft being available as payload, conversely the reducing battery capacity as in reducing the fuel on board doesn't give you more payload as would happen with an ICE powered aircraft. Not as much flexibility.

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#2977493 4-Oct-2022 21:57

johno1234:

The logistics for hydrogen are really bad - it is hard to distribute and store. If you needed one tanker of JetA1 you might need 18 tankers for equivalent energy in hydrogen. I don't believe it will ever play out with anything resembling current technology. This is a very interesting listen: How Clean is Hydrogen, Actually? With Prof. David Cebon — The PLUS Podcast by The Fully Charged Show — Overcast

I'd argue the logistics of a battery powered aircraft are even worse.

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#2977494 4-Oct-2022 22:01

PolicyGuy:

tweake:

of course is hydrogen fuel cell better than just burning the hydrogen in an engine ??

A today's technology fuel cell is about 60% efficient in converting chemical energy into electricity, a gas turbine (i.e. jet) engine is about half as energy efficient (30 - 35%). Fuel cells are, relatively speaking, at the beginning of their development and refinement whereas the gas turbine has been under intensive development for more than three quarters of a century.

Burning hydrogen in an engine is relatively quick and inexpensive to develop, and is certainly less polluting than burning a hydrocarbon fuel. For really large-scale applications, it may be the only way to go - we don't really know how to build 10MW electric motors that don't weigh tens of tonnes

I'd suggest the weight of the batteries to power those 10 MW electric motors are an even bigger show stopper.

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Scott3

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#2977497 4-Oct-2022 22:49

johno1234:

The logistics for hydrogen are really bad - it is hard to distribute and store. If you needed one tanker of JetA1 you might need 18 tankers for equivalent energy in hydrogen. I don't believe it will ever play out with anything resembling current technology. This is a very interesting listen: How Clean is Hydrogen, Actually? With Prof. David Cebon — The PLUS Podcast by The Fully Charged Show — Overcast

I think for basically any hydrogen aviation application, going cryogenic will make sense.

With hydrogen as a liquid, volumetric energy density is only about 4.25x worse than Jet A1 (not counting the volume of tank insulation). Liquid hydrogen has a much high weight energy density, which would give it an advantage when transporting in applications which are weight constrained, but not volume constrained (like a fuel truck).

But yeah, you basically can't truck large volumes of gaseous hydrogen. You need to pipe it (and even that is a pain), or make it on site.

TwoSeven

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#2977843 5-Oct-2022 19:06

PolicyGuy:

tweake:

of course is hydrogen fuel cell better than just burning the hydrogen in an engine ??

A today's technology fuel cell is about 60% efficient in converting chemical energy into electricity, a gas turbine (i.e. jet) engine is about half as energy efficient (30 - 35%). Fuel cells are, relatively speaking, at the beginning of their development and refinement whereas the gas turbine has been under intensive development for more than three quarters of a century.

Burning hydrogen in an engine is relatively quick and inexpensive to develop, and is certainly less polluting than burning a hydrocarbon fuel. For really large-scale applications, it may be the only way to go - we don't really know how to build 10MW electric motors that don't weigh tens of tonnes

i think this is an assumption.

we most certainly do know how to build large electric motors that don’t weigh much. The question is why would there be a need to?

I think electric motors in vehicle usage today are becoming the axial flux type, and these can be run in series as well as in different confugurations.

A thing to think about is that when moving to an electric design, the architecture of the solution can change from having a central monolithic power plant to a distributed one. Also, electricity production can be done in proximity, distributed or remotely to the power plant.

An good example of different thinking is the Alstrom Cordia iLint train. Another good design is the FCEB (electric busses) in use in Pau france.

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