What will power our vehicles in the future?

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#2765138 22-Aug-2021 22:02

Gurezaemon:

Genuine question: So are the people at Sounds Air and other places investigating this idea just ignoring scientific reality and blowing all that money on expensive consultants, merely so they can be woke or engage in virtue signaling?
If the idea was truly pie-in-the-sky unrealistic, I would have thought that the vast amount of information out there on this topic (including that information not on YouTube) would have put them off even looking into it.

Good question.

Even United Airlines have signed agreements to buy 100 ES19's.

https://www.aerospace-technology.com/news/united-airlines-heart-aerospace/

To me there is no logical reason for anyone to sign up to buy this aircraft. I don't think it'll see the light of day. Unless someone buys Heart I don't see them surviving long term. There has to be a massive step change in battery technology for it all to work.

I'm not an aircraft design engineer but I have enough aircraft knowledge to know that with the current technology and even reasonable advances of that technology the physics don't add up. There's significant differences between the energy demands for the flight profile of an aircraft and that of a motor car journey.

For example on flat ground once you have a motor vehicle moving you only have to overcome the form or shape drag of the vehicle plus tyre friction/rolling resistance. With an aircraft you have the form drag plus the drag that is created due to the lift being produced. In that article I linked the electric aircraft was well over twice the weight of the equivalent turbo prop. Straight away you have nearly doubled the power required to maintain flight let alone anything else.

To give an example of how critical weight is in an aircraft, a few years ago as a means of reducing fuel burn Air New Zealand removed the in flight magazines from the long haul aircraft. I also remember being told about the significance of Air New Zealand being able to use Hamilton airport as an alternate for Auckland rather than using Ohakea. It cost something like 7 tons of extra fuel burn just to carry the extra fuel to go the Ohakea on a flight from Hong Kong. Please don't hold me to these as exact figures as it was a while ago but the cost in fuel burn was staggering.

My point in saying all this is to show how critical weight is in the economic operation of aircraft. The problem with batteries is their weight.

Back to your question, I really don't know why the likes of Sounds Air and United Airlines are saying they are planning to introduce electric aircraft. For sure some of Sounds Air's routes could work but I'd still question the economic sense of supporting an aircraft in your fleet that can only do one or two of your routes and even then be potentially restricted by weather conditions on some days.

One could speculate, there has already been one suggestion on this thread of virtue signalling and or government money for research and development. I've seen no evidence of that but I cannot think of any other reasons either. It makes no sense to me. Perhaps I'm missing the obvious, but I don't think so. There's plenty of others whom I think know more than I do who think the same way as I do.

Finally there have been plenty of futile projects in history where governments and supposedly intelligent private investors have wasted a lot of money. For example, nuclear powered aircraft. This won't be the last.

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Technofreak

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#2765139 22-Aug-2021 22:12

PolicyGuy:

Dingbatt:

In Technofreak’s post about battery weight substitute ‘pressure vessel’ and there’s your answer about hydrogen in commuter sized aircraft. As well as handling cryogenic fluid both during refuelling and inflight, the pressure vessel would need to be in the fuselage because the shapes they come in don’t tend to fit well into wings and therefore require more structure to carry them. This problem does not occur with either liquid fuels or batteries, both of which can be distributed in the wings. Swapping out wing mounted batteries may introduce its own problems though.

There are already designs - yes, paper only at this point - for short-range aircraft with under-wing lightweight carbon fibre tanks for liquid hydrogen. Like this B-N Islander based design:

https://www.flyer.co.uk/project-fresson-opts-for-hydrogen-for-islander-flights/

Interesting, they started of with a hybrid system which is arguably lighter than pure battery but weight was still the killer.

“The hybrid electric range extender option looked quite promising, but when we started doing the project, doing the detailed analysis and understanding the weight implications, whichever angle we took we couldn’t get a solution which was greener, while still being safe and still providing a usable range.”

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morrisk

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#2765180 23-Aug-2021 07:19

Technofreak you note "For sure some of Sounds Air's routes could work..." which I guess is the reason that they have placed an order.

Having some routes, some of the time flown by an electric plane will reduce their emissions so that is an improvement if the goal is to reduce emissions as a company. It may come at a cost but they must have thought of that and accept this.

The key point is the cost of no one doing anything is as predicted by all credible scientists - significant global warming and the cost of that in relation to the world as we know it.

tdgeek

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#2765183 23-Aug-2021 07:35

morrisk:

Technofreak you note "For sure some of Sounds Air's routes could work..." which I guess is the reason that they have placed an order.

Having some routes, some of the time flown by an electric plane will reduce their emissions so that is an improvement if the goal is to reduce emissions as a company. It may come at a cost but they must have thought of that and accept this.

You could argue that while you save a few emissions on just a few routes, you have added emissions by building an aircraft that you didnt need as you already have them, and given its just a few short routes, you may never recover that.

Sidestep

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#2765186 23-Aug-2021 07:43

Gurezaemon:

Genuine question: So are the people at Sounds Air and other places investigating this idea just ignoring scientific reality and blowing all that money on expensive consultants, merely so they can be woke or engage in virtue signaling?
If the idea was truly pie-in-the-sky unrealistic, I would have thought that the vast amount of information out there on this topic (including that information not on YouTube) would have put them off even looking into it.

Nope – they’re just being very (very) optimistic about near-term battery development.
As Technofreak points out existing battery technology is THE constraint on electric aircraft.

There are three major areas where existing batteries fall short: Energy Density, Chemistry and Cycling.

Aircraft battery power is measured by a ratio of Watt-hours per kilogram.

A viable electric regional passenger aircraft will likely need > 400 to 500W-hr/kg at the System Level.
'System level' is the overall energy density of the installed, integrated battery pack.

With existing battery chemistries that would require ‘cell level’ energy densities in the range to 600-800 W-hr/kg, as the cells derate 30-50% when divided into the mass of pack integration - the physical structure, safety devices, battery management and thermal/fire management systems.

The large derating from individual cell level to installed pack level has a lot to do with battery chemistry.
The issue is when using any battery with a flammable electrolyte (eg lithium-ion) - provision must be made to prevent thermal runaway.
Existing systems rely partly on physical cell separation causing mass inefficiencies when in packs.

Cycle life > 10,000 cycles is considered the standard for a commercial fleet to avoid excessive maintenance costs.
Currently at 3-5,000 cycles, advances in battery chemistry mean 10K cycles is within the near-term realms of possibility, but still not-quite-there in production packs.

Finally – Certification. From building and flying a preliminary/experimental prototype to a certifying a passenger aircraft is a considerable and expensive process.

All this, and the whole system must be Cost Effective enough to run an electric air service at a profit, when many existing air services, in spite of cheap, energy dense fossil fuels, are running on the ragged edge of bankruptcy.

Currently the word leader in production aircraft batteries is H55, the Swiss based av-tech spun off from Solar Impulse, (remember when it was the first electric plane to fly around the world?) who produce state-of-the-art certified battery modules with the highest energy density on the market - 200Wh/kg (pack level).

So, within reach of electrifying very thin/short haul routes like Harbour Air’s but still not viable on 99% of commercial flights.

For all practical purposes Li-ion batteries are nearing maximums so new chemistry(s) or energy storage types are likely required to meet electric aircraft needs.

Hydrogen meets the energy-density requirements for electric aircraft but has big hurdles to overcome around storage-refuelling and safety, as well as provision through a carbon free supply chain.

Dingbatt

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#2765199 23-Aug-2021 08:25

Hence my comment about the low hanging fruit. Put the most energy (pun intended) into de-carbonising surface transport. Battery technology and hydrogen technology will be improved by that, the offshoot being improving the viability for aviation.

As far as that picture of the Islander goes, two words, airframe icing.

“We’ve arranged a society based on science and technology, in which nobody understands anything about science technology. Carl Sagan 1996

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#2765246 23-Aug-2021 09:25

Dingbatt:

Hence my comment about the low hanging fruit. Put the most energy (pun intended) into de-carbonising surface transport. Battery technology and hydrogen technology will be improved by that, the offshoot being improving the viability for aviation.

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RobDickinson

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#2765253 23-Aug-2021 09:34

Aviation esp how we have it now is hard for current energy density of batteries.

It'll get replaced part by part when it can, electric will work out cheaper so when they can the industry will change because fuel is a massive cost, and they wont avoid external costs for co2 etc for long.

frankv

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#2765311 23-Aug-2021 11:10

PolicyGuy:

There are already designs - yes, paper only at this point - for short-range aircraft with under-wing lightweight carbon fibre tanks for liquid hydrogen. Like this B-N Islander based design:

Literally pi(e) in the sky. Those pods are the wrong shape for cryogenic hydrogen storage. Ideally you would have spheres, to maximise volume/surface area. Next best would be cylindrical or ovoid. But a cuboid (albeith with rounded corners and ends) that is small in one dimension is just about the worst shape you could choose. So whoever designed that hasn't thought about it much at all.

Sidestep

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#2765319 23-Aug-2021 11:25

frankv:

Literally pi(e) in the sky. Those pods are the wrong shape for cryogenic hydrogen storage. Ideally you would have spheres, to maximise volume/surface area. Next best would be cylindrical or ovoid. But a cuboid (albeith with rounded corners and ends) that is small in one dimension is just about the worst shape you could choose. So whoever designed that hasn't thought about it much at all.

The Innovatus Shyft tank technology uses very novel latest generation carbon composite manufacturing techniques to create multi-chamber hydrogen storage tanks which are super lightweight, very high pressure capable but most importantly, completely formable to the application required. So, in this case aerodynamics are key, weight is paramount and hydrogen storage volume is a principal descriptor of the range of the system. Innovatus brings this technology into the programme to carry enough hydrogen efficiently in the form factor to release the performance of the platform.

SHyFT Tank

RobDickinson

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#2765320 23-Aug-2021 11:27

So basically 2 cylindrical cells in an aero shaped cover.

Technofreak

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#2765332 23-Aug-2021 11:52

RobDickinson:

Aviation esp how we have it now is hard for current energy density of batteries.

It'll get replaced part by part when it can, electric will work out cheaper so when they can the industry will change because fuel is a massive cost, and they wont avoid external costs for co2 etc for long.

Did you read that article I linked? Fuel costs aren't as massive as you might think. Compared to the jet fuel costs, battery energy is 5 times more expensive. There's a long way to go before battery energy costs match jet fuel for cost.

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Dinga96

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#2765336 23-Aug-2021 11:55

RobDickinson:

So basically 2 cylindrical cells in an aero shaped cover.

Would you better off putting those drop tanks somewhere else apart from the undersides of the outer wing. There just going to get in the way there.

If you take the Cessna Caravan for instance .Some varients have a quiet large hold under the forward fuselage.I wonder how many tanks could sit in that hold.More than that concept drawing Islanders I suspect.

RobDickinson

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#2765346 23-Aug-2021 12:13

Technofreak:

RobDickinson:

Aviation esp how we have it now is hard for current energy density of batteries.

It'll get replaced part by part when it can, electric will work out cheaper so when they can the industry will change because fuel is a massive cost, and they wont avoid external costs for co2 etc for long.

Did you read that article I linked? Fuel costs aren't as massive as you might think. Compared to the jet fuel costs, battery energy is 5 times more expensive. There's a long way to go before battery energy costs match jet fuel for cost.

Sigh.

"It gives an energy cost per kWh of 17.4 dollar cents for the Turboprop aircraft and 7.1 dollar cents for the electrical aircraft (both engines drive the propellers, which are assumed to be equally efficient in the two cases)."

https://leehamnews.com/2021/07/01/the-true-cost-of-electric-aircraft/

Now imagine if we apply correct carbon pricing to jet fuel...

RobDickinson

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#2765348 23-Aug-2021 12:14

Dinga96:

Would you better off putting those drop tanks somewhere else apart from the undersides of the outer wing. There just going to get in the way there.

If you take the Cessna Caravan for instance .Some varients have a quiet large hold under the forward fuselage.I wonder how many tanks could sit in that hold.More than that concept drawing Islanders I suspect.

No idea I assume there are considerations of weight etc and I also assume the cargo hold might be needed for cargo?

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