Researchers Explore New Batteries To Power Electric Planes (technologyreview.com) 141
Can researchers built a new kind of battery powerful enough to fuel an electric airplane? MIT's Technology Review profiles a company co-founded by MIT materials science professor Yet-Ming Chiang:
He and his colleague, Venkat Viswanathan, are taking a different approach to reach their next goal, altering not the composition of the batteries but the alignment of the compounds within them. By applying magnetic forces to straighten the tortuous path that lithium ions navigate through the electrodes, the scientists believe, they could significantly boost the rate at which the device discharges electricity. That shot of power could open up a use that has long eluded batteries: meeting the huge demands of a passenger aircraft at liftoff. If it works as hoped, it would enable regional commuter flights that don't burn fuel or produce direct climate emissions...
The initial plan is to develop a battery that could power a 12-person plane with 400 miles (644 kilometers) of range -- enough to make trips from, say, San Francisco to Los Angeles, or New York to Washington. In a second phase, they hope to enable an electric plane capable of carrying 50 people the same distance.... Last year, the company announced plans to deliver a line of "hybrid to electric" aircraft with room for 12 passengers in 2022. At launch, the company intends to offer a hybrid plane with a gas turbine and two battery packs capable of flying around 700 miles (1,127 kilometers), as well as an all-electric version with three battery packs and a range of less than 200 miles....But crucially, the plane itself is expected to feature an open architecture that allows owners to switch out these modules over time, enabling them to upgrade to better batteries developed in the future or shift from hybrid to all-electric operation.
About 2% of the world's CO2 emissions come from air travel, and it's one of the fastest-growing sources of greenhouse-gas pollution. "More than a dozen companies, including Uber, Airbus, and Boeing, are already exploring the potential to electrify small aircraft," the article points out, "creating the equivalent of flying taxis that can cover around 100 miles (161 kilometers) on a charge. The hope is that these one- or two-passenger vehicles -- in most cases envisioned as autonomous vertical takeoff and landing aircraft -- could shorten commutes, ease congestion, and reduce vehicle emissions."
But with less ambitious batteries, "these would largely replace car rides for the rich, not displace air travel."
The initial plan is to develop a battery that could power a 12-person plane with 400 miles (644 kilometers) of range -- enough to make trips from, say, San Francisco to Los Angeles, or New York to Washington. In a second phase, they hope to enable an electric plane capable of carrying 50 people the same distance.... Last year, the company announced plans to deliver a line of "hybrid to electric" aircraft with room for 12 passengers in 2022. At launch, the company intends to offer a hybrid plane with a gas turbine and two battery packs capable of flying around 700 miles (1,127 kilometers), as well as an all-electric version with three battery packs and a range of less than 200 miles....But crucially, the plane itself is expected to feature an open architecture that allows owners to switch out these modules over time, enabling them to upgrade to better batteries developed in the future or shift from hybrid to all-electric operation.
About 2% of the world's CO2 emissions come from air travel, and it's one of the fastest-growing sources of greenhouse-gas pollution. "More than a dozen companies, including Uber, Airbus, and Boeing, are already exploring the potential to electrify small aircraft," the article points out, "creating the equivalent of flying taxis that can cover around 100 miles (161 kilometers) on a charge. The hope is that these one- or two-passenger vehicles -- in most cases envisioned as autonomous vertical takeoff and landing aircraft -- could shorten commutes, ease congestion, and reduce vehicle emissions."
But with less ambitious batteries, "these would largely replace car rides for the rich, not displace air travel."
Already here (Score:1)
Take a page from the Navy and catapult them into the sky.
Or maybe some capacitors to hold the 'launch' charge.
Slightly significant (Score:5, Informative)
This could be slightly more significant than one might think. While these small planes aren't the main type most people think of when they think of "airplanes", they happen to be roughly the least efficient transportation available. Less efficient per passenger than large airliners.
To give one well-known example, when Al Gore and his wife go to dinner, his G-11 B burns 578 gallons per hour. ( 0.8 mpg).
Replacing transportation that gets 0.8 MPG with potentially renewable energy is an easy win.
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This could be slightly more significant than one might think. While these small planes aren't the main type most people think of when they think of "airplanes", they happen to be roughly the least efficient transportation available. Less efficient per passenger than large airliners.
To give one well-known example, when Al Gore and his wife go to dinner, his G-11 B burns 578 gallons per hour. ( 0.8 mpg).
Replacing transportation that gets 0.8 MPG with potentially renewable energy is an easy win.
How did you convert "gallons per hour" to "miles per gallon"?
Mpg = mph / gph (Score:3)
Mpg = mph / gph
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Just measure fuel efficiency in square meters. Simplest way to do it.
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It's not just the fact that fuel economy is atrocious when it comes to flying. Release of CO2 exhaust occurs high up in atmosphere, making it much more potent in terms of greenhouse effect relevance.
Then there's the whole "much more efficient engines" aspect of it. You could turn the entire wing trailing edge into a bunch of small engines, something effectively impossible with ICE.
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Except the use case discussed here is on takeoff and landing.
The burst of power needed for takeoff is a big limit on the payload of electric planes. So this alleged breakthrough could make electric planes more feasible. An electric booster could also make fueled jets better able to take off on short runways, with bigger payloads, and/or with smaller more efficient engines optimized for cruising.
It is not just about takeoff, and it is not about landing at all.
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Except the use case discussed here is on takeoff and landing.
The burst of power needed for takeoff is a big limit on the payload of electric planes. So this alleged breakthrough could make electric planes more feasible. An electric booster could also make fueled jets better able to take off on short runways, with bigger payloads, and/or with smaller more efficient engines optimized for cruising.
It is not just about takeoff, and it is not about landing at all.
Yep; also, too, and furthermore, batttery tech development is fortuitously important to several ancillary, temporarily popular, pursuits... wouldn't it be funny (funny strange, not funny ha-ha) if the Kardashian-level Instagram popular-culture craze of the masses led to the necessary battery development?
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It would be a reasonably straightforward exercise to build an electric launch catapult mechanism into runways to get that first 100 mph or so.
EMALS delivers about 3-G of acceleration. I don't think that is acceptable in a passenger plane.
Also, the airframe has to be built to withstand the 3-Gs, which means extra weight.
Re: Slightly significant (Score:1)
It does because it can, and because carriers are short. It doesn't have to.
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Take off also produces a lot of pollution with the engines working hard. Hybrid planes that use electricity for the take-off and near major cities could have quite significant benefits for particulate pollution and of course noise pollution.
Re: Slightly significant (Score:5, Informative)
Power really is not the limit; energy is.
The model 3 battery pack - which also includes not just modules, but the charger, DC-DC converter, cooling, etc etc - can deliver 370kW and weighs 478kg, or 774 W/kg. It also has 77,8kWh usable, so 163Wh/kg Note that the modules (which also include an integrated BMS) are just over 3/4ths of the mass, so there's some real potential for weight reduction when you go to larger scales and use lighter materials (as aircraft do vs. cars). Let's say that in an aircraft pack you get 1kW/kg and 200Wh/kg (the modules are 223Wh/kg, and the cells even higher).
(Note: Even this may be somewhat pessimistic with respect to power. The Model 3 pack is rated for 1200A at 402V when fully charged (aka at takeoff) - that's 482kW rather than 370kW. But we'll stick with the amount you can actually use in current Model 3s)
Now let's look at a case where you try to push range and power to their limits - half the aircraft's mass as batteries. So the net power and energy densities of the plane are 0,5kW/kg and 100Wh/kg, respectively.
Now let's say that we're trying to reach a cruising height FL330 (10km) and a velocity of 600mph / 965 kph (268m/s). The energy required for the altitude is 9,81*h*m, so per unit mass, 9,81*10000 = 98100J/kg (27,5Wh/kg). Kinetic energy is 1/2 mv^2, so per unit mass, 0.5*268^2 = 35912J/kg (10Wh/kg). So 3/8ths of your energy is just required by fundamental physics - ignoring all losses - to get up to your flight level and velocity. If you get 80% net propulsive efficiency (between the drive units and propellers), now you're at half your energy just to reach cruising altitude and velocity. Now factor in the drag losses during your climb, particularly at low altitudes... and remember that we're talking about an aircraft where half its mass is batteries...
Clearly, electric aircraft are highly energy limited. You get more of your range during the glide down than you do cruising at altitude.
Now let's look at power. To accelerate up to... oh, let's say 70m/s... that's 1/2* m *70^2, or 2540J/kg (2540 W/s / kg). Our batteries can provide power at a rate of 500W/kg. Thus it could reach 70m/s in just over 5 seconds, or an average acceleration of 14m/s^2 (1,42 lateral g forces). Even factoring in the above assumed 80% drive unit / prop efficiency, you're still at an average of 1,1 lateral gs. Commercial aircraft are normally only 0,2-0,3 lateral gs. So clearly we are not power limited; indeed, with such extreme power possiblities, electric aircraft would be prime candidates for VTOL.
Summary: focusing on power is focusing on the wrong problem.
A side note: energy density improvements in batteries have a much more significant impact to range than one might think. With an electric car, if you double the energy, you double the range. But with an electric aircraft, you far more than double the range. Not simply due to the fact that the first half-or-more of your energy is needed just to get up to cruising altitudes and velocities, either. Electric aircraft have a much higher altitude theoretical operating envelope than combustion-based aircraft, due to the lack of need to maintain sufficient pressure inside an engine to sustain combustion, and avoiding the problems that occur with trying to maintain combustion at ever-increasing airspeeds. Higher altitudes come with lower air densities; optimal speeds increase and energy consumption per unit distance drops significantly.
There's another factor at play that combines that those high accelerations that we calculated previously with the energy density issue: if you can have full - or even just partial - VTOL, then you don't have to have the wetted area for takeoff and flight at lower velocities. Aka, you can make a more stub-winged aircraft. This makes your aircraft lighter (lower lift required, aka less drag via the L/D ratio) and more efficient at higher altitudes. In short, there's a significant virtuous cycle at work. You use the high power provided b
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Electric aircraft have a much higher altitude theoretical operating envelope than combustion-based aircraft, due to the lack of need to maintain sufficient pressure inside an engine to sustain combustion, and avoiding the problems that occur with trying to maintain combustion at ever-increasing airspeeds.
Is this really a problem, given scoops and turbocharging? Is anyone actually trying to take small airplanes to altitudes at which the density of the atmosphere and the ability to sustain combustion is the big issue?
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Could the burst of power be provided by a supercapacitor rather than a battery though? Of course, supercapacitors have density issues, but if you could get 5-10 minutes on a supercapacitor, then you could optimise the batteries for cruising rather than for takeoff.
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It's not just the fact that fuel economy is atrocious when it comes to flying.
Not per passenger it isn't.
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Depends on the plane. You're thinking of the big jets that carry hundreds. This is for the tiny passenger aircraft that serve small airports, isolated communities and island ferry service.
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No, I'm thinking any fixed wing aircraft. Aerodynamic advantages of being able to control flow of air with a set of small engines instead of having to have aerodynamically harmful control surfaces is present on any fixed wing.
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Not easy at all. I'm building one now (Score:4, Interesting)
Indeed airplane design is largely about keeping weight as low as possible. The lighter the plane is, the farther, faster, and better it will fly per [any useful measurement]. Pretty much anything you try to improve on a plane can be improved by reducing the weight and then re-optimizing* the other parameters, especially fuel efficiency.
Tomorrow I'll finish building yet another electric-powered model I'm building. It flies for a long time for a battery-powered model, 20 minutes of more. To achieve that, I ended up with a max speed of only about 22 MPH. To make the batteries last twice as long, I'd need about four times as much battery, because roughly half the battery power is used to lift the batteries.
* Someone who knows gliders may be thinking about the fact that a glider will go faster if you add weight. That's true it'll glide for a shorter time, faster - if nothing else changes. If you don't optimize for the lighter weight, it'll go down faster and go forward faster. If you DO design for the lighter weight, the lighter glider will plain fly better all around.
Re:Slightly significant (Score:4, Informative)
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Actually small propeller planes get about 25mpg.
On leaded fuel. mmmmm, lead. It's not OK for the average person to spew it out of their tailpipe, but it's just fine for the five-percenters or whatever who can afford a private airplane. Guess they vote.
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The problem is not the fuel type, but rather how inefficient business jets are when they're only transporting 1 or 2 people. If you actually fill the plane, then it would be getting 10 mpg per passenger.
Switching to electric doesn't help. His Gulfstream II B uses 21.6 MJ of energy per hour, which requires 12 tons of batteries to store. Since the plane is only 30 tons when loaded, I imagine this would cause some problems during takeoff.
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Slight problem: Al Gore does not own a private jet [climatedepot.com], and he buys carbon credits to offset any commercial airline travel.
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Re: (Score:2, Funny)
Spelling wasn't the actual problem with your post.
Debunked (Score:1)
https://www.popularmechanics.com/cars/hybrid-electric/news/a27039/tesla-battery-emissions-study-fake-news/
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First of all, common sense tells us: this is completely not plausible.
Secondly, you have enough IQ cells to realize that yourself.
Anyway: people who actually research such matters disagree with you. https://www.ivl.se/download/18... [www.ivl.se]
Re: (Score:2)
However, I do recall, now that I have been reminded, that the study I referred to may have made some unwarranted assumptions.
On the other hand, apparently so does the report you linked to. Which does not appear to be a peer-reviewed paper.
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On the other hand, apparently so does the report you linked to. Which does not appear to be a peer-reviewed paper. ... there are simply not enough journals, and usually you have to pay to be published. For university research that makes no sense at all.
Obviously not. It comes directly from the research institute. No idea if it ever will end up in a peer reviewed journal. Probably less than 1% of scientific research results get published in peer reviewed journals
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That's interesting.
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I've had this account for many years. I don't make any bones about the fact that it's a pseudonym. Most people who know me know who I actually am.
And a pseudonym is far different from an Anonymous Coward. Slashdot's own moderators use pseudonyms, dumbass.
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Who told you that? They lied to you, and repeating their lie makes you look stupid.
Not sure if this can be profitable (Score:2)
San Fran to LAX is a heavily traveled route using aircraft like the A320.
I don't know if 12 and 50 passenger flights can compete on price.
Re:Not sure if this can be profitable (Score:4, Insightful)
San Fran to LAX is a heavily traveled route using aircraft like the A320.
I don't know if 12 and 50 passenger flights can compete on price.
They compete on convenience by NOT flying from SFO to LAX, and instead flying from/to smaller regional airports.
I would pay a premium to fly directly from Reid-Hillview [wikipedia.org] in San Jose, which is a 15 minute walk from my house, directly into Santa Barbara or Orange County Airports. That would save me $60 on Uber cost for every trip, and I would be happy to pay that much more for the airfare just to save the time.
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You can get a ticket from San Jose to Long Beach for $60 today. Why would you pay double that for Reid-Hillview to John Wayne? Not to mention a prop plane is going to be much slower so you won't be saving the overall travel time.
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San Fran to LAX is a heavily traveled route using aircraft like the A320.
I don't know if 12 and 50 passenger flights can compete on price.
They compete on convenience by NOT flying from SFO to LAX, and instead flying from/to smaller regional airports.
I would pay a premium to fly directly from Reid-Hillview [wikipedia.org] in San Jose, which is a 15 minute walk from my house, directly into Santa Barbara or Orange County Airports. That would save me $60 on Uber cost for every trip, and I would be happy to pay that much more for the airfare just to save the time.
Where I live there is an alternative to air travel called "rail". Rail "stations" are much smaller so they can be put at many more locations. Also they do not have the intensive infrastructure requirements of airports and many stations can be effectively unmanned. I can take a rail trip to a city 400 miles away for about the same time as flying considering that my nearest airport is a 25 mile drive. Granted that a city 400 miles from my current location has to be in another country. Perhaps you can petitio
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A 12-50 person aircraft is often used by people with more money than sense, such as CEOs or hollywood types. Cost per passenger mile may be less important than the appearance of being environment conscience. They can also write these costs off as a business expense.
Re:Not sure if this can be profitable (Score:5, Interesting)
They are also how people get from small local airports to larger hubs and form the working group of the various small commuter airlines that go from hubs to regional or local airports.
For the "power at take off" issue, why not steal the idea of an assisted take off from the Navy and the steam catapult? Since there is a much longer runway to work with the assistive acceleration wouldn't need to be as violent and sudden, which could make it usable for passenger if not cargo. No need to borrow the other half of the Navy solution and install arrestor hooks, still have a nice long runway to land on.
Re: Not sure if this can be profitable (Score:4, Interesting)
why not steal the idea of an assisted take off from the Navy and the steam catapult?
It's one of those catch-22 situations; no manufacturer is going to build a plane which requires that system until the system is in use on a very large number of airfields .... and no airfield is going to pay to install those systems until there are planes which actually need them.
Re: Not sure if this can be profitable (Score:1)
Youâ(TM)re a bit behind the times. Look up the new EMALS electromagnetic catapult system thatâ(TM)s replacing steam catapults. Much less violent acceleration and more throttle control, I.e. can handle planes of many sizes. Also much lower maintenance than steam systems.
https://en.m.wikipedia.org/wiki/Electromagnetic_Aircraft_Launch_System
Re: (Score:1)
An auto-detaching power cord could work even better and is readily available - spin up the engines as much as you can while breaking, then release breakes. You better have good brakes ;)
A very long (think: mounted on a pick-up) auto-detaching power cord that can be reeled up can power you even until liftoff.
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Reading the web site, I think the /. summary is misleading.
They wouldn't go from SFO to LAX. They would go SQL to SMO. From their site:
Today
Route SFO to LAX
Door-to-door time H:MM 4:40
Fare $130
Zunum
Route: SQL to SMO
Door-to-door time H:MM: 2:16
Fare $121
They must be projecting significantly cheaper operational costs to make regional airport service profitable.
I like the smaller regional airports but they may not have the connectivity you need to get where you want to go.
Another thing they mention: pos
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They must be projecting significantly cheaper operational costs to make regional airport service profitable.
The operational costs will be dramatically reduced, because the electric motor is heroically simpler than any of the other propulsion options except maybe solid rocket boosters — fine for takeoff assist, but impractical for other purposes. And then there's all the up/downstream stuff you don't have to check, like for water in the fuel, etc.
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They must be projecting significantly cheaper operational costs to make regional airport service profitable.
The operational costs will be dramatically reduced, because the electric motor is heroically simpler than any of the other propulsion options except maybe solid rocket boosters — fine for takeoff assist, but impractical for other purposes. And then there's all the up/downstream stuff you don't have to check, like for water in the fuel, etc.
For a full electric aircraft I think the new tech will eliminate some things and create some new challenges, like
Lengthy recharge time will increase aircraft turnaround time
Unlike conventional fuel, battery weight will be the same on landing as it is on takeoff. This will affect landing gear and tires.
Battery replacement costs depending on how many cycles they can handle (and the FAA will allow)
Hybrid tech will probably be more complex and costly but save money on cruising fuel cost..
I saw one study where
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What do you think how often I sit in a plane that has 100 or more seats and only has a hand full of passengers? Once a year minimum. However, one reason for that usually is: the plane is expected to start the next morning from the other airport ... and then it is filled better.
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Well, the example of LAX to SF was not about actually flying that route but giving an impression about the distance.
Too little, too late (Score:2)
As much as they claim this as a solution to global warming it should be obvious it is not. First of all they admit that this is limited to very short flights, the kind of travel better suited to rail. Second, they have to know this will not make it to market any time soon. Even if they had flying prototypes today no passenger service would be allowed by any regulatory agency in the world without considerable testing. Then, even if they are approved to fly, there is the problem of infrastructure. They p
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It does not make much sense to plaster scandinavia with a rail way system, that supports small cabins of 10 - 20 people.
Your jet fuel idea, or the navies idea will never be commercial viable. If you would watch the video you promote tho badly since months, you had realized that. Because they explain in details why that only makes sense for the navy. Hint: transportation cost of fuel to all places on the world where the navy has a carrier.
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Here's someone with a doctorate that disagrees with you. Professor Gordon Aubrecht finds synthesized fuel from nuclear power is certainly viable. I don't recall how much detail he goes into it here but he's known to support synthesized fuel from nuclear power.
https://www.youtube.com/watch?... [youtube.com]
He makes the interesting case that the ultimate solution will be in solar power but we will need nuclear power to get us there.
Here's another idea on a "bridge" to alternative energy. T. Boone Pickens thinks natural
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You tell me it will never work?
No, I did not tell you that. I simply pointed out that the links you provide are for the navy, to cut down their costs and supply problems. You most certainly would be the first one complaining if a gallon of gasoline at the station costs what the navy would pay for artificial fuel.
Electric planes won't fly any time soon. ...
They are already flying
Synthetic fuels can happen very soon if we are truly concerned about a zero carbon future.
In Europe, yes. On the rest of the worl
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I simply pointed out that the links you provide are for the navy, to cut down their costs and supply problems.
Then you are not clicking on the links I am providing. The US Navy is but one of many groups working on this problem. They get mentioned a lot because they have proven the technology. All that's left is working out the details to ramp it up to commercial scale production. This is very much unlike battery powered airplanes where there's no functioning prototypes. While it's true that the Navy has only tested their fuel (publicly at least) on a model airplane, the fuel works. They tested the fuel in a l
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That's a laugh, no government will be lowering fuel taxes. Assuming that's true then you've proven my point.
Of course they do. Or why is Bio-Diesel cheaper than ordinary Diesel? Because the tax, already right now, is on "mineral oil". Not on Bio oil or synthetic oil. Mix in Ethanol or Bio Diesel into your fuel and the amount of tax on the bill is lower.
I obviously only watched your navy video ... I don't waste my time with video watching. Reading is 10 times faster.
All that's left is working out the detai
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It most likely will be bio gas and/or oils made from algae.
No, it won't. I've seen the math and bio-fuels simply cannot provide the energy we need for transportation. Citation:
https://www.withouthotair.com/... [withouthotair.com] (You'll have to read through the next few pages to get it all, not just the page I provided a link to.)
Everything in your post is a steaming pile of unsubstantiated bullshit. There is no energy future for the world that does not include nuclear power or widespread poverty. Oil prices will rise as it runs out, at some point this price point will reach to
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The future of "synthetic" fuel if you want to call it that way is Algae.
Not nuclear power. You can not produce competitive priced "gasoline" with electricity until the gasoline at your gas station has hit the $5.5 mark.
No idea what is so complicated in grasping that. It is in your own links.
You spreading your lies is not helping.
I don't spread any lies, asshole! A lie means the person is knowingly telling something that is not true. If I say something that is wrong, it is not a lie, asshole!!
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The future of "synthetic" fuel if you want to call it that way is Algae.
Not nuclear power. You can not produce competitive priced "gasoline" with electricity until the gasoline at your gas station has hit the $5.5 mark.
First, gasoline getting to $5.50 is certainly possible and the technology developed by the Navy, if deployed essentially as-is, would mean fuel costs never get above that. Absent such technology the costs could keep rising as petroleum becomes more difficult to obtain. Second, that price of synthetic fuels is based on no future development in cost reductions for nuclear power or this synthesis process. That $5.50/gallon isn't just the top end for petroleum based fuels then, as synthesized fuels would beg
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Here's something you could educate us both on, how much would this algae based fuel cost?
Why don't you google it?
https://www.google.co.th/searc... [google.co.th]
1.7 million hits ...
https://www.sciencedirect.com/... [sciencedirect.com] an easy read, you can even download the PDF.
And as you are so fond of youtube videos: https://www.youtube.com/watch?... [youtube.com]
Or if you like a more official one: https://www.energy.gov/eere/bi... [energy.gov]
So, your defense is your ignorance?
Ignorance about what? If you disagree with me or I say something wrong: it is not a lie
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Why don't you google it?
I believe I explained this to you before. I know what I know because I "googled it". I shared what I know with you and where I got it from so we can both know of what we are talking about. If you don't share your sources then I cannot know what you know except what little bit you've shared. If you know of a reputable source on all of this then point it out to me so I can soak it in, not just the tiny bits you put in a few words on a web forum. By not sharing your source I have no idea on if what you kn
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If you want me to believe algae has any possibility of producing enough fuel to meet any nation's transportation needs
ROFL.
I did not say enough ... it simply is much easier and more effective to make bio fuels with algae than making synt fuels with nuclear power (or other electricity, or heat).
Again, if you don't want to google stuff: it is your problem, not mine. I gave enough links regarding algae based fuel.
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lol (Score:2)
Uber getting mentioned in front of Airbus and Boeing.
Seems like a hydrogen fuel cell or two (Score:2)
could generate enough electricity and not create pollutants other than water vapor.
Or if you're Al Gore, maybe a couple of diesel generators. /s
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Brilliant! But...where does the energy come from to make the hydrogen?
In the future? Solar power. Today? Nuclear power.
https://www.youtube.com/watch?... [youtube.com]
Re: Seems like a hydrogen fuel cell or two (Score:2)
I don't think you realize just how much electricity is needed. No, "a small hydrogen fuel cell or two" would not provide anywhere near the necessary power for the type of aircraft they're talking about. Maybe for something like a single engine 2 seater cesna ...
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Fuel cells - a great idea that completely sucks (Score:2)
The basic idea of a fuel cell seems so cool.
The actual physics suck. The practical considerations of trying to use them utterly suck. They aren't close to being practical for other than some niche uses.
Here's some more info from people who have built fuel cell vehicles, including a couple of good links in the article:
https://energypost.eu/hydrogen... [energypost.eu]
As for aircraft, in aircraft design it's all about weight.
Decrease the weight and you increase the efficiency, speed, and performance. Unfortunately fuel cells
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fuel cell specific power in watts.
Depends on the fuel cell. In Germany there is a market for high power fuel cells in the range of up to10kW - 20kW to heat houses and feed excess power into the grid. However for normal use, they are in the 1kW range.
Specific power is a ratio (Score:2)
> In Germany there is a market for high power fuel cells in the range of up to10kW - 20kW
And those weigh thousands of kilograms, therefore their social power is a few watts. As originally noted within parentheses, specific power means power-to-weight ratio, how many watts per kilogram.
It's a lot like specific energy, where hydrogen again sucks because it requires a pressure vessel that weighs more than the fuel does.
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The fuel cells I mentioned are installed stationary in houses. The weight is completely irrelevant.
where hydrogen again sucks because it requires a pressure vessel that weighs more than the fuel does. ... there are other solutions to store it. Most "normal" fuel cells run on natural gas anyway.
If you pressure it
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> The weight is completely irrelevant.
You claimed I was incorrect about the power to weight ratio, also known as specific power. Specific power is, by definition, the power (watts) divided by the weight in kilograms. Weight is very much relevant to calculating power divided by weight.
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First of all I did not claim that.
I did not see any mentioning of "specific" in your post. That is all.
And the definition you give here is wrong anyway. Specific power is related to fuel and its weight. Not the mass of the engine. Obviously you could argue that high power fuel based engines have a better weight to power ratio than a conventional fuel based engine. E.g. a rotary/Wankel engine versus a piston one.
But: what has that to do with fuel cells?
That's specific energy (Score:2)
> Specific power is related to fuel and its weight.
That's called specific energy. Power is how much can be done right now. Energy is how much can be done for how long.
Horsepower is power. Watts are power. You measure the power of a motor.
Watt-hours measures energy. You measure the energy of a battery or an amount of fuel.
Hydrogen gas decent specific energy (you can go far without carrying much hydrogen), but only if you ignore the weight of the tank, which can weigh a lot.more than the hydrogen.
Hydroge
An example (Score:2)
Maybe an example would make it more clear. The Emrax 268 is a 20kw motor. It weighs 44 pounds. To provide the 20kw needed to power that 44 pound motor, you'd need a 4,400 pound fuel cell. Plus the hydrogen.
That Emrax 268 is appropriate for a 3,000 plane. To power a motor capable of lifting 3,000 pounds of plane, you need 4,400 pounds of fuel cell.
Ergo a hydrogen fuel-cell plane can't get off the ground - it's too heavy, it doesn't provide enough power to lift itself.
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Then use a different fuel cell ... so simple.
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Hydrogen fuel cells have horrible specific power - it makes a weak motor, because they can't provide a lot of power at any given time. You need a huge fuel cell to power a tiny motor.
I don't know why you continue to claim this. It is simply wrong, even when I misread and gave an inappropriate answer to your "first post".
Here is an example: https://www.hydrogenics.com/hy... [hydrogenics.com]
Read your link (Score:2)
Read your link. You linked to a 32,000Kg fuel cell capable of 1Mw. A 32,000Kg plane would need 7Mw.
Again, the fuel cell can't provide enough power to fly itself - much less the weight of the fuel, tank, motors, wing, fuselage, etc.
Fuel cells can't fly.
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Then I misread your point.
I was not aware that you are talking about fuel cells for flying.
Anyway, your fuel cell example, if I may nitpick, is for hydrogen fuel cells :D there are plenty of other types.
Such as? (Score:2)
I don't know of any type of fuel cell that has a specific energy anywhere near 100Kw or better Do you?
All the types I'm familiar with are four to six orders of magnitude too weak.
Turbofan engines are about 80,000 Kw/kg. (80Mw)
Turboshafts are about 8,000-40,000 kw/kg. (40 Mw)
The fuel cells I'm familiar with are around 100 watts / Kg.
Lithium ion batteries are up to 4,000 watts / kg so they are impractical, but physically possible for short flights. Fuel cells pf any type would be at least 40 times as heavy, a
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Why use a fuel cell on an airplane when it is perfectly suited as a fuel for jet engines?
I can understand such use as a means for backup electric power but to provide power to propel the plane sounds quite silly.
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Very useful even now. (Score:2)
If this means not having to completely shut down a large section of the city every time the President flies into the airport (because he can air-taxi rather than road-caravan back out), then let's fucking do it already. I don't care what President or what city, this will be economically helpful by eliminating a half day of downtime for a large chunk of the city.
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The president already has helicopters. How is an electric plane that needs an airport going improve his mobility?
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It doesn't need an airport, it's supposed to be VTOL. It's also closer to the size of a car than that of a helicopter, so they could carry it inside Air Force One, wheel it out, and fly away. Go to the event, then fly back, load it back into the plane, and move on to the next stop. Don't paralyze half a city for a caravan.
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Do you realize that helicopters are already designed to be as small as possible while carrying a pilot and passenger? If they could have it any smaller (and thus lighter and cheaper to build) they would have done so already.
Enough juice to create a plasma? (Score:2)
Fuel will always beat batteries in aircraft. (Score:1)
The reason is very simple:
Battery: same volume and weight whether charged or drained.
Fuel in a tank: consumed as it drains. As the vehicle travels, it becomes lighter and more efficient. A Boeng 777 or an Airbus A380 would have a far reduced range if it was not shedding a huge weight of fuel along the way.
The physics, rather than some nebulous conspiracy by "big oil", simply rules out batteries as a serious competitor to fuel-in-a-tank in a flight vehicle.
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Re: Fuel will always beat batteries in aircraft. (Score:2)
Also, there are other aspects of aircraft design that may decrease efficiency in this use case. Will aircraft manufacturers have to significantly increase the strength (and probably weight) of landing gear systems to accommodate a plane that doesn't decrease its weight over the course of the flight?