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Solar Planes Aren't the Green Future Of Air Travel (vox.com)
An anonymous reader writes: By any standard, the Solar Impulse 2 is a marvel of engineering. This solar-powered plane didn't use a drop of kerosene on its epic trip across the Pacific Ocean. It's a real testament to how far solar technology has advanced. Unfortunately, for anyone hoping that we'll all be puttering around in solar planes soon -- well, that's pretty unlikely. From a Vox report, "Consider: The Solar Impulse 2 features 17,000 solar cells crammed onto its jumbo jet "size wings, along with four lithium-polymer batteries to store electricity for nighttime. Yet that's still only enough power to carry 2 tons of weight, including a single passenger, at a top speed of just 43 miles per hour. By contrast, a Boeing 747-400 running on jet fuel can transport some 400 people at a time, at top speeds of 570 miles per hour. Unless we see some truly shocking advances in module efficiency, it'll be impossible to cram enough solar panels onto a 747's wings to lift that much weight -- some 370 tons in all. Nor is it enough to load up on batteries charged by solar on the ground, since that would add even more weight to the plane, vastly increasing the energy needed for takeoff. A gallon of jet fuel packs about 15 to 30 times as much energy as a lithium-ion battery of similar weight. That fundamental difference in energy density is a big reason we're unlikely to see large commercial airliners powered by batteries fill the skies."
Having a solar driven plane circle the world is still cool.
A gallon of jet fuel packs about 15 to 30 times as much energy as a lithium-ion battery of similar weight. That fundamental difference in energy density is a big reason we're unlikely to see large commercial airliners powered by batteries fill the skies."
This isn't even the whole story. As a plane flies, it burns fuel, essentially throwing mass out the engines for thrust. Getting lighter allows the plane to climb to a higher altitude where it is more efficient.
"A gallon of jet fuel packs about 15 to 30 times as much energy as a lithium-ion battery of similar weight."
Which means we need about a 40x-50x increase in battery energy-density to weight before electric planes become efficient.
As you burn fossil fuel your plane becomes a lot lighter. Not so much with a battery.
So per unit of weight the battery has to be more efficient than fuel to be comparable.
That's the only known way aside from hydrocarbons to store that much energy in a small space. The reactor can be tightly sealed to prevent radiation contamination even in the event of a crash.
May as well go back to sail ships... Maybe, not as fast, but certainly much more capable.
In Soviet Washington the swamp drains you.
Nuclear powered flight is the way of the future. Like turbines at Indy, it's a natural.
...catapults are!
I'm sure the Boeing 747-400 is the first of its kind too, right? No iteration over time or anything?
Using a prototype commercially is as ridiculous as assuming that it won't be improved upon.
It's like these things you hear every so often, about a bunch of students breaking a distance record with a solar car. Cute, but pretty much irrelevant, and almost useless.
We already have aircraft that can go 80MPH and take almost no fuel: they're called zeppelins. If people wanted something faster than a bus, train or car that costs less than an airplane, we'd be on earth2, where the Hindenburg never happened and people have much more convenient options available. Alas, c'est la vie, there's no interest in flying cheaply and efficiently across country, state or even town.
Changa hates change.
Probably Hybrid planes first to allow electricity use for times when fossil fuel use is inefficient. Like any technology it will evolve over time and adapt to be used where appropriate. Seems like battery use to takeoff and then solar for slower transit times might be workable.
Elbonian Air?
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
Just over 100 years ago man figured out heavier-than-air flight. About 70 years after that, we had flying buses and a man on the moon. To say anything is "not the future" in air travel is stupid.
The future could still hold electric air travel as a foreseeable and even likely outcome of this experimental tech. And if you decouple solar energy production from storage, i.e. battery powered plane, and ground based solar energy plant/airport. Then you could still literally have a solar powered plane. I think that short duration small aircraft flights and decentralized flight (non-airport hub based) are the primary implementation of this type of tech. All electric VTOL is the way of the future, way of the future.
Unless we see some truly shocking advances in module efficiency
It wouldn't work with 100% efficiency, so why would increase in efficiency matter as far as making it practical? What is happening to critical thinking skills?
I think it's pretty apparent that the solar concepts are just concepts. Obviously there's not enough energy output to replace passenger flight.
But the question is, can solar panels on a plane offset the energy consumption enough to make a difference? That's probably also a no, but that's where the question should start.
Keep in mind, some cargo ships have been experimenting with massive kites/sails that help offset the energy needed for their engines:
http://www.skysails.info/english/skysails-marine/skysails-propulsion-for-cargo-ships/
I thought the energy density gap between batteries and jet fuel was greater than a factor 15-30. Batteries are still being improved, and getting the energy density into the same ballpark doesn't seem completely impossible. Of course there's also the actual propulsion to consider; you need something able to put out as much power as a jet engine and at the same efficiency. But all in all it seems a lot more feasible than it did only a few years ago.
Not sure if solar panels on the airplane make sense though. Wing area of a 737 is around 250m^2, say you get the same again on the fuselage, and you end up with 500m^2. Cover it in solar panels generating around 200W/m^2 = 100kW. That's not even 2% of the power required to keep a 737 at altitude (7.2MW). I just grabbed these figures off the web so they are probably not very accurate, but it looks like there's not much point using solar panels on regularly shaped airplanes (as opposed to the typical solar powered ones, which look more like sailplanes)
If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
We have 3D printers now and Elon Musk landed a firecracker on its ass. Oh and computers got better, so doesn't that mean everything gets better??
> Unless we see some truly shocking advances in module efficiency, it'll be impossible to cram enough solar panels onto a 747's wings to lift that much weight [...]
Besides that, I strongly suspect there isn't enough power in the form of sunlight falling on a surface the size of a 747's wings to achieve the objective. In other words, it's not just a matter of solar panel efficiency, it's also a matter of total energy available for capture.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
You answer everything in the summary while actually everything put is not news in the slightest anyway. Holy shit I hate you Manishs - get a blog and go away
Batteries, or solar cells, don't make thrust by themselves either. You'd still need the same turbofans, just with heavy electrical windings in the middle rather hollow combustion cavities. Electric motors tend to be quite a bit heavier than empty cavities are, so I'd expect the electric engine to be probably a bit heavier.
You could put a prop on an electric motor. That limits maximum speed, and still electric motors are heavy.
> The fuel system itself
Such as the fuel lines and fittings , the hollow copper tubes? Compare with the copper required to carry thousands of amps safely, with heavy-duty insulation. The fuel line and fittings are probably lighter than electrical lines and fittings capable of transmitting the same amount of power.
> If wing didn't have to carry fuel could it be more efficient?
Wing efficiency is determined by shape and surface smoothness. What's inside doesn't matter, except a snall effectbthat carrying load in the wing is slightly more efficient than carrying the same load inside the fuselage, by eliminating the bending moment on the wing root. Putting solar panels on the SURFACE of the wing, where it's right in the critical boundary layer airstream , is a much bigger design constraint than putting something IN the wing.
Vertical take off and landing, light airplane with not too much training required (compared to helicopters) and 400 km/h speed.
Must be plugged to fill batteries, though, no solar cells.
But not done yet.
http://www.esa.int/Our_Activities/Space_Engineering_Technology/TTP2/Personal_aircraft_aiming_to_take_off_from_your_home
Air travel is doomed. It will be the first to go when we find out that renewables cannot do what oil could. Say goodbye to intercontinental travel and even long rage continental travel. Maybe some trains will work, but the fares will be too high for the ordinary citizen. We will see some oceangoing vessels, but they will have sails. It's going to become a big world again and most of us will live and die exactly in the place they were born. Welcome to the past.
Fire is hot.
"Hydrocarbon fuel" doesn't necessarily imply "fossil fuel," you know! Synthetic fuels and biofuels are easy sustainability solutions that even work with the infrastructure and aircraft we have now, without the physical impossibility of solar or the political impossibility of nuclear.
"[Regarding the 'cloud,'] ownership was what made America different than Russia." -- Woz
to increase efficiency of solar cells - Sun radiation is not increasing, pretty much constant, I would say. Probably need a football-field size surface constant to generate enough oompf to compare to kerosene-propelled turbines.
Generating fuel from solar/wind/water and propel airplane traffic will probably show the discrepancy between necessity and actual use - no one will even touch restricting air traffic, so....
Compared fuel efficiency/use per person from airplanes to cars, airplanes are winners, hands down, but looking at the distances traveled, it looks bad.
Interesting though, how the consumption has gone down and the difference between domestic and international, but that's US carriers only, whole world would be interesting...
http://www.transtats.bts.gov/f...
yeah, this whole airplane thing reminds me of that fool who thought people would have computers in their houses. pfft! how can you fit a giant electromechanical machine that fills a warehouse into your living room? some people, am i right?
Anons need not reply. Questions end with a question mark.
Elbonian Air?
More like "railgun airways".
Make sure everyone's vote counts: Verified Voting
Solar powered flight is for payloads that need to loiter for a long time in the upper atmosphere.
So...
Science experiments
Experimental radio networks
Military surveillance
etc.
Not humans particularly. Unless you have an irrational craving to spend a week or more in the upper atmosphere, this is not the technology you are looking for.
They are lightweight relative to their power output and are approaching 60% efficiency.
They also are very durable requiring little maintenance over their lifetime.
Fuel density and turbine efficiency are pretty hard to beat when it comes to aircraft.
Can't get enough energy out of solar power to do the job, not news.
Solar Planes Aren't the Green Future Of Air Travel
I never thought they were. Jeez, why always looking for the negative?
Next: The LHC can't solve global warming.
systemd is Roko's Basilisk.
The wall street journal estimates that for a 100 seat airliner, 30% of the cost of a flight is fuel. And another 14% is govt fees and taxes. Thus if batteries let you get cheaper fuel, don't know if thats true, then there's a large margin for cost savings. And if the gov't were willing to kick back taxes for not polluting the upper atmosphere. Then there's an even greater margin. So there's a powerful incentive to come up with electric power aviation if the total cost of ownership for electric power can be achieved.
Denver internation airport occupies over 10^8 sq meters. Solar cells have peak efficiencies around 15% but lets derate that. so if you could get 100 watts of power per meter then that's 10^10 watts. Obviously you can't use the whole airport area, and modulo all the other issues with solar power and battery round trip efficiency.
a flying 737 plane uses about 750 gallons per hour. thats 28 443 206.8 watts if you assume every BTU is converted to kinetic energy. Perhaps jets are wasteful and electric motor planes are less wasteful? I would guess so but don't know how to derate that.
Thus in raw numbers that 10^10 could power 350 aircraft. Since batteries have loses assume 75% of that is more practical. Still that's more than the number of aircraft taking off per hour.
So the numbers for the energy requirmements seem plausible. Thus perhaps it comes down to weight, safety and how fast you can charge the batteries. These are all technological issues which while formidable may not be insoluble.
jet fuel is about 42MJ/kg. the current best flow battery is about 5MJ/kg. But recent advances suggest this could rise 10 fold in the near future. Flow batteries have been made with >99% energy recovery if I read the literature correctly. Now not all of these charateristics are achieved in the same designs and scaling these can be an issue.
Thus technologically it seem plausible one could store electric energy at the same weight density as jet fuel
Some drink at the fountain of knowledge. Others just gargle.
Elbonian Air?
More like "railgun airways".
Sounds like takeoffs could be rather unpleasant.
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.
I wonder if there's any potential to beam power to a plane by microwave, either from a satellite or from a network of ground stations?
(I'd read a proposal to do space ship launches this way, to save on fuel weight.)
We won't see a solar powered 747, or 787. That's just not physically possible. But that doesn't mean we'll keep flying around in fossil fuel powered planes, or that future plane engines will burn fuel instead of being electrically powered, or that planes won't be covered in solar panels.
This is silly. Don't put the solar panels on the plane. Use liquid fuel derived from solar energy and waste biostock. Break down all the waste kitchen scraps into their component molecules/atoms, and then use solar energy to recombine them into liquid jet fuel, and then use that to fuel your regular planes.
If the fuel is derived from carbon sources already in the biome and the energy source used to make it is renewable, then it's carbon neutral, and that's all we really care about.
Am I missing something here? Yes, this will be more 'expensive' initially than regular jet fuel, but so what? I'm sure economy of scale would solve that problem.
Yet hydrogen could do the job http://www.boeing.com/defense/phantom-eye/
Unless we see some truly shocking advances in module efficiency
It wouldn't work with 100% efficiency, so why would increase in efficiency matter as far as making it practical? What is happening to critical thinking skills?
Regarding critical thinking, why couldn't we just use solar panels on the ground to make jet fuel(*)?
Jet fuel in this instance is just an energy carrier, and has a much higher energy density than lithium. While Lithium batteries may be appropriate in some cases (portable devices, ground transportation), for air flight it's more appropriate to use something else.
(*) Or perhaps a biological method such as GM modified algae or a bio-yielding plant. The Wikipedia page of crop yields indicates that Algae can yield 80,000 kg/ha/yr, with "ha" being the area of a square 100 meters on a side.
A quick calculation shows that a 747 holds around 183,000 kg of fuel, so 3ha of open-pond algae could supply enough fuel for one tank each year.
Anyone who has driven across the "great basin" and other nearby sections of the US (western part of Utah, Nevada, parts of Arizona) knows that we have lots and lots of unused area that gets a lot of sunlight, and water is generally available from wells.
It seems reasonable that we could put up large solar and wind installations in these places, generate biodiesel and other organics, then ship them by tanker truck to where they are needed.
About 11 million gallons of fuel used in the US for aviation annually, that's 31 million kg, which requires 387 of those 10m x 10m algae pools(*).
At roughly $5 per gallon, the output of such an installation would be worth $55 million per year.
This seems like a futuristic prediction, but it makes sense.
Once the price of fuel goes up, this sort of installation may not be far in our future.
(*) This seems low. Have I dropped a digit somewhere?
To slashdot's new masters: your readers aren't so ignorant that we think that Solar Impulse 2 means we'll be seeing solar powered 747s. Sheesh.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
... In order to make commercial solar, one has to abandon the wing, not solar power per se. Imagine a blimp whose entire bag is made up of ultrathin solar cells. Now lift is "free" -- all one needs is enough power to run a pusher that can exceed the drag force of the prevailing wind, and surface (of the blimp) to volume works in your favor, as increasing the surface area increases net buoyancy and hence the total weight of storage batteries one can lift. The Chinese are building a prototype already, as are several other folks. They may not go fast, but they can probably go as fast as the solar winged plane did.
Norman Spinrad speculated on a hybrid/inflatable wing solar plane (single person) run by a mix of muscle and wind in "Songs from the Stars". It isn't even a particularly new concept. If any of the new designs for flexible, cheap, e.g. "printable" solar cells work out so one can buy solar plastic by the yard and make up with cheap quantity what one loses in efficiency, people will be building stuff like this in their back yards (right after covering their roofs and houses with cheap siding made from it).
The top article's headline asserting that solar planes aren't the future may be true, but solar powered flight, on the other hand, may work out just fine. And that isn't even considering doing it the easy way -- using solar power to make biofuels to run existing kinds of airplanes or jets. Or directly synthesizing fuels with solar energy. Will solar blimps happen anytime soon? Prototypes, sure, but the real payoff comes when solar technology advances the next notch, as it is very likely to do. Some of the organic solar cell technologies being investigated could yield quite reasonable efficiencies and drop costs by as much as an order of magnitude on mass production compared to solid state cells. One could imagine cars, boats, houses and more being coated in a solar film in a decade that doubles as weatherproofing and dumps power into high storage capacity next-gen batteries all day long, for a cost that isn't that much higher than existing e.g. siding or surface coatings.
The problem with solar is it is (largely) a premature technology. But there is a ton of R&D being done, and I'm pretty confident that it will bear substantial fruit, if it isn't killed dead by functional fusion power making fuel costs for electrical power irrelevant compared to everything else in the distribution system.
rgb
Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.
What we need is to use Solar power to create airplane fuel directly from CO2 in the Atmosphere, This gives you energy dense furl which is carbon neutral, Biofuels already do this (CO2 > Plants > Fuel) but a direct method would be better.
"A gallon of jet fuel packs about 15 to 30 times as much energy as a lithium-ion battery of similar weight. That fundamental difference in energy density is a big reason we're unlikely to see large commercial airliners powered by batteries fill the skies."
Electric engines are much more efficient than turbines (not sure on the exact number, but approx an order of magnitude I suppose). This difference in energy density rapidly shrinks when this is taken into account.
... progress is made by refining the process ...
Yes, and the bias against internal combustion and jets and the bias towards solar are causing people to miss a major piece of that process. The fuel. There is nothing wrong with internal combustion and jets, the problem is only their current petroleum based fuels. Switch to bio fuels that are carbon neutral and we have no problem. Carbon is not the problem if it is taken from and returned to the current environment, as with bio fuels. Carbon is only a problem when we mine ancient sequestered carbon and reintroduce it to the current environment, as with petroleum.
Liquid fuels have incredible energy density. We would probably need a Back-to-the-Future-like "Mr Fusion" reactor, not improved batteries, to make electrically powered fixed/rotary wing aircraft practical.
Synthetic fuels and biofuels are easy sustainability solutions
If they were easy sustainability solutions, we'd be using them by now. But they're not:
Bio-fuel powered flight is far farther along than solar powered flight. The US Navy has had some F/A-18 Hornets flying on bio-fuel since 2010. Scaling up bio-fuel generation is quite a bit more practical/doable that batteries that have the energy density of jet fuel.
Synthetic fuels may be easy but fossil fuels are so cheap that they can't compete. A carbon tax would level the playing field.
So would passing peak petroleum production, which we may have already done.
So would national security concerns about foreign petroleum supply lines. Note the military has had jets flying on biofuels since 2010. They can justify the higher cost with more secure supply lines. Satisfying the military's need for jet fuel, or a large part of it, can jump start the biofuel generation infrastructure and bring costs down.
We would probably need a Back-to-the-Future-like "Mr Fusion" reactor, not improved batteries, to make electrically powered fixed/rotary wing aircraft practical.
Technically, we only need 1960's "let's make it nuclear" optimism and it doesn't even need to be electric. That thing is that's so awesome it needs a use. Maybe a supersonic atmospheric flyer on Jupiter for planetary research?
SJW n. One who posts facts.
Synthetic fuels and biofuels are easy sustainability solutions
If they were easy sustainability solutions, we'd be using them by now. But they're not
Bio-fuel powered flight
Biofuels are not the same as synthetic fuels.
"I don't know, therefore Aliens" Wafflebox1
FTS: "A gallon of jet fuel packs about 15 to 30 times as much energy as a lithium-ion battery of similar weight."
And what multiple was it 5 years ago? 10? 15? 20?
What multiple will it be 5, 10, 15, or 20 years into the future?
*What happens when our best batteries (be they lithium-ion or another) become more energy-dense than jet fuel?*
There are lots of small savings to be made
For a short commuter flight, say between LA and SFO. the speed of the plane is just one consideration, there are lots of on-the-ground delays that add to the total travel time
Here's my plan...
Step 1 - abolish the TSA, they're worthless and that saves an hour off the trip for a start
Prior to flight, batteries loaded, fully charged, into plane on the runway. The batteries here have a different function, they are a power boost for a daylight flight not a reserve for overnight / deadweight during the day
Plane full of passengers towed by an electric tow plane to 40,000ft and 700miles/hour and released in the direction of its destination for a gentle downhill glide
solar cells on airplane body only need to power propulsion and maneuvering and don't have to charge the batteries for an overnight reserve
plane has a conventional fuel emergency engine, so it need not retain too much in the way of emergency battery charge, it can plan to run the batteries near flat in the normal course of a flight
Those provisions have each earned incremental increases in mass/speed over the original 2-tonne/43mph plane.
Taken together and with the help of some improvements in battery capacity that we might ordinarily expect, I would have thought that even adding, say 10 tonnes of passengers the plane should be able to average a few 100 miles / hour over a commuter-length flight.
Now that I think of it, just towing a conventional plane to cruise altitude and letting it go would probably save a lot of fuel, It would be interesting to know how much of the fuel is used up in the first 25% of the flight when it is fully loaded and climbing.
Nullius in verba
Wright Brothers were screw-ups, but ruthless business competitors and that's why so many still think they flew first.
First in "Sustainable, powered, controlled" flight is their claim. Compare:
1903 Wrights launch from a rail downhill into a wind, 'fly' straight, and land so hard that after three "flights" the plane is damaged so much it doesn't fly again while being repaired for several months.
1901, August 1, Gustav Whitehead takes off from a level field flies higher than treetops, makes a wide turn (wing-warping) and lands safely.
The Wrights, and their estate, made a pact with the Smithsonian that their Kittyhawk Flyer can stay at their museum only if the Smithsonian NEVER mentions anyone flying prior to the Wrights.
Intriguing.
I'm sure nothing can go wrong when aiming a couple dozen megawatts of laser power at a moving target.
I hope you don't literally mean a nuclear powered aircraft. If so you are simply replacing heavy batteries with heavy shielding and a heavy nuclear core. Weight is a deal-killer when it comes to flight.
Ever notice the tiny legs and feet of most birds? They shed the weight of those and thus gave up all hopes of being great runners. The roadrunner aside.
It used-to be just in the comment section that idiots would spout-off idiotic nonsense like this. Now Bizx is publishing any worthless crap some moron submits...
It'll be impossible for a horse to haul the extra weight of a fuel tank, wheels, and an internal combustion engine...
Massively, idiotically, wrong. Liquid fuels are subject to horrendous conversion inefficiency, while batteries are not. See: Carnot's Theorem. This is the same drooling moron nonsense we heard about electric cars... And guess what; existing electric cars aren't any heavier than their conventional brethren, while having similar range between refueling. They're not quite comparable, yet, but they're damn well not 15-30 times heavier, are they?
If you want to go full-retard, why don't we talk about the amount of energy we can get from nuclear reactions of Lithium atoms versus carbon atoms? It's just as relevant as this spewing crap.
Here's what I said here last month, on exactly the same damn subject:
"Compared to advanced piston engine airliners of the 1950s, current jet airliners are only marginally more efficient per passenger-mile."
Fuel cells are more thermodynamically efficient than even the best turbines at converting hydrocarbons into work, and they conveniently happen to output electricity, directly.
Fuel cells are being developed that can run directly on common liquid hydrocarbon fuels, not just hydrogen.
At lower-speeds, props are much more efficient than turbofans, and props can of course be easily driven by electric motors.
The lower speeds of prop-driven planes gives additional added efficiency in lower aerodynamic drag, as well.
Instead of retrofitting such a system onto current jets, combine electric propulsion with "blended wing" aircraft, and the future of passenger air travel could be vastly quieter and more fuel efficient, albeit slower.
And electrically-driven aircraft is incredibly simplified, to the point that airlines would want them for their lower maintenance costs and less downtime, even if the efficiency wasn't substantially better... See my quote above, as airlines previously embraced inefficient turbines for just this reason.
https://slashdot.org/comments....
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Well the Tesla has half the range, costs 50%, and it's 30% slower 0-60. On the other hand, they are both cars. :)
Combustion has horrid conversion efficiency, explosive fuel adds ample expense and dangers, requires tons of extra equipment weight, etc.
Bio fuels will have the same lousy efficiency. They won't reduce the environmental effects of contrails, won't eliminate smog and small particulate emissions, or otherwise improve air quality at all.
Existing bio fuels are every bit as dirty as fossil fuels... requiring clearing (by burning down) big sections of rain forest, or extensive use of petroleum based fertilizers, and more. The EU was on a big biofuel kick until they saw the damage caused by their feel-good policy.
And yet electric cars are on their way to overtaking internal combustion cars in the next decade.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Remember airships? Lot's of area for panels, plenty of lift for passengers/cargo. If the electric motor didn't have to propel the plane at 400mph to generate the lift required, solar powered forward thrust is totally doable.
Just means air travel won't be as fast. And it'll end up even safer if the airships don't use hydrogen :)
"Nor is it enough to load up on batteries charged by solar on the ground, since that would add even more weight to the plane, vastly increasing the energy needed for takeoff."
Fuel Cells can rectify liquid hydrogen (and some other hydrocarbons), and you would have the same operating parameters as jet fuel: Lighter on landing than on take-off.
Solar planes may or may not happen, but the bias of the author seems pretty obvious to me.
Even though I would debate if plane that flies on liquid fuel derived from solar panels is really a "Solar Powered" craft but... Bias is still evident.
"Don't fear death... fear not living..." -me
Airliners powered by onboard solar panels? No.
Solar-powered drones? Those seem very likely. They work like satellites for some applications, but they're cheaper, and are likely to remain so unless SpaceX makes some incredible breakthroughs.
Battery-powered airliners? Maybe. At the very least we might get battery-assisted airliners.
(T>t && O(n)--) == sqrt(666)
> . You can design a ultra-high-bypass turbofan that's electrically driven and suffer no loss of speed. It'll just be a fan and the turbine engine core is replaced with an electric motor.
So you're basically saying?:
>> You'd still need the same turbofans, just with heavy electrical windings in the middle rather hollow combustion cavities.
If you're an aerospace engineer, you'll recognize. pmin=2â...mâ...g(Mach2â...cL)maxâ...a2â...S.
If you're not, suffice to say that wings work by air pressure, and speed. As air pressure reduces with altitude, velocity must increase. The highest flying aircraft (SR-71) had to also be the fastest - planes can't go that high without going that fast. Designing planes to fly mach 3 means making different design decisions than designing an airliner. That's why a 777 flies half as high as jets can fly - because otherwise it would have to be built like the SR-71. Two-seater airliners don't work so well.
You may note that an electric motor must use a propeller/ fan design. It can't be a ramjet, scramjet, etc. Fans (electric or otherwise) need air to operate, more air pressure than scramjets need. Therefore an electrically powered plane will have a LOWER service ceiling than a jet has.
I suspect there are all kinds of niche reasons for an electric plane. Farmers monitoring fields, scouting for poachers, or other situations where carrying huge fuel sources for small planes is not good. Even hopping from place to place in the Australian bush might justify a solar plane.
But it all boils down to energy density and economics. Batteries are getting better and better which will drive battery planes into more niches. Then the day may very well come when the economics for boring commercial flight might be a reality. It won't be that simple as turnaround time on a plane is very important, also the amount of energy required to charge a large number of commercial flights at the same time could be staggering.
So I would put away the popular mechanics ideals of us all taking an electric commercial flight in a few years, but I am willing to bet that we will see more and more small electric craft popping up, and they will slowly grow in number and size. At that point you could probably point to when on an extrapolated graph they will move into commercial passengers.
Remember, respected publications around 1910 thought that commercial passenger flights were never ever going to happen, they had a laundry list of insurmountable obstacles that had to be first overcome.
You may be presumptive in asserting electric cars will overtake ICE in the next decade. Without a breakthrough in battery tech to increase storage capacity and reduce recharge time by 2 to 3 orders of magnitude, they will remain a richie rich boytoy. I'd love to have an electromotive passenger car, but should I choose to travel long distances, I'd rather not do it as the pioneers did in their Conestoga wagons on the prairie.
Have a Day!
It's almost as if you can apply an understanding of basic physics concepts (like say, conversation of energy, the laws of thermodynamic, concept of energy density, etc) to immediately understand why certain things (like say, a perpetual motion machine, the EmDrive, cold fusion, faster than light travel, powering a heavier than air vehicle with solar cells, gasoline made from plants, solving our civilization's energy/pollution issues without using nuclear, etc) aren't workable.
Existing bio fuels are every bit as dirty as fossil fuels... requiring clearing (by burning down) big sections of rain forest, or extensive use of petroleum based fertilizers, and more. The EU was on a big biofuel kick until they saw the damage caused by their feel-good policy.
And yet electric cars are on their way to overtaking internal combustion cars in the next decade.
The logic you applied to biofuels being "dirty" also applies to electric power generation. And if demand for electricity is significantly increased due to the adoption of electric vehicles then "dirty" electric power generation will likely still be required in the next decade.
In other news, perpetual motion machines will not be powering aircraft any time soon!
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This got me thinking.
Oxyhydrogen may be a good "energy transport" medium for use in PV aviation. (Hear me out here. I am well aware of the fringe BS associated with oxyhydrogen. I am not going to spout any of that here. I am much more interested in how it can actually be leveraged.)
According to wiredchemist.com, distilled water has a vapor dissolution capacity for hydrogen and oxygen gasses as follows:
100g of water can dissolve .00016g of hydrogen gas and .0043 of oxygen gas, at 293K.
According to wikipedia (yay.) oxyhydrogen, when burned at 2:1 ratio produces 241kJ for every mole of H2 burned.
1 calorie is 4.186 Joules, and 1 calorie is the amount of energy needed to raise 1g of water 1C. (C and K conveniently align on the same scale by design.)
1 mole of hydrogen weighs 1.00794g.
With these values, we can determine how many moles of hydrogen can be suspended in a water based carrier, and how many degrees we can raise the temperature of that water via combustion.
This works out to 629962.5 g of water needed to hold the full 1mole hydrogen gas.
The combustion of the 1mole hydrogen produces 241kJ of energy, which is 60250 calories. It takes one calorie per gram of water to be raised one degree. Doing the math:
60250cal / 629962.5g water = .09C increase in temperature.
Not surprising, this is why we dont have water powered cars. :)
What we need is a way to increase the amount of hydrogen we can store in the water. The best way to do that is with reactive polar molecules that contain a lot of hydrogen, that are highly soluble in water. Sadly, the best candidates are also major contributors to smog formation. (Ammonia being a very good candidate. Ammonia is highly exothermic in the creation of nitrous oxide in the presense of a platinum-rubidium catalyst, causing a self-sustaining reaction as long as there is oxygen to combust with. It contains a shitload of hydrogen, and is highly soluble in water. However, the resulting compound is basically nitric acid, and is basically acid rain. Yay.)
Since all the usual chemical additives to add more hydrogen all contribute to atmospheric pollution, we have to sideline them.
Thankfully, water ice can form stable molecular cages for dense hydrogen gas-- eg, "Hydrogen Clathrate" is a real thing that can be made.
Instead of the paltry .00016g/100g ratio of liquid water, solid hydrogen clathrate can have ratios 48mole hydrogen gas to 136mole water ice! (ratio of 1 : 2.8333)
1 mole of water is 18.015g.
Now, that 1 mole hydrogen still will produce the 60250cal of energy on combustion, but now only has to heat 51.04g of water. The net temperature increase from 0c (ice) is 1180 degrees C from combustion of this fuel!!
60250cal / 51.04g water = 1180.44670 delta-C
Now we're talking!
But there's a rub:
Hydrogen clathrate can only be formed under absurd pressures. How absurd? 300MPa @ 250k, and takes over 30 minutes to form.
So, let's compromise.
We dont really need a steam exhaust stream hot enough to melt aluminum, now do we? And, efficient combustion of a solid is very much dependent upon particle size, and rate of reactant intermix. So, let's not use solid hydrogen clathrate. Let's use a combination of hydrogen peroxide and distilled water, with hydrogen clathrate slush as the fuel. This gives us our oxidizer in liquid form, gives us our fuel in the form of the clathrate ice microcrystals, and gives us bulk propellent in the liquid water. We can add a tiny amount of sodium silicate to help prevent the mixture from freezing solid. (On combustion, it will turn into trace amounts of silica gel in the exhaust stream. Basically, microparticle glass dust. You dont need very much of this stuff to combat ice formation. Alternatively, you could add alcohol if you dont mind the production of some CO2 in the exhaust stream.)
This reduces the amount of hydrate nee
Nonsense. Power generation by coal is quickly going away. Natural gas is far cleaner than gasoline, kerosene, or bio equivalents. Solar (thermal or PV) and wind are being installed at a quick and increasing pace, far faster than demand is growing.
A decade isn't far enough out... Jets take more lead-time than that even when just based on conventional and established tech, while electric is still only a concept.
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I must assume you don't know what an order of magnitude is. a Tesla Model S has a range of 300 miles, and charges up to 170 miles of range in 30 minutes.
3 orders of magnitude would be a 300,000 mile range, and when charging would get 170,000 miles of extra range every 30 minutes. Safe to say they'd be practical vehicles long before that point.
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You're probably thinking of the two SR-71B trainer aircraft which had an extra cockpit added above and behind the SRO position. The SR-71A, the standard model, had one cockpit - with two seats. One seat for the pilot and one for the RSO (reconnaissance system officer). You can see the RSO's window in this photo:
http://www.sr-71.org/photogall...
Here's a video of a SR-71 pilot showing the two positions and talking about the roles of the pilot and the RSO.
https://www.youtube.com/watch?...
Interestingly, neither person can fly and land the plane by themselves. The RSO did the navigation, telling the plane where to go (auto navigation to specified points is required at mach 3), while the pilot controlled altitude, rudders for landing, etc. If either the pilot or the RSO became incapacitated or the intercom was lost, they would have to bail out.
I prefer hydrogen as a fuel, it can cleanly power turbines.
Just a few problems to iron out.
When the cost of pollution gets too great,
someone will work out a clean alternative.
Go well
What makes you think there's a bias against internal combustion for aircraft?
There are several projects aimed at using biofuel for jet engines. There have been commercial flights already that were powered in part by biofuels.
The unsolved problem here is the currently very limited supply of biofuels, but that's being worked on as well.
Liquid fuels have incredible energy density. We would probably need a Back-to-the-Future-like "Mr Fusion" reactor, not improved batteries, to make electrically powered fixed/rotary wing aircraft practical.
Thank you! Someone said it. Again. And btw we do have "Mr Fusion" type tech for aerospace applications from 70s I think. I just wouldn't put living cargo we care about anywhere near it. Just in case you didn't know. Not many people do.
Energy density has always been the reason why we drive gas powered cars and fly in kerosene-fueled planes.
It's never been an evil plot by some nefarious scheming "Big Oil" executives, who are simply making money efficiently providing what the market demands at prices the market is willing to pay.
The Sun, Wind, etc simply do not pack as much energy into a cubic inch/millimeter or into a pound/kilogram as the highly-optimized-by-nature fossil fuels (which are created over time by extreme pressures and temperatures compressing huge volumes of plant and animal matter, making it into VERY dense energy sources). There's nothing magic here and no conspiracy.
Solar planes are a good, geeky,stunt that demonstrate how far battery tech and solar panel tech have come. They are not, however, even a display of advancing aviation tech - there's nothing here that is even an advance over the human-powered planes of Paul Macready from 30+ years ago. People who dream of "free stuff" and therefore dream of solar powered planes should ask themselves a few questions:
1. How big would you have to scale the plane to make an airliner for 100+ passengers? (this was an airliner-sized plane to haul just one guy)
2. How much did the solar panels and motors on this plane cost to haul just one guy through the air? (and thus how much for a plane to haul 100+?)
3. How many passengers would pack onto an airliner like sardines if it would fly at the speed of a bicycle, rather than getting to the destination in only several hours by traveling at over 300mph???
4. How many people would be willing to board an airliner constructed as light and fragile as this crate had to be to make it even possible? Most people would probably be frightened if they knew how thin and light the structure of current airliners actually is, and THAT is far too heavy for solar-powered flight.
OK, slight exaggeration with the Montgolfier brothers. Their aircraft took off about a decade before the first telecommunications networks were developed.
Moving bits between points 'A' and 'B' is always going to be greener than moving meatbags between points 'A' and 'B.'
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Switch to bio fuels that are carbon neutral and we have no problem. Carbon is not the problem if it is taken from and returned to the current environment, as with bio fuels. Carbon is only a problem when we mine ancient sequestered carbon and reintroduce it to the current environment, as with petroleum. .
Sorry, I like flying too, but it is hopeless.
Carbon neutrality only works if carbon dioxide is immediately removed directly from the atmosphere by a process that is outside and in addition to the Earth's natural systems. It does not matter where the sequestered carbon comes from, whether living trees or dead coal: emissions are emissions -- farts are farts -- and they all stink.
Greenhouse gas emissions are economy-wide, so shuffling the emissions over to some other place or shifting them to other sectors doesn't help much. The problems are (1) planes being heavier than air and (2) trying to go faster than Ivan Illich's speed limit.
catapult on runways will cut energy use on take off and catch hook cut braking energy
especially for cargo planes
"Switch to bio fuels that are carbon neutral and we have no problem"
I'm not sure you have a very good grasp of the basics of energy flows as in ecosystem thermodynamics.
Bio Fuels have very poor EROEI ratios, meaning you need more energy going in than you get out. Fossil fuels have the great advantage of having concentrated solar energy over millions of years before being cooked in the earth for another couple of milion They do have the disadvantage of being a finite resource..
Google Exxon's funding of Craig Venter's research into bio fuels from algae
Though Bio fuels still have their uses for niche application while fossil fuels long term are a dead end, that's our civilization's current dillema.
While solar energy probably will not power air cargo transport any time soon, wind and solar can certainly power high speed trains...
nuclear is possible using thorium reactor tech, electric props or laser jet turbines that heat compressed atmosphere without fuel. thorium is safe,cant meltdown and would be safe in a crash by design. thorium wasn't supported during the cold war on both sides since you cant make nukes with it. the tech could be used for ships cars and planes and trains. solar electric would work for lighter than air ships. in fact if we shaped air ships like a flying wing forward movement would add to lift. and solar on top.unmanned could aid with radar early warning midair refueling, cell coverage and drones the size of a bird to the size of a B-52. all solar with very high loiter times, a traditional design with a gondala which could be a turret,with a reconciles cannon, cameras, laser designator and bomb bay with hellfire and air to air missiles.
Nonsense. Power generation by coal is quickly going away. Natural gas is far cleaner than gasoline, kerosene, or bio equivalents.
Actually, that is the nonsense. Nat Gas is still introducing sequestered carbon. Bio is not.
Your description of bio was BS. Cutting down the rain forest is not necessary. Massive fertilization is not necessary. Biofuel can be generated by bacteria. Ex: Intestinal bacterium producing propane.
http://www.nature.com/ncomms/2...
"The authors isolated bacteria that make high concentrations of alcohols including ethanol and 1-butanol, and other strains that make hydrocarbons, like hexane and octane. These compounds are similar to components already found in gasoline. Although the Department of Energy and many investors have invested millions of dollars trying to genetically engineer organisms like these, the scientists from Maryland led by UM professor Rick Korn say that such organisms are already common in nature."
http://www.biofuelsdigest.com/...
Biofuels are not only plant based. Biofuels include bacteria generating key chemical compounds of the fuel themselves. These bacteria are the heart of a carbon neutral liquid fuel.
Though Bio fuels still have their uses for niche application ...
A niche, like aviation. Aviation fuel is a very small portion of fossil fuels.
The US Navy and US Air Force are aggressively pursuing a switch to biofuels. Supply line concerns outweigh initial cost issues, these military programs jump starting the research and infrastructure needed for civilian use.
The US did design and build a nuclear powered plane, though the plane was not technically powered by the reactors that it carried. Really interesting stuff.
"A nuclear-powered aircraft is an aircraft that is powered by nuclear energy. During the Cold War, the United States and Soviet Union researched nuclear-powered bomber aircraft, the greater endurance of which could enhance nuclear deterrence, but neither country created any such operational aircraft. One inadequately solved design problem was the need for heavy shielding to protect the crew from acute radiation syndrome. The advent of ICBMs in the 1960s greatly diminished the tactical advantage of such aircraft, and respective projects were cancelled; the inherent danger of the technology has prevented its civilian use."
https://en.wikipedia.org/wiki/Convair_NB-36H
"The NB-36H was converted from a B-36H that had been damaged by a tornado. The original crew and avionics cabin was replaced by a massive lead and rubber lined 11 ton crew section for a pilot, copilot, flight engineer and two nuclear engineers. Even the small windows had 10-12 inch thick lead glass.[1][2][3][4] Unlike the planned Convair X-6, the three-megawatt air-cooled reactor in the NB-36H did not power any of the aircraft's systems, nor did it provide propulsion, but was placed on the NB-36H to measure the effectiveness of the shielding.[1]"
It's clearly necessary, as that's how most biodiesel is produced, today.
They've been trying for decades and decades, and can't get it to work outside of a lab. It doesn't scale up to even the tiniest production quantities. Bacterial growth and biofuel films are apparently mutually incompatible.
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The vast majority of US foreign petroleum supplies come from Canada. Not exactly an unsecure supply
Airships can carry much more weight than a 747 even if they fly slower. An airship covered with solar panels could possibly generate enough electricity to propel itself through the air, and as a substitute for cargo sent by ships rather than as a substitute for passenger traffic. Or they could build one like a luxury liner. Getting enough helium is the stumbling block though.
"..One hosts to look them up, one DNS to find them, and in the darkness BIND them."
NASA and its contractors studied landing and re-using launch vehicle first stages in the 1960s. Von Braun's team immersed a Saturn I first stage in salt water to study the effects and see if the stage would be reusable in the even it landed in the sea and was towed back to shore. There was a lot of interest. NASA at that time, however, switched from a long slow march to the moon begun under Eisenhower to complete immersion in the Kennedy moon-in-a-decade plan. Re-use options, along with other concepts like lenticular Apollo shapes, and Gemini capsules coming down under a parawing and landing horizontally like a plane on retractable landing gear became something the schedule could not handle.
After the moon landings, NASA and the contractors again studied re-use. Convair, Martin, Boeing and others offered designs for reusable 1st stage launch vehicles, but NASA opted for a re-usable spacecraft. They hoped to mate the reusable shuttle orbiters to reusable winged launch vehicles but the Nixon administration decided the R&D would cost too much and take too long, so the agency went with the reusable spacecraft mated to recoverable and reusable boosters and a disposable external tank.
There's tons of documents about all the reusable launch vehicle concepts NASA and the contractors studied. It was well understood to be possible, but the contractors were never going to spend their own money developing a capability if there was a chance the government might fund it at some point, and they certainly were never going to do it to lower launch costs as long as their launch contracts were "cost plus" (lower costs would produce a proportionally lower "plus" which would upset share holders).
There's a HUGE difference between "the physics says NO" (as in solar powered airliners) and "the physics works, but nobody currently wants to pay to develop it" (as in the reusable launch vehicle).
The vast majority of US foreign petroleum supplies come from Canada. Not exactly an unsecure supply
US political policies could see Canadian exports shift from the US to China.
Yes, lots of work is still to be done on the bacteria side. Again, I argue that for a ten year window additional electrical power generation needs are likely to include dirty fossil fuels to meet demand.
But in the long term bacteria is still an option, its not a dead end. Internal combustion and jet engines are not a dead end. Battery powered aircraft are probably even less farther along than bacterial biofuels. That is my point, not that we'll be switching to bacteria any time soon.
Also the US Navy program is not going the burn the rainforest and/or heavily fertilize and devote farmland/farmcrops to biofuel. I believe they are using a grass (weed?) that naturally grows in austere conditions in land not traditionally used for farming.