Hate noisy jets above you? What if they were charging your phone? A researcher with Boeing has floated a plan to convert the noise from departing planes into a power source. A US patent application filing by Chin H Toh of the Boeing Company published earlier this week describes a method for using the energy from acoustic waves made by jet engines to power a turbine and generate electricity …
The amount of energy required for research, design, manufacture, installation and maintenance would no doubt be significant.
Would the energy recovered ever be sufficient to offset all the set-up and ongoing maintenance expenditure?
I don't know, but somehow I think it would be a very long term project to break even, maybe never.
Any clever people want to invent some sums to have a go at the problem?
No sums here but as I recall from sound powered transducers, the power out is miniscule compared that going in. If they have some breakthrough in the mechanics of this, there's a lot of applications waiting in the wings...
The other issue, is that aircraft don't take off or land continuously except at the major airports. Storage of the power would be much the same issue as with wind and solar.
For now, it seems to be nice mental exercise that might get some others thinking and tinkering things out.
Last year when new Formula 1 engine rules resulted in engines that were merely deafeningly loud instead of insanely loud, I had made a back-of-the-envelope calculation to see how much extra power the engines needed to produce to equal the previous noise level. I can't remember the details but what I do remember was that the result was extremely and surprisingly low.
I believe the noise of a jet taking off is about the same order of magnitude as an F1 engine (a bit less than130 dB iirc), so bottom line, I highly doubt that any such installation would even be measured in kW rather than simply W.
Of course I stand to be corrected by anyone more knowledgeable and/or with more time on their hands to go into more detailed numbers
While it wouldn't do anything to diminish the noisy takeoffs and landings, being able to harness a bit of power from the process could make engine noise a bit more tolerable.
This doesn't stand up as 1) the array would act as a physical baffle just by being in place and 2) converting sonic energy to another type would mean less of it around and therefor less noise. Rather than installing the system at airports or near Formula 1 racing venues, I suggest Nascar raceways. People attending Nascar events would appreciate the ability to boost their phones volume to the point where they can hear them over the music which has been turned up high enough to be heard despite the ear plugs everyone most people attending the race wear to protect their ears from the engine noise. Being able to harvest all that noise to produce some more seems like a good plan.
Best acoustic horns are about 110dB at one meter per watt input.
So 100W can produce 130dB at a meter,
In practice most loudspeakers aren't that good, but a good 5KW PA can easily squish out 120-130dB at reasonable range.
And a good overdriven Marshall 100W is up at that level within a couple of meters.
Yes, making the sound uses far more energy than you'll ever get out of it. The rest turns into that thermodynamic tax called "heat".
A far better way to be energy efficient is to not make the noise in the first place. Since the proposed process is 5% efficient at best, just reducing sound energy production by 10% would be a big win.
Of course the "boffin" would already know this. The idea looks like a daft window dressing supposed to appeal to people who don't understand physics. You know the sort - the people who think harvesting energy from people walking on piezoelectric tiles yields free energy and the only reason the roads are not paved in the stuff is because of the Evil Oil Companies.
"piezoelectric tiles yields free energy ..." Oh god that reminds me of that whole "solar roadways" bollocks from a little bit ago...
I love how projects like this tend to leave out the part about "This would require more tantalum than currently exists on Earth, assuming we mined every bit of it". Or the insane length of time it would take for the benefits to offset the production cost...
What would really reduce air traffic noise would be to install proper high-speed trains rather than the crap diesel-electric behemoths we currently depend on that cost more, and take longer, than flying...
An intensity of 120 dB is equivalent to one watt per square metre. 130 dB would be 10 W/m^2. There would be inefficiency in converting this sound to a continuous air flow (assuming this works at all - it's not clear from the diagram). The air would then have to be collected and sent to a windmill, with further losses, and the windmill would probably have low efficiency in such a low power air flow. Then as Mark85 pointed out, planes don't take off continuously, and even if they did, they wouldn't pass the "generator" continuously. So, if you're lucky, maybe a few watts from a big array. There is no way that this device will give a useful output, let alone repay the energy and cost that it would take to make it.
"So, if you're lucky, maybe a few watts from a big array."
So just to finish your calculation... Over an entire day, maybe a kilo-Joule of output, which is enough to run an electric fire for a second or two, in a world where you can run that fire for an hour for about 10p, so the earnings are about 3p per year.
I suppose if interest rates stay at 0% for the next couple of geological eras then you might turn a profit.
(Actually the best bit is that you'd need to keep the patent alive for several millenia to repay the filing costs. Even Disney might have trouble with that.)
Would be more efficient to just put the windmills at the sides of the runway - like you sometimes see along train tracks - and catch the air blast directly from the engines. But there's probably safety issues with having structures on the sides of the runways. Hmm, how about a ground-based cable launch assist to help get aircraft up without having to wind their engines up so much?
Sorry to pick on your comment - but FFS, Tony W (above) has posted the sums and anyone who thinks that this even asymptoticly approaches a sensible engineering proposal is either barking or just hard of thinking. Probably did PPS or Environmental Studies...
That said, I'm sure that a suitable level of Feed-In Tarrif can, and probably will, be set. It would need to be about 10^5 times the value of electricity produced to encourage development of this new (and recycled) green energy.
(doomed, we are)
That's what I was thinking of when I commented. Only instead of ploughing up 81 acres, you suck the energy out of the sound at the runway. Planes landing drift in and crank up their engines to stop. Planes taking off crank up their engines all the time; but the noisy bit is mostly pointing back at the runway.
Sod-all good for powering up a city; but might be good at sound reduction; and if you can run some emergency airstrip lights off it, all the better.
Unfortunately it's still far too much stuff that has prior art, or is obvious to expert in the field or are too broad, or otherwise totally lack merit. The USPTO should have to get paid x2 for rejected applications. Then they would be proper patents.
At least this patent is "mostly harmless" even if totally pointless, or is the real target something else?
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This is clearly a case where an engineer was ordered by a PHB to produce more patents. As long as it doesn't go viral on social media, the engineer will get away with it.
If there are any PHBs reading this ... it's a fine idea and you can ignore the naysayers and detailed calculations in these comment pages.
How many gym rats are sweating away on their hamster wheels for hours every day? If we harnessed that energy it would easily outweigh the "noise energy" from every airport in the country.
Also , every time a driver touches a brake pedal - which i estimate happens " A lot" - thats energy being thrown away that could have been saved and used
>every time a driver touches a brake pedal - which i estimate happens " A lot" - thats energy being thrown away that could have been saved and used <
That describes Regenerative braking - used particularly by railway authorities - turning the motor into a generator, which reduces the need for friction braking and brake-pad wear.
title: "What if they were charging your phone?"
answer: Even then, fuck no.
And why are they allowing development anywhere near airports, which are mostly constructed "away from everything" for a damn good reason? They *know* the bastards are going to whine about the noise within a short period of time! Anyone moving near an airport should have to sign an agreement "no whinging about the noise, even when they increase the flights, which always happens".
This system could create a bit of an upside to the noise pollution complaints that plague many airports in metropolitan areas. While it wouldn't do anything to diminish the noisy takeoffs and landings, being able to harness a bit of power from the process could make engine noise a bit more tolerable.
That's a rather stupid comment. It won't make it at all more tolerable as it doesn't reduce the noise if you happen to be under a flight path.
And before anyone says anything about not buying house near airport/flightpath, just look at Heathrow flight path trials. Residences quite considerable distance from LHR were (and still are) suffering from low flying aircraft.
We could save on the infrastructure costs of transmission lines by installing jet engines along the road way in residential zones and have people purchase their own sound to power systems.
Some might object to 24/7 noise but they could purchase Sound-Mufflers for their bedrooms..
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