Jet Engine on a Chip 463
Roland Piquepaille writes "Today, our handheld devices are powered by batteries, which are heavy and inconvenient. Fuel cells are just arriving on the market as a replacement. But there is a new contender: micro gas turbine engines under development at the MIT. Engineers there shrunk jet engines to the size of a coat button. And their blades which span an area smaller than a dime can spin a million times per minute and produce enough electricity to power your PDA or your cell phone. While there are still a few hurdles to overcome, these micro turbine engines should be operational in two or three years, with commercial products available four years from now. These micro jet engines also have the potential to free soldiers or travelers from carrying heavy batteries. The engineers even think their engines on a chip could be used in poor countries to bring electricity there. This summary gives you the essential details about a technology which promises to free us to carry extra fuel instead of batteries."
Cool, but misleading title (Score:5, Interesting)
2. Saying that a Gas Turbine == a Jet Engine is a bit misleading. It's a bit like saying "Scientists have shrunk an electric motor to 4 nanmometers", then before you even finish thinking about all the MEMS devices, you read "Scientists have produced a 4 nanometer electric genertor for use in making power for MEMS devices." Still very cool, but not the same thing.
Roland Piquepaille! (Score:3, Interesting)
What about pollution? (Score:2, Interesting)
Roland Piquepaille (Score:4, Interesting)
http://science.slashdot.org/search.pl?query=Rolan
MOD PARENT UP (Score:3, Interesting)
Re:Cool, but misleading title (Score:5, Interesting)
Gas turbines seem to only become highly fuel efficient when the heat of their exhaust gas is captured by a secondary system, like a steam recovery boiler. http://www.ornl.gov/info/ornlreview/v33_1_00/turb
Re:exaust (Score:3, Interesting)
What about hydrogen? I know that's kind of a played-out concept but look at the possibilities. You could have your own electrolyser at home and bottle your own hydrogen, then slap it into your laptop and go. You could generate the electricity off the grid, or whatever. Output is water vapor, which is pretty harmless as long as it's exhausted outside the case of the laptop.
Re:What about start procedure ? (Score:3, Interesting)
Using the generator as a starter motor is probably the absolute best way to go. This is probably coming on automobiles, too; we'll end up with a combination AC motor/alternator-generator for starting and charging. This will be driven by everything and I mean everything on the car going electric. No more vacuum lines, no more hydraulic system. The system will be higher-voltage (automobiles are about to go 48V, even in the US) and that will reduce the gauge of wire necessary for the electrical system, further saving weight. Doing this would allow us to eliminate all the pulleys and belts on the vehicle. This will require using higher-technology batteries, like the Optima [optimabatteries.com] types, because electrical system problems (especially battery failure) are the #1 cause of breakdowns.
Noise (Score:3, Interesting)
size and efficiency (Score:5, Interesting)
You will also notice that (in general) the smaller the gas turbine, the less efficient.
I have been to multiple talks on these engines, I used to work for one of the industry colaborators on the project as an aerodynamicist. These engines are no exception to that rule. The turbine on these engines hardly extracts enough work to run the compresser when you are running the combuster just below the melting point of the engine.
Also (addressing the summary, not the parent post), these things have been "2-3 years away" for at least 6 years.
Re:Cool, but misleading title (Score:3, Interesting)
Re:MOD PARENT UP (Score:5, Interesting)
I dunno, I found this article very interesting.
Also, did you actually read some of the other stories on his blog? Mongolian monks and fish? Hydrogen Economy? Phoning Home from the Bottom of the Ocean?
I actually found that blog to be quite interesting and unlike most, he took the time to post illustrations. I say: Good job Slashdot! That was indeed a "News for Nerds" article.
1 million rpm? (Score:5, Interesting)
A better TR article blasts "hydrogen hype" [technologyreview.com] but in fact H2 would be about the best fuel for these little buzzers:
And aren't you just all breathless, when the "batteries die", to take your cellphone to the out-of-work airline mechanic who got re-trained at a watch factory ?
Re:Cool, but misleading title (Score:5, Interesting)
You are correct. However, much of the fluid mechanics of very small microturbines is rather well understood, so the basic goal isn't unreasonable. And usually the answer to viscosity is speed---small turbines generally spin very, very fast.
(Disclaimer, I work for a company that makes very small turbines [creare.com].)
Foundational research (Score:2, Interesting)
more information here (Score:3, Interesting)
Jet engines are relatively inefficient at low speeds but once they get up to speed, the efficency goes back up and the process feeds on itself becoming a self-sustaining process.
Combustion engines are the opposite, they run fine at regular speeds but at high speeds, you get the same effect as the economic term "diminished returns" where it states that with additional units of work provide lesser and lesser additional power. In other words, it requires more and more work to achieve the same speed increase.
The only time I listened to Jay Leno was when he was talking about the difference when showing off his jet bike (a motorbike with a jet engine instead of combustion engine).
Re:What about cars? (Score:1, Interesting)
Re:Roland... (Score:5, Interesting)
Re:exaust (Score:2, Interesting)
Re:Roland... (Score:2, Interesting)
I would rather see good articles posted under Rolands name than half the other crap weve had recently.
Yet again, I must point out that the summary he places at the bottom of each submission is just that - a summary, the main articles ALL have real links which don't involve going anywhere near his blog. Infact, I tried to find a submission of his that forces you to pass through his blog to reach the article, just to see if I had infact missed something, but I couldn't see any. Perhaps you could show me.
http://www.google.com/search?q=+%22Roland+Piquepa
I can see the point in getting irate about ny times or other registration sites where the article is posted, but I just see his blog as a bit of a mirror.
Interesting radial velocity (Score:2, Interesting)
1 million RPM at the diameter of a dime.
An American dime has a diameter of 17.91 mm [enchantedlearning.com].
At 1 million revolutions per minute, a point on the edge of the turbine blade will travel:
or
56,265.9 meters per minute, or 937.8 meters per second.
The speed of sound at sea level [google.com] is 340.29 meters per second.
So this thing's blades will have a tangential velocity of mach 2.76.
I think the sonic boom when it starts up will be as much if not more of an issue as the whine from its operation...
Re:What about pollution? (Score:3, Interesting)
Is there something inherent in the scale of these devices that means that this kind of reversal makes sense?
Re:Roland (Score:2, Interesting)
Proof? Attend one of the Slashdot IRC conferences that Slashdot holds yearly or so (or look at the logs of ones past). Popular requests and complaints are ignored or give some type of excuse to not deal with.
More Proof?
The post in which someone criticised the moderation system that received many hundreds of downmods - the only post ever to receieve that many - something only the editors of
I come to Slashdot for the news and some of the comments, but thats it. I don't subscribe and I block all ads.
Re:Cool, but misleading title (Score:3, Interesting)
Gas Turbines are some of the most efficient fuel -> energy converters known to man.
False!
I work in the energy sector. Gas turbines are, for the most part, only turned on when there is either (a) a sudden increase in demand or (b) nothing else available. Believe it or not, a steam-powered plant will generally do the job on as much as 50% less fuel than a gas turbine, but may take several hours to get up to speed.