Two Tiny Gas Turbines

Turbines are in the news this morning. bobtheimpossible writes to point out a BBC article on a Swiss turbine that runs at half a million RPM and generates 100 watts. It's the size of a matchbook. And af_robot alerts us to an even more diminuitive gas turbine on a chip, developed at MIT, that generates 10 watts — plenty for portable electronics — and should run 10 times as long as a battery of comparable weight and cost. A commercial version is 3 to 5 years away.

Still Mechanical Conversion to Energy

[ackthpt]

It's still a mecanical conversion of a compounds to energy, with all the inefficiencies that go with it, including disposal of waste heat. Where's these fuel cells I keep hearing about?

10 props for neat, anyway.

also, can it do this? [asciimation.co.nz]

Re:Still Mechanical Conversion to Energy

[bogie]

"Where's these fuel cells I keep hearing about?"

Why "A commercial version is 3 to 5 years away" of course...

Re:

[God'sDuck]

"A commercial version is 3 to 5 years away"

Remember: 3 years = 1 of work, 1 of stalling, 1 of resume writing. If you're especially good at stalling or especially bad at resume writing, estimate 5.

Re:

[onepoint]

>>If you're especially good at stalling or especially bad at resume writing, estimate 5.

this should be a reference note withing the Hitchhikers guild to the Galaxy

Onepoint

Re:

[HaeMaker]

Fuel cells are still very hot (at least in the reformation process).

Not only the heat, but am I going to have to get my notebook smogged?

Re:Still Mechanical Conversion to Energy

[roseblood]

Fuel cells are still very hot (at least in the reformation process).

Not only the heat, but am I going to have to get my notebook smogged?

Just don't let SONY make these. They will have a rootkit and burst into flames, even when turned off.

Inefficiencies?

[the_REAL_sam]

I hate to say it, but RT*A. It says the device is 95% efficient.

"...The matchbox-sized motor generates the equivalent of 100 watts..." "...and has an efficiency of close to 95 percent..."

Re:Inefficiencies?

[Colin Smith]

Sorry, but bollocks it is. A gas turbine is a heat engine, the efficiency is determined by difference between the temperature at combustion and the exhaust gases. 50% would be excellent for a gas turbine.

 

Re:

[John Hasler]

The BBC article is about a _generator_, not a turbine. 95% is quite reasonable for a small generator.

Re:

[be-fan]

It's a generator powered by a gas turbine.

Clearly, what the article is referring to is not the efficiency of the turbine, but the efficiency of the generator connected to the turbine. Ie: the turbine is probably very inefficient, but the generator is 95% efficient in converting the mechanical energy of the turbine to electricity.

Re:

[John Hasler]

> Now, efficiency is one of those numbers that people play fast and loose with,
> so who knows what they actually mean...

It is fairly clear that they mean that the efficiency of the generator at converting mechanical energy into electical energy is 95%. The BBC article where the 95% number appears mentions gas turbines only in passing, noting that one could be used to drive the generator (which is what the article is about, despite what the Slashdot summary says).

6000C combustion?

[Overzeetop]

That's what it would take for a carnot cycle to be 95% efficient (give or take) with a room temperature heat sink. Is it really burning this hot, or is the article full of shit? (or is my thermo just that rusty?)

Re:

[Fordiman]

I'd say so. With such a tiny combustion chamber, it's entirely possible that the system can be at 6000C without problem. It's like the reason you don't get burned from an inch away from a cigarette butt; it's freakin' hot, but there's not enough thermal mass to heat much.

Re:

[amorsen]

With such a tiny combustion chamber, it's entirely possible that the system can be at 6000C without problem.

Which materials do you propose lining the combustion chamber with?

Re:

[billstewart]

The glass beads we trade to the natives are getting ever more shiny

At 6000 degrees? I'd certainly expect them to be shiny, if they haven't evaporated altogether :-)

Re:

[Fordiman]

Well, depending on the size of the combustion chamber, I'd say anything from steel to ceramic. It's the surface to mass ratio of the combustion chamber that matters, and in this case, I think it's likely high enough to allow for very high temperatures, even 6620K (calculated value for 95% efficiency at 100F room temp).

It's all about mass here; the amount of mass in the combustion chamber can't be much at all, so even if the gas is 6620K, the metal shouldn't quite get to the breakdown point of the liner mat

6000C past temp limit of combustion gases

[Latent Heat]

The National Aerospaceplane (NASP) was supposed to burn hydrogen in a "scramjet" to propel and airplane-like vehicle to Mach 20 and into orbit. The funding got pulled on it, and there was some speculation that it was cover for "black" programs.

Anyway, the scramjet is the ultimate exercize in drinking from the firehose. A normal turbo or ram jet engine has a diffuser to slow the incoming airstream to some managable subsonic value, burn fuel, and drive the turbines. Trouble is that if you are going fast

Re:

[syphax]

I just posted the same. Most likely answer: Journalist heard 95% (probably efficiency for some part of the system, likely the electronics), wrote 95%. Alternatively, both of our memories of thermo suck.

Re:

[WARM3CH]

This is a gas turbine: flow of gas turns the rotor. The similar thing that is used in dams to generate electricity. It is not a machine that burns the gas so it is has nothing to do with carnot cycle.

Re:6000C combustion?

[John Hasler]

A gas turbine is a heat engine and is limited by Carnot efficiency. However, the machine described as being 95% efficient in the BBC article is not a gas turbine. It's a generator.

Re:6000C combustion?

[Overzeetop]

That's true, but my (poor) memory seems to recall that no thermodynamic cycle can exceed the Carnot efficiency - it is the theoretical limit. A turbine does have a cycle, though I can't remember the name offhand - it's been almost two decades, and I don't do any thermo in my line of work. ...Okay, google is my friend. The answer is the Brayton cycle, and the effeciency appears to be 1-T1/T2, which is identical to the effiency of the Carnot cycle, presuming theoretical gasses and adiabatic conditions (neither of which exist in turbines). So the answer is still about 6000 Kelvin (not celcius, and extra , which is a good bit above the melting point of most materials. From Wikipaedia: The chemical element with the highest melting point is tungsten, at 3695 K (3422 C, 6192 F). The often-cited carbon does not melt at ambient pressure but sublimates at about 4000 K; a liquid phase only exists above pressures of 10 MPa and estimated 4300-4700 K. Tantalum hafnium carbide (Ta4HfC5) is a refractory compound with a very high melting point of 4488 K (4215 C, 7619 F) I'm banking that this isn't running at 6000K.

Re:

[georgewilliamherbert]

I don't know why this got modded insightful, it's entirely wrong. A turbine is a axial or centrifugal flow gas or liquid flow to mechanical energy converter. A gas turbine, as the article is about, is a heat engine with a compressor, combustor, and power take off turbine which at least powers the compressor, and for non-jet gas turbines also powers the mechanical power output. As a heat engine, the Carnot cycle is entirely appropriate.

Dams are subject to Carnot as well

[marcus]

Combustion is NOT required. It is still a heat engine.

You simply have not considered the rest of the cycle.

The falling water does work. In order to do work, the water has to be lifted, that is, work must be done. The work is done by the gases in atmosphere. The heat comes from the sun. Gases in the atmosphere absorb the heat and expand(do work).

How much solar energy is required to lift X Kg of water Y meters when the starting and ending temps are both between 273 and 373 K? A lot more than is delivered at t

Re:

[syphax]

RTF Textbook [wikipedia.org] Unless I'm missing something, this turbine is a heat engine, just like any other turbine. Heat engines' max. efficiency is 1 - T(cold)/T(hot), where T = absolute temperature (Kelvin or Rankine). At T(cold) is likely room temp (~300K), if this thing is 95% efficient, T(hot) must be around 6000K. That's... hot.

Re:

[be-fan]

That's unpossible. The best gas turbines are in the 60-something range for efficiency, and making gas turbines smaller tends to make them less efficient. Clearly, there is something the author of the article is missing.

Re:Inefficiencies?

[jandrese]

What's 5% of 100 watts?

Um, about 5 watts? That's pretty low heat dissipation all told. Exaust and mechanical stress are definatly a concern though, although with components that small at least the masses will be tiny, even if the RPM is exceedingly high. I wonder about the sound though, is it going to drive dogs insane everytime you turn on your Laptop?

Re:

[jandrese]

Well, the good news is that the mass of the turbine will be tiny, so it will hold only very little latent heat when spun down. Depending on what kind of berings they use (I wouldn't be surprised if they use magnetic berings in here) that may not be an issue at all.

As other Slashdotters have mentioned however, this turbine appears to greatly exceed the theoretical max efficency for a heat engine unless they run it at insane temperatures. This fact tends to set off the BS alarm in my head.

Re:

[Fordiman]

"What's 5% of 100 watts?"

5 Watts, which isn't a lot of heat to remove.

Still, I'd think about using it as a power source for vehicles, if I believed they could scale it from 100W to about 125kW. (125kW, given 80% motor efficiency, is about the right amount to get 0-60 in about ten seconds given a load of 1 tonne or 1,000 kg. It's an engineering magic number, so far as I'm concerned).

Fuel cells aren't much more efficient

[Colin Smith]

50% if you're lucky, with corresponding 50% heat to get rid of.

 

Re:

[Smidge204]

These devices are claimed to operate at close to 95% efficiency. Even if that wasn't the case, efficiency doesn't seem like that big a deal when you consider the device of the same size and weight of a battery will provide more than ten times the energy.

=Smidge=

Re:

[purpledinoz]

I wouldn't want this on my laptop, even if it can power it for 10h straight (which would be awesome for the long overseas flights that I have to take on occasion). I would imagine a gas turbine exploding would be worse than exploding lithium batteries.

Re:

[John Hasler]

> To say nothing of using one of these for dental work, as alluded to in the
> article.

Perhaps you should read the BBC article. Hint: it isn't about gas turbines.

Comparason to battery is flawed

[EmbeddedJanitor]

It is all very well saying that this device cranks out more juice than a battery of the same size, but the comparason is a bit flawed.

A battery stores all its fuel + waste products onboard. A turbine needs a bunch of extra peripheral stuff to store its fuel and waste products. Come back when you have a wholse solution.

Re:

[Doc Ruby]

Even the chemical reactions at the center of all these fuel->energy devices are "mechanical". The Swiss turbine is in the cm^3 scale, yet claims 95% efficiency (presumably from the energy content of the fuel delivered to the power of the spinning rotor). Fuelcells operate on catalytic mechanisms for separating electrons from molecules, mechanics at the nanoscale. But the highest fuelcell efficiency I've seen claimed is only about 60%, from fuel to DC current. I wonder what kind of efficiency could be gai

Re:

[John Hasler]

> The Swiss turbine...

Read the damned article. The Swiss device is a generator, not a turbine.

Warning

[Supersonic1425]

Do not shake.

Actuallly should be pretty tough

[wsanders]

If the trend is anything like hard disk drives, the device should get tougher as the dimensions get smaller.

I'd hate to see one of these things throw off a blade while it's powering your iPod on the subway, though.

Re:

[Anonymous Coward]

You would have a hard time shaking it as the 500,000rpm turbine would act like a Gyroscope.
I would worry about dust, sand, bugs and other small bits getting pass the air inet.

http://en.wikipedia.org/wiki/Gyroscope [wikipedia.org]

gyroscope?

[Burlap]

at half a million RPMs, what kind of damage would happen to this thing if it was put in, say, an MP3 player for a jogger?

Re:

[Overzeetop]

Or, more interestingly, how much resistance will you get when trying to rotate it cross-axis.

Also, at 500k rpm, what kind of damage will it do if/when it fails.

Re:gyroscope?

[BoberFett]

Imagine how tough it will be to bend over and tie your shoe with that thing on your hip. That could be a workout on it's own: The Gyroscopic Abdominzeratertron.

Re:gyroscope?

[necro81]

Probably not very much. In the picture, you can see the rotor is about the size of a match and probably weighs less than a gram. This means that its moment of inertia isn't all that large (moment of inertia goes like radius squared, in this case, r is on the order of 10^-3 m). Even at 500,000 rpm, the amount of kinetic energy stored in the rotor probably isn't large enough to be a major concern. The relative bulk of the stator probably would be enough to contain it, should it catastrophically fail.

The same is true of the gyroscopic motion - the reactive force is a function of the applied force and the angular momentum. If the moment of inertia of the rotor is very small, the reactant force is likewise small.

Also keep in mind that this device has a designed power output of 100 W, which is at least one, if not two, orders of magnitude greater than what you'd need for an mp3 player.

Re:

[TubeSteak]

Also keep in mind that this device has a designed power output of 100 W, which is at least one, if not two, orders of magnitude greater than what you'd need for an mp3 player.

So how many Amps does it put out?

Can I use one to power an electric motor in a remote control vehicle?
Or to charge a super capacitor in a remote control vehicle?

Re:

[mspohr]

voltage * current = watts

Your questions really relate to power (watts), and amperage only one aspect of power.

Re:

[Burlap]

i wasnt so much concerned with centripital forces but rather what would happen due to the jarring action of jogging on the ultra-highspeed bareings.... even at such a small mass, what would happen if there was a catastrophic failure in your shirt pocket?

Re:

[Burlap]

true, however they are also generally made of metals that are a HELL of a lot thicker then what would be used here.

you also dont generally wear one in your shirt pocket.

Dupe with no more info

[ryanov]

Two postings now and the obvious question is still not answered... where the hell are you supposed to get the fuel for these things? How are they supposed to be refilled? Still nothing.

Not the first portable gas devices!

[MadRocketScientist]

Refillable butane lighters have been around for quite a while, I'd imagine this technology would have a similar refueling mechanism.

Re:

[dheltzel]

where the hell are you supposed to get the fuel for these things?

They are gas turbines, silly, eat a bean burrito and you're golden!!

"Cluster"?

[bigattichouse]

Not to play up to the running "beowulf cluster" gag... but could you use a slew of these to run your house?.. backup gen with 10 or 20 of these?

Re:

[Overzeetop]

Try 100 or 200 for a house with low power demand and a segregated backup panel for limited circuits. I'd need 960 of these to fully backup my house (all electric). Heck, you need twenty just to fire up the old lady's hair drier.

Re:"Cluster"? Not a bad idea!

[marcus]

A smoothly scalable power supply. THAT would certainly boost the overall efficiency of your house. When the old lady spins up her blower, the control circuits sense the load and start up additional gens until the load is matched. When she shuts down, so do the extra gens. Same for the TV, microwave, etc. No waste running, even idling, unneeded gens and dumping power!

Re:

[Overzeetop]

No, they just reside outside in their own enclosure, just like anormal backup. A little wart on your house next to the electrical entrance. Of course, I didn't see what either ran on (maybe I missed it) - if it's hydrogen then you're golden, if a little soggy over an extended period. High carbon HCs, then you're not so good.

Power generation

[harryk]

I think it's neat that it can output upto 100watts of energy, but at what Amperage and Volt? Could I use a couple of these things to say... act as a battery charger for an electric car?

Re:Power generation

[Overzeetop]

At 95% efficiency (a dubious claim, imho, given that the cold sink temp is presumably room temp), it would be a good source for constant charging and potential peaking current. You'd need a good number, though, at roughly 8 to the horsepower.

I think the future might be in portable power and backup devices - having a refillable, continuous 7-15kW power supply in a breadbox. With the right gear ratios, it could put out sinusoidal 60hz power for AC backup, though synchronizing the signals and preventing drift across the array would be a task in itself.

Re:

[Ant P.]

Instead of going to crazy engineering lengths to generate AC directly, you could just stick a DC-AC converter on the end.

Re:

[Lumpy]

it generates 100 watts. 20 amps at 5 volts. 10 amps at 10 volts 1 amp at 100 volts or .1 amp at 1000 volts.

Take ypur pick, you can generate from 0.001 volts at insane amps or millions of volts at nearly no amps.

Watts are universal and translate to all voltages.. anyone with a very basic background in electricity or electronics knows this.

Re:

[harryk]

Perhaps I'm asking the wrong question, but what I'd like to know is could I use a couple of these things to recharge my electric vehicle, or supply enough power to power the electric motor. Probably not, but here's to being hopeful that it could act as a charging system to the say the least.

Re:

[zippthorne]

You need to describe your vehicle better. If you've got something roughly the size of mid-size sedan, you'll need somewhere on the order of 30 kWe to operate it. So one 100 We generator could provide enough energy over a full day to operate the vehicle for about five minutes.

On the other hand, if you've got one of those spindly, death-trap solar racers, you get two and a half hours of daily operation from a single generator.

(assuming 100% conversion efficiency all around.)

fill them up?

[joe 155]

"one tankful of fuel drives the generator for about 10 hours at peak 100 watt performance"

they talk about putting these in mobile phones, but I wonder if they are gas powered how they will be re-filled. I wonder if we will end up in a situation where we have to wait for the gas man to come each morning if we run out

Re:

[Knuckles]

That's what you get after stamping out the smokers. Worthwhile locations have shops stocking butane gas refillers for cigarette lighters on every corner.

Exhaust?

[MankyD]

Is it safe to use engines like this in enclosed spaces? An airplane is a great example, but even my office with sealed window could be a problem. Anyone have more details? Similarly, it says it can run 10 hours, but how much fuel is that? My car engine could run all year if I left it hooked up to a gas pump.

Re:

[imsabbel]

Dont underestimate the energy of chemical reactions.
With 100W at 95% efficiency, it doesnt output more CO2 than a human breathing.

Re:

[MustardMan]

How exactly does the energetic efficiency automatically tell you something about the amount of CO2 being put out?

Re:

[MankyD]

What he/she is saying is that 100W at 95% efficiency gives you the CO2 output. (95% efficiency would mean ~105.3 Watts worth of chemical energy is required. 1 watt = 1 joule/second.) Whether or not they actually did the math or know what type of fuel is being used is a different story, but it is, in theory, possible to figure it out.

Re:

[megaditto]

S/he assumes this runs on some fuel similar in CO2/energy ratio to our food. Since each human generates 100W give or take, this engine should produce comparable amounts of CO2.

Re:

[the_REAL_sam]

>it can run 10 hours, but how much fuel is that?

OK I JUST HAD TO look this up. Check my math if you must. I make no promises.
Lets break the question into its constituent parts:

A gallon of gasoline contains about 31,000 Calories
1 watthour = .860420 Calories (So, an ideal Calorie is equal to 86.042% of a watt.)
A gallon of gas contains 31000 Calories
Convert Calories per gallon into watts hours per gallon: 31000 * (86/100) = 26660 watt hours per gallon (at 100% efficiency)
That means the device would produc

momentum?

[Sebastopol]

so do these things act like gyroscopes? i realize it is a small mass, but a super high rpm generates a big L. hate to have one powering my ipod, i could only jog in a straight line...

Ear plugs?

[jo42]

Will these devices come with ear plugs or noise blocking head phones?

Re:

[KillerBob]

your hearing can still be damaged by a loud enough noise, even if it's in a frequency range you can't hear....

Reversal of use

[LParks]

So our portable energy used to come from batteries, and now its becoming gas-powered. And our large vehicle engines used to all be gas powered, and now it comes from batteries. Interesting reversal.

Heat?

[Zach978]

Wouldn't this thing get pretty hot in my pocket?

None have run yet?

[sidles]

It takes a lot of reading to realize that none of these sub-centimeter turbines has actually run yet. Perhaps the laws of combustion physics prevent this? There's a reason why candle flames are the size they are ... see Michael Faraday's classic lecture The Chemical History of a Candle [bartleby.com].

Material fatigue?

[qwertphobia]

What happens after one of these has been used off and on for a few years and the materials start to fatigue? Have we all seen the videos of the CD-Roms spun on a Dremmel tool until they explode? Hint: convert 500k (or 1M) rpms into linear velocity at the outside radius of the turbine.

Re:

[Cthefuture]

Well lets see:

Assuming a 5 mm diameter (could be slightly larger or smaller, I dunno) at 500k RPM that's about 4.6 MPH on the outside. Also consider the parts would have very little mass and could probably be blocked with nothing more than a thin sheet of aluminum.

ie. less than 5 MPH, no real risk there unless maybe a tiny bit of metal went in your eye but as I said this should be trival to shield.

Of course my math might be wrong as I'm in a hurry, please double check me.

Re:

[JesseL]

Assuming this has a 20mm diameter turbine, at 500KRPM it will have an angular velocity of 130 meters/second at the outside edge. While this is enough velocity to put your eye out if it was too close to a turbine disintegration, it would be trivially easy to make a suitable scatter shield.

Re:

[menkhaura]

Google says 130 m/s is 468 km/h, or 290 mph. Wikipedia says that an average .22 bullet weighing 1.9g have a velocity of about 110 m/s. How much does the turbine weigh?

Uncontained turbine failure = bad Ju Ju

[russ1337]

Ever seen the results of an uncontained turbine failure on a jet engine? Just make it 100 times smaller 10 times faster and in your pocket.

Re:

[Knuckles]

Take an elephant make it 100 times smaller and you've got a rabbit?

Re:

[shis-ka-bob]

I did see the results of a turbo pump failure & heard about the results of a time of flight chopper failure. These were blades of 10s of centimeters. They were considerably larger than the turbines being described, but both were potentially lethal. I also saw a much smaller pump fail & it made a bang & turned the insides blades into scrap metal but didn't do anything dangerous. The amount of kinetic energy is proportional to product of the mass and the the square of the radius, so little tur

Re:

[dschuetz]

Ever seen the results of an uncontained turbine failure on a jet engine?

Have you ever seen the results of a *contained* failure? A while back, as the Boeing 777 was just coming into commercial use, PBS ran a long special (or maybe a series of episodes, I forget) about the plane. They showed how they wrapped the engine in some kind of special kevlar blanket, then tested it by shooting something into a fully spun-up engine.

The outsides of the engine (the whole chamber) sort of bulged out maybe 6-12", then c

Re:

[russ1337]

>>> Have you ever seen the results of a *contained* failure?

I'm an aeronautical engineer (although Avionics bent) and get sent pictures of contained and uncontained failures and crashes all the time. Yeah, as someone ^ pointed out, its all about the mass. If you can contain it then great. I'm just sayin.

SO this thing (with tiny mass) spinning at 1 million RPM going to have much gyroscopic rigidity? I guess you might need a few of them all orientated the same way before they'll stop you from t

Re:

[John Hasler]

> Yeah, as someone ^ pointed out, its all about the mass.

No, it is _not_ all about the mass. It also about the square of the radius. If you are really an aeronautical engineer you can do the math.

Re:

[russ1337]

No, it is _not_ all about the mass. It also about the square of the radius. If you are really an aeronautical engineer you can do the math.

u'm dude... we know the approximate size and its approximate RPM... but TFA didn't mention the mass (or its distribution), Or the orientation of said mass or relitave rotational direction of masses (one compressor might spin one way and the turbine or the other compressor might spin the other)..

I guess we can wait and see.

Re:

[budgenator]

well i've got a 150K RPM turbine in my hand right now, from a dental High-speed handpiece, I'd feels about half the weight of a nickel so that 2.5 grams, and I'd estimate 3/4 the weight is bearings and shell so the rotating portion would be about 0.75 grams for the actual turbine, the shaft and the 1 mm press to release chuck.

Would you buy one?

[bmetz]

I honestly wonder who these are for. I wouldn't use a cell phone or a laptop with a gas turbine in them. The noise, the vibration, the fumes, the refill process; even in the most ideal circumstances I am too spoiled by 'good enough' battery technology.

I'd like to see more work on battery technology and more pervasive conductive surfaces so every place I set my laptop and cell phone down helps charge it.

Not a Turbine

[John Hasler]

The BBC article is about a generator, not a turbine. The article merely mentions in passing that it could be powered by a turbine.

Article close to pure crapola!

[Ancient_Hacker]

An efficiency of 95% ! ?

The best large gas turbines do about 35%.

And efficiency drops very quickly with size-- you see friction goes down as the square of the size, while power goes down as the cube. Somewhere between the size of a sausage and a hot dog, all the turbine power is going into overcoming friction.

And the biz about 1 million RPM is pure hokum-- the worlds record is a bit below that, and that was with a tungsten alloy rotor in a vacuum chamber.

Methinks some press agent was drinking while on duty.

Re:

[Big_Breaker]

Efficiency is often quoted as a % of Carnot efficiency, which is the efficiency limit for a pure heat engine and it's around 35%-40% depending on temperature. I think turbines are subject to a lower limit which happens to be around 90-95% below Carnot.

Anyway - who cares? Efficiency in small devices is MEANINGLESS. What matters is power and energy density by volume and weight. This has both in spades.

Batteries are incredibly efficient, but you need to generate the power to charge them somehow. They also

Re:

[John Hasler]

> Methinks some press agent was drinking while on duty.

Methinks some slashdotters have reading comprehension problems. The BBC article which mentions 95% is about a Swiss generator, not a turbine. 95% is quite reasonable for a small generator. The article only mentions turbines in passing, noting that one could be used to drive the generator.

This is a DARPA spinoff

[Animats]

DARPA has been funding this kind of thing for years. Small turbines [m-dot.com] have resulted. DARPA was originally trying to develop bird-sized unmanned aerial vehicles. [wikipedia.org] That R&D program produced some flyable devices, but they didn't have the low cost and 2-hour endurance DARPA wanted.

DARPA-funded work at MIT resulted in some microturbine parts [memagazine.org] back in 1997. Progress has been slower than expected, but it's happening.

The microgenerator thing was intended as a military application. The idea is to have something small, maybe even wearable, a soldier can use to recharge all the battery-operated gear. Battery recharging in the field, where power outlets are rare, is getting to be a huge hassle in the US military. Current technology is to put power outlets on everything with wheels and an engine, but that creates its own headaches.

Not for laptops

[Shotgun]

New battery? Must be for laptops!!

'Cmon? Does everything have to be "a new way to power your laptop"? First, who the hell wants a 500,000 RPM anything sitting in their lap? The high squeal resonant frequencies will be hell once it is about two weeks old. I'll pass, and I'll ask the stewardess to shut down the guy trying to use one next to me. Second, what happens when the enterprize standardizes on this thing, and you have a cubicle farm of laptops spew CO2 (and a small component of CO) into the closed office atmosphere. I'll pass, and I'll use the Worker's Compensation claim to its max if I survive the asphixiation.

The guy says that he was surprised that designing the combustion chamber turned out to be easy, but the bearings were hard. He expected it to be the other way around. Well, no shit, Sherlock? Stationary components are easy and moving parts are hard. That applies to all mechanical systems. Duh? Someone else justified the high RPM in a previous post, noting how small the rotor will be. The gyroscopic forces trying to pull the laptop from your hands when the taxi rounds the corner will indeed be small, but the forces on the rotor bearings in relation to their size will be huge. The laptop may not rip from your hands, but it will get quiet (which the taxi driver will appreciate).

How about putting one of these in a container the size of a breadbox, and mounting it above a septic tank in a small village or country farm. Have it charge a battery as it feeds off the methane produced?

Re:

[object88]

First, who the hell wants a 500,000 RPM anything sitting in their lap? The high squeal resonant frequencies will be hell once it is about two weeks old.

I don't know a lot about resonant frequencies, but I can't imagine that you'll end up with many audible frequencies in the range of human hearing from a turbine running at 500kHz. CRT monitors used to squeel at a very high pitch-- let's say 10kHz just for the sake of argument-- and they were running at ~80kHz refresh rates? Where's that put the squeel of a

Re:

[John Hasler]

> How about putting one of these in a container the size of a breadbox, and
> mounting it above a septic tank in a small village or country farm. Have it
> charge a battery as it feeds off the methane produced?

That would be silly. Such applications have no need for the tiny size and therefor no need to pay the extra costs required to achieve it.

10 watts -- plenty for portable electronics?

[constantnormal]

I guess that "portable electronics" does not include notebook computers. I see that the power brick for my G4 iBook provides 65W and the power adapter for the new MacBook Pro provides 85W.

And I can't wait to read the headlines of the first bunch of software developers, found dead from carbon monoxide posoning after a long weekend of burning the midnight oil (or kerosene, butame or propane). Personal oxygen supplies may become the next big thing in office equipment.

Does it twist your arm?

[cohomology]

The rotor of the Swiss turbine must be pretty beefy. How much angular momentum does it have at 500,000 RPM? If you've ever played with a large gyroscope, or twirled a bicycle wheel while holding onto its axle, you can see the problem. If you try to change the direction of its angular momentum vector, the thing will twist around an axis perpendicular to both its angular momentum vector, and the direction of the torque you apply. If this thing is in a laptop, spinning around an axis parallel to the floor, and

house droid power?

[wonkknows]

I would love to see something like this on a small cleaning droid like the iRobot if the C02 output was minimal.

http://store.irobot.com/product/index.jsp?productI d=2475131 [irobot.com]

But can I fly with it?

[Refried Beans]

It would be pretty cool to run a laptop for hours on a gas engine, but will I be allowed to take it with me when I fly? I can't imagine that TSA is going to allow me a small quantity of flamible liquid so I can run my laptop on the plane. What about the emissions in a closed environment?

The Sweet Spot

[El_Smack]

3 to 5 years. Close enough to gather VC money, far enough that no one expects a working model.

This is a generator. Not a gas turbine

[viking2000]

how is it possible to feature a story with glaring errors. The headline talks about a gas turbine. The BBC article talks about an electrical generator.