Jet Engine on a Chip

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."

Comments

Fear...

[grub]

Engineers there shrunk jet engines to the size of a coat button

Naturally the Department of Homeland Security will declare that people with 4 or more buttons on their coat are 'terrorists'

Re:Fear...

[doublem]

Naturally the Department of Homeland Security will declare that people with 4 or more buttons on their coat are 'terrorists'

I see it all now!

It's part of an Amish plot to take over the country!

They don't ware buttons you know, they consider them to be an unnecessary vanity!

Soon, the government will only trust Oil Barons and the Amish. That way, the middle class can finally be crushed, with society stratified into the Amish, who will have little motivation to challenge the corporate overlords, and the ultra-wealthy.

Of course, it'll all collapse once the corporate overlords realize their fabulous wealth can't be sustained by a nation of farmers

Re:Fear...

[Anonymovs Covvard]

The Amish do wear buttons, it's zippers that they don't use.

Re:Fear...

[doublem]

What kind of conspiracy theorist would I be if I let something as trivial as facts get in the way?

Sheesh.

Re:Fear...

[Hatta]

Engineers there shrunk jet engines to the size of a coat button

Hell with the fuel cells, I'm waiting for jet packs!

Re:Fear...

[uujjj]

Any Amish /.ers willing to back this up?

Re:Fear...

[ArsonSmith]

I have to post this anonymously otherwise the elders may read this and I'd get in trouble. Oh wait why would the elders be reading this?

Oh wait I'm not amish.

Re:Fear...

[Midnight Thunder]

What kind of conspiracy theorist would I be if I let something as trivial as facts get in the way?

Fair enough, and quite honestly I reckon the the FUD makers in Washington take the same approach.

Re:Fear...

[Bob McCown]

Hell with the fuel cells, I'm waiting for jet packs!

Don't you mean jet pants?

Re:Fear...

[mesach]

It's all fun until someone get sucked into their coat button!

Re:Fear...

[ScrewMaster]

Or, as the actor who played Deep Space Nine's Commander Benjamin Sisko once asked in an IBM TV commercial:

Avery Brooks: "It's the new millennium. Where are my flying coats? I was promised flying coats!"

Producer: "Psst ... Avery ... that's flying cars."

Avery Brooks: "As I was saying ... cars! Where are my flying cars!"

Re:Fear...

[Raumkraut]

To quote Weird Al's Amish Paradise:
"I never wear buttons, but I got a cool hat"

I believe they use hook-and-eye fasteners, not buttons. It must be true, because I read it on the internet.

Cool, but misleading title

[AKAImBatman]

1. That's pretty damned cool. Gas Turbines are some of the most efficient fuel -> energy converters known to man.

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.

Re:Cool, but misleading title

[maeka]

Why do you say that gas turbines are some of the most efficient fuel to energy converters known to man? Every link I can find in a google search says otherwise. http://www.britannica.com/eb/article?tocId=45726 for example.

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/turbi ne.htm

Re:Cool, but misleading title

[kaszeta]

Gas Turbines are some of the most efficient fuel -> energy converters known to man.

Actually, in terms of the overall thermodynamic efficiency, they aren't all that great. 40% efficiency is *very* good for a Brayton cycle (i.e. turbine engine) system, but is fairly easily done with a large-scale steam system. Microturbines tend to run around 25%, which means that (a) you need a fairly big recuperator to run efficiently (which doesn't seem to be part of the MIT design), and (b) you need to be able to reject a lot of waste heat (so running your laptop on one of these means you'll be blowed 200+ watts out the back).

Not that gas turbines are without their advantages. Their specific power (weight per kW) is very good, so for the same amount of power the engine is very light compared to most other engine types (which is why they use them in aircraft). They also start and stop quickly compared to steam turbine systems. And they can be nicely combined with other systems like a steam system to make a combined cycle, the whole system can be fairly efficient.

But, by themselves, they aren't all that efficient.

Re:Cool, but misleading title

[AKAImBatman]

Why do you say that gas turbines are some of the most efficient fuel to energy converters known to man? Every link I can find in a google search says otherwise.

That used to be true, but the current breed of Gas Turbines are amazingly efficient. From wikipedia:

They can be particularly efficient -- up to 60 percent -- when waste heat from the gas turbine is recovered by a conventional steam turbine in a combined cycle.

The primary issue in obtaining high efficiencies is in (as you stated) efficiently recycling the waste heat. I can only assume that the inventors would be attempting to shrink the secondary cycle along with the gas turbine. The physics really aren't all that different, so it should just be a matter of materials.

Also from the wikipedia link above:

Typical micro turbine efficiencies are 20 to 35 percent. When in a combined heat and power system, overall efficiencies of greater than 90 percent may be achieved.

Re:Cool, but misleading title

[Rei]

Trying to make an efficient micro-turbine like this should be quite interesting. Viscosity will play a much bigger role - your entire flow regime will have the effects normally confined to the boundary layers on larger turbines. I wonder if they had to modify their CFD analysis programs to be able to handle the sort of flows you get inside such a tiny turbine.

Re:Cool, but misleading title

[AKAImBatman]

You're not making any sense. In one breath you say that the analogy is flawed, then in the next breath you say that gas turbines and jet engines are very similar just like electric generators and motors.

???

You'll have to pardon me, but I'm quite confused by your statements.

Re:Cool, but misleading title

[kaszeta]

Trying to make an efficient micro-turbine like this should be quite interesting. Viscosity will play a much bigger role - your entire flow regime will have the effects normally confined to the boundary layers on larger turbines.

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.)

Re:Cool, but misleading title

[maeka]

Your quote from wikipedia:

Typical micro turbine efficiencies are 20 to 35 percent. When in a combined heat and power system, overall efficiencies of greater than 90 percent may be achieved.

I don't believe that a laptop, PDA, or most other consumer electronic item these would be so cool for would be an ideal candidate for a combined heat/power system. Laptops get hot enough running on batteries.

Re:Cool, but misleading title

[fwankypoo]

If the foreign-born-president amendment passes could we see a Schwarzenegger VS. Soros campaign in 2008?

Good God, please no.

Re:Cool, but misleading title

[AKAImBatman]

I don't believe that a laptop, PDA, or most other consumer electronic item these would be so cool for would be an ideal candidate for a combined heat/power system. Laptops get hot enough running on batteries.

Not internally, but an external cooling surface could be provided.

Phones and PDAs should be fine, though. Most of their heat comes from the battery discharging. Now that I think about it, why don't we go for micro-stirling engines? They'd be WAY more efficient than these gas turbines! ;-) :-P

Re:Cool, but misleading title

[kaszeta]

The primary issue in obtaining high efficiencies is in (as you stated) efficiently recycling the waste heat. I can only assume that the inventors would be attempting to shrink the secondary cycle along with the gas turbine. The physics really aren't all that different, so it should just be a matter of materials.

It's more complicated than that. The 60 percent efficiencies mentioned are for large combined cycle plants, in which the secondary cycle is a steam cycle. The second you do that, it's not just a gas turbine any more...

Additionally, using a secondary cycle requires not just a second flow loop, but also requires a heat exhanger to move energy from the first cycle to the second, and those generally aren't small or light.

As another poster mentioned, a lot of these factors don't scale well, i.e. small turbines just don't work as well as large ones.

Re:Cool, but misleading title

[TamMan2000]

Hmm... a heat exchanger would definitely be problematic. How about a tiny heat pump? I've seen heat pump designs that could easily fit in a microchip design like this.

You do realize that heat pumps use heat exchangers, right?

Re:Cool, but misleading title

[maeka]

My point was that the efficiency numbers you were quoting are based upon using the heat, not simply dissipating it through "external cooling surface(s)"

Re:Cool, but misleading title

[AKAImBatman]

You do realize that heat pumps use heat exchangers, right?

Umm... nooo.... Not unless my peltier is a heat exchanger.

Feel free to correct me if I'm wrong, though.

Re:Cool, but misleading title

[TamMan2000]

When people talk about heat sources and heat sinks, what exactly do you think those are?

Re:Cool, but misleading title

[AKAImBatman]

Since heat tends to flow to cooler areas in an attempt to equalize the temperature, you usually only need a proper cooling surface somewhere so as to channel the heat for use. Stirling engines are a perfect example of this as they operate as long as one side of the engine is hot and the other is cool. In fact, stirling efficiency is entirely based on the temperature differential between the two sides.

OTOH, I don't know enough about how the secondary cycles of gas turbines work to state with certainty that providing a cooling surface would solve the problem. My only point is that devices do have proper surfaces for some forms of heat recovery.

Re:Cool, but misleading title

[AKAImBatman]

When people talk about heat sources and heat sinks, what exactly do you think those are?

A heat source is anything that generates heat, whereas a heat sink is a device for channeling and dissipating heat.

A heat pump (as I understand it) is a a device that forces heat in directions that it wouldn't normally flow. The physics behind heat pumps are what make refrigeration possible.

Now when we're talking about heat exchangers, my understanding is that we are talking about devices which exchange heat between fluids. Thus a heat exchanger is a form of a heat pump, but a heat pump is not a heat exchanger. Am I wrong?

Re:Cool, but misleading title

[TamMan2000]

A heat exhanger is not a form of a heat pump.

In the case of pumping from one fluid to another (the case of a secondary cycle) the source of heat (as far as the pump is conserned) is a heat exchanger sitting in the waste stream of your gas turbine taking heat from that waste stream and pumping it to another heat exchanger (the sink as far as the heat pump is concerned) sitting in your secondary cycle loop.

Re:Cool, but misleading title

[IvyKing]

Actually, in terms of the overall thermodynamic efficiency, they aren't all that great. 40% efficiency is *very* good for a Brayton cycle (i.e. turbine engine) system, but is fairly easily done with a large-scale steam system.

GE has an industrial turbine with a 46% thermal efficiency - this is a straight turbine, not a combined cycle. Solar has one model with a claimed 44% efficiency, achieved with the help of a regenerator. The high efficiency of the GE design is due to the compressor - an industrial turbine does not have to be as small as an aircraft engine with the attendant compromises in compressor design.

The best steam plants are barely over 40% (typical coal plant is now 33% due to emissions controls). They do have the advantage of maintaining high efficiency at low output levels. Steam plant efficiency has not improved since the 1950's when the supercritical cycle was introduced - steam becomes too corrosive when heated above 1100F.

Re:Cool, but misleading title

[AKAImBatman]

You'll forgive me, but that sounds like a heat pump. If I understand you correctly, the two heat exchangers + intermediary fluid loop are used to transfer heat from the turbine exhaust to the secondary turbine (usually a steam turbine). In short, the heat is being "pumped" to the secondary turbine.

My original question is: why can't we use a smaller heat pump (e.g. a thermoelectric pump) to replace the fluid pump?

A heat exhanger is not a form of a heat pump.

You are correct. A heat exchanger is a component of a phase change heat pump. Sorry for the confusion. I'm just trying to grasp what you're getting at.

Re:Cool, but misleading title

[dgatwood]

That isn't the point. The heat being dissipated is, by definition, wasted energy (unless the user is in Siberia or something.

What Wikipedia is saying is that gas turbines can be highly efficient if the waste heat is used to heat water to turn into steam to provide steam heating for a -building-. The reason it isn't wasted is that the excess heat is being used, but none of it is being used to create power. It is being used to create heat somewhere where heat is -needed-.

In a consumer device, there is no place where heat is somehow useful, therefore a gas turbine design will suck in terms of efficiency. It isn't inefficient because it can't get rid of the heat. It is inefficient because the extra heat doesn't provide any benefit, and is therefore wasted.

<rant> Great. Just what I want. Greater dependence on big oil companies. It isn't enough that they're screwing me on fuel prices for my car, now they want to have a cut in providing power for my laptop and/or cell phone, too. This technology is not the answer. It's the question. "HELL NO" is the answer.</rant>

Re:Cool, but misleading title

[arminw]

The law of entropy mandate that all energy conversions suffer losses. Any kind of system or engine that converts fuel energy to heat, then to mechanical energy and finally to electricity can't possibly be anywhere near as efficient as a device which directly converts fuel energy directly to electric power. The turbines will never compete on efficiency with fuel cells, but a gas turbine can put out a lot of mechanical power for its size/weight. Another problem with turbines is that they are not exactly quiet. Turbines run at very high RPMs and having a screaming micro turbine in a laptop may not go over too well. My vote for a good electricity source for the future is a hydrogen powered fuel cell. It is efficient, long understood technology with no moving parts to wear out or need maintenance.

Re:Cool, but misleading title

[AKAImBatman]

Fair enough. But what about a micro-stirling engines (as I suggested earlier)? They're already being used in waste heat recovery, and are far more effective in the lower power ranges. In that case the heat *is* useful.

Great. Just what I want. Greater dependence on big oil companies. It isn't enough that they're screwing me on fuel prices for my car, now they want to have a cut in providing power for my laptop and/or cell phone, too. This technology is not the answer. It's the question. "HELL NO" is the answer.

True 'dat.

Re:Cool, but misleading title

[AmericanInKiev]

The trick is to capture and convert the heat - not the exhaust and convert it into more power.

At the end of the day - power density is more important than effeciency for portable power - so don't expect a great deal of concern about the cogen issue.

AIK

Re:Cool, but misleading title

[kd5ujz]

Shit, Nokia has problems with batterys blowing up and burning people. This is just what they need, a gas turbine imbalance or a boiler explosion. Im sure lawyers are drooling at this invention.

Re:Cool, but misleading title

[zogger]

But maybe these gizmos would run on ethanol, which you could make yourself. Every boy needs his own still!

Re:Cool, but misleading title

[bwd234]

"That isn't the point. The heat being dissipated is, by definition, wasted energy (unless the user is in Siberia or something."

In Soviet Siberia the energy wastes you!

Re:Cool, but misleading title

[TamMan2000]

A heat pump does work to transfer heat. If there is no compressor in the intermediate loop all you have is a fancy heat exchanger.

The reason you can't just use a smaller heat pump is that none of them are good at getting much of the available heat from the jet exhaust. It really takes a big heat exchanger of some kind (doesn't nesisarrily have to be fluid based) to get most of the heat.

Basically, in heat transfer, there are small, efficient, and good at scavanging, pick 2 and you can likely get the combo, but get all 3 my friend, and you will revolutionize many fields. And fail on any one of them, and it is useless for the application we are discussing here.

Re:Cool, but misleading title

[visgoth]

Actually I think it would be interesting, but only as long as the rules for the Presidential debate are: Two men enter, one man leaves!

Re:Cool, but misleading title

[AKAImBatman]

So basically, after all this back and forth, what you're trying to say is that you don't think a small heat pump would work very well.

Well then, glad we got that cleared up. :-)

Thanks for sticking in there.

Re:Cool, but misleading title

[conradp]

Great. Just what I want. Greater dependence on big oil companies. It isn't enough that they're screwing me on fuel prices for my car, now they want to have a cut in providing power for my laptop and/or cell phone, too. This technology is not the answer. It's the question. "HELL NO" is the answer.

Where do you think the power that charges your batteries comes from now? According to this, 64% of generated electricity comes from fossil fuels, with hydroelectric and nuclear making up another 34%. So basically you're currently powering your laptop and PDA with mainly fossil fuels anyway.

Re:Cool, but misleading title

[Pooua]

They can be particularly efficient -- up to 60 percent -- when waste heat from the gas turbine is recovered by a conventional steam turbine in a combined cycle.

That's what he said in his post that you are contradicting. His specific words were, "Gas turbines seem to only become highly fuel efficient when the heat of their exhaust gas is captured by a secondary system."

Another name for it is a co-generation plant, which became popular about the late '80s to early '90s (just after I finished my career working on steam turbines).

Re:Cool, but misleading title

[Friggo]

Depends on where you come from.
Here in Sweden about 45% comes from hydro power, 31% from nuclear power and the rest is either gas, oil or imported where a large part of the imported power is from norway or finland which uses lot of hydro and nuclear power.

Re:Cool, but misleading title

[Phreakiture]

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.

Re:Cool, but misleading title

[hesiod]

> maybe these gizmos would run on ethanol

I was thinking the same thing. What are the chances your laptop would run on gasoline? Not much.

Re:Cool, but misleading title

[smoker2]

If you could use that 200+ watts of energy to drive a heat exchanger, just imagine how cold/fast you could get the cpu to run ?!

exaust

[tubbtubb]

What about the exaust?
I can't wait to get kicked out of a snooty coffee shop because my dual core G5 laptop was asphyxiating the customers . . .

Re:exaust

[AKAImBatman]

What about the exaust?

Well, your cell phone only needs about a watt, a PDA about 2-10 watts, and your laptop about 20-100 watts. If you consider that cars produce kilowatts of constant power output, you should realize that the amount of exhaust shouldn't be anywhere close to what your car puts out.

In addition, these turbines will probably use something a smidge cleaner than gasoline. Even kerosine is better, but ethanol would probably rank the cleanest.

Speaking of kerosine, these turbines shouldn't even be as back as burning a kerosine lamp. :-)

Re:exaust

[Anonymous Coward]

Well, your cell phone only needs about a watt, a PDA about 2-10 watts, and your laptop about 20-100 watts. If you consider that cars produce kilowatts of constant power output, you should realize that the amount of exhaust shouldn't be anywhere close to what your car puts out.

Which is quite good, as they don't let you run your car on a plane. But using your numbers, 20 or so people using laptops on a plane would be the same as someone running a car in the passenger cabin. That's not good.

Re:exaust

[drinkypoo]

In addition, these turbines will probably use something a smidge cleaner than gasoline. Even kerosine is better, but ethanol would probably rank the cleanest.

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:exaust

[AKAImBatman]

The primary difference is energy density. As fuels go, petroleum is the the most energy dense fuel short of nuclear. While there are attempts to find even denser fuels, none of the alternatives that have been investigated are stable enough or safe enough for use.

Re:exaust

[upsidedown_duck]

Why not use a small tank of compressed gas (i.e., nitrogen) to drive the turbine? For small portable power, the inefficiency inherent in compressing the gas in the first place isn't that big of a deal.

Re:exaust

[gl4ss]

waste heat?

getting rid of some 300w+ of heat on your lappy..

Re:exaust

[drinkypoo]

I think the point for me is that even hydrogen is considerably more energy-dense than a battery, and turbines are probably the most efficient way to make use of a combustible fuel. I think it's worth it to take a hit in runtime in order to get a dramatic improvement in emissions. Burning hydrogen essentially means zero or negative emissions; you're going to want to filter your intake air which will filter crap out of it. There are already hydrogen-burning vehicle prototypes which have negative emissions. Burning just about anything else including alcohol (which I admit is pretty inoffensive) is going to have nastier emissions.

Re:exaust

[flyingsquid]

What about hydrogen?

I'm just imagining what would happen if I dropped my hydrogen turbine powered laptop just a little bit too hard: "Oh, the humanity!"

Re:exaust

[underworld]

Yes, but you rarely operate your cell phone, PDA, or laptop in the vicinity of your car exhaust....

Re:exaust

[misleb]

I am normally one to pooh pooh hydrogen as a solution, but you make a good case. I like hydrogen for small applications such as this. It is very easy to make on small scales and the energy loss due to inefficiencis is not significant given the small quantities involved. Of course, those inefficiencies could add up if hydroden is used for more and more devices, but that would have to play out. People might see their electricity bills getting a little high.

-matthew

Re:exaust

[Naffer]

I've got a 125 horsepower car. At fast highway cruising speeds, its probably putting out about 60 horsepower. Thats 45 kilowatts. You'd need more then 20 laptops.

Re:exaust

[Lodragandraoidh]

What about using hydrogen gas? It would produce H2O as a result of burning.

This would be great on a survival phone - the more you talk the more fresh water you produce!

Re:exaust

[hazem]

I'm kind of partial to the ethanol for fuel. That way, I can actually get work to pay for filling my hip flask!

Of course, then I might need to carry two of them.

Re:exaust

[NardofDoom]

The idea that the Hindenberg crashed so spectacularly because of its hydrogen is false. Yeah, its hydrogen burst into a big fireball, but I'm sure it wouldn't have been as deadly if they hadn't painted it with aluminum powder in paint varnish.

Re:exaust

[Anonymous Coward]

Which is quite good, as they don't let you run your car on a plane. But using your numbers, 20 or so people using laptops on a plane would be the same as someone running a car in the passenger cabin. That's not good.


No problem. Everyone who tried to get through security with a vial of gasoline/kerosine/ethanol missed the flight anyway.

If you pack volitile fuels in your carry on you might want to bring some vasiline too. Otherwise you are gonna be walking funny for a week.

Re:exaust

[Feanturi]

In addition, these turbines will probably use something a smidge cleaner than gasoline.

The article mentions diesel, which makes the whole thing sound like it will be messy and smelly. Changing cartridges you'd probably get some in the air, and it doesn't smell good. Using the device, then (because you're in a hurry, say) quickly sticking it in your shirt pocket while the engine is still winding down, you'd be smelling like diesel exhaust the rest of the day. Yuck...

Re:exaust

[NardofDoom]

Yes, but I like to operate my phone near my face.

Hang on a minute, I have to take this...

Hello? /me passes out from carbon monoxide poisoning.

Re:exaust

[stanmann]

You are aware that the new generation of diesels don't stink, and some produce cleaner output than input. Also, with biodiesel, you can select you smell, from peanut oil based diesel to burger grease based diesel.

Re:exaust

[HybridJeff]

I dont know about you but, I wouldnt like any car exhaust filling up a small confined room im going to be inhabiting for the next few hours. EVen if its just 5 laptops, by your calculations thats 1/4 of cars exhaust. Not somthign I want to be exposed to for long peroids of time.

Re:exaust

[saider]

But at idle it is producing around 4HP ~= 2.8kW. So now we're back down to a few notebooks. It is still dangerous to idle a car in an enclosed space.

Perhaps we need gadget/non-gadget sections. Maybe some gov't regulation. Hi-flow catalytic converters for your computer. /sarcasm

Re:exaust

[networkBoy]

"There are already hydrogen-burning vehicle prototypes which have negative emissions."

I call shenanigans!
This is the single biggest line of BS being fed to the media to promote H2 as a fuel.
The truth is that any (current) form of hydrogen fueled vehicle has more emissions than a properly tuned hydrocarbon fuel based vehicle of reasonable efficiency (hybrid for example).

Why? Because the production of the Hydrogen uses energy and lots of it! Most is begotten from petrol anyway because cracking the hydrocarbon chain takes less energy than cracking water (which takes nearly twice the amount of useful work energy as you'll get back burning the hydrogen IIRC).

Re:exaust

[Mysticalfruit]

Here is an idea. Instead of nitrogen, just have a tank of compressed air that you could pump up manually via a foot/hand pump. My idea would be that this turbine would be a suppliment for a battery in the laptop, so when you started to run low on pressure just give it a couple of pumps and off you go again. I can't imagine that you'd need anything more than 20lbs/in^2 (which is easily achievable with a hand pump) and this thing would last a very long time.

Re:exaust

[Old Telco Guy]

In addition, these turbines will probably use something a smidge cleaner than gasoline. Even kerosine is better, but ethanol would probably rank the cleanest.

And, interestingly enough, jet fuel IS kerosene. Jet fuel is sold as "JET-A", and it's essentially kerosene like you would put in a kerosene heater. Any traveler who has walked out onto an airport tarmac to board a flight has smelled the exhaust from the jets, and it smells just like a kerosene heater.

Re:exaust

[AKAImBatman]

And, interestingly enough, jet fuel IS kerosene.

Precisely. As I understand it, Jet Fuel differs only in some of the additives used for improving fuel efficiency in Jet Engines. :-)

Re:exaust

[Anonymous Coward]

Now if we could only get one to burn Kerocosine then we'd be in business!

I think you meant kerosene.

Re:exaust

[DJStealth]

or the volume?

A Jet engine is generally well over 100dB, that kind of noise will definitely get you kicked out of a cofee shop.

Re:exaust

[zangdesign]

Using the device, then (because you're in a hurry, say) quickly sticking it in your shirt pocket

Am I the only one not enthused about sticking a running jet motor in my pocket? Men have nipples, too. Well, we will until the first time we forget to let the dang thing spin down.

Re:exaust

[AKAImBatman]

No, I meant kerosine. Kersene is an alternate spelling.

Re:exaust

[AKAImBatman]

Errr... Kerosene. Damn. ;-)

Re:exaust

[mdvolm]

So now instead of just blowing out exhaust fumes, it's blowing out water vapor? I'm sure that would do wonderful things for your laptop/pda...

Re:exaust

[Yartrebo]

Most is begotten from petrol anyway because cracking the hydrocarbon chain takes less energy than cracking water (which takes nearly twice the amount of useful work energy as you'll get back burning the hydrogen IIRC).

Actually, it's worse than that. Noone in the right minds would use $55/barrel oil when coal, especially dirty lignite coal, is so plentiful and cheap.

Perhaps once having the entire electric grid run on renewables is in sight (like 3-5 years away) a big push for hydrogen for transportation would be advisable if an efficient storage method for electricity isn't found by that time, but even if the whole world was run by hippies tomorrow, it would be at least 15 years for that to happen.

Re:exaust

[tonyr60]

For some reason the idea of someone using a hand pump in front of a laptop may not be socially acceptable, except on /.

Re:exaust

[upsidedown_duck]

Instead of nitrogen, just have a tank of compressed air that you could pump up manually via a foot/hand pump.

It depends on how sensitive the small turbine would be to humidity and dirt in the air or to oil from the pump. I was thinking more in terms of pre-packaged tanks, like those CO2 cartridges for paintball guns, which could have consistent quality control.

Re:exaust

[Mysticalfruit]

Well, you have to pass the air through a regulator anyway, you might as well just put a filter cartridge in there as well that would filter out stuff like dirt / cigarette smoke that would destroy a turbine. Depending on the materials, I wouldn't think humidity would be such an issue.

Re:exaust

[ipsender]

Ethanol? Add Prozac to fuel, post-combustion fuel-feed vapouriser, hey presto! Great plot to make /.ers using PDAs all over the world happy and less cynical despite themselves.

Re:exaust

[Jeremi]

So now instead of just blowing out exhaust fumes, it's blowing out water vapor? I'm sure that would do wonderful things for your laptop/pda...

I doubt the effect would be any harder on your equipment than the water vapor you already blow out every time you exhale...

Re:exaust

[darco]

While civilian jets are presurized, the air supply is still being refreshed constantly from the air intake on the engines. The air inside of a plane is quite fresh--it's just that it's so dry that it tends to mess with people's noses and make them think otherwise.

Remember, a few decades ago people smoked cigarettes while these planes were in the air. Without proper air circulation, the smoke level in the cabin would have quickly become intolerable.

The use of these turbines to power electronics in an aircraft should have a imperceptible impact on the air quality in the cabin, especially when compared to cigarettes.

Re:exaust

[sdpinpdx]

I think people just get sloppy with the use of the word fuel. I'll bet most people here realize you don't just find hydrogen laying around ready to burn. It's a fuel from the point of view of your car or laptop, but an energy storage medium in the larger context.

Making hydrogen from oil is of course a mistake if you want to avoid the emissions associated with burning it, and the problems of relying on foreign countries to sell it to you.

So make your hydrogen from wind power, or whatever is handy near where you want to use it.

It's a mistake to toss out the whole idea of powering mobile devices with hydrogen just because the way we make hydrogen now is dirty.

Re:exaust

[networkBoy]

My point is that there is not a clean method to make it. The closest is frow corn, ferment it, distill it, crack it.
If you use wind there is an environmental impact in killing birds (notably birds of prey), solar is so dirty it almost makes oil look clean. Nuke is the best but has such a bad rep that it'll never happen in my lifetime.
-nB

Re:exaust

[HermanAB]

Hey, mix two parts hydrogen with one part oxygen in a 350ml glass coke bottle an hold up to a bunsen burner...

The problem with making your own hydrogen is that it is very hard to exclude oxygen. Not recommended for the average Joe.

Re:exaust

[sdpinpdx]

I think the bird kill thing is FUD.

Re:exaust

[HybridJeff]

Well there's somthign I diddn't know. But then I guess it makes sense that they keep the plane well ventalated.

My only other beef with them then is that if these thigns go mainstreame and they start putting them in evreything. A few hundred million extra sources of exhaust fumes wouldnt exactly help in the pollution department. But then again, nobody really cares about the environment anyways.

Re:exaust

[MrCreosote]

Never mind that, what about bird strike?

Re:exaust

[Friggo]

Actually it is very easy to exclude the oxygen when you make hydrogen from water...
The hydrogen is sp well behaved that it only bubbles up at one of your electrodes, and the oxygen bubbles up only at the other, I leave it as a trivial exercise to to the reader to construct a device that captures the 2 gasses without mixing them...

Re:exaust

[networkBoy]

Actually I live fairly close to a wind farm in CA and it would appear that it is not FUD. The personal sized wind turbines are not the problem, it is the large three blade ones that get within a foot of the ground. On a windy day the outside edge of the blades are moving fast enough to "not be there" through persistance of vision. A hawk will see it's prey and fly at it, often enough the path is through the blades zone of travel and THUNK, dead bird.
-nB

Re:exaust

[darco]

Lets hope that if that scenario turns out to be the case that it puts enough of a dent in disposable battery use to make it environmentally worthwhile. We are at least a few decades away from "hundreds of millions" of these things though.

Honestly, with the right fuel, these devices should operate quite cleanly--otherwise the market for them would be prohibitively small.

Re:exaust

[drinkypoo]

It does, however, move the emissions from the vehicle to the electric plant. In confined spaces where ventilation is difficult, that's a useful feature. For highways, it's less useful, although a tall chimney can help prevent ground-hugging smog.

There are other benefits to using hydrogen as well. First, even in a worst-case hydrogen burns cleaner than gasoline, and you don't need a catalytic converter to reduce emissions. That allows you to eliminate pretty much all the smog equipment on a car if you move to hydrogen, and in the long term we can move the burden of pollution monitoring away from a jillion smaller sources to just the power generation facilities.

The real benefit then becomes that as we reduce power plant emissions all electric and hydrogen vehicles will put less of a pollution burden on our world. As it stands today, pollution must be addressed at millions of sources.

Roland Piquepaille!

[recursiv]

Fantastic! Glad to see a post by you Roland! You see, I really enjoy absolute shit, so I am glad to see another of your presumably bought and paid for fluff stories.

Re:Roland Piquepaille!

[Sheetrock]

A couple of decades ago, journalism relied on the efforts of hardworking individuals who would go to great lengths for a story. Sometimes to the point of sacrificing their liberty for refusing to name a source or even their lives for walking into places that could only be described as Hell on Earth -- where even the ones fortunate enough to leave physically whole were not unscathed.

Chumps.

What about pollution?

[Antony-Kyre]

What about pollution from this? Has that even been considered?

Re:What about pollution?

[djh101010]

If the fuel is a clean hydrocarbon, the exhaust will be CO2 and H2O. Using batteries pollutes too, you just don't see it right there because it's either at the power plant where your battery charger got it's energy from, or it's in the chemical pollution of used dead batteries, or both.

Re:What about pollution?

[wolenczak]

I'd bet it is neglectible compared to the pollution caused by regular alkaline batteries that end up in the dumpyard.

At most the pollutants would be CO2 and some other carbon based compounds.

Re:What about pollution?

[fk319]

What about contrail?

Re:What about pollution?

[pclminion]

What about pollution from this? Has that even been considered?

Compare with traditional rechargable batteries.

First, there is the one-time environmental cost of manufacturing the batteries. Making a battery requires fuel for mining equipment, transporting the materials, running the manufacturing equipment, and producing the electrolyte.

Second, there is the energy required to charge the battery. This energy comes from the power grid. Ultimately, it comes from burning fossil fuels in power plants. This energy must be transmitted via wires to an electrical outlet, turned into DC by a rectifier, and finally, used to charge the battery.

In other words, here's the energy path for the turbine:

Fossil fuel ---> Combustion ---> Turn turbine ---> Generate DC power

And for the rechargable batteries:

Fossil fuel ---> Combustion ---> Turn turbine ---> Generate AC current ---> Transform to high voltage ---> Transmit down wires ---> Transform back to low voltage ---> Rectify to DC power

Which do you think is more efficient?

Re:What about pollution?

[Antony-Kyre]

Except my batteries (mouse batteries) are rechargeable ones I recharge from a grid that gets its power from hydroelectricity if I'm not mistaken. Of course, there's probably pollution from that still, but minor compared to other methods.

Re:What about pollution?

[azmatsci]

Who cares? Don't be a tree-hugging hippie when this is obviously a cool concept that may not even be used on this planet.

Re:What about pollution?

[NanoGator]

"What about pollution from this? Has that even been considered?"

Compared to all the old batteries now sitting in landfills?

Re:What about pollution?

[mikael]

Hmmmmm, the last thing I would want to happen, is to go into a restaurant/bar/nightclub with a PDA in my trouser pocket, stand up, and have everyone notice there's a damp patch somewhere personal.

Re:What about pollution?

[Jerf]

I think the key will be how high they can get the efficiency. Some other commenters have said that turbines can be really efficient, but I don't know how well that will scale, and the article IMHO didn't really give us much to go on.

It is, however, encouraging that they are seriously discussing putting these into laptops. Since waste energy almost always comes out as heat, and while a lot of that will presumably come out the exhaust, a lot will also go into the laptop itself. If they aren't going to toast the laptop they much be expecting some pretty decent efficiency.

If they can get the efficiency to a point comparable to the efficiencies attained at large, centralized power plants... and that is quite a challenge because due to the ecomomies of scale power plants can do a lot of things to improve efficiency (or decrease pollution) that last little .05% that make no sense on smaller scales... then it'll basically be a wash in pollution terms for household power generation vs. what we have now.

Only large scale use like millions of people using it as their primary power generation matter. Even if I used it to power my laptop, and I am a heavy laptop user, do you have any idea how long it would take me to go through even a gallon of fuel? Compare that to a single truck. Small scale, I'd guess these will be several times more friendly than conventional really-quite-nasty batteries, just looking at it from a thermo-dynamic-limit point of view. Many fewer conversion inefficiencies.

Re:What about pollution?

[Ignignot]

Well, IAAEE (I am an electrical engineer) and I'm gunna have to say that the turbine is going to have to transform its output voltage somehow anyway. Not that transformers deplete much power at all, but still, it is almost certainly more efficient to use a transformer after the turbine than screwing with the turbine to produce different voltage / frequencies. Also, the tiny turbine is going to have to rectify to dc power also. AC power is the "natural" form of electricity produced by power plants. It always requires an extra step to get dc. Finally, there is an economy of scale involved. A small turbine is simply not going to be as efficient as a large one. I would expect one that small to be nowhere near as efficient as a power plant. I would expect that the difference in efficiency of turbines would more than equal out the benefit of avoiding transformation (which is a very efficient process, for good transformers at least).

The important question is actually, which one weighs more? Which one is cheaper to use? Seriously, who cares about the environmental effects. We have millions and millions of big engines in the form of cars, a few hundred thousand small gas turbines aren't going to matter much.

Re:What about pollution?

[Bloater]

Did you see the size of the damned thing?! I could fart more pollutants than that thing!

Seriously though, the cluster of generators for the home could pose a problem, as large power stations are pretty good on the pollution front, and they are far away from hot densly populated area's with little air flow such as ground level in urban regions.

Re:What about pollution?

[confused one]

Then you're one of the exceptions to the rule. Most people get power from nuclear or fossil fuel. I, for example, get power from nuclear(primary) and coal(secondary) powered generators.

Re:What about pollution?

[Unkle]

In the article, it seems to imply they mean to have diesel as the fuel. Now, I don't know if they mean regular diesel or biodiesel, but I would guess regular.

If it is regular diesel, it would have to be one of the cleaner varieties. One of the main byproducts of a diesel engine is NOx. This stuff can do some nasty things to you if you breathe in too much. Plus, there's the particulate matter.

But hey, I say bring it on. My company makes emissions testing equipment, and I'd love to work on developing a tester for laptops and PDAs!

Re:What about pollution?

[SpecBear]

Damp patch? You're worried about a damp patch??
I'd be more worried about having blades rotating a million times a minute right next to my genitals!

Re:What about pollution?

[sbaker]

It is certainly ironic that the world seems to be rushing to convert cars from internal combustion to battery/electric - whilst rushing in the exact opposite direction (in this case) to convert laptops from battery/electric to internal combustion.

Is there something inherent in the scale of these devices that means that this kind of reversal makes sense?

Re:What about pollution?

[cmaurand]

Never mind the pollution. What about the noise? We're talking about exhaust under pressure. Gas turbines are very noisy. Diesel fuel is about the dirtiest fuel known to man (any number heating oil is worse) and is listed as a carcinogen by the epa/cdc. Diesel/turbine output is very high in carbon monoxide and ozone. My laptop is going to need a tail pipe, catalytic converter and muffler. A turbine at a million rpm has gotta make mechanical noise, too.

Re:What about pollution?

[arminw]

The article summary states that the competition to these turbines will be fuel cells. Fuel cells efficiently convert hydrogen and oxygen directly into electricity with no moving parts and the attendant noise. The only pollution they make is clean drinking water. NASA has been using them for many years. There is no known practical means of convert chemical energy to electric power anywhere nearly as efficient as a fuel cell. Virtual all of the stored energy of the hydrogen-oxygen reaction is available as electric power to the load.

As their size and cost decreases, fuel cells will become competitive in many applications that require electricity. Hydrogen can be produced from sunlight and stored in metal hydride tanks using only moderate pressures. The conversion of sunlight into hydrogen is considerably less efficient. However these losses occur in a location where they have less impact than they would have in an electronic device or most other places where the electric power from the fuel cell might be used. Using hydrogen, or any other combustible fuel to power the passengers electronics on an airplane will always involve risk which may be deemed unacceptable anyway, rendering the pollution aspect in the passenger cabin moot.

Hydrogen produced by renewable sources such as hydro, wind and solar could eventually replace all fossil fuels. On the much more distant future horizon, the thermonuclear fusion power generation could be used to produce hydrogen to satisfy all power needs without any pollution.

Re:What about pollution?

[Jerf]

I assumed the original poster was concerned about the pollution in general, not as compared to fuel cells.

Another interesting question is to compare construction pollution costs of a turbine vs. a fuel cell, but it's probably too soon to tell yet, since neither tech is mature.

Re:What about pollution?

[majid_aldo]

We have millions and millions of big engines in the form of cars, a few hundred thousand small gas turbines aren't going to matter much.
this was exactly what was said about cars when *they* first came out.

Re:What about pollution?

[cocotoni]

Well, IWAEE (I WAS an eletrical engineer), and I seem to remember that in the battle between AC and DC (between Tesla and Edison) for the power generators AC won not by being more efficient to produce, but by being more efficient to transport.

The DC generators do exist. Edison was proposing them, but the problem was that the losses in the Cu were forcing you to have the devices using the current close to the generator. Tesla solved that problem with AC. The existing DC generators could not be converted to AC (you cannot make a nice sine from a DC current of that power), so there you got AC generators.

Since most of the power generation happens far from the user, most of the power is generated by AC generators. However, if the distance is not the limit (as in cars, or here where you would power a laptop or some such) DC generators are an option.

However, you were correct about the efficiency of the small vs. large turbines.

Re:What about pollution?

[djh101010]

A turbine engine can burn nearly anything. I can't imagine why they'd choose diesel fuel, it's not adequately explained in the non-details in the article. Noise, though, should be manageable, and careful selection of an appropriate fuel should mitigate that problem as well.

What I find annoying about this is that we keep seeing the same picture of the non-functional prototype with a promise that it'll be ready in 4 years. Same picture, different year, same distance from getting done. From this I can only assume they aren't making any progress but the funding keeps coming in...

Re:What about pollution?

[wolenczak]

Less pollution than that of a cigarrete for sure. Probably they should design a tobacco based jet engine, hehe.

Yeah, uhm, wait what?

[DoorFrame]

Am I going to need to crary jet fuel around with me, because that could become real inconvenient. Also, is it going to make that jet engine noise? Am I going to have to deal with exhaust? If I were to attach one to a balloon, would it be able to propel the thing around the room?

Geh, what a weird idea.

Re:Yeah, uhm, wait what?

[wertarbyte]

Also, is it going to make that jet engine noise?

Can't be worse than those low-cost P4 notebooks. Those fans can already be calles "turbine on a chip".

Re:Yeah, uhm, wait what?

[EvilCowzGoMoo]

Am I going to need to crary jet fuel around with me

Will my PDA now have a fuel guage on it? How will this affect gas prices? Can I use regular or will i need the 92 octaine? Will I need a yearly emissions test?

Re:Yeah, uhm, wait what?

[flyingsquid]

Am I going to need to crary jet fuel around with me, because that could become real inconvenient.

Yeah, getting ten hours on a canister of fuel sounds great compared to a few hours for my laptop on a battery, but there's the issue of the availability and cost of fuel, whereas AC is cheap and outlets are easy to come by. Unless my laptop ran off of ethanol. Then you'd just walk into a bar and be like, "one for me, and one for my computer".

Re:Yeah, uhm, wait what?

[RatBastard]

Lighter fluid, kerosene, gasoline, etc... there are tons of options. "Jet fuel" isn't all that special. People think it's some form of super-explosive gasoline or something. Most jets burn kerosene or some very similiar product.

Roland Piquepaille

[Anonymous Coward]

http://science.slashdot.org/search.pl?query=Roland +Piquepaille

Re:Roland Piquepaille

[Drakonian]

Wow, what a tool. This guy has about 4 sentences of content on his blog and the rest is copied verbatim from the original article. That's pretty embarassing that Slashdot is potentially providing this guy with revenue.

Re:Roland Piquepaille

[moofdaddy]

Your new here arn't you

Re:Roland Piquepaille

[Burgundy Advocate]

Holy. Shit. You're right! Slashdot search is working again!

Surely a sign of the apocolypse.

Re:Roland Piquepaille

[RzUpAnmsCwrds]

Did you ever think that maybe Roland is paying the Slashdot editors to accept his stories?

Think about it.

Re:Roland Piquepaille

[recursiv]

Sure. A percentage of his ad revenue ought to cover it.

Is that a...

[stecoop]

I like Dave so here is a top ten list:

10) Just a second, my jet isn't ready.
9) Mr. hot pants and all - yeah I know it's an excuse to take'em off.
8) You're so hot that you glow with enthusiasm.
7) Need a light - let me pull out my P.D.A. if you know what I mean.
6) Wowoowow those just engines dooo last.
5) How many would you like to buy madam?
4) Do you smell smoke?
3) Hey that's my jet.
2) Where did I put my jet engine - ahh there it is.

1) Jet engine in your pocket or are you glade to see me.

Noise?

[Paster Of Muppets]

What about the noise created? Last time I was near a jet engine, it made quite a racket...

Re:Noise?

[tindur]

so most of the noise ought to be ultrasonic.

Poor dogs!

Vaporware

[n1ywb]

How many years now have we been hearing about miniature turbine power sources? Too many. Just because some kids at MIT did it doesn't mean it's even close to being commercially viable, and even if it is viable doesn't mean anybody will adopt it. That aside, I do think it's a great concept and I hope it DOES eventually get adopted, especially if they can make the turbines run on vegetable oil :)

Re:Vaporware

[Keebler71]

Actually, I hear Duke Nukem Forever will be powered by one of these...

no kidding dept.

[lottameez]

While there are still a few hurdles to overcome...
Ya think?

Re:no kidding dept.

[jav1231]

Yeah but the hurdles will be easier to overcome with a turbine engine in your pocket! VROOM!!

MOD PARENT UP

[jmays]

This is exactly true. Roland Piquepaille submits fluff stories to /. over and over and over just to generate traffic to his blog. Slashdot ... come on. You can do better.

Re:MOD PARENT UP

[AbbyNormal]

Fluff?

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.

Re:MOD PARENT UP

[jmays]

Roland generally posts a link to an (interesting) article on a technology site and then paraphrases it under the guise of a 'useful summary'. He offers zero insight and could instead just submit the original article without his unnecessary boring commentary. It is filtered and it is bullshit.

Re:MOD PARENT UP

[jmays]

What? Are you serious? His name could be Tom Smith and I would still bash him.

Re:MOD PARENT UP

[Tim C]

Rubbish. It's because he submits articles linking to his blog, which essentially contains a summary of and a link to the real article, and yet slashdot sees fit to post lots of them.

He's driving traffic to his blog to increase ad revenue and his reputation (he's now working as a professional blogging consultant), and slashdot are helping big-time. If there's money changing hands, or it's a favour for a friend, then fine - but the slashdot guys really ought to tell us.

Re:MOD PARENT UP

[jmays]

Why? Are you concerned, coward?

Re:MOD PARENT UP

[pVoid]

paraphrases??

If anyone had actually looked at the original site, they would have seen Roland basically copied pasted the paragraphs he found interesting onto his blog.

Which then got copied and pasted to slashdot.

Thank god he actually links to the f*cking article, because it's basically on the verge of being copyright theft here.

Yay slashdot.. Yay circle j*rks...

Re:MOD PARENT UP

[feronti]

He's driving traffic to his blog to increase ad revenue and his reputation (he's now working as a professional blogging consultant)

Ok, someone enlighten me. WTF does a professional blogging consultant do? Show you the proper way to whine about your pathetic life and get people to read it and boost your ego? Or have blogs evolved in some way I haven't noticed?

This sounds promising

[Anonymous Coward]

"a technology which promises to free us to carry extra fuel instead of batteries"

That's just what we need, more dependence on combustable fuel. Besides that I feel MUCH safer carrying around extra batteries then a highly explosive fuel.

Re:This sounds promising

[pclminion]

That's just what we need, more dependence on combustable fuel.

Umm.. Where do you think the energy in batteries comes from?

Re:This sounds promising

[mistshadow]

> That's just what we need, more dependence on combustable fuel.

Umm.. Where do you think the energy in batteries comes from?


Uh, from chemical bonds?

Re:This sounds promising

[JFitzsimmons]

Nuclear power?

Re:This sounds promising

[orasio]

I don't know you, but I feel much safer recharging a flammable lighter than a highly explosive battery.

Re:Just what we need...

[SHiVa0]

What about hydrogen fuel cell... Not all fuel cell gas are dynosaur based...

gas powered calculator

[morcheeba]

There was a bit of calculator one-up-manship in some of my classes, so I always wanted to connect a little model airplane engine to a little generator and use it to power my calculator during exams. Besides the roar of the non-mufflered engine (dropping in RPMs during every keypress as it consumes more power), there would be the smell half-burnt gas coming out of that little two-stroke. The intimidation factor alone would have skewed the curve in my direction.

So, wow, my silly dreams could become reality!

Re:gas powered calculator

[Linker3000]

One of my friends at college (1981) had a solar powered scientific calculator. It was his pride and joy.

One term we had to do an extra maths test and it was scheduled for 7pm. It was winter and we were in an outbuilding with basic lighting.

My friend was some way into a complex calculation when the examiner, who had been walking around, passed by his desk, throwing his shadow over the calculator - the display gracefully faded as the calculator powered down. My friend jumped up uttering a burst of expletives and was nearly thrown out of the exam!

Priceless!

Fan mount...

[graveyhead]

Sweet! All I need for my self-powered computer is a fan mount! Cools my processor and powers it at the same time ;)

Runs on Fart Gas?

[zungu]

I read somewhere that farting releases methane. May be these micro-jet engines can be powered by far gas. On an airplane, the PDA can be inserted in a pocket on the seat and just a fart will power the PDA micro-jet ;-)

Re:Runs on Fart Gas?

[Ichijo]

I'm still waiting for an airplane that runs on static electricity. The passengers would walk around barefoot on wool rugs touching things in order to power the propellor.

Good Laptop Power Source for Travelers?

[xxxJonBoyxxx]

TSA Drone: "What do you have in that bottle?"
You: "Oh, it's just some gasoline for my laptop."

Sure...this technology will be a GREAT laptop power source for travelers...

AWESOME!

[positroniumman]

this is totally the solution to our current energy problems! more gas burning engines...

Geese

[Anonymous Coward]

Do these things still make a horrid mess when they accidentally suck geese in through the intake?

Re:Geese

[hb253]

Wow, talk about crash and burn!

Re:Geese

[anzha]

Geese aren't a problem, but flies on the other hand...

Good luck doing anything on a plane

[MalHavoc]

With the way air travel is now, you're not likely going to be able to take anything powered by a turbine engine and diesel fuel with you on a flight. A flight full of wierdos with fuel-powered cellphones and PDAs is just what we need. Electric power isn't going anywhere.

Re:Just what we need...

[saintp]

Are you familiar with the abbreviation "RTFA"? Half of the frikkin' article is devoted to extolling the benefits of micro gas turbines over hydrogen fuel cells.

Real Beanie Jet Engine Hat

[Anonymous Coward]

If I can take 1000 of these microjets, I can convert my Beanie Propeller hat to a Beanie Jet Engine Hat and fly. Since this is posted freely and publicly, this can't be patented anymore.

Ready to take off
5
4
3
2
1

Where did my body go?

WhatMeWorry!

Re:Real Beanie Jet Engine Hat

[Trespass]

Now *that* was funny. I should make an animation of that. :)

Conspicuous omission

[Engineer-Poet]

Neither "reference" (they aren't worthy of the term) mentions a thing about efficiency.

This matters a lot, because small turbines suffer much more from viscous flow losses and heat-transfer losses than large ones. If a 50 W microturbine is 10% efficient, its waste heat will amount to 450 watts; if it is 5% efficient, the waste heat will be 950 watts! This could easily lead to them being banned from commercial aircraft, because the extra heat load and oxygen consumption would drive A/C loading too high (not to mention the discomfort of adjacent passengers).

Re:Conspicuous omission

[bobbis.u]

Also, nothing is mentioned about wear. From my understanding, the rate of wear is a real killer for these tiny devices.

Just think, if 0.5mm wears off the sliding surfaces in a conventional turbine, not big deal... if 0.5mm wears off the surfaces of this device you have nothing left.

Re:Conspicuous omission

[C. E. Sum]

if it is 5% efficient, the waste heat will be 950 watts! This could easily lead to them being banned from commercial aircraft,

I think I would be more worried about 950W of anything sitting in my lap. But maybe that's just me.

Re:Conspicuous omission

[Suidae]

if 0.5mm wears off the sliding surfaces in a conventional turbine

I'm no mechanical engineer, but it seems like any normal turbine with 0.5mm of play in its bearings would be well on the way to destruction. I'd expect less than half that much. /nitpick

Re:Conspicuous omission

[Deliveranc3]

Not being particularly interested in cars I was bored once listening to a friend talking about his engine.

He seemed to be very impressed with how much power was in his car, when I pointed out that it really wasn't all that powerful when compared to serious commercial equipment he tried to explain the limitations of the fuel injection engine.

So I looked around for a jet engine to put in my parent's minivan (I am so pathetic but I think my dad would secretly appreciate this). There are many problems with jet engines, first there is cost. Jet engines use materials that are expensive because of their rarity, this is not something that mass production(or technological improvement) would alleviate only increase. Second they are vastly inefficient in terms of fuel power to output power.

Third they are loud and HOT!

There were several other reasons why the jet engine will never be put in a rice burner but I think the ones above are enough to crush our hopes of this technology as a battery replacement.

Re:Conspicuous omission

[WolfWithoutAClause]

There's no necessary reason that it has to wear at all: hydrostatic or hydrodynamic bearings are used on hard-drives and don't wear.

Re:Conspicuous omission

[fatcatman]

There were several other reasons why the jet engine will never be put in a rice burner

It's already been done. What, you missed the Jet powered MR-2 on eBay? I saw that sucker listed a few years back. As I recall it went for some amazingly low price - a few grand, about the normal blue book value of the car.

What about start procedure ?

[Jesrad]

Starting a turbine engine is a complicated procedure. How will we be supposed to start such a tiny engine ? Perhaps using the generator in motor mode to give it enough RPM ?

It could be a nice replacement for hydrogen fuel cells, if it can be tuned to run on hydrogen like some real turbine engines out there. No pollution ! And the hot steam could be used for something else.

Re:What about start procedure ?

[ricochet81]

take a deep breath and blow on it.

Re:What about start procedure ?

[drinkypoo]

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 types, because electrical system problems (especially battery failure) are the #1 cause of breakdowns.

Re:What about start procedure ?

[Kiryat Malachi]

Not necessarily - 48V is far from a done deal. There are issues (arcing, for one thing). It may well happen eventually, but I wouldn't look for it to become mainstream anytime in the next couple years - probably not until hybrid adoption reaches critical mass, or until someone develops a good camless system, since those will probably require higher voltages.

You also planning to use this excuse in elevators?

[StressGuy]

Beats blaming it on the dog I guess... :)

Energy = energy, danger = danger

[dpbsmith]

"Each disposable cartridge would pack as much energy as a few heavy handfuls of lithium-ion batteries."

We don't really want to carry larger and larger packages of energy on our person. As it is, we are seeing accidents like this one due to today's ordinary lithium-ion batteries. And I recently got a recall notice from Verizon about the kind of batteries used in my cell phone, so this isn't an isolated incident.

When someone tosses a 9V battery in their pocket and it gets shorted out by a coin, they are startled, yell, and pick the hot coin out of their pocket.

When a cell phone battery acts up, Shelley Kaehr got a handful of battery acid and set fire to the floor.

Multiply that by "a few heavy handfuls" and you start to get the possibility of really serious personal injury.

What we need are breakthroughs on the power consumption side, not ever-increasing power supplies

Re:Energy = energy, danger = danger

[qray]

Ah yes, the shorted 9 volt battery. I remember it well. Ouch

Lithium Ion's sound bad, but what happens when you short a fuel cell?

Re:Energy = energy, danger = danger

[mwlewis]

Well, TFA says that you'd perhaps have a disposable container about the size of a D battery filled with diesel fuel. Diesel fuel is really efficient, but it's not really explosive. It might smell worse than the battery acid if it leaked in your pocket, and it might ruin your pants, but it would almost certainly be a lot safer.

Re:Energy = energy, danger = danger

[Harinezumi]

I don't know about you, but I'd be perfectly happy to trade a little security for a lot of convenience.

No matter how much more power-efficient you manage to make your electronics, they would still run much longer (and/or much faster) on batteries that store much more power.

Re:Energy = energy, danger = danger

[NardofDoom]

Yes, but the cartridge doesn't contain acid. It will probably be fueled by ethanol.

Yeah, it *could* set fire to your floor, if you're near an open flame, but it's not going to give you chemical burns or melt stuff.

Re:Energy = energy, danger = danger

[przemekklosowski]

Multiply that by "a few heavy handfuls" and you start to get the possibility of really serious personal injury.

Let's see: my little laptop battery (as given by 'cat /proc/acpi/battery/BAT1/info') has a design capacity of 38880 mWh

OK, time to check out the wonderful 'units' program, which can convert between an amazing array of, well, units. It says:

You have: 12 * 38880 mW hr
You want: kg tnt
* 0.3641783

i.e. a dozen batteries would have energy storage equal to a third of a kilogram of a TNT explosive.

These could really take off!

[kick_in_the_eye]

The sky's the limit

5 years away, like everything else

[frovingslosh]

From the article: Spearing estimates a version capable of putting out enough power to run devices would take two to three years more, with another year or two beyond that to produce a marketable version.

So, it's 5 years away, like flying cars and jet packs and everything else that stays 5 years away. Why don't I feel good about this?

By the way, so anyone else remember seeing TV comercials in the 60's that showed a new miracle insulation material (made of low tech aluminum foil and cardboard) that they showed in a refrigerator keeping both hot coffee steaming hot and live chicks alive, and that we were supposed to have in just a few years to insulate our homes so well that we wouldn't need heat in the winter? What happens to all this good stuff?

Re:5 years away, like everything else

[bhima]

hey, at least it's closer than the 20 years of cold fusion!

Re:Brilliant

[avandesande]

the energy density of rechargable batteries sucks

Re:Just what we need...

[SHiVa0]

True bue, why limit ourself to a blog. Fuel cell are a great way to move away from petrol based energy. I'm sure there is a way to use their technology with renewable sources.

Units...

[melted keyboard]

"The engines on three 747s put out as much power as a nuclear power plant."

We need that expressed in a more useful unit of measure, such as burning libraries of congress.

Look Out Dennis!

[marktaw.com]

Nanobots, tiny jet engines. Has anyone warned Dennis Quaid?

Obvious joke

[SuperKendall]

"Hey, what is that?"

"WHAT?"

"I said, what is that"

"MY NEW JET-POWERED MP3 PLAYER"

"cool , what are you playing?"

"I'M NOT SURE"

Re:Just what we need...

[Anonymous Coward]

I hope to see a world where everything from my watch to my telephone is powered with good old Arab oil. Fuck nothing gets me hotter than imagining the day I get to pour a couple of gallons of Middle East crude into P4. A great discovery for all!

Cool? Sure. The technology that will save us? NOT.

[TigerNut]

What developing countries (and us) really need is NOT another technology that requires petroleum/gas refinery infrastructure. I don't have the background but it would be interesting to do a cost-benefit tradeoff between existing lithium-ion battery technology vs. portable turbine generator technology. Costs, of course, include the energy put into making the batteries and turbine/generators, as well as the industrial effluent from the plants that make the parts for both.

Real progress will be made when you can teach someone with little prior education how to build a generator or water pump from stuff that he or she can find within a 10 mile radius from their house.

Mod parent up...and...

[reality-bytes]

And please don't forget to mod *down* all the muppets that think that Hydrogen is in any way more dangerous than Petrol(gasoline), Kerosine or Ethanol ;)

Re:Mod parent up...and...

[Unoti]

Is it more dangerous on an airplane than batteries?

Re:Mod parent up...and...

[reality-bytes]

Where exactly in my post did I compare Hydrogen, Kerosine, Petrol and Ethane to a battery?

Re:Boom!

[sqlrob]

That was the magnesium struts that caused most of that explosion.

Hydrogen is safer than gasoline

Does anyone else think this is

[greenstork]

Jet Engine Vaporware

Roland Piquepaille strikes again

[ColonPOWL]

Why does this guy continue to link his logs to the story submissions? There has to be some conflict of interest for this guy to continue to submit stories...

Can we PLEASE STOP linking to this guy's blog???

[sczimme]

In all seriousness, why does /. continue to link to his ramblings instead of to articles that contain real, useful, technical content?

Yes, this is probably off-topic (as in "not about tiny turbines") but it is still relevant. At least give us the option to ignore him.

Roland...

[addie]

Can we please stop posting directly to stories on this guy's weblog? It's embarassing for Slashdot. The real news link you're looking for is:

here

Re:Roland...

[LiquidCoooled]

Thats the same link as the article text up there?
Informative? mods on crack its 100% redundant.

As for linking to his summary at the bottom of the story text, I couldnt care less, unlike you I read from top to bottom.

Its more embarrasing to see people complaining when they should be opening their eyes.

Ive stopped by this guys blog once, and tbh the style isn't my scene (still better than mirrordot or IT.slash), but as far as I'm aware his posts are relatively informative and technical.

This guy is giving slashdot the fodder and has come up with some of the best stories of late. Should the editors stop accepting his posts altogether?

Also, linking to a secondary summary page is probably helpful to lots of people, and it allows a discussion to continue even if the original site is overloaded.

Re:Roland...

[hopemafia]

By now it should be clear that Roland is either one of the slashdot editors in disguise, or a close friend of one of them.

Re:Roland...

[imsabbel]

Errr. Put your head out of your ass, fucktard.
This guy has got a doutzend "stories" the last week or 2 alone. Each of them on his blog, wich copies the original articles.
Sounds very much like a hit/advertising whore.

Re:Roland...

[LiquidCoooled]

I'm here a lot. I see he gets a lot of things accepted. Does it bother me - No it certainly doesn't, the things he finds are cool and certainly newsworthy.

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+Piquepai lle+writes%22+site:slashdot.org

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.

Re:Roland...

[siesta at uni]

If you translate Piquepaille, French to English, as "Pique paille" you get "Prick straw". If I remember my French, it could also be "Bite straw".
I always wondered if it was a spoof in some way, and the name meant something...

Re:Brilliant

[dykofone]

Cept where did the energy come from to charge that 80% efficient battery? From your local gas turbine powerplant, which once you factor in the efficiency loss of the grid, will come out to much lower efficiency than your hand held gas turbine.

Roland

[Lord_Dweomer]

Yet another Roland story. You know, you'd think that if there was enough outrage about this (which I'm SURE the editors are more than aware of) they would have the common decency to listen to their readership instead of just posting more Roland stories.

For as much as I love Slashdot, there exists little recourse for people who want their input on the site to be heard, even when its on as large a scale as the current hatred of Roland posts.

Re:Roland

[Anonymous Coward]

So, tell us why you hang around here then? To get dates or masturbation material?

Re:Roland

[Anonymous Coward]

There is no input. The staff here are completely against reader input, they're only interested in pure profit.

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 /. are capable of doing.

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:Roland

[Lord_Dweomer]

While I still think you are trolling, I will bite.

I love the comments on here. And yes, I browse at +3, so most of what I'm getting is actually worth reading. There's a reason that we have an inside joke on here about not RTFA. Its because the real value of the site is in the comments.

Exhaust?

[baudilus]

I wouldn't worry about the exhaust, I would worry about shock. What are the implications of having a relatively tiny turbine spinning that fast and be dropped / jostled / jiggled / wiggled? Would that interrupt the rhythm and therefore the power output?

Storage

[Andy Dodd]

Long-term storage of hydrogen is still a bit of a problem. Hydrogen has a tendency to penetrate ANYTHING you try to store it in, resulting in hydrogen embrittlement. In short, anything you store hydrogen in (esp. pressurized hydrogen) will eventually become weakened by the hydrogen permeating it.

Re:Storage

[AKAImBatman]

That's a good point. Hydrogen embrittlement is a serious issue with rocket engine design. I hadn't considered that it would be an issue with fuel cells. That may be why many laptop cells utilize methanol as a hydrogen storage medium.

Re:Storage

[drinkypoo]

Sure, hydrogen is the smallest molecule around, but that's why the tank gets replaced periodically. Make the tank leak more to the outside than the inside to protect the laptop and put an inexpensively replacable shield on the laptop side of it, problem solved. We're not talking long-term storage here.

I wonder, because I am too lazy to google, if you can help prevent the loss of hydrogen ionically.

Re:Storage

[TummyX]

Hydrogen has a tendency to penetrate ANYTHING you try to store it in

Or you store it in a molecule like water.

Noise

[your_mother_sews_soc]

What about noise? A physical device spinning that fast is going to produce hypersonic as well as audible noise. Phase I: Put jet engine in cell phone. Phase II: ? Phase II: Profit from putting even smaller jet engines in hearing aids.

What about cars?

[hike2]

This sounds all great and stuff ... but if the engine scales down so well how about trying the same thing with cars? Is there an efficiency issue or maybe worse polution or is it just something that people always thought would be overkill? (In case you are wondering I was thinking about using the electricity produced to power the car rather than the thrust which is not that easy to control if I understand the principles correctly)

Re:What about cars?

[Anonymous Coward]

the trick is, turbines are ten times more powerful per pound, but, unless you are using waste heat recovery (steam plant?) they are 1/3 as efficient per horsepower. On the other hand, it's true that a significant portion of that would be worthwhile, so as to not have to haul around a 300lb motor, rather instead a 30lb motor. But, given the number of cars, you'd better stick with the most efficient method possible.

How is this better, again?

[Kalven]

Now I'm going to have to carry a fuel around with me. I just don't understand how that's better than the current solution. Most fuels are not renewable and are quite volatile, where as batteries, in most cases, are rechargeable and are very stable. Even if the fuel is hydrogen where does the water (a bi-product of hydrogren combustion) go? Not to mention refueling a hydrogen fuel cell is not the easiest procedure. Granted the idea is pretty cool, but the last thing I want to have to do it stop, refuel my PDA and then pull start it to get it going again.

I can see it now....

[RealProgrammer]

"Yeah, honey, I'll be home around [nnnnnnuuuuuuuuaa] just a second [aaaaaaAAAAAAAAAA] my phone is recharging!!! [...AAAAAAAAAA...] I said just [...AAAAAAAAAA...] a [...AAAAAAAAAA...] second! no, [...AAAAAAAAAA...] NOT SEVEN, [...AAAAAAAAAA...] SECOND![...AAAAAAAAAA....]"

size and efficiency

[TamMan2000]

1. That's pretty damned cool. Gas Turbines are some of the most efficient fuel -> energy converters known to man.

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.

Frozen Chicken Cannon

[nick_davison]

Jet engines in laptops? Cool! Can I do the frozen chicken cannon testing, to see if it can survive a bird strike?

What do you mean it's not the same thing? Your new technology sucks then.

Re:Frozen Chicken Cannon

[slars]

Be realistic - you need a frozen gnat!

heh

[devphaeton]

While there are still a few hurdles to overcome

Is that the setting your clothes on fire hurdle, or the asphyxiation in closed in spaces hurdle?

One day, my car will sound like KITT !!!

[potus98]

I can't wait to pull into the grocery ...

Shhhheeeeewwwoooooooooossshhhhheeeeeeeeeeee

Failure mode?

[khendron]

I wonder what the failure mode is like. I mean, even a tiny turbine spinning at millions of RPM must contain a lot of angular momentum.

Can you imagine the engine failing and the little turbine slicing its way out of your laptop and through the side of the building?

Somebody want to geek out for me?

[Jerf]

Would somebody care to geek out for me, and estimate how much power is contained in a standard fart's methane content, if you conventionally combust it? (Remember, even the worst farts aren't 100% methane, although if you do the math based on that assumption it'd be trivial to scale, if you tell us.)

This invention could be the best thing that ever happened to the baked beans market, no?

Re:Somebody want to geek out for me?

[WormholeFiend]

Remember, even the worst farts aren't 100% methane

The sun is a mass of incandescent gas... ^H^H oops sorry... wrong comment.

Here's the lowdown on fart gas content, for those interested in such things:

(source: Facts on Farts)

What is fart gas made of?
The composition of fart gas is highly variable.
Most of the air we swallow, especially the oxygen component, is absorbed by the body before the gas gets into the intestines. By the time the air reaches the large intestine, most of what is left is nitrogen. Chemical reactions between stomach acid and intestinal fluids may produce carbon dioxide, which is also a component of air and a product of bacterial action. Bacteria also produce hydrogen and methane.
But the relative proportions of these gases that emerge from our anal opening depend on several factors: what we ate, how much air we swallowed, what kinds of bacteria we have in our intestines, and how long we hold in the fart.
The longer a fart is held in, the larger the proportion of inert nitrogen it contains, because the other gases tend to be absorbed into the bloodstream through the walls of the intestine.
A nervous person who swallows a lot of air and who moves stuff through his digestive system rapidly may have a lot of oxygen in his farts, because his body didn't have time to absorb the oxygen.
According to Dr. James L. A. Roth, the author of Gastrointestinal Gas (Ch. 17 in Gastroenterology, v. 4, 1976) most people (2/3 of adults) pass farts that contain no methane. If both parents are methane producers, their children have a 95% chance of being producers as well. The reason for this is apparently unknown. Some researchers suspect a genetic influence, whereas others think the ability is due to environmental factors. However, all methane in any farts comes from bacterial action and not from human cells.

Re:Somebody want to geek out for me?

[mav[LAG]]

I see that you must have taken the advice in your sig. Very informative stuff.

Re:Brilliant

[Anonymous Coward]

Most powerplants exceed 80% efficiency thanks to reclamation of the heat energy in the exhaust.

Of course, all that goes straight out the window if you get energy from nuclear, wind, hydro, or solar.

Re:Nevermind the exaust

[Concerned Onlooker]

What about the intake? You'll be in big trouble the moment you suck somebody into your turbine.

Terrorist apparel

[RealProgrammer]

I don't see the rationale for that, as long as they file a flight plan for their coat.

What's top speed for a London Fog?

Re:Terrorist apparel

[Orne]

African, or European?

Irrelevant.

[baudilus]

You're using the wrong word here - I think you mean "which do you think is simpler?" Just because there are more steps, doesn't mean it's less efficient. Think of driving to a destination, and you can either take a highway [10 miles] or local streets [8 miles]. Just because there are less miles in the local trip, doesn't mean it's more efficient.

Re:Irrelevant.

[mark-t]

Entropy ensures that all other things being equal a system with more steps will be less efficient than a system with fewer steps.

Re:Irrelevant.

[YankeeInExile]

Entropy ensures that all other things being equal a system with more steps will be less efficient than a system with fewer steps.

The catch is, other things are never equal.

1 million rpm?

[museumpeace]

I saw this in TR yesteday and, given my dismal batting average with the /. eds, just let it slide.
A better TR article blasts "hydrogen hype" but in fact H2 would be about the best fuel for these little buzzers:

• a fuel spill will dissapate very rapidly
• the byproduct, in answer to the questions posted re pollution is just water.

A set of bearings however will be an awsome thing to handle the gyroscopic reaction torques as you wave your jet powered cellphone about. You turn the corner, the phone does not. I don't have my old physics books handy but the linear velocity of a point on the tip of a blade is

1000000*60*2*pi*0.6/(12*5280) = 3570 mile/hour

and is changing direction 180 degrees about 2000000 times a minute. The F=MA to pull this constant direction change will be staggering unless M is damn near zero.
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:1 million rpm?

[imsabbel]

Well, f=mv^2/r.
Lets assume r=0.25 cm (the centre of gravity of a blade with the 5 mm length).
The speed of the centre of gravity= 1.000.000rpm /60sec/min*2*pi*2.5mm=260 m/s (about 1km/s, btw, i cannot really follow your calculation)
Lets assume the blades have a total weight of 0.1g (very assumable, the thing is about 1cm*1cm*2mm, the fill factor should be less than 0.3, lets assume 10g/cm^3.
That means the energy stored in the blades is 0.5 m v^2= 0.5*10^-4kg*67600m^2/s^2=3.38 joule.
Less than a airgun.
Inside a metal enclosure.
No danger.

Re:1 million rpm?

[Beryllium Sphere(tm)]

Good point, but the gyroscopic loads are going to be proportional to the centrifugal loads, which are tolerable at a million RPM precisely because the mass is so close to zero.

Re:1 million rpm?

[The 13th Duke]

This is your Captain speaking. It is time for our flight to change course. Please turn off all mobile phones, laptops and calculators so that we may carry out this manouevre. Thank you.

Re:1 million rpm?

[Kiryat Malachi]

I'm going to use a solid disc rather than try to deal with calculating blades, as a solid disc is higher mass and therefore higher inertia than a bladed construction, so my calculation will be erring on the side of caution.

Assuming the (very rough) idea of the blades as a solid disc, a 10 mm turbine blade (which is what is suggested for a 20 W turbine, running at 100krpm, from other experimental papers I've seen) comes out as follows:

I = .5m*r^2 = .5*25*10^-6*mass

Density of silicon nitride, a commonly mentioned blade material, is 3.28 g/cc.

Volume of a solid disc 10 mm blade, assuming it is 1 mm in thickness (a value pulled from some of the experimental papers), would be pi*r^2*h, giving us pi*25*10^-6*1*10^-3, or 2.5*10^-8 m^3.

2.5*10^-8 m^3 is 2.5*10^-2 cm^3, yielding a mass of 3.28*2.5*10^-2, or 8.2*10^-2 grams, which is 8.2*10^-5 kg.

Thus, moment of inertia is .5*25*10^-6*8.2*10^-5, or 1.025*10^-8 kg*m^2.

The correct equation for energy is .5Iw^2.

So, at 100krpm (2*pi*100000/60 rads/s), the turbine I'm thinking of is carrying: .5*1.025*10^-8*109662271 = 0.562019139 J.

Even if its spinning at 1 million RPM, we get: .5*1.025*10^-8*1.09662271*10^10 = 56.2019139 J.

TNT explodes with an energy of 2.175*10^6 J/kg, meaning that the turbine disintegrating at 1 million would yield something roughly equivalent to 0.025 grams of TNT. Not exactly a big explosion.

Yes, it is spinning very, very fast, but it is also very very small and very very light. These counterbalance the speed.

Batteries are not a concern

[J3zmund]

I'd rather carry batteries than flammable fuel any day. Especially if it means I won't be to take any gadgets onto an airplane, train, courthouse, etc.

Nevermind the noise, the smell, and the heat. I just don't want the hassle.

cool idea ... err... hot idea.

[brentcastle]

Yeah I wonder what kind of heat this device puts out... Anyone want to use a fuel burning device and carry it around in their pocket? Not to mention, bearings ought to get quite hot at 1M RPM.

Ouch!

[CPNABEND]

And here I thought it was only money that burns a hole in your pocket. :)

See same story from 1997

[Animats]

Here's a very similar article from 1997, from the same guy at MIT, making about the same claims. They sounded closer to success back then.

They've been working on this since 1993, and in 1997 they said they'd have it working in three years. In 2004, they say they'll have it working in three years.

It doesn't work yet. They can fabricate the individual parts, but it doesn't really generate power.

It's not an unreasonable idea, but if this was going to work, there should already be little gas turbine powerplants a few inches long, machined out of metal by standard techniques. The smallest turbines available weight around 1.5Kg, and are used for model aircraft, and they don't have to run for very long. There's a "microturbine" industry, but they mean 10KW units taller than a man.

Little turbines are hard. Automotive turbines and light-plane turbines have been attempted many times, but have never been cost-effective.

Re:See same story from 1997

[One Louder]

They've been working on this since 1993, and in 1997 they said they'd have it working in three years. In 2004, they say they'll have it working in three years.

It sounds like their schedule will fit nicely with the Moller Skycar.

Re:See same story from 1997

[Goonie]

The smallest turbines available weight around 1.5Kg, and are used for model aircraft, and they don't have to run for very long.

And, if I recall correctly, they use fuel very inefficiently; the fuel consumption is like nothing else you've ever seen. The friction losses on this thing would probably be far worse, so unless there's breakthroughs in the design elsewhere I'd be very surprised if you could carry enough fuel to keep the things powered up.

Re:See same story from 1997

[jhack]

To address you're claim that it doesn't generate yet: it does. I was present on the second generation run on this device. That was within the last year.

Re:See same story from 1997

[choochus]

Here is another Slashdot story posted in 2001 about a micro gas turbine: http://science.slashdot.org/article.pl?sid=01/11/2 6/2011228&tid=134

Re:See same story from 1997

[HermanAB]

Well, they are consistent. Ten years ago, they said it will take 3 years and they still say so. What is your problem with that?

Cool just like on history chanel

[nurb432]

Just like they showed on the history channel.. over a YEAR ago..

What about the plane or rotation?

[cebarro]

What happens when the little teeny 1million RPM turbine in the Cell Phone that's up to my ear shells itself out and spits little tiny slivers of unobtanium in a nice little line into my skull?

Re:What about the plane or rotation?

[jstave]

Not to worry, you'd have your cell phone right there to call 911 on!

Wrong fuel

[PygmyShrew]

Errr. That's why he said diesel.

Although granted, diesel fuel doesn't last forever and the flashpoint gets lower as it denatures over time. Still, there are much more hazardous fluids you can carry around with you perfectly legally. Sunny Delight, anyone?

The question of exhaust fumes still stands, though. All those particles; arsenic, benzene, dioxins, toluene, formaldehyde, 3-nitrobenzanthrone and 1,8-dinitropyrene. Horrible.

I can see it now - a special carriage reserved on the train for laptop users. PDAs banned in public places? Special rooms at work for anyone with those 12th generation iPods. :)

Not Quite True.

[temojen]

What makes you think the entire grid is powered by fossil fuel buring plants? There are alternatives already in use [1] [2] [3] [4]

But...

[Angst Badger]

But my computer already sounds like a jet engine when it powers up!

Heat generation

[slars]

So, will these mini engines be generating heat? You may not want to carry your PDA or phone in your pocket, if they do.

I can see it now - woman to man in a bar: "Excuse me, your crotch is smoking. Is that a PDA, or are you just happy to see me?"

Cool paper airplanes!

[erroneus]

Wow! And once my cell phone dies or I switch away from a carrier such as Sprint (I hate you Sprint! You suck!) who only uses proprietary phones with built-in limitations, I will have a cool little jet engine I can tape onto a paper fuselage and send it flying around the building here at work.

That oughta be a lot of fun!

Calculator Ricers

[doublem]

Oh great.

Just what we need, people putting spoilers, after market exhaust systems and neon lights on their calculators and PDAs.

Suddenly, this technology sounds like a BAD idea.

Foundational research

[erick99]

While this is not exactly basic research, I think it is the kind of research that ends up contributing to something a little more realistic rather than being used itself. A lot of people here are very critical of the jet engine but keep in mind that new technologies do look a bit strange in the beginning and it may be that this engine is simply a step in the direction of something proves very useful.

Two lessons for you:

[Engineer-Poet]

1. Wikipedia is not trustworthy.
2. The microturbines the authors appear to be talking about are in the neighborhood of 30 kilowatts and bigger, not 15 watts. A non-micro turbine would have an output of megawatts; some are capable of hundreds of megawatts.

Re:Two lessons for you:

[graffix_jones]

But in this case Wikipedia is actually correct. Don't fall victim to logical fallacies, just because one entry isn't correct doesn't mean that ALL their entries are incorrect.

Gas turbines are inefficient by design, because they use combustion to produce power, and the combustion process is inherently inefficient from an energy transfer point-of-view.

I'm an environmental econ major, and we talk extensively about fossil fuels and alternative energy sources. The size doesn't matter... you're dealing with the 1st and 2nd laws of thermodynamics here, you get a little energy and a LOT of heat. Unless the mini turbines have somehow figured out how to turn all that excessive heat from the combusted fuel into energy they're gonna suffer the same problems of their larger brethren.

The only way to make gas turbines more efficient is to pump the excess heat from the exhaust into a steam turbine and gain a bit more bang for your buck... but I doubt we'll see any miracle breakthrough's on the combustion front, even though these mini turbines are intriguing.

Re:Two lessons for you:

[idlemachine]

In order to prove the questionable authority of one website you point us at another?

What makes your reference any more trustworthy?

Finger Nubs

[LouSir]

I want to be the first one out with the finger tip re-attachment kiosk in the mall. If you think cpu fans leave a mark these 1,000,000 rpm fans are going to slice, dice and chop many a finger. My side business will be kevlar finger tip protectors and pencil sharpner conversion kits. Lou Sir

more information here

[LighthouseJ]

I'd like to add something to what you said...

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:more information here

[TamMan2000]

You probably want to use the term "reciprocating piston engine" (or "reciprocating engine" or "piston engine") rather than "combustion engine", gas turbines (jets included) are (internal) combustion engines too...

Re:more information here

[LighthouseJ]

you got me there, good differentiation.

Shrapnel and Lacerations?

[rwire326]

And what happens when this little wonder fails due to lint, sand, or possibly even a violent impact? (I can't count how many times I've dropped my cell phone.) Radial velocity at over a million RPMs has to be ridiculous. The pieces might be small but I imagine they could fly through a leg or two....

Re:Shrapnel and Lacerations?

[Forbman]

Yes, but you're assuming a bladed turbine wheel or impeller. I'm thinking you could do this with some variation of a Tesla pump, which uses a flat, solid impeller wheel.

6 o'clock news, "man killed by PDA turbine failure

[Blitzenn]

Yea, that will come to past. Shortly after they resolve how to stop that dime sized blade spinning that fast from killing the person carrying it around in their pocket when it fails. Great idea, but the hurdles are extremely high, and prohibitive I believe. Lawyers in the US would have a field day with the liability attached to this one.

Say it with me, people....

[Conspiracy_Of_Doves]

Got a ROCKET in my POCKET!

Or at dinner...

[jpetts]

Beats blaming it on the dog I guess... :)

A guy goes to dinner with his girlfriend's family, and finds he is a bit windy about the arse. Anyway, he is sitting down at table, and the family dog is lying down behind his chair, so he figures he'll try a little experiment. So, he shifts his weight to his left cheek, and squeezes out a fairly quiet fart.

The mother looks up at the noise, and says "Baron!" (this being the dog's name). Encouraged, the guy lets out another one, quite a bit louder this time.

Again, the mother looks up, and exclaims "Baron!" in a more urgent tone.

By now the guy figures he's got carte blanche for whatever trouser stunts he wants to pull, so he let's rip with all his might, and lets one go that sounds like the curtains are being ripped in half!

At this, the mother stands up, panic-stricken, and shouts "Baron! Get away from that man before he shits all over you!"

Problems already

[Ced_Ex]

Jet engine the size of buttons eh? I can see a whole wack of problems he failed to mention.

1. Explosive power pack. - Nothing like shorting your electronics and causing an explosion, or having one leak in your pants.

2. Turbines. - I wonder what pocket lint would do to clog the fans?

3. Heat. - Think the heat from your laptop video card is hot? Get a load of engine blast!

4. Exhaust. - Enclosed areas like airplanes, cubicles, the air will get stale.

5. Waterproof devices? Fuggit 'bout it.

I could probably go on an on... but I'm sure someone will elaborate.

Re:Cool? Sure. The technology that will save us? N

[Gordonjcp]

Real progress will be made when you can teach someone with little prior education how to build a generator or water pump from stuff that he or she can find within a 10 mile radius from their house

www.otherpower.com

Welcome to the "Diamond Age"

[rlp]

Life imitates science fiction.

Re:Just what we need...

[saintp]

Yes, hydrogen fuel cells exist. But, had you RTFA, you would know why these microturbines have advantages over them. Plus, I hardly think that a D-cell sized fuel tank for 10 hours of operation is petroleum dependence. Of course, you wouldn't know that they consumed so little fuel, not having RTFA and all.

You forgot a step

[TyrranzzX]

It takes energy to transport materials, ya know.

... why not a turbine in a car? ...

[ninjagin]

I was a big fan of the Rosen Motors turbine-powered hybrid electric car, yet it seems that it never caught on.

Info?:

http://www.designnews.com/article/CA150458.html

http://longman.awl.com/englishpages/tech_talking_h ardware.htm

My feeling is that the Rosen Motors concept would do well for the consumer, but not so well for automobile producers and mechanics.

OK, maybe it was teensy bit offtopic. To return to the topic ...

I guess the really small size and relatively high output of electricity from these little jobbers in the article is appealing for some things DoD, but as the responses have alluded -- there's still exhaust. There's also the given that people are going to be walking around with little vials full of flammable materials. Do you think you'll be let on a plane with something like this? No way. OTOH, I can see something like the micro turbine having great use for powering portable televisions, sat phones, lighting systems, etc.

I guess I see the advantages of this technology being more outdoor-ready rather than applying to all portable devices.

Re:... why not a turbine in a car? ...

[Forbman]

Turbines are incredibly inefficient fuel suckers when idling. The car companies did in fact try a few turbine-powered cars in the 50's and 60's, but gave up on them. One of the locomotive companies (EMD? Alco? GE?) also tried a turbine-electric locomotive, same problem. Great when actually moving, but incredibly fuel-inefficient when idling.

Re:... why not a turbine in a car? ...

[ninjagin]

Understood. Naturally, beccause a turbine is meant to run at a relatively consistent speed, it can't really idle efficiently, or accelerate/decelerate nearly as fast as the internal combusion engine. One approach might be to store a charge (in a battery, presumably) that would keep the turbine moving (though not actually burning anything) for about ten minutes. Once movement is required, fuel would be added to the intake and power could be continued.

I do know that turbines have become more efficient since the 50s and 60s. At the time of those experiments you refer to, the turbine was not used in a hybrid context -- the rotational power of the turbine was being directed to the wheels of the car through some clever transmission engineering of the type you see in turbine-powered helicopters. Idling (while admittedly inefficient) may be more within-scope today than it was then.

Regardless of how you approach the idle problem, it seems to me that the idea of the turbine-powered hybrid electric car is worthy of re-examination. That's all I meant to say.

The potential problem with these things...

[sexylicious]

is that many of the physicists working on the problem don't understand fluid mechanics at such a small scale. The viscous forces are huge compared to the inertial forces, and you have a completely different set of physics.

That's why you don't see very many working concepts of small aircraft (the kind that fit in the palm of your hand) with what most people recognize as wings. They're usually equipped with small flat-plate type wings, or a ribbon-like system like on a cuttlefish.
And the reason that many folks that do happen to understand the physics don't try and do things at such small scales is that the problem is difficult. Not impossible, but difficult.

As a person with a background in fluid mechanics, I don't see how the approach in the article will ever work well or efficiently. It might work, but it's not using the kind of principles that you need. (The whole point of my post is that you can't scale a device down without adjusting or remaking how it does what it does. The physics change.)

Re:The potential problem with these things...

[Forbman]

How well could you scale down a tesla pump? Maybe it works this way? IN fact, now that I think about it, it very well could be based on a Tesla pump.

The impeller in a Tesla pump is not finned like in a turbocharger, but a flat, solid disc, with a thin space between it and the housing. It's an axial flow turbine.

Re:The potential problem with these things...

[sexylicious]

You could conceivably scale that kind of axial flow turbine down to very small levels. You wouldn't necessarily need to extremely high rotation speed for a bladed turbojet. The only problem again is viscosity... There is just too much friction between the plate and the working fluid and the working fluid and the wall.

Now, if there was a way to directly extract the energy from the flow, rather than having the flow do some work on some mechanical device, than the efficiency of the process would be improved. I'm thinking of using a material that just so happens to get excited in such a way that it lases; then you collect photons at the exhaust. Conversely, you could use some material that gets excited when you irradiate it with something (radio, light, IR, whatever), and chemically react it with something (say as in combustion), and the reaction also just so happens to produce material that is excited and spontaneously emits radiation.

The irradiation, chemical change, and spontaneous emission processes would mirror the processes in an engine: compression, combustion, expansion. The problem is, I don't think any materials have been discovered that could satisfy the requirements for the process I outlined. I also don't think people have looked at that kind of thing too much, considering I couldn't find anything during a quick (20 minute) literature search. It could be a PhD in the making??

You are definitely on the right track with using a Tesla pump, over a bladed system. That kind of device better exploits the physics at such small scales. You'd want to stack the plates though, and you'd either want the wall very close to the plates (to minimize frictional losses), or you make the plates have holes of an appropriate size in them to minimize how much mass has to move.

Another thing to note is that at small enough scales, Coulomb effects could be exploited to have say, bearingless devices.

Also, if you get small enough, and rotate your plates fast enough, you might start running into problems with synchroton radiation. That's just a result of whipping the electrons of the atoms in your plate around the axis of rotation. At slower speeds, you get the rare emmission, but as you increase speed, the chances of an emission goes up.

headphones

[accelleron]

Hmm...

If I know anything about jet turbines, we're all going to need a LOT bigger headphones.

Walking around with combustable liquid

[Uosdwis]

Okay so the chip is small but still needs to lug around a gas tank. Yeah have fun getting through airport security with this. They don't even let butane cigarette lighters on planes, you think you are going to use a PDA the has .. D battary sized container of fuel that can be punctured and lit on a plane? Plus I have to either refill the container with a caustic material (in an office, train) or buy a new one? Batteries won't leak nearly as much as these things will.

question?

[objwiz]

The question in my mind is how much thrust do this little jets push out. I would like to add them to my shoes to make me run really fast.

Great but.....

[samberdoo]

Don't get too close to a flock of very tiny seagulls

What about FOD?

[Skudd]

FOD:
Foreign Object Damage or Foreign Object Debris. Involves items eg. shells, stones, plastic, building materials etc which may be ingested by an aircraft engine causing damage.
Source: Wellington Airport Information Glossary

Re:What about FOD?

[y2imm]

I was wondering what would happen when the disk ruptured. Like if you're on the phone and the first-stage disk 'plodes against your head, isn't that gonna hurt even a little?

Nice Cross Section of the Micro Turbine

[homerito]

From The Economist, this drawing shows the air intake, combustion chamber and turbine. There is not much information about the generator anywhere..

http://www.economist.com/science/tq/PrinterFriendl y.cfm?Story_ID=1020811

A bewolf... never mind...

Re:Nice Cross Section of the Micro Turbine

[Forbman]

It looks like a simple axial flow turbine (think: half of a turbocharger). I wonder if it would not be possible to set up a turbocharger sort of in this fashion, instead of having the turbocharger's compressor stage pump air into the turbine, instead just use tricky inlet design to optimize air flow at operating speed. Will be terribly inefficient at speed, but once it gets going...

There are people out there who do take turbochargers and run them like jet engines...

Re:Brilliant

[dykofone]

Try 60% with some of GE's newer STAG units (STeam And Gas, taking the exhaust from the gas turbine to essentially run a boiler for a steam turbine). That's the number for just straight up energy produced to energy available in gas ratio. Most of the high numbers you see like 80% use gimicks suck as "operational" efficiency, taking things into consideration like heating the offices of plant operators and how many people are on staff.

Now, the next generation of power plants will use gas, steam, and fuel cells to produce a true 80% efficiency, but that's probably a decade off (like flying cars).

What about noise polution?

[PhaxMohdem]

Considering a fan in my computer spins at around 5K RPM and makes enough noise to drive me nuts, I'm thinking 1 mil RPM would produce a little background hum in that cell phone.

Needs a new starter motor

[honestmonkey]

So, yeah, I'm kind of missing a point here, I guess. Instead of plugging my laptop into the wall socket to recharge, I, what-

Get out my little funnel, pour gas or alcohol or whatever into my laptop's gastank, pull on the cord to start the engine back up?

And does it give a warning when low on fuel, like a flashing yellow light ("Tank is almost empty").

Dunno if this sounds like an improvement to me. I just had this picture of someone yanking and yanking on the cord on the back of their laptop, and someone else coming by telling them they needed a new spark plug. "Nah, it's the clutch!"

What is the difference between....

[StressGuy]

a tavern and an elephant fart?
.
.
.
A tavern is a bar room while an elephant fart is more of a barroom.
.
.
.
careful with that joke...like yours, it's an antique.

Re:What is the difference between....

[MrCreosote]

Man travelling through India, overhears 2 local arguing

"It is 'w-h-o-o-m-b'"

"No. it is 'w-a-h-o-o-m'"

He interrupts them - "I think you will find it is spelt 'w-o-m-b'"

One of the locals replies "Excuse me sir, but I cannot believe you have heard an elephant pass wind, let alone know how to spell it"

Business Plan

[Minna Kirai]

1. Subscribe to MIT Technology Review, other science mags.
2. Summarize an article from each issue on my ad-banner-laden weblog
3. Submit my journal link to a web site whose name is synonymous with overwhelming floods of HTTP traffic
4. Profit?

blow...

[TamMan2000]

All you have to do to start these is pump a bunch gas through it.

At one of the talks I went to, they said they had a tube going into an early prototype that you blew into to get the engine stated.

And not exactly no polution... You still get NOx if you are burning at a high enough temperature to be even remotly efficient.

Yeah, it SOUNDS cools...

[rainwadj]

...but property values are sure to go down in and around the flight paths of everyone's PDAs/cell phones/laptops/etc.

Have they considered F.O.D.?

[silicondecay]

Quite simply put, foreign object damage. I used to be a crew chief in the US Air Force, and one of the biggest dangers to our aircraft was F.O.D.

Our engines were essentially huge vacuums that had a lust for stones, birds, and the occasional rabbit. A small pebble could literally cost millions of dollars. Once a pebble breaks off a piece of metal, it just cascades from there.

How can they even hope to prevent this?

Also, how can they prevent the "I wonder if it will hurt to stick my finger in it" syndrome?

Re:Have they considered F.O.D.?

[Rick Genter]

Could the solution be as simple as putting a fine-meshed screen over the intake?

Hes thinking too small

[t_allardyce]

It certainly has applications in the military, I just can't see people carrying these around in their pockets though, The advantage of batteries is that they are rechargeable (which to the consumer means free) and that there are millions of products out there that all take AAs or Ds etc and you'll have a tough time convincing people to use anything that doesnt fit in those holes. mobile phones, pds and notebooks generally have their own batteries so maybe theres a market there, but the idea of buying fuel is just going to be weird, because all those devices are already rechargable and people are used to that. Also people are just going to be concerned with the idea of having any kind of flammable/explosive liquid in their pocket and producing fumes. Anyway, what exactly does happen if you cover up all the air vents?

This would totally rock the out-door portable mini-generator market though, If it was the size of a coffee-cup you would be able to power stuff in your tent and take it walking with you to power your GPS etc. Also it would be great if it could take almost anything as fuel - the army would love that.

Is that a jet in your pocket....

[syousef]

...or are you just glad to see me?

Rotating blades?

[drlake]

I'm just visualizing the destruction if you drop one of these suckers and it breaks while spinning at 1 million rpm...

Interesting radial velocity

[Rick Genter]

Let's see.

1 million RPM at the diameter of a dime.
An American dime has a diameter of 17.91 mm.
At 1 million revolutions per minute, a point on the edge of the turbine blade will travel:

10**6 * 2 * pi * (0.01791 / 2) meters per minute

or
56,265.9 meters per minute, or 937.8 meters per second.

The speed of sound at sea level 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:Interesting radial velocity

[my_fake_account]

wouldn't something this size make more of a faint sonic *tic*? Swinging a bullwhip doesn't break windows a quarter mile away.

Re:Interesting radial velocity

[Rick Genter]

It's not so much the sound that I would worry about as the shock. A sonic boom is a shock wave. This turbine is in a tiny enclosure that would have to absorb that shock.

I just think it's an interesting engineering problem to deal with.

It has to be said.

[The One KEA]

How about a Beowulf cluster of these things! You could run another Beowulf cluster from a power source the size of a shoebox!

watch out for nano-birds!

[CheeseTroll]

You just have to be careful of those nano-birds, lest they get sucked into your micro-turbine!

Cool Idea

[Charcharodon]

Is that a jet engine in your pocket, or did I cause your pants to burst into flames?

A cool concept for portable power production. A turbine is a very flexible power plant when compared to other combustions based engines since it takes little to no modification to get them to run on practically any type of fuel.

Of course does this mean I need to start carrying around a small fire extinguisher and a blast proof cell phone case to protect my ass when the inevitable rotor burst occurs?

Uh

[wicka_wicka]

YES! More dependence on oil! This is exactly what we need.

I've done it...

[Cyno01]

*Hangs head*

Not one mysql comment?

[mgkimsal2]

Damn people! Am I the *only* one who read it like that?

Waiting for the obligatory JET cracks...

[RTMFD]

...so if JET's on a chip, does that mean we'll soon have Exchange on a Dorito?

Now your hip flask is your battery pack...

[vudufixit]

Every sip is a waste of energy?

Spool-up

[cft_128]

I for one cannot wait to hear the sound of my phone spool up its turbine when I answer the phone, there is something cool hearing that wind up.

WHAT? ... no, I'm not at the airport ... WHAT?, I CAN'T HEAR YOU, SPEAK UP ... oh, sorry, that is just my new cell phone's turbine

Re:Can we PLEASE STOP linking to this guy's blog??

[Lord Crc]

In all seriousness, why does /. continue to link to his ramblings instead of to articles that contain real, useful, technical content?

Cause they did? Or did you completely miss the first link in the story?

Yes, this is probably off-topic (as in "not about tiny turbines") but it is still relevant. At least give us the option to ignore him.

And just how did any slashdot editor FORCE you to click on the second link? I'm curious. Do they stand behind your back or something?

so this means

[gfody]

the turbo button on my computer case could activate an actual turbo! fuckin awsome

Re:so this means

[my_fake_account]

Is that an afterburner in your pocket or are just happy to see me?

Cool your jets

[Doc Ruby]

It would shoot a tiny stream of hot exhaust gas, for one thing, making it more suitable for devices clipped to belts or carried in briefcases than for those stuffed in pockets.

The heat in that exhaust gas, as well as its velocity, represents waste energy lost to the process rather than the product. What is the net efficiency of even a theoretical MEMS gas turbine?

What Mileage does your PDA get?

[PerlPo8]

Do we really want to continue to promote energy sources that rely on fossil fuels?

home turbines

[Doc Ruby]

The dreams in that article mostly live in mobile devices, which need lightness and coolness as much as efficienct power. Much more interesting is microturbines harnessing high efficiency (perhaps up to 90%, with an afterboiler) for home use. Natural gas costs about $0.01:Mj, so a 2KW house at 90% efficiency costs about $60:month to power off existing residential gas lines, about 1/3 the cost of electricity direcly from the grid. If these 100W clusters are practical, the unit could fit easily in 0.25 cubic meters, which could fit in any home.

Comes with ear-protectors

[DaoudaW]

State-of-the-art generator/PDA. Comes complete with noise-canceling headphones so you can listen to your mp3 in relative quiet!

Re:exhaust (cell phone doubling as a hair dryer)

[LemonFire]

I love it, a jet engine powered cell phone can now also double as a hair dryer....

This is great news!

-- This sig .... needs a new muse

Screaming Eagles

[Ydna]

"You should check out my new pocket 'puter!"

"WHAT?"

"I said you should check out my new pocket 'puter!"

"I CAN'T HEAR YOU. WHAT DID YOU SAY?"

"Oh, let me turn it off."

Re:Obvious joke, can also be used to cook hot dogs

[LemonFire]

Not only that, you can also use your jet-powered MP3 player to cook hot dogs, now that very useful!

-- Call 1-800-GET-SIGS for your own custom SIG today!

microturbines may work better than big ones.

[twitter]

There are two reasons big gas turbines have low efficiency. The first is that gas compression is expensive in terms of work. It's also tricky, and it took decades to make working models even though the materials and techniques were well known. The second problem is that you are typically blowing lots of hot and unexpanded gas back into the environment.

Combined cycle generation overcomes these limits by using water as a working fluid for the gas turbine's "waste heat". Water is much easier to compress, you just condense it and run it through a pump. The condenser makes a vacuum, which further adds to cycle efficiency. Steam turbines can expand steam all the way down to vacuum pressures and nearly ambient temperature.

The working fluid, air, in a micro turbine is going to behave in a more compressible fashion than it will in a big turbine. It should be easier to compress and suffer fewer losses due to turbulence. This will partially be offset by increased viscous losses to walls and pipes, but those can be kept low with short paths.

Is that a turbine in your pocket?

[twitter]

The thing will make a good power source for tommorrow's vibrators. It warms itself, and bad bearings only make it better.

The poor and electricity

[line.at.infinity]

From the article: ...he has an even more ambitious vision: that small clusters of the engines could serve as home generating plants, freeing consumers from the power grid, with its occasional black- and brownouts.

and:

The technology could be especially useful in poor countries and remote areas that lack extensive and reliable grids for distributing electricity.

Being free from the grid has some benefits. For instance if your country loses a reliable source of power because the US People's Liberation Army decided to "liberate" your country, this option may be the only way to go for once again obtaining reliable source, which some companies need more than others.

It could save you money also as a result of being freed from an expensive local Electric monopoly, and from not using a rather inefficient solution. Producing power at home means electricity doesn't have a long way to travel, hence there won't be all that energy loss that happens when power is transported traditionally over a long distance of high-power grids.

But isn't the benefit of a micro-generator somewhat lost if you're going to be using a cluster of them? Why power our homes with generators designed to be small enough to fit into our PDAs? I would think a single generator for a home would be a cheaper solution (both short and long term) than a cluster of micro-generators, natch.

The /. summary states:
The engineers even think their engines on a chip could be used in poor countries to bring electricity there.

More like power for the rich people with PDAs in poor countries without decent infrastructure, rather than a solution for the poor? Wouldn't it be a cheaper solution overall to just get a decent infrastructure for the country? I cannot see how a cheaper solution can exist for poor countries only. If it was a truly cheaper solution than what rich countries have already, it'd be a solution for rich countries as well, but since that doesn't seem to be the case, it probably means that we already have the better sollution for the poor countries' woes.

Case Mods

[Bryan_K]

Think of the potential for case mods. A laptop with a huge chrome stack or two. Or a PDA with afterburners.

Just what we need..

[sl4shd0rk]

Gee, another Oil Whore mongering device. Now I have to fill up my car AND my fucking laptop at the gas station.

Turbine - DC?

[Colin Smith]

How do they get from Gas Turbine -> DC? I'd bet there's an AC and rectification stage in there.

Anyway. A single big gas turbine on it's own would be 39%, 40% efficient. Small ones less so. Big power plants are closer to 55%, 60% efficient because they are Combined Cycle, they add an extra steam turbine stage to the exhaust of the gas turbine. If they're really clever about it they then capture the waste heat from the steam turbine and pump it to local houses for central heating and hot water giving an overall energy efficiency of up to 90%.

Transmission losses aren't that big, it obviously depends how far you're sending it but for the UK, 2%-3% on average. Rectifiers, 90% efficient, chargers 95%+.

Overall, I reckon the battery is probably several times more efficient than a local small gas turbine. Not only that, I can simply plug it in to a local electrical outlet to recharge, usually for free. You're a bit stuffed if you don't have a replacement fuel cartridge for a fuel cell or turbine.

In terms of performance batteries have improved significantly anyway. They simply aren't heavy anymore and the next generation Li-S cells have a higher energy density than a tank of compressed hydrogen.

Exhaust and muffler

[HermanAB]

Man, you don't want to run these things indoors. Think of the noise and polution.

How the hell can you talk on a cellphone powered by a screaming one million rpm turbine, while the exhaust gas burns your hair???

Only deaf, bald, anaerobic alians need apply...

engines the size of walnuts

[poleshifter]

Bones, they'll show us medical advances,
miracles you never dreamed possible.
Scotty, engineering advances --
vessels this size
with engines the size of walnuts.
Ach! You're joking.
No, he's not.

We dont need....

[Uplore]

Another way to burn fossil fuels. We need renewable energy sources.

I don't think so

[Alceste]

Would you like some fries with that hype.

So let's say that somehow the thermal insulation and mechanical integrity are good to go.

Here are some other potential issues:
-Plumping
-Storage of fuel
-Energy Conversion (engines and low duty cycle devices are a tough match)

Batteries are still pretty good.... closed systems save a lot of grief.

Ripped-off site layout

[MochaMan]

The best part of the whole thing is he couldn't even be bothered to put together his own site layout and graphics, he ripped it from Groklaw. Here's his site for comparison.

Re:No, I'm New Here

[Drakonian]

Wow, who knew there was a user dedicated to my pet peeve mentioned in my sig! It looks like it's only the "You must be new here" that gets the funny mods, the easy followup doesn't seem to have been treating you too well.

bias

[mnemonic_]

If you open up any copy of Encyclopædia Britannica you'll easily find articles you consider to be "biased." This is inevitable; Britannica is written by humans, and one man's "bias" is another man's absolute fact. No man willingly writes bias against his own judgment.

In the case of Wikipedia, it is not whether bias exists that matters. It is impossible to remove bias from human-made media. What matters is how that bias compares to those of other comparable media.

Dawin Award

[Jasa]

Reminds me of a guy who was made some coffee cup sized jet engines for his bicycle!

The "Best Out-Of-Context Quote" award goes to...

[hesiod]

From the article:
"that seemed stupid. Of course, we hadn't counted on the DoD."

That's the best quote from the article and sums up quite a few of the USA's problems.

I wish it were that easy

[Engineer-Poet]

But in this case Wikipedia is actually correct.

How does the reader know that without going back to primary sources? Cite the primary sources instead. Wikipedia is good for illustrating general concepts but not as a reliable source.

The poster even misquoted his own cite, implying that microturbine systems can reach 90% efficiency despite the fact that "combined heat and power" is completely irrelevant to a system for powering a computer. He appears to make a habit of such things.

Gas turbines are inefficient by design[1], because they use combustion to produce power[2], and the combustion process is inherently inefficient from an energy transfer point-of-view.[3]

1. No they aren't. Gas turbines can be considerably more efficient than steam turbines, because they aren't subject to the temperature limits of a system which has to work with steam (steam pressures go through the roof and steam itself becomes corrosive). Higher temperatures mean greater efficiency.
2. Combustion engines can be quite efficient. Large gas turbines and over-the-road (high speed) diesel engines can hit 40%. Low-speed diesels can reach 50%.
3. Combustion implies an increase of entropy, but the rest of your statement makes no sense to me.

I'm an environmental econ major

I'm an electrical engineer with a lot of side study in other areas. If you want to argue thermodynamics with the numbers and equations, bring it on. One of us cannot help but become enlightened.

The size doesn't matter...

What makes you say this? Losses affect efficiency, and size affects many things which influence losses. Heat transfer and viscous friction are two things which decrease in importance as size increases.

The only way to make gas turbines more efficient is to pump the excess heat from the exhaust into a steam turbine and gain a bit more bang for your buck...

Any kind of vapor turbine would do. So would a Stirling engine, Ericcson-cycle engine, or Peltier junction system (these would require larger radiators with much more cooling air than the turbine itself would... though you'd probably need a heat diffuser for the turbine just to keep case temperatures safe). The generic term for the use of the exhaust heat from one engine to run another is a "bottoming cycle".

I mostly agree with you on your last statement, though I question whether this microturbine represents any kind of breakthrough at all. I just don't see what kind of application is served by a high power-density, high energy-density, low-efficiency, high-temperature device; most of the cybernetic applications appear to be incompatible with characteristics like the heat output. This is not to say that there are not applications out there, they just don't seem to be any of the familiar ones.

Imagine...

[BigWhiteGuy_27]

...a Beowulf cluster of these!