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Hydrogen Micro Turbine Only 4mm In Diameter
savaget writes: "Luc G. Frchette of the Columbia University Microsystem Engineering Laboratory has developed a 20W electrical generator powered by a hydrogen turbine just 4mm in diameter. For more details, read the Wired
article or an older Popular Science
article. The tiny generator is more efficient than any battery and is expected to find military and commercial uses including robotics." Imagine the uses ...
That's 40 KHz.
Your dog is going to go totally nuts every time you turn on your PDA.
--Blair
Hydrogen is hardly a fossil fuel; it's abundant, and the combustion byproduct of hydrogen and oxygen (the two fuels used in this case) is none other than water. Pure water, at that.
This is why hydrogen is being looked at so heavily as an "alternative" fuel source -- it's abundant, clean, and very inexpensive.
--
I Hit the Karma Cap, and All I Got Was This Lousy
One of my drinking buddies worked on a project similar to this. He told me that the heat problems mentioned in the article were the single biggest obstacle to making a successful mini-turban. Apparently researchers have been working for years on these devices, but they have watched as battery technology has advanced and their heat problems remained. Basically the main problem is that the intense heat generated by combustion places an upper bound on the lifetime of these devices, and that upper bound is substantially lower than the upper bound on a Li-Ion battery's lifetime. Back in the days of NiCd, shoddy "Renewal" cells, and expensive alkalines, this might have provided some much-needed competition. But for now it is just behind the time, despite the fact that it is so small.
~wally
Apparently it generates a lot more heat than a conventional battery. Too hot for a cell phone. New slogan:
"Reach out and torch someone."
-tim
There was a movie at some time or other where they had an electronic bee, run by remote control. A tiny power generator could make such things possible in the not-so-distant future. Imagine how far we've come.
There was a discussion several days ago about batteries that are refilled with gas, rather than recharged. It sounds rather messy to me, while a system that uses a hydrogen generator certainly sounds cleaner and more efficient.
I wonder what kind of noise this system makes. If it is very quiet, we may very soon find that batteries in some of the higher end consumer devices are replaced by some mechanical generator such as this.
It may even be suitable for use in larger power generation scheme. Think of clustering a whole bunch of these tiny generators. Although they are currently quite expensive to manufacture, I believe that micromachines and nanotech will soon advance to such a level that it will be very possible to mass produce tiny machines.
Which brings me to the idea of tiny machines that have their own built-in hydrogen power generator. Now that's technology!
Oh well.
"But where does the exhaust go?" - well, out, that is rather the definition of exhaust. The exhaust is water vapor, unused combustion air, and heat. That shouldn't be a problem. Well, you won't want 20W to 40W of heat running in your pocket, but other than that it should be fine.
"And isn't this kind of a step back in our attempt to stop using fossil fuels..." - I am an American. My goverment has no such policy. All your oil are belong to us. For those of you in conservation minded countries, hyrdrogen is not a fossil fuel. It is a theoretically handy way to store electrical energy. There are technical hurdles. Not insurmountable, just insurmounted. Once there is a demand, there will be a way of distributing and storing the hydrogen.
Why would anyone *want* a tiny hydrogen-powered turbine generator? Fuel cells are already more efficient than they are even hoping this will become; fuel cells also likely to live much longer since they don't have any moving parts.
I'll agree that it's cool to take things that we are used to at macroscopic scales and make them tiny, but it usually isn't going to be an efficient way of doing anything.
Tarsnap: Online backups for the truly paranoid
Umm, Hertz equals cycles(or rotations) per second.
(2.4E+06RPM (Rotations / Minute) / (60 Seconds / Minute) == 40000 Hertz
Or 40KHz
H2 in gaseous form is NOT explosive unless it's in a mixture with O2 where it is about 4% to 85% of the mixture. Pure H2 is perfectly safe. And even if the H2 tank ruptures there is not going to be enough H2 to do anything. It might burn for a second or two and thats about it, most likely not enough H2 mass there to really do any damage (beyond the device it's in). Certainly not enough to cause an explosive misture in a large enough volume of air to matter.
And since this tank is gonna be small, it can be made really freakin tough. Think about how tough a good quality propane cigarette lighter tank is.
Yes, hydrogen is abundant. But it is mostly tied up in covalent bonds with other elements, such as oxygen, in water, or some other such bound form.
To burn the stuff, you first have to split it from whatever it is bound to, and that takes some deltaE.
In fact, it takes as much deltaE to split the hudrogen off as you get back by burning it and puttign the bonds back together (first order calcs).
Hydrogen is a *storage* fuel. It is simply a new way to take energy from one place and move it to elsewhere, where it might be more convenient to use it.
If you plan on using hydrogen to create a lot of usable energy storage, as in to replace some of our curent fossil fuel dependency, you have to get the energy from somewhere. Like say, fossil fuel.
Or nukes, or some such thing.
The point is, it can't reduce our curent dependency on our current fuel sources (well, it might add some efficiency at sa few points, like al.owing us to use excess generating capacity at off-peak hours. The laws of thermo-goddamnics still apply.
Hydrogen technology doesn't create any new energy reserves, it simply allows us to store some of our energy reserves in a different (H2) and potentially differently-useful form.
I always thought his head was kind of small for regular sized turbans.....
Most micromotors demonstrated to date have simply succeeded to overcome the viscous drag on the rotor, leaving no power to drive other com-ponents and limiting their use for low-load actuation.
Luc Frechette just published ASSESSMENT OF VISCOUS FLOWS IN HIGH-SPEED MICRO ROTATING MACHINERY FOR ENERGY CONVERSION APPLICATIONS in which he lays out the constraints of micro-motors and how he hopes to overcome them.
Liquid hydrogen is cold at 1 atmosphere of pressure. You can make it as hot as you want, if your container can handle the increased pressure.
Gaseous hydrogen isn't really any more explosive than the butane in your lighter or the natural gas piped all over your house.
You prefer children playing with toys powered by batteries that are packed with lithium, mercury, etc?
"Prefiero morir de pie que vivir siempre arrodillado!"
Better yet, and more American...
If this microturbine can be mass produced for pennies, like many other semiconductors, and eventually we can make a cheap aluminum tubule sandwich sheet that is thin enough to make cans...
We could make disposable self-cooled cans of Budweiser! Who wouldn't marvel at the combination of technology and wastefulness!
That, and now the "Turbo" switch on the front ofthe old machines will be literally accurate--instead of slowing down the machine for old games, it will kick in the generator and boost cpu voltage . . .
hawk
Being perfect to the last atom or so, there should be no vibration at the fundamental frequency. I counted 20 blades in the Popular Science picture, so the actual noise peak should be at 800kHz. Easily damped, and out of pet hearing frequency range.
No. My parents always had cats at home, and, as a teenager, I did a lot of experimenting with electronics. Cats do not mind sounds above 20 kHz (maybe they can't hear them?). They hate mostly the sounds between 8 and 12 kHz. Not coincidentally, that's the frequency range of the "hissing" sound cats make when annoyed or angry.
2.4 million RPM on a turbine that is 4mm in diameter... its math time... .3 miles per second for the metrically challenged. Very long range rifles shoot at speeds on that order of magnitude.
2400000 R/M = 40000 R/S
1 R = 4mm*pi = 12.56mm
40000 R/S = 502656 mm/s linear velocity
503 m/s is pretty fast. Thats about
I havent done basic physics in a long time so i am rusty on the formulas; could someone do the energy/force calculations for me? Just off the top of my head i think 1 milligram (thats the equivalent weight of one cubic millimeter of water, which i think would be about the right order of magnitude for the blades on this turbine) moving at 503 m/s could do some daage to organic tissue, more so than a splinter at least.
Louise, baby, try to finish your stories prior to Thanksgiving weekend next time...sheesh...
-- @rjamestaylor on Ello
The exhaust is water vapor, unused combustion air, and heat. That shouldn't be a problem. Well, you won't want 20W to 40W of heat running in your pocket, but other than that it should be fine.
The 20-40 watts is the power delivered by the device to the laptop and eventually (except for a miniscule amount leaving as light, radio waves, telephone modem signals, etc.) disipated as heat by the laptop's circuitry.
But the generator is a HEAT ENGINE and this one runs at 10% efficiency. So to generate 40 watts it burns fuel at a 400 watt rate. 40 watts to the laptop, 400-40 = 360 watts of heat in the exhaust.
And you CAN'T improve it very much. It's a heat engine. Perfect efficiency for a heat engine is the carnot cycle limit: 100% * (Th - Tc)/Th.
Call that about 30% for a fuel-burning engine at room temperature, and you're still talking 133 watts of heat sitting on your lap for a 40 watt load. But you can't get anywhere near carnot cycle in a practical device, and the smaller and faster the device the more you'll fall short - you need something like a power-plant to approach it. So back to 10% and 400 watts.
What gets me about the Scientific American article is the apparent claim that the efficiency of batteries is ten times worse. Batteries and fuel cells can approach 100% efficiency.
I think what happened is they confused efficiency with energy density. A battery contains both its fuel and its oxidizer - and oxidizers tend to be heavy, due to heavy atoms and extra atoms to hold them down. Heat engines and fuel cells, on the other hand, can get their oxidizer from the ambient air, and expell the combustion products. So they only need the engine/cell proper plus the fuel tankage. Yes a heat engine would probably beat a battery by a factor of ten on energy density. But a fuel cell, if it can be adequately miniaturized, might do still better.
Nevertheless this engine looks like a good solution (if you're willing to put up with the waste heat), at least until fuel cell technology approaches it in power density.
The use of hydrogen is curious. Handling it is a real bitch. It crawls right through steel and burns with an invisible, super-hot, ultraviolet flame. Very dangerous.
They are probably using it, rather than a liquid hydrocarbon like butane, to simplify the design and to get the maximum energy-density numbers for the engine/tank system. With butane/air you need to do emission control for NOx, CO, and unburned hydrocarbon. With hydrogen/air you only need to sweat NOx. Hydrogen's energy/ounce of fuel is higher and it's easier to light. Liquid hydrocarbons - especially impure and "odorized" formulations - produce a number of combustion products that can potentially foul the engine or its exhaust as well. You don't need fancy controls for a hydrogen engine, while a butane engine might need a catalytic converter and some serious compute power.
What I'd like to know is whatever happened to the ceramic oxygen-concentration fuel cell - the one that uses the same basic cycle as the exhaust-gas oxygen sensor in a car?
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
The way I interpreted the Wired article, this thing is still theoretical. They didn't even mention a working prototype. I refuse to read anything real into a Popular Electronics/Mechanics/Science article. That's all complete crap.
/. will instead be discussing the latest vapor being hyped.
I'm sure a couple years will pass and we'll all wonder what happened to that "micro turbine thing". We won't be discussing it much, though, because
Why are you letting these clowns ruin our country?
You wish. Actually, burning hydrogen in air generates some NOx emissions. Hydrogen in air is a complicated combustion system. NASA has been working on scramjet designs that burn hydrogen in air, so this problem is gettimg some attention. It's the subject of some big number-crunching simulations.
If you want a totally clean burn, you have to burn hydrogen in pure oxygen.
It's not PC to note this but did you realize that all the fuel from 40 years of operation of a nuclear plant will fit into the same volume as a large semi-trailer?
That's incredible really.
Imagine, all the electricity needs of a family of four for 40 years generate about 3 pounds of fuel waste.