I couldn’t find any info specifically on this particular application of a flywheel. After the third power outage this week (fvsking thunderstorms…) I began to wish that I had a UPS (Uninterruptable Power Supply). This got me thinking that a hard drive is similar to a flywheel. Has anyone ever tried making a flywheel that would fit in a drive bay that would give a few extra minutes of power so the system could shut down smoothly? I can think off the bat a few reasons that it might be impractical:
Too noisy. It would have to be in thick layers of sound insulation that may make heat buildup an issue.
Catastrophic failure. Having a piece of flywheel break off an rip through your PC at 200mph, hoping your Palm Pilot is enough of a barrier to keep the shards from ripping through your face.
Cost. Engineering this would likely be pretty complex and the cost/benefit ratio would be far out of whack.
On the plus side:
Computer is now an impromptu gyro.
Everyone wants to know where that “cool jet engine sound” is coming from.
If you could put data on the flywheel seek times would be around 0.00012ms due to the 100,000 RPM disk speed.
Still, I think it would be a neat solution to a little emergency power supply for your computer. Perhaps there is even a way to make it act as a voltage regulator for the system and outside power is used to keep it spun up.
What do you think? Is this crazy talk? Could it be done?
I’d think one problem would be getting it up to speed when booting the computer. How long will it take to get there? Without a very high torque motor and high strength materials, you’re forced into a relatively slow acceleration. And since flywheels are designed with a relatively high mass to both store more energy and (through inertia) resist outside acceleration forces, the initial acceleration is all the more problematic.
So maybe it would need to be designed to run 24/7, spun up and left at speed.
Another problem, the tolerance of the system to reading from the disk at varying speeds. During a power outlet, the disk would be continuously decelerating. The heads would have a lot of tracking issues.
I would assume that the flywheel would be running 24/7. It is my understanding that they are most efficient when on all the time. So no good on a laptop.
I was actually joking about the data on the flywheel, but if you were to do it, perhaps it could contain only special data. Something like being an instant on boot disk. When you are experiencing a power outage and drawing power from the flywheel you would not be accessing the data on it. Just a thought.
Hmm, they claim it’s the only one, but I’m pretty sure I have seen others like that in stores. There are also power supplies with built-in batteries, and PCI cards which act as a UPS (the battery is on the board itself).
Sure, I guess you could use a battery in a drive bay…, but where is the “WOW” factor? I talking about having freakin’ flywheel spinning like a dervish on speed!
Actually, I was thinking that a flywheel could provide much more power than a battery in the same space. I’m curious if any one with technical knowledge can shed some light on the theoretical length of time you could power a PC off of a drive-sized flywheel. The battery version in your link has a model that est. 18 min. (with 17" monitor). Would a flywheel be able to significantly out last that?
Straying a bit from the original intent, but here’s a Google search that returns about 380 hits, but they all seem to be large commercial units. I suspect a useful capacity requires significant size.
No problem with the motor…just use some small-scale Ramjet engines on the wheel, with a small solid fuel rocket booster to get it up to enough speed to get the ramjets to the right speed, of course. There might be some problems with exhaust, heat, fuel supply, fire hazard, etc. But it would sure be cool!
Ranchoth
(Can I interest you in an RTG for your cell phone, in lieu of a battery?)
There’s a great deal more to the operation of a computer than keeping the hard drive spinning; in order to store enough energy to be useful (that you could draw off using a dynamo or similar), the flywheel would have to be massive or if you made it small enough to fit inside a drive bay, it would have to spin at incredible speeds (possibly higher speeds than may be achieved using materials currently available).
The simple answer is, no, flywheels are not a cost-effective method of energy storage, except in a few very special applications. Those special aplications usually involve a huge number of charge/discharge cycles, or extremely fast cycles. If it were better than batteries for powering electronics, it would be used in cell phones, laptops and digital cameras.
[hijack]I remember reading some article in an old magazine (where they had predictions about the house of tomorrow and such like), where they suggested that cars would be powered by enormous flywheels spinning at phenomenal speeds on frictionless bearings, I don’t quite know why (beyond the WOW factor) what the point would be, I suppose it’s the idea that you’re storing mechanical energy/work, rather than converting chemical or electrical energy on the fly.[/hijack]
Another problem with the idea of using the disk platters themselves as a flywheel is that as you drew off energy from them to power the rest of the computer, they would slow down; your drive would have to be engineered to allow for this.
But I think the main problem would be that storing enough energy to power a PC for, say five minutes, in a flywheel as small as a hard drive would mean that you’d have to spin it unbelievably fast - it would probably be impossible to engineer bearings that would stand up to the job, it may not even be possible to make the flywheel out of materials that wouldn’t simply fly apart under the stresses involved, also when the disk was spinning at this speed, it would be going too fast for the drive heads to be able to read anything.
It’s an interesting thought experiment though; it’s crackpot ideas like this one (no disrespect intended) that sometimes provoke new lines of thought, leading to real innovation.
You need power for your computer and monitor - if you have power then you don’t need a flywheel to spin the HD.
Actually I think it would be better to have a UPS providing the voltage the computer needs (12 V and the other lower voltages on the power cable). instead of 120 volts but it’s easier to install a ups that produces 120 (and you can run the monitor)
You may be misunderstanding my point. The flywheel would work just like a normal UPS (power the computer and monitor if the power went out). It isn’t specifically oriented towards the hard drive. The hard drive reference is just the size and placement of the flywheel.
Overall, it sounds like this idea would be impractical in reality. Still, I think that as a “thought experiment” (as Mangetout pointed out) it is an interesting idea.
So, if a flywheel isn’t practical, how about a mini fuel cell. Works as a generator if the power goes out. I would imagine a fuel cell would have a much longer life than a battery. You’d have to figure out a way to deal with any heat and a way to vent the water vapor.
Besides the problem of storing enough kinetic energy in that small of space, the generator powered by the flywheel would probably generate a lot of electromagnetic interference, and I’m guessing that it would be a real pain to shield the rest of the PC from this. Also, the rectified and inverted power might still be too noisy for some power supplies and may cause a lot of snow on the monitor display.
OK I thought you wanted to keep the HD spinning. But flywheel batteries are being researched and already have a greater energy density of chemical batteries.
If you have a fuel cell you basically have a generator. Which instead of spending all the money on such high tech stuff why not get a ups and a standby generator?
