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Atomic MEMS Battery has 50 Year Charge
notestein writes "Working for DARPA, a couple of Cornell researchers (Amil Lal, Hui Li ) have developed a battery that uses decaying nickel-63 to drive a flexing MEMS cantilever to generate electricity. They expect a production version to produce useful energy for at least 50 years."
The article mentions attachign a magnet to the lever to generate electricity as it moves up and down.
If the movement is caused by electric charges, why not have the lever contact an electrode, and funnel the electric charge off through whatever it is you're powering, and then back to the isotope film? Surely that would be a more efficient way to harness the power...
Or, for that matter, why does the arm have to move at all?
=Smidge=
Just wait until the no-nuke freaks, flat-earthers, Nader kooks and other Luddites get a whiff of how this technology works. They'll try to scare the public into keeping this from becoming a reality.
Of course we could really fry their minds by reminding them that the reason the earth is still hot inside is mostly because of radioactivity.
Still, I think ignorance could be a factor in the public perception of this product. Of course, I'll be first in line to buy one.
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The latest pentium laptop will still only get 2 hours use out of it.
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I know I'd never keep a laptop for 50 years, but I might keep one for 5 years. I'd be happy to have a 5 year battery. Or a flashlight, or a radio, etc. 50 years is an unintentional side effect. Besides, if they use some sort of standard cells, I can just transfer them to whatever device I end up using down the line. That would make it worth the high premium for something like this.
Microwave replacement
Heater
Photographic film eraser
Electromagnetical warfare
Rodents killer
Hair remover
And I'm sure Al Qaeda can think of more wonderful uses.
The quantity of energy you'd get would be less than the energy of a decaying isotope, which is not very much. Even with advances in technology, this can't be very much. Furthermore, even if sufficient densities were achieved by mass producing cells, I'd keep an atomic MEMS laptop away from my lap unless I felt like nuking my nuts off.
I strongly doubt that you would be able to (safely) generate enough energy from the radioactive decay of any isotope to power anything larger than a pocket calculator. Sure, nuclear waste gives off a significant deal of heat as it decays, but then you're talking about nuclear waste.
One detail conveniently left out of the article is how much actual *power* is generated by this device. If a 1cc device produces only 10mA sustained, you're far better off with standard batteries for most anything except devices that actually *require* a long-running power source, and don't draw any significant amount of current. Consider this: I use 4 1700mAh AA cells in my digicam. They're, what, 3-4cc each? So at 10mA per MEMS device, you get only 160mA from that same volume.
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A 1-kilogram chunk of Nickel 63 will give off about 25 Watts of pure beta radiation -- assuming that you configure it in such a way that the beta particles aren't reabsorbed by neigboring nickel atoms. Even assuming 100% efficiency, a battery capable of powering your laptop would weigh at least a few kilograms.
The quantity of energy you'd get would be less than the energy of a decaying isotope, which is not very much. Even with advances in technology, this can't be very much.
Actually, this turns out not to be the case.
Consulting Ye Rubber Bible, Nickel-63 liberates about 67 KeV per decay (quite low; decays are typically in the 1 MeV range). This gives an energy density of about 35 kW/hr per _gram_ over the lifetime of the battery. _Energy_ density is far higher than anything based on chemical reactions.
It's _power_ density that's low for most practical battery materials. With a half-life of 92 years, you get about 20 mW per gram released (actually a bit more than that at first; it _averages_ to this as it emits half its decay energy over the whole 92 years).
The nice thing about Nickel-63 is that the decay produces beta rays (high-energy electrons) and nothing else. This could be shielded by a thick sheet of plywood, or a thin sheet of lead. Most radioisotopes aren't nearly as friendly (there is usually gamma emission as the decay product sheds excess energy, which is difficult to shield against). [ObDisclaimer: I'm assuming that the lead also blocks the x-rays produced as the high-energy electrons smack into the shielding.]
The other nice thing is that the decay product is stable and is a solid (Copper), and so both inert and likely to stay in the battery. Carbon-14, the other "friendly" radioisotope that I can think of offhand, has a lower power density (though a higher energy density), and produces a gas as a byproduct (Nitrogen), which could eventually cause problems if allowd to build up near your MEMS devices.
I have this 10 year old calculator which the battery is yet to die in. It's powered by that never ending, limitless supply of radiant energy that we seem to ignore quite frequently.
(Doesn't Voyager and all other longterm probes to the outer solar system use beta emitter batteries?)
No.
Radioisotope Thermoelectric Generators (RTG's)
Three RTG's provide electric power to Voyager. The generators produce about 1800 watts of heat by the radioactive decay of plutonium. The heat is then converted to about 400 watts of electric power by thermocouplers. The RTG's are mounted on a boom to protect the scientific instruments from excess heat and radioactivity.