Beta-batt: A nuclear battery that lasts 20 years
by TreeHugger on 05.12.05
There has been a lot of discussion recently in Treehugger about how new high tech batteries may obviate the need for "the hydrogen economy" as a medium of energy transfer- just go straight electric if the batteries are getting so good and so fast.
Here is yet another new battery that has interesting possibilities and a lot of possible problems: The beta-batt. Its developers combine radioactive tritium with a porous silicon diode- the silicon semiconductor generates electricity by absorbing the electrons generated by beta decay , just like a solar cell generating electricity from incoming photons.
The upside- a D battery that lasts 20 years. Tritium emits only low energy beta particles that cannot penetrate a piece of paper, let alone the battery casing. The downside- it's made in nuclear reactors and someday will have to be disposed of. Betabatt's website says its "Green and Safe- No harmful radiation, leaching, or contamination". Green? that's a bit of a stretch. Safe? Maybe we just have to think of it like we do about the polonium in our smoke detector- The usefulness of the device outweighs our trepidation. ::Betabatt via ::Eurekalert by [LA]
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Tritium just decays from 3H to 3He + e- (helium and a beta particle) so unless the Tritium + Porous silicon battery is contaminated with something else, I don't see why disposal would be a proble. The silicon might even be recyclable for photovoltaics or computer chips if we're still using silicon for either of those in 20 years. So, the reactor used to make the tritium is probably more of a concern than the product here.
This is not useful for anything like a laptop or cell phone unless you can afford around $50,000 (cellphone) to 1 Million+ per battery- and that is on the low side. Assume you can get ALL the power out of the tritium used and do the math (or have a highschool physics student do it for you). It comes out to about $10k per watt of power at 100% efficiency, now assume the efficiency is low because you can't capture all the power with perfect efficiency in 5 - 10 keV electrons, and you quickly find your technology is commercially useless.