Text 4140, 87 rader
Skriven 2005-05-15 22:38:22 av Rich Gauszka (1:379/45)
Ärende: Personal nucear power - 12 year battery?
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From: "Rich Gauszka" <gauszka@hotmail.com>


http://story.news.yahoo.com/news?tmpl=story&cid=96&e=2&u=/space/20050513/sc_spa
ce/personalnuclearpowernewbatterylasts12years

A new type of battery based on the radioactive decay of nuclear material is 10
times more powerful than similar prototypes and should last a decade or more
without a charge, scientists announced this week.

The longevity would make the battery ideal for use in pacemakers or other
surgically implanted devices, developers say, or it might power spacecraft or
deep-sea probes.


You might also find these nuclear batteries running sensors and other small
devices in your home in a few years. Such devices "don't consume much power,"
said University of Rochester electrical engineer Philippe Fauchet, "and yet
having to replace the battery every so often is a real pain in the neck."


Fauchet told LiveScience the batteries could last a dozen years. They're being
developed at Rochester and the technology has been licensed by BetaBatt Inc.


How it works


The technology is called betavoltaics. It uses a silicon wafer to capture
electrons emitted by a radioactive gas, such as tritium. It is similar to the
mechanics of converting sunlight into electricity in a solar panel.


Until now, betavoltaics has been unable to match solar-cell efficiency. The
reason is simple: When the gas decays, its electrons shoot out in all
directions. Many of them are lost.


"For 50 years, people have been investigating converting simple nuclear decay
into usable energy, but the yields were always too low," Fauchet explained.
"We've found a way to make the interaction much more efficient, and we hope
these findings will lead to a new kind of battery that can pump out energy for
years."


Fauchet's team took the flat silicon surface, where the electrons are captured
and converted to a current, and turned it into a three-dimensional surface by
adding deep pits.


Each pit is about one micron wide. That's four ten-thousandths of an inch.
They're more than 40 microns deep.


Tritium is a radioactive form of hydrogen. Mixed with chemicals that emit
light, it is used to illuminate exit signs without electricity -- the sort
commonly found in schools and other public buildings.


"It is safe and can be implanted in the body," Fauchet said. "The energetic
particles emitted by tritium do not penetrate inside the skin."


Tritium emits only low energy particles "that can be shielded by very thin
materials, such as a sheet of paper," said Gadeken of BetaBatt. "The
hermetically-sealed, metallic BetaBattery cases will encapsulate the entire
radioactive energy source, just like a normal battery contains its chemical
source so it cannot escape."


The device is detailed in today's issue of Advanced Materials.


Improvements needed

The manufacturing process is standard to the semiconductor industry, so no
other technology breakthroughs are needed to bring the batteries to market.
Still, don't expect anything on the store shelves for at least two years,
Fauchet said. His team is now working to improve the manufacturing process,
aiming for batteries many times more efficient than those announced today.


"If we are as successful as we think we may be, it will take less than five
years before this technology is adopted," he said.

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