Well I'll be damned
by
AKAImBatman
·
· Score: 5, Informative
I've been harping on the idea of using nuclear batteries in cell phones and laptops for the past year or so. To date I've been called a variety of names for it, the least of which is "crazy". Yet here we are. Researchers are SERIOUSLY talking about using radioisotopes as power sources!
In case anyone is wondering how these work, the idea is that the radiation from a small amount of radioactive material (NOT fissable material!) is captured and converted into electricity or other forms of energy. There is very little radiation emitted by these devices, because the radiation IS the power! Letting it escape would be poor economy.
NASA has used these sorts of devices in spacecraft for 40+ years, starting with the Apollo missions. NASA's earlier designs produced about 75 watts utilizing a few pounds of Plutonium-238. Pu-238 was an excellent choice because it is useless for bombs, and has a short half-life (~80 years). With the public finally calming down about nuclear technology, NASA is now developing a more efficient device called an SRG. These devices get about 55 Watts per 600 grams of PU-238. This is way more efficient than current RTGs, like the ones used on Apollo.
The primary downsides to Nuclear Batteries is that they are expensive and they don't scale. They are expensive because the nuclear materials are very rare and expensive to process. If we started using these materials in massive quantities, it's a certainty that the prices would drop. They are not scalable, because the amount of materials required means that a few hundred watts is the largest device one could construct with a reasonable size, weight, and expense.
As for anyone who's worried about dirty bombs, I suggest you read this and this. The threat has been greatly overstated, and is actually less effective than a regular bomb. The real problem is the issue of keeping the materials out of landfills. Even today, there's a big problem with Lead, Cadium, and other dangerous materials ending up in landfills. Radioisotopes wouldn't be much worse, but there is an upper limit on how much you want to add to the sub-soil.
Re:Well I'll be damned
by
AKAImBatman
·
· Score: 5, Informative
In all seriousness, there are larger RTGs. The Cassini probe started off with a few kilowatts of power at its disposal. Over time that has dropped, but the probe still has a significant amount of power to pull from. According to Wikipedia, the craft will still be producing ~628 watts at the end of its 11 year mission.
Re:Unknown Error In The Submission
by
Anonymous Coward
·
· Score: 5, Informative
Yup, you're right. If you even read the article, it says that the thin layer of dead skin on your body is enough shielding.
The emitted particles only travel 25 micrometers (!) once they hit humans.
They just need a good PR department to call it something benign. Maybe PATRIOT batteries?
Re:but...
by
AKAImBatman
·
· Score: 5, Informative
What happens when they blow up?
They're not explosive. Most nuclear batteries use a radioisotope that's already "burned". i.e. Pu-238 oxide is used in RTGs so that there's no chance of it burning. It still emits plenty of radiation once it's chemically stable, so the only thing you have to worry about are rednecks who think it's funny to melt down the batteries and mix them with paint for glow-in-the-dark wallpaper. Even then, I rather doubt it will have much effect on them.
Re:New addition to the Patriot Act?
by
phlegmofdiscontent
·
· Score: 4, Informative
Or he could buy several thousand smoke detectors today, which also contain radioisotopes (americium, I believe) for about the same price and have even more radioactive material. What's your point?
Re:Someone who knows their physics please tell me
by
AKAImBatman
·
· Score: 4, Informative
Some kind of reverse Peltier gizmo can't be used to create a solid-state nuclear battery?
You know, they used to use these things in pacemakers before Chernobyl happened. After Chernobyl, everyone got scared about "nuclear" anything. Now dead batteries in a pacemaker are a very real concern, whereas they used to be good until you were dead from other causes.
Re:"My Child Swallowed WHAT?" (a rant 8-)
by
topynate
·
· Score: 5, Informative
Google for thermeonics. Two entires.
Spell it right - thermionics. You get over 5K. And if you add up the results for googling different sub-fields I bet you get way more.
Re:Unknown Error In The Submission
by
Aglassis
·
· Score: 4, Informative
You said: " The layer of dead skin blocks it outright. The radiation can only travel 25 micrometers through most liquids."
This is correct, but misleading. An alpha particle (a helium nucleus) has a charge of +2e. This makes it difficult to travel through dense matter as it will quickly loose its kinetic energy (typically about 5 MeV range--normal matter on Earth has about 0.025 eV) by being scattered by electrons in the absorbing material (note that chargeless particles like neutrons or neutrinos have very large ranges in matter). Therefore, it's energy will be dispersed throughout the matter that slowed it down. For living cells this amount of energy is enough to kill the cell or cause some reaction that will cause the cell to mutate (where it may survive on mitosis or die). Obviously this is not a concern for dead cells.
If the alpha emitter is volatile or made into a dust, it can be inhaled. In this case, your respiratory system is affected. Additionally if it is ingested, your gastrointestinal system is affected. So obviously the greatest concern in the design of this battery is how its containment prevents it from being released. Logically if the alpha particle can't penetrate your dead skin cells, it won't penetrate a thin containment shield. If the containment breaks down and particles are easily disolved in water or break up and become dust easy, there is more concern about the safety of this device.
-- Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
Re:Unknown Error In The Submission
by
carlos92
·
· Score: 4, Informative
But this won't explode. It stores a lot of energy, but the POWER (energy/time) is very low. It's not like the wall outlet, which can give large amounts of energy in a very short time.
The article says that it could be used to trickle charge rechargeable batteries. Think of it as a battery "helper".
Re:Random thought here...
by
Quantum+Jim
·
· Score: 4, Informative
In short, you take a small amount of the radioactive substance and wrap all but one face in a lead shield, only allowing alpha particles out one face.
One possible problem, to form a narrow alpha-particle beam for small devices, a small slit or hole has to be used. Heisenberg's Uncertainty Principle shows that the range of (normalized) highly probable momenta will be large since the range in location is small. This means that some particles will be fast and some will be slow; however, the actual event is hard to predict.
Since kinetic energy is proportional to the momentum (squared), your device will produce energy in hard-to-predict spirts. You can calculate an average energy; however, that applies only after a large number of particles go through your device. That's one reason why these kind of devices work well as trickle-chargers yet poorly as generators.
Another problem is that you lose 5/6th of the particles from the device, or more. This is because the probability of a radioactive atom emitting a particle in a specific direction is relatively uniform. However, only one face of the material is unshielded to the device. So particles most will hit the shielded face. One one face, 5/6th of the total area, will have a flux out.
Place a wire coil around that face, voila... moving charge (alpha particle) induces voltage and current in a conductor (coil). Insulate the coil, and draw power off it's ends.
When you extract energy from the particle's kinetic energy, it will slow down. When it does, it will emitt electromagnetic energy, breaking it furthermore. All this energy is not converted into electrical energy in your device.
In the article, two methods are getting energy were tried. In the first device, the scientiests use a material that emitts beta particles - electrons - and injected them directly into a pn-junction of a semiconductor device. Normal semiconductor devices (i.e. diodes) work by moving electrons to unfilled energy levels in one substance (p-material) from filled energy levels in another substance (n-material). Moving electrons means a current forms.
This is usually induced by thermal or EM energy. In this case, the radioactive element emitts electrons directly into the semiconductor. The imbalance causes a current to form through the junction. This can be miniaturized well. It also is not as sensitive to the direction that beta particles are emitted as your device.
The second device uses a (really small!) lever attached to a piezoelectric material. Piezoelectric crystals produce electric current when stressed or vibrating. (The reverse is also true; hense why the crystal in your digital watch creates the ticks for the clocks.) The lever gets hit by - and absorbs - beta particles emitted from the radioactive element. Since beta particles are charged, the lever aquires a negative charge and the element aquires a positive charge. This pulls the lever toward the radioactive element. When they get close, electron tunnel over the gap and return their charge to the radioactive element. Once uncharged, the lever spings back to its origional position. The movement of the lever causes the piezoelectric material to generate current.
This things scientists and engineers create are truely fascinating! (...to me at least!)
-- It is impossible to enjoy idling thoroughly unless one has plenty of work to do. - Jerome Klapka Jerome
Slashdot Mirror
I've been harping on the idea of using nuclear batteries in cell phones and laptops for the past year or so. To date I've been called a variety of names for it, the least of which is "crazy". Yet here we are. Researchers are SERIOUSLY talking about using radioisotopes as power sources!
In case anyone is wondering how these work, the idea is that the radiation from a small amount of radioactive material (NOT fissable material!) is captured and converted into electricity or other forms of energy. There is very little radiation emitted by these devices, because the radiation IS the power! Letting it escape would be poor economy.
NASA has used these sorts of devices in spacecraft for 40+ years, starting with the Apollo missions. NASA's earlier designs produced about 75 watts utilizing a few pounds of Plutonium-238. Pu-238 was an excellent choice because it is useless for bombs, and has a short half-life (~80 years). With the public finally calming down about nuclear technology, NASA is now developing a more efficient device called an SRG. These devices get about 55 Watts per 600 grams of PU-238. This is way more efficient than current RTGs, like the ones used on Apollo.
The primary downsides to Nuclear Batteries is that they are expensive and they don't scale. They are expensive because the nuclear materials are very rare and expensive to process. If we started using these materials in massive quantities, it's a certainty that the prices would drop. They are not scalable, because the amount of materials required means that a few hundred watts is the largest device one could construct with a reasonable size, weight, and expense.
As for anyone who's worried about dirty bombs, I suggest you read this and this. The threat has been greatly overstated, and is actually less effective than a regular bomb. The real problem is the issue of keeping the materials out of landfills. Even today, there's a big problem with Lead, Cadium, and other dangerous materials ending up in landfills. Radioisotopes wouldn't be much worse, but there is an upper limit on how much you want to add to the sub-soil.
Javascript + Nintendo DSi = DSiCade
Yup, you're right. If you even read the article, it says that the thin layer of dead skin on your body is enough shielding.
The emitted particles only travel 25 micrometers (!) once they hit humans.
They just need a good PR department to call it something benign. Maybe PATRIOT batteries?
What happens when they blow up?
They're not explosive. Most nuclear batteries use a radioisotope that's already "burned". i.e. Pu-238 oxide is used in RTGs so that there's no chance of it burning. It still emits plenty of radiation once it's chemically stable, so the only thing you have to worry about are rednecks who think it's funny to melt down the batteries and mix them with paint for glow-in-the-dark wallpaper. Even then, I rather doubt it will have much effect on them.
Javascript + Nintendo DSi = DSiCade
Or he could buy several thousand smoke detectors today, which also contain radioisotopes (americium, I believe) for about the same price and have even more radioactive material. What's your point?
Some kind of reverse Peltier gizmo can't be used to create a solid-state nuclear battery?
Congratulations, you've just described an RTG.
You know, they used to use these things in pacemakers before Chernobyl happened. After Chernobyl, everyone got scared about "nuclear" anything. Now dead batteries in a pacemaker are a very real concern, whereas they used to be good until you were dead from other causes.
Javascript + Nintendo DSi = DSiCade
You said: " The layer of dead skin blocks it outright. The radiation can only travel 25 micrometers through most liquids."
This is correct, but misleading. An alpha particle (a helium nucleus) has a charge of +2e. This makes it difficult to travel through dense matter as it will quickly loose its kinetic energy (typically about 5 MeV range--normal matter on Earth has about 0.025 eV) by being scattered by electrons in the absorbing material (note that chargeless particles like neutrons or neutrinos have very large ranges in matter). Therefore, it's energy will be dispersed throughout the matter that slowed it down. For living cells this amount of energy is enough to kill the cell or cause some reaction that will cause the cell to mutate (where it may survive on mitosis or die). Obviously this is not a concern for dead cells.
If the alpha emitter is volatile or made into a dust, it can be inhaled. In this case, your respiratory system is affected. Additionally if it is ingested, your gastrointestinal system is affected. So obviously the greatest concern in the design of this battery is how its containment prevents it from being released. Logically if the alpha particle can't penetrate your dead skin cells, it won't penetrate a thin containment shield. If the containment breaks down and particles are easily disolved in water or break up and become dust easy, there is more concern about the safety of this device.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
But this won't explode. It stores a lot of energy, but the POWER (energy/time) is very low. It's not like the wall outlet, which can give large amounts of energy in a very short time.
The article says that it could be used to trickle charge rechargeable batteries. Think of it as a battery "helper".
One possible problem, to form a narrow alpha-particle beam for small devices, a small slit or hole has to be used. Heisenberg's Uncertainty Principle shows that the range of (normalized) highly probable momenta will be large since the range in location is small. This means that some particles will be fast and some will be slow; however, the actual event is hard to predict.
Since kinetic energy is proportional to the momentum (squared), your device will produce energy in hard-to-predict spirts. You can calculate an average energy; however, that applies only after a large number of particles go through your device. That's one reason why these kind of devices work well as trickle-chargers yet poorly as generators.
Another problem is that you lose 5/6th of the particles from the device, or more. This is because the probability of a radioactive atom emitting a particle in a specific direction is relatively uniform. However, only one face of the material is unshielded to the device. So particles most will hit the shielded face. One one face, 5/6th of the total area, will have a flux out.
When you extract energy from the particle's kinetic energy, it will slow down. When it does, it will emitt electromagnetic energy, breaking it furthermore. All this energy is not converted into electrical energy in your device.
In the article, two methods are getting energy were tried. In the first device, the scientiests use a material that emitts beta particles - electrons - and injected them directly into a pn-junction of a semiconductor device. Normal semiconductor devices (i.e. diodes) work by moving electrons to unfilled energy levels in one substance (p-material) from filled energy levels in another substance (n-material). Moving electrons means a current forms.
This is usually induced by thermal or EM energy. In this case, the radioactive element emitts electrons directly into the semiconductor. The imbalance causes a current to form through the junction. This can be miniaturized well. It also is not as sensitive to the direction that beta particles are emitted as your device.
The second device uses a (really small!) lever attached to a piezoelectric material. Piezoelectric crystals produce electric current when stressed or vibrating. (The reverse is also true; hense why the crystal in your digital watch creates the ticks for the clocks.) The lever gets hit by - and absorbs - beta particles emitted from the radioactive element. Since beta particles are charged, the lever aquires a negative charge and the element aquires a positive charge. This pulls the lever toward the radioactive element. When they get close, electron tunnel over the gap and return their charge to the radioactive element. Once uncharged, the lever spings back to its origional position. The movement of the lever causes the piezoelectric material to generate current.
This things scientists and engineers create are truely fascinating! (...to me at least!)
It is impossible to enjoy idling thoroughly unless one has plenty of work to do.
- Jerome Klapka Jerome