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Material Converts Radiation Into Electricity
Posted by
kdawson
on Fri Mar 28, 2008 11:11 AM
from the don't-irradiate-me-bro dept.
from the don't-irradiate-me-bro dept.
holy_calamity writes "Nuclear powered space probes like Pioneer have 'nuclear batteries' that (very inefficiently) convert heat from decaying isotopes into electricity. US researchers think a new material that converts radiation directly into power instead could make nuclear batteries 20 times more efficient. (Unfortunately they will likely not be user-replaceable.) The material consists of gold, carbon nanotubes, and lithium hydride."
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Carbon nanotubes (Score:5, Funny)
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Re:Carbon nanotubes (Score:5, Insightful)
Parent
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Get a life.
There could be a serious benefit (Score:5, Interesting)
I would think, assuming of course this proved as pratical in pratice vs theory, that this could dramatically reduce our dependance on fossil fuels. Assuming of course you could use the "pure" radiation of the waste into electricity.
Re:There could be a serious benefit (Score:5, Interesting)
To heck with that, and with batteries - imagine being able to generate electricity from nuclear power plants themselves, rather than using them to heat water, shove it through an inefficient turbine, and then let most of the energy evaporate off in a cooling tower. The steam turbine system is horrendously inefficient. Cutting all of that out of the loop would make nuclear power so hilariously efficient that nobody would care about the waste storage (we wouldn't need much of it anyway). It would also be far safer: a lot of the stuff in a current nuclear plant goes into managing the water moving through the reactor, which is all expensive, fragile equipment that gets mildly contaminated. Replacing all that junk with some electrical cabling would be a major breakthrough.
Parent
Waste...? (Score:5, Interesting)
Cutting all of that out of the loop would make nuclear power so hilariously efficient that nobody would care about the waste storage (we wouldn't need much of it anyway).
Actually, you've missed an important point about nuclear waste. Nuclear waste is dangerous because it's still radioactive. However, it's useless because it's no longer fissile and hence can't be used in a nuclear power plant.
This technology should be just as efficient with nuclear waste as with fissile materials. However, the problem with this technology is time. Fission releases a lot of energy very quickly, but most most common radioisotopes have very long half-lifes, releasing their radiation over thousands of years. (Anything with a short half-life will have "died" millenia ago.) The applications for this will be relatively low-power, long-term projects.
HAL.
Parent
Re:Waste...? (Score:5, Informative)
Not true, spent fuel is discharged not because it is depleted of fissile material but because other elements generated in it absorb neutrons. If you remove those elements chemically the fuel can be re-used, and with some fast reactor designs you can even ensure that they produce the same amount of fissile material as they consume ( by converting U-238 into plutonium ). The end result is about 100 times better uranium utilization and nuclear waste which decays to uranium levels of radioactivity within 300 years or so.
Parent
Re:Waste...? (Score:5, Interesting)
Seriously thou, modifying the reprocessing cycle for a fast breeder and then use the very low grade plutonium to produce a nuclear weapon would be so unpractical that it would probably be easier to just start a uranium based weapons program from scratch. Simply separating the plutonium from traces of very troublesome elements with high spontaneous fission rates ( think californium, einsteinium
At the end of the day the effort involved would likely surpass that needed to build a more traditional graphite moderated reactor and extract the plutonium from that. I.e, even if somebody was to give you the reprocessing plant for a fast breeder with actinide recycling, as well as the spent fuel, you would probably have an easier time trying to do it the old fashion way. In addition it is hardly as if a rogue nation with the necessary economics would not be capable of building a nuclear weapon anyway. The technology is more than 6 decades old.
Parent
Re:Waste...? (Score:5, Interesting)
The only reason it's not done is that re-enrichment produces large amounts of bomb-grade material, which could theoretically be stolen and used to make a nuke, as opposed to our normal waste which is pretty much useless.
This is getting to be a poorer and poorer excuse as time goes on, as more and more unstable countries learn to do the bomb thing for themselves. All we're really doing is saddling ourselves with a nasty radioactive waste problem.
Parent
Probably much less efficent than steam (Score:3, Informative)
Steam turbines are mechanically complicated and smell of old tech but they are actually rather efficient. Large steam turbines have thermodynamic efficiency in the 90% range. I rather doubt this new nuclear photocell is anywhere close.
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That's the loss in the turbine itself - the number most favourable to the turbine manufacturer's marketing department. The main loss in a steam turbine system is in the required cooling/condensing apparatus that must accompany the turbine to close the cycle.
Actual thermal efficiency for nuclear plants tends to be in the 5-30% range. The 40-year-old designs that comprise most plants in the US and western Europe are appalling; current designs
Re:There could be a serious benefit (Score:5, Interesting)
The second law of thermodynamics says that no engine can be 100% efficient. The reason is, a 100% efficient engine would require an infinitely hot source of energy and infinitely cold surroundings, assuming there is no friction. Carnot, [wikipedia.org] says that the best we can hope for is more like 60-70% efficiency, and Rankine, [wikipedia.org] suggests that a more realistic number is somewhere between 40-50%. That "inefficient turbine" you speak of is 40% efficient in reality. That's pretty good considering the best we can hope for is 60-70%.
I am not a nuclear physicist, but the laws of thermodynamics still apply. We can still only hope for 60-70% efficiency, but for various reasons we still won't be able to archive this. Now, instead of letting "most of the energy evaporate off the cooling tower" we will be radiating it to the surroundings instead. Fine for spacecraft, not fine here on Earth. Even though this technology sidesteps the creation of thermal energy it still must obey the laws of thermodynamics.
Parent
Re:There could be a serious benefit (Score:5, Interesting)
Compared to the amount of energy wasted. Most of it is lost in the cooling towers that are needed to keep the cycle closed, the rest is lost in transfer from the core.
Yes. And guess what? The most efficient system we have is not very efficient at all. Also note that the main problem is not the turbine itself, but the system as a whole used to transfer energy from the nuclear core to the grid output.
Which is precisely why a system based on a new material like this, which does not involve the Carnot (or Rankine) cycle at all, would be hugely more efficient. The whole point is that heat transfer systems are not a good way to extract energy from a nuclear power plant, because of those intrinsic inefficiencies.
Parent
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Let's consider that for a moment. Nuclear fission releases about 200 MeV per nucleus, while radioactive decay releases about 5MeV per nucleus( assuming alpha emission ). Thus even assuming 100% efficiency for this tech, and only 30% efficiency for existing reactors, fission gives you more than 13 times more energy than the radioactive decay, and this is assumin
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Let me put things into perspective for you. Sweden's current fleet of nuclear reactors provide 25% of it's energy demand. If operated for about 60 years they will produce enough spent fuel to fit in a 10m cu
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waste material sitting around than is active in cores of reactors. Also, I
would think that that waste material would be producing at the lower figure,
but for a much longer period of time.
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Doesn't matter, you get 200 MeV per fission ,and about 5MeV per alpha decay, if those events happen instantaneously or over the course of millions of years make little difference, fissioning a nucleus simply emits more energy than radioactive decay. The amount of energy that can be extracted from a given number of nuclei when they fission is simply greater than the energy that can be extra
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Yes, use fission, and reprocess the fuel to the extent possible, and work to
increase reactor efficiency, but once that fuel is out of the reactor, why not
*add* this new technique and continue to generate lower levels of electricity
from that. Assuming it works, of course.
During that same 60 year cycle, you will have, each year, one more core set
to do something with. You are not going to get that 200 MeV from it, it is not
in a reactor, why not go ahead and get that ( 5 * number
Why is it... (Score:5, Funny)
Today's news: hobo sweat and nail clippings mixed with Diet Coke and mentos == cold fusion.
Re:Why is it... (Score:5, Funny)
You think hobo sweat and nail clippings are easy to obtain? Trust me, chasing them and holding them down while you get the supplies is a lot more work than you expect. Unless we set up some sort of hobo farm, I don't see your plan being feasible.
Parent
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Because most of our existing technology comes from adapting what we've observed occurring more-or-less naturally in the world around us, and we've already plucked all the low-hanging fruit.
If you want to understand how to extract energy from hydrogen sulfide, you can study deep sea vent bacteria. If you want to understand how to directly convert radiation to electricity... Well, we don't know of anything that already does that,
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I was with you right up to the end. I'd like to think the substances in question were chosen for the experiment because of their physical characteristics, and not JUST because they are exotic.
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In fact, there's an entire army of people who've figured out you can power an automobile entirely from plain water.
They have videos and everything. It's totally amazing.
What's really surprising is that the auto industry hasn't incorporated this amazing discovery into their new vehicles.
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The ater powered aoutomobile is a fraud. Or I should say, all studies of them have only found some fraudster at the heart.
You're right, if they could make practical cars that are fueld by water the Auto industry would be all over it. It would litterally save the American autoindustry, as well as meen billion dollar bonuses. If not the US car companies, then any one of the other car companies. Hell If you could gat a car, prove it runs
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Simply because we have been juggling petrochemicals around for decades and have found most of the useful things they can do already.
Nanotechnology is developing as petrochemicals did decades ago. When substances are reduced to nanoscale particles, their properties change so drastically they might as well be new materials. This means that physicists are suddenly discovering thousands of new substances at once and want to see what they can do, just as chemists did with petrochemicals.
Analogy to Photoelectric effect (Score:2)
I need a rest (Score:2)
Shielding? (Score:3, Insightful)
Hirsch-Meeks fusor? (Score:4, Interesting)
Or are the unnamed "radioactive particles that slam into the gold" not neutrons?
Is the energy recovery from this material, even 20 times better than thermoelectric materials, not nearly good enough to extract enough energy from the fusor?
Betavoltaics (Score:3, Informative)
Re:I'm sorry (Score:5, Insightful)
Parent
Re:I'm sorry (Score:4, Insightful)
Parent
Re:I'm sorry (Score:5, Insightful)
I think once we get to the level of space probes, "User Serviceable" is not particularly essential. Christ, I wont even change my car battery (due to laziness as much as anything).
Were you envisaging using these in your remote or something?
Parent
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If you mean being able to replace the fuel but not the conversion hardware and shielding - almost surely not.
If you mean being able to replace the whole fuel + conversion stuff + shielding assembly - possibly. This whole assembly would be very expensive, but could potentially be sent back to a facility for recycling. (i.e. replacing the fuel inside the assembly)
Keep in mind that depending on the type of fuel used, a low power density (large and heavy for its power outpu
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Um. Yeah.
* I say "power-source" because nuclear batteries are not act
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'Tis true, but generally when we refer to batteries, we're referring to something you "store" energy in by moving it from a lower chemical state to a higher chemical state. You can then retrieve that energy at a later time, minus the entropic losses.
Dude, you're killing me here. Really. I'm on the floor, dying from the uber-groan I just let out. Help! Auuuuugggggghhhhhhhhh---
(Who writes
Re: (Score:3, Interesting)
Some isotopes proposed for this use have lifetimes longer than yours, making the battery and device containing it effectively permanent.
In fact half the problem is finding ones that have a half-life short enough to give good power for say 10 years yet don't decompose into poisons or release gamma rays. Which isn't really a problem on interstellar space probes, but makes it difficult to develop consumer devices.
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Among these are:
creating life in a test tube
genetically modifying viruses
advanced AI in combat robots
Anything to do with nuclear materials
Building a car around a tank of compressed hydrogen
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Re:no obvious tags please (Score:4, Funny)
2.
3. Profit!
Parent