Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: Kosh on April 19, 2009, 04:51:19 am
-
possible? (http://www.physorg.com/news158848950.html)
"Direct conversion of nuclear energy has not been possible previously," said Mark Prelas, professor of nuclear engineering and director of research at MU's Nuclear Science and Engineering Institute. "Current nuclear technology has an intermediate thermalization phase between the nuclear reaction and when the energy is converted to electricity. This phase reduces the efficiency of the energy conversion process."
MU researchers have developed a process called Radioisotope Energy Conversion System (RECS). In the first step of the process, the ion energy from radioisotopes is transported to an intermediate photon generator called a fluorescer and produces photons, which are the basic units of light. In the second step of the process, the photons are transported out of the fluorescer to photovoltaic cells, which efficiently convert the photon energy into electricity.
-
So.. how much more efficient is it?
-
Interesting. IIRC using steam can only ever be 50% efficient anyway due to the need for a heat sink. So potentially this could be a lot better.
-
A drastic reduction in heat production?
-
Solar powered nuclear submarines?
Awesome.
-
just nuke everything, then we wont need energy
-
just nuke everything, then we wont need energy
And to think, I have an urge to manufacture a "Nuke For President" T-Shirt
-
isn't one of the biggest problems in green technology the low efficiency of photovoltaic cells?
-
The low efficiency is linked to the low power of the sunlight hitting them IIRC. The brighter the light hitting the cell the more effecient they become.
-
The low efficiency is linked to the low power of the sunlight hitting them IIRC. The brighter the light hitting the cell the more effecient they become.
Is it really less efficient in changing light -> energy when there is low light, or is it just the fact that there is low light preventing it from making a lot of energy?
-
just nuke everything, then we wont need energy
And to think, I have an urge to manufacture a "Nuke For President" T-Shirt
You're falling for carefully constructed attention whoring though
-
just nuke everything, then we wont need energy
And to think, I have an urge to manufacture a "Nuke For President" T-Shirt
You're falling for carefully constructed attention whoring though
Fair enough
*Scraps idea*
-
So.. how much more efficient is it?
This. Is it twice as much energy for the mass of radioisotope? 10 times? 100 times? The issue is does the increased efficiency make up for the increase in complexity. A famous Scottish engineer once said, "The more they overtech the plumbing, the easier it is to stop up the drain".
-
The low efficiency is linked to the low power of the sunlight hitting them IIRC. The brighter the light hitting the cell the more effecient they become.
Is it really less efficient in changing light -> energy when there is low light, or is it just the fact that there is low light preventing it from making a lot of energy?
What I mean is I recall reading that they are more efficient under 3000 suns than under 1. :D
-
PV cells are inefficient due in large part to the diffuseness of the light hitting them. In orbit they are considerably more effective, but only out to about 2 or 3 AU, past that the light is again too diffuse to efficiently convert it to electricity. This is why the Voyager probes and the Mariners and so forth had the experimental radiologic power sources.
-
Where's HerraTohtori?
-
Dead.
-
Reports of my death have been greatly exaggerated. :rolleyes:
...So, a pretty interesting topic. Some inaccuracies in the article though:
Currently, the only method to convert nuclear technology into electricity is through nuclear fission. In the process, water is heated to create steam. The steam is then converted into mechanical energy that generates electricity.
This is not actually true; in addition to full-blown nuclear reactor that just generate heat and run the turbines with it, nuclear technology itself is also utilized in atomic batteries.
Actually this kinda reminds me of the principle of betavoltaic batteries where the electrons emitted by beta-active isotope are directly utilized as voltage. And while we're at it, there's also optoelectric (http://en.wikipedia.org/wiki/Optoelectric_nuclear_battery) method of collecting the energy of beta particles (in this case they excite some matter which starts to emit photons, which is converted to electricity).
So the interesting bit is how the conversion of "ionic energy" is converted into light. But the article doesn't go into details on how it actually happens, so I'm reduced to guessing as searching for "Photon-Intermediate Direct Energy Conversion" just returns links to different versions of the same news...
What is ionic energy? I've never heard of ionic energy being used as a scientific term, but I would hazard a guess that it means the high kinetic energy of ions that are generated in nuclear reactions. It's unclear what that means though, as "ion" has a pretty broad definition - technically a proton is an ion, and alpha particles as well. The daughter nuclei of a split nucleus could become high velocity ions. The ionizing radiation released in the reaction could, well, ionize particles nearby. It could be all these.
The most likely way to make the conversion of kinetic energy of ions into visible light is pretty much the same idea the optoelectric nuclear battery uses, but instead of beta particles (electrons) there's probably a variety of ions that does different things.
A question arises though, why couldn't these ions not be converted directly into voltage, same as how betavoltaic batteries do it. Obvious answer might indeed be that it's easier with jsut a stream of electrons and no other nasty isotopes messing things up. Plus betavoltaic batteries require the isotope to be in fine dust form that the beta particles just pass through so they can be utilized.
Of course, I also find myself asking why wouldn't it be feasible to simply use the thermal radiation instead of visible light - the same as thermophotovoltaic batteries do... and again obvious answer is that nuclear reactors work on so large power output levels that the thermal radiation isn't simply sufficient for this kind of use - or the size of the facility would be darn huge.
Which leads to the follow-up question; how much nuclear energy can feasibly be converted into visible light and that visible light into electricity?
The main advantages of this system, as I see it, would be the possibility of making much smaller reactors much more feasible and it would basically remove the most risky and malfunction-prone components of nuclear power - the high pressure steam and fluid circuits that cool the reactor and run the turbines.
In short, it would be possible to run the reactor cool and keep the temperature at safe levels with the control rods; there would be no need to ever let the reactor run hot enough to need an active cooling system, and the reactor would not need to be in a pressurized vessel. All this would improve the safety of nuclear power rather immensely.
However, at the same time it seems to me that this method would have some inherent limitations on the power output. How much light can you direct at a normal photovoltaic cell before it start to heat up and eventually melt or ignite? The intensity of the light would determine the size of the panel array constructed around the shining reactor. So the more power you planned on getting from individual reactor, the bigger sphere of "solar panels" you need to build around the photon generator.
I can't bother doing calculations at the moment but you get the picture. This method might be more efficient way of converting nuclear fission power into electricity, but unless the power output matches the amount of energy you can carry away from the reactor core with a stream of fluid (like water), it might not be a commercially viable option... or if it requires a panel array the size of Gluben arena (http://en.wikipedia.org/wiki/Stockholm_Globe_Arena), it might be a tad bit unpractical.
Then there's also the question, how well and reliably will all this equipment (the photon generator as well as the photoelectric cells) work in continuous environment of ionizing radiation? Betavoltaic batteries suffer damage to their internal components by the high energy electrons in the beta particle stream, so most likely this stuff will have a limited service time no matter how it's built, and then it needs to be changed. As I have no idea what kind of components is required and how pricey this would be, I can't say how viable this would be... but then again, the turbines and coolant pipes of traditional nuclear reactors require servicing as well.
-
Not really in a position to add much to Herra's post... But... With any system, the more complex it becomes, the greater the possibility of something important breaking at an inconvenient time. Not really willing or able to do much research at the moment, but there are several alternative methods of generating energy that are being researched- most of them involve a turbine somewhere along the line. If the turbine should become obsolete due to advancements such as this, there may be considerable potential.
-
I've noticed a couple posts in this thread expressing concern about making things more complex, but I was under the impression that the whole appeals of this was that it would reduce complexity. Unless this "photon generator" is really complicated, I don't see how this whole system would be more complex than a normal nuclear plant with pumps and heat exchangers and turbines and cooling towers and all that.
-
The way I read that was that they're saying they've found a way to use the ionizing energy from a radioactive pile to ionize an intermediate element which will then emit light upon returning to its ground state. Not sure if this has been done before, but that's the mechanism that stands out for me.
@HerraTohtori: Batteries that run off of thermal energy from a nuclear source already exist: Radioisotope Thermoelectric Generators. Only drawback is they're incredibly inefficient. http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator (http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator)
-
The way I read that was that they're saying they've found a way to use the ionizing energy from a radioactive pile to ionize an intermediate element which will then emit light upon returning to its ground state. Not sure if this has been done before, but that's the mechanism that stands out for me.
Yes, that's the impression I had as well.
@HerraTohtori: Batteries that run off of thermal energy from a nuclear source already exist: Radioisotope Thermoelectric Generators. Only drawback is they're incredibly inefficient. http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator (http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator)
Yes, I know that, and the reason they are so inefficient is because thermal radiation is by and large black body radiation, which by definition spreads the radiation on a wide spectrum.
This is a problem with photoelectric phenomenon, because it can only utilize photons that have high enough energy levels, and thermal radiation has very low energy levels by definition compared to visible light even. And semiconductors with low enough barrier energy to utilize thermal radiation in a photoelectric reactionare, as far as I know, rather rare and expensive...
This means that the panels that can utilize thermal radiation are first of all expensive, and secondly a large part of the radiation is just lost in translation because it has too low energy levels per photon to trigger the photoelectric reaction.
Converting large portions of ionizing radiation into visible light of narrow spectrum means the photoelectric cells can be optimized for those wave lengths, and there's much less of those photons that can't be converted to electricity.
All in all it sounds interesting and promising, but large scale utilization reeks of practical problems I already mentioned (mainly the fact that photoelectric panels can only handle limited intensity (power per surface area) before they heat up, melt and/or ignite), so the larger the desired power out put of a single unit, the bigger the photon collecting sphere around the reactor and photon generator needs to be.
Anyway, the point is indeed in reducing complexity. Photons are much safer and efficient way to transfer energy than high pressure steam or liquid. Requires much less maintenance, too. The reactor can be run at much lower temperatures during normal operations. There's no need for extremely heavy duty pressure vessel for the reactor core. There's no need for pumps for cooling.
All this means the reactor will be very much lighter than current systems, and that means you could hypothetically use it as energy source for, say, airplanes. The biggest block of mass involved would be radiation shielding, but because the process itself would be much more effective, the actual amount of radiation would be smaller than from a current reactors of equal power output. Assuming the dimensional size limitations don't hamper it's use as a mobile energy source, that is.
So, yeah, it's definitely interesting.
But it won't beat fusion. :lol:
-
But it won't beat fusion. :lol:
QFT.