With fuel prices running better that $4.00/gallon in some of the villages, like Galena and with several large mining projects (Pebble and Donlin Creek) in the planning stages, these small packages make sense. Unfortunately,they have a huge bias to overcome.
I'm straining to remember my college level thermodynamics, but the lithium, I'm guessing, has a higher melting point than sodium, thereby allowing it to store my energy from phase conversion before passing it through the heat exchanger for steam production. Is that about right?
Unless the working fluid undergoes phase change in the other direction (liquid to solid in this case) you don't get the latent heat back out. For example, in the steam cycle, the latent heat of vaporization is generally lost, because running "wet steam" through a turbine is destructive to the blades. "Dry steam" heated well above the boiling temperature is used, bit the cooler steam on the low-pressure side is still well above the boiling/condensing temperature, and is cooled and recondensed before it is reheated for the next cycle. The heat energy required to boil the water is lost each time the steam is recondensed.
From what I can determine, the choice of lithium is due to its higher boiling point, 1615K vs. 1156K. Both systems run unpressurized, so the lithium-cooled reactor can run much hotter without risk of boiling.
Lithium melts at about 360ºF, which makes for pretty hot steam.
What I find curious is who makes a reliable steam turbine rated for 200kW? A 1MW unit is the smallest I'm aware of, and they are, quite literally, tiny.
So, how is Toshiba converting the heat of the reactor into electricity? Peltier or Seebeck effect thermoelectrics? Magnetohydrodynamics directly from the lithium flow? Teeny-tiny steam turbines? What?
The military (and NASA, IIRC) have had what could be called, technically, "micro nukes" for years for remote (and spaceborne) power, using thorium as a heat source and a Peltier junction for generation.
This looks like something entirely different and I suspect that Toshiba is willing to give it away in order to get USNRC approval so they can sell it. I don't think that they could get NRC approval if the first person to want one was in, say, the City of Industry.
Has anyone ever commercialized MHD? I know that the Navy stuck huge amounts of R&D money into years ago, with no apparent results.
Yes, Bud, but those power supplies were one to two orders of magnitude smaller (watts to a few kW). They also operate at well below the temperature of liquid lithium, and since the cold side of the junction is near absolute zero (being in the vacuum of space) the thermoelectric generators work quite well.
I don't know what technology they're using, but I'd like to.
"From what I can determine, the choice of lithium is due to its higher boiling point, 1615K vs. 1156K. Both systems run unpressurized, so the lithium-cooled reactor can run much hotter without risk of boiling."
This was what I was thinking and just very ineloquently attempting to explain earlier.
The system can take a little more abuse from running hotter without meltdown. Got it.
Here is some more publically available information:
http://www.roe.com/about_techgalena.htm
Note:
All avatars and any images or other media embedded in comments were hosted on the JS-Kit website and have been lost;
references to haloscan comments have been partially automatically remapped, but accuracy is not guaranteed and corrections are solicited.
If you notice any problems with this page or wish to have your home page link updated, please contact John Hardin <jhardin@impsec.org>
JS-Kit/Echo comments for article at http://smallestminority.blogspot.com/2007/12/it-aint-mr.html (10 comments)
Tentative mapping of comments to original article, corrections solicited.
As I understand it, these are known as "street-corner nukes" in Japan, were there are some running already.
$87,600 a year to operate. I wonder if I can sell electricity to the neighbors...
With fuel prices running better that $4.00/gallon in some of the villages, like Galena and with several large mining projects (Pebble and Donlin Creek) in the planning stages, these small packages make sense. Unfortunately,they have a huge bias to overcome.
Unfortunately,they have a huge bias to overcome.
Why do you think Toshiba is willing to give one away?
I'm straining to remember my college level thermodynamics, but the lithium, I'm guessing, has a higher melting point than sodium, thereby allowing it to store my energy from phase conversion before passing it through the heat exchanger for steam production. Is that about right?
Err, no.
Unless the working fluid undergoes phase change in the other direction (liquid to solid in this case) you don't get the latent heat back out. For example, in the steam cycle, the latent heat of vaporization is generally lost, because running "wet steam" through a turbine is destructive to the blades. "Dry steam" heated well above the boiling temperature is used, bit the cooler steam on the low-pressure side is still well above the boiling/condensing temperature, and is cooled and recondensed before it is reheated for the next cycle. The heat energy required to boil the water is lost each time the steam is recondensed.
From what I can determine, the choice of lithium is due to its higher boiling point, 1615K vs. 1156K. Both systems run unpressurized, so the lithium-cooled reactor can run much hotter without risk of boiling.
Lithium melts at about 360ºF, which makes for pretty hot steam.
What I find curious is who makes a reliable steam turbine rated for 200kW? A 1MW unit is the smallest I'm aware of, and they are, quite literally, tiny.
So, how is Toshiba converting the heat of the reactor into electricity? Peltier or Seebeck effect thermoelectrics? Magnetohydrodynamics directly from the lithium flow? Teeny-tiny steam turbines? What?
The military (and NASA, IIRC) have had what could be called, technically, "micro nukes" for years for remote (and spaceborne) power, using thorium as a heat source and a Peltier junction for generation.
This looks like something entirely different and I suspect that Toshiba is willing to give it away in order to get USNRC approval so they can sell it. I don't think that they could get NRC approval if the first person to want one was in, say, the City of Industry.
Has anyone ever commercialized MHD? I know that the Navy stuck huge amounts of R&D money into years ago, with no apparent results.
Yes, Bud, but those power supplies were one to two orders of magnitude smaller (watts to a few kW). They also operate at well below the temperature of liquid lithium, and since the cold side of the junction is near absolute zero (being in the vacuum of space) the thermoelectric generators work quite well.
I don't know what technology they're using, but I'd like to.
"From what I can determine, the choice of lithium is due to its higher boiling point, 1615K vs. 1156K. Both systems run unpressurized, so the lithium-cooled reactor can run much hotter without risk of boiling."
This was what I was thinking and just very ineloquently attempting to explain earlier.
The system can take a little more abuse from running hotter without meltdown. Got it.
Here is some more publically available information:
http://www.roe.com/about_techgalena.htm
Note: All avatars and any images or other media embedded in comments were hosted on the JS-Kit website and have been lost; references to haloscan comments have been partially automatically remapped, but accuracy is not guaranteed and corrections are solicited.
If you notice any problems with this page or wish to have your home page link updated, please contact John Hardin <jhardin@impsec.org>