Basically, have a large lake or small sea of molten lava kept hot by periodically dropping a nuclear weapon in and exploding it. Since the bomb goes off under a mile or so of molten rock, the explosion doesn’t reach the atmosphere and hopefully most radioactive isotopes remain in situ. Use the thermal energy to create electricity. Since we’re talking VERY large-scale power production here, you use superconducting cables or piped hydrogen to provide a continent-wide power distribution system.
Not that I see this ever happening, I was just curious if there were any technical show-stoppers I haven’t thought of.
Somebody could run the physics calculations, but to keep the mass of a mile of magma molten is going to require hundreds of nuclear detonations per day, I WAG.
Color me mildly curious as to how you are going to manage to insert a thermonuclear weapon a mile deep inside molten lava. Or indeed, how you are going to liquify this rock to begin with (which would require several tens of thousands of high yield nuclear detonations), and what you are going to do about the environmental impact of all of the waste heat produced therefrom, assuming that you aren’t building some kind of big-ass containment dome out of high temperature unobtainium ally.
I’d presumed some sort of protective cladding that would last long enough.
That indeed is the one thing I wasn’t sure about; actual underground nuclear explosions tend to produce a hollow cavity where vaporized rock was removed while leaving the surrounding rock only somewhat warmer. That’s why I envisioned exploding the bomb in a liquid mass-primarily to distribute the energy produced more evenly. Getting the liquid mass in the first place… umm… maybe start with very low yield devices detonated in deep loose sand until you get a melt going? As for the number of devices needed, I’d presumed that the setup would be scaled to whatever size that a five-megaton device would release enough energy to raise a 2000C melt up by another few hundred degrees C at a time.
I hadn’t thought of that one at all; a permanent source of waste heat large enough and hot enough to alter weather patterns. I dunno, grow oranges in Siberia?
I do wonder with current underground bomb tests, what’s left underground, how physically hot it stays, for how long, etc. A variant on your scheme may at least be possible, if not exactly practical…
Reviving this thread because I thought of a possible dodge but I need someone better at number crunching than I am. I need to figure out the energy requirement in joules to raise silica from room temperature to molten, including the latent heat of melting. And if possible how much further energy it takes to raise the temperature of molten silica further per degree Kelvin.
I’m pretty sure that Teller did propose a power-generation system that worked something like this. Then again, the man never found an excuse for setting off nukes that he didn’t like.
The point of using thermonuclear bombs is to utilize comparatively cheap lithium and deuterium, and even cheaper U-238 as nuclear fuels. You do have a point in that fission reactors don’t need highly enriched fissionable material; in fact now I’m wondering if using a reactor to deliberately create a meltdown might be the best way to get the original melt started. But here’s the idea I’d had:
As we originally discussed in Why don’t nuclear explosions create pools of lava?, the problem is distributing the energy released evenly enough to create a large volume of magma. Nukes produce high-temperature plasma, which blows away any liquid melt produced. But as long as we’re talking engineering projects that use measurements in kilometers, maybe this would work: build a huge hollow sphere, suspend your nuke in the center of it, evacuate all the air from the sphere and detonate the nuke in a vacuum. As the Atomic Rockets page on nukes in space explains, detonating a nuke in a vacuum produces mostly a pulse of high-energy radiation, which falls off rapidly in strength with distance due to the square-cube law. Make the sphere big enough and the radiation flux is only enough to melt the surface it encounters instead of vaporizing it.* To know how big, I would need the figures for melting silica.
*The Atomic Rockets page talks about the radiation pulse hitting aluminum metal. Silica is less dense and has a lower average atomic weight, so presumably radiation penetrates better, leading to more even heating. Possibly something like a silica aerogel would be even more likely to melt rather than vaporize.
Thermonuclear weapons typically produce the bulk of their power by nuclear fusion reactions (primarily D-T reactions) with the desired output being in the x-ray spectrum, which is subsequently absorbed by the atmosphere. This generates significanty more energy than the same mass of pure fissionable material per weight, and can also be scaled up essentially without limit (although a very high yield device would be too large for conventional weapon delivery systems), unlike fission devices that will blow themselves apart above a certain threshold.
Part of the problem with the concept proposed by the o.p. is that it assumes perfect onversion of the energetic output into thermal energy which will melt or heat rock into magma. This just isn’t very realistic unless you could convert the output into the microwave range, where it will more evenly diffuse. With output in the x-ray or gamma ray range it will be almost fully absorbed by the strata within a few tens of centimeters, and rather than become molten it will just vaporize material which will then generate a mechanical shock wave. If the surrounding material were already molten the shock wave might cause heating via compression and shear forces, but with solid rock it will just fracture. And if it were already molten, it would be extremely problematic to encapsulate and sink the device deep enough into the magma so that it wouldn’t just blow material outward. All in all, the impracticalities of this scheme outweight any possible benefit, notwithstanding the difficultly in recovering more than a tiny fraction of the energy for power genreation.
And yes, Teller was a nutter for all things pertaining to the use of the ‘Super’, and completely oblivious to even the most obvious hazards and persistent effects. He also was later a strong proponent of directed energy missile defense (lasers, particle beams, et cetera) powered—wait for it—by nuclear weapons. That such weapons are no more practical today than they were during the Strategic Defense Initiative era and have some fundamental limitations that no advances in technology are likely to overcome demonstrates just how out of touch Teller was with the actual technology he was pandering for. He has more recently been promoting the supposed availability of ‘red mercury’ (a mythical ballotechnic substance that could initiate fusion without a fission primary or explosive containment) which has the hallmarks of being drawn from a Dan Brown knockoff technothriller and by all credible accounts has been used as a lure to locate would-be nuclear terrorists.
A meltdown is a partial or complete melting of the fuel elements, rendering the system unable of being controlled. It will not, despite the hyperbole you may have heard or read, melt through the Earth’s crust. There is some concern that should it contact the water table or a source of water the thermal shock or generation of explosive gases would result in dispersal of radioactive material as happened with Chernobyl #3 and Fukushima #1, #2, and #3. The comparison to boiling water with a stick of dynamite is apt; while there is certainly considerable energy in dynamite, the rate at which it is released is far too rapid for conversion to controllable thermal energy (and in fact that brisance is what is desirable about chemical explosives).
This is just not a practical idea for energy production for a large number of reasons.
Hmm… so having the surrounding material be liquid doesn’t help that much. You still get a ball of high-temperature plasma which tends to simply blow away before it can transfer its heat to its surroundings. Sort of like boiling water with dynamite indeed.
I was tempted to dispense with the lava and simply have the nuke heat the shell I mentioned earlier, but then you get into how expensive the highly-enriched fissionable material for the primary is. <sigh> Too bad; generating power on a vast scale using nukes is just so Rule Of Cool.
