# Would this work? Fusion power by "Hellpit" **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2008, 12:33pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911 "2008-05-11T12:33:16Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![msmith537](https://avatars.discourse-cdn.com/v4/letter/m/d9b06d/32.png) [@msmith537](https://boards.straightdope.com/u/msmith537)\ **Post date:** [November 22, 2016, 4:41pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/21 "2016-11-22T16:41:30Z")
> [@Grey](#): > > Or, you know, you could just use the thermal difference between ocean water at 2000’ vs surface temperatures. It’s more fun to do it with nuclear weapons. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [November 22, 2016, 5:43pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/22 "2016-11-22T17:43:42Z")
While powering it with nukes is silly sci-fi stuff, the idea of using a lava pit for power is actually being done (kinda). There are some solar power plants that basically use a bunch of mirrors to focus the sun’s rays on a pit filled with salt. The salt gets so hot that it melts, and the heat from the molten salt is used to turn water into steam, which is then used to power a conventional steam turbine type generator. This type of solar plant doesn’t require expensive photovoltaic panels and also continues to provide power at night since the molten salt contains so much heat that it won’t solidify and remains molten even through the dark hours. A couple of days with little to no sun due to cloud cover would allow the molten salt to cool down and solidify, so these types of solar plants only work in sunny areas like the Southwestern US. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 22, 2016, 7:30pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/23 "2016-11-22T19:30:26Z")
And it’s \*still \*fusion powered. Rule of Cool yet applies! We fly over this molten salt project fairly often [Crescent Dunes Solar Energy Project - Wikipedia](https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project) Damn those mirrors are bright. Sometimes we get a little too much concentrated fusion power on us and we’re 20 miles way from the darn thing. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [November 22, 2016, 8:02pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/24 "2016-11-22T20:02:32Z")
> [@Lumpy](#): > > [snip] … I was just curious if there were any technical show-stoppers I haven’t thought of. Lava isn’t exactly a homogeneous substance … it’s density can change and I’m wondering if having the lava overflow on a regular basis might not stop this particular show … we have these environments scattered around the globe … the problem is some of them have a tendency to explode at a Biblical magnitude … big enough to put any Mark 39 to shame … rock in it’s liquid state is tricky stuff to deal with … ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [November 22, 2016, 8:27pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/25 "2016-11-22T20:27:39Z")
> [@LSLGuy](#): > > We fly over this molten salt project fairly often [Crescent Dunes Solar Energy Project - Wikipedia](https://en.wikipedia.org/wiki/Crescent_Dunes_Solar_Energy_Project) This is awesome, I had never heard of the project before. > [@](#): > > …including during the evening hours and when direct sunlight is not available.[4] I like how it gives many technical details, and then the way it’s written it looks like they are providing a citation to support the claim that sunlight is unavailable at night. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [November 22, 2016, 9:08pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/26 "2016-11-22T21:08:01Z")
> [@engineer\_comp\_geek](#): > > While powering it with nukes is silly sci-fi stuff, the idea of using a lava pit for power is actually being done (kinda). Well, using lava for power is actually being done way more than kinda. Heck I’ve seen it done commercially. If you can get to Iceland, [you can see it too](https://en.wikipedia.org/wiki/Hellishei%C3%B0i_Power_Station) Though it is ultimately only fission-derived energy, so maybe not quite as cool as fusion power. ---
**Author:** ![Valgard](https://avatars.discourse-cdn.com/v4/letter/v/7feea3/32.png) [@Valgard](https://boards.straightdope.com/u/Valgard)\ **Post date:** [November 22, 2016, 10:23pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/27 "2016-11-22T22:23:24Z")
Here’s some information on a US attempt at the OP’s idea from back in the 1960s. > **[Project Gnome (nuclear test)](https://en.wikipedia.org/wiki/Project_Gnome)** > > Project Gnome was the first nuclear test of Project Plowshare and was the first continental nuclear weapon test since Trinity to be conducted outside of the Nevada Test Site, and the second test in the state of New Mexico after Trinity. It was tested in southeastern New Mexico on December 10, 1961, approximately 40 km (25 mi) southeast of Carlsbad, New Mexico. > First announced in 1958, Gnome was delayed by the testing moratorium between the United States and the Soviet Union that lasted from Nove... 3.1kt underground detonation. 6 months later it was still about 140F in the cavity. File this all under “Ideas, Questionable”… ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 23, 2016, 12:00am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/28 "2016-11-23T00:00:19Z")
> [@Riemann](#): > > This is awesome, I had never heard of the project before. > … Here’s one 4x as big. [Ivanpah Solar Power Facility - Wikipedia](https://en.wikipedia.org/wiki/Ivanpah_Solar_Power_Facility) These things have been sprouting like weeds out there where there’s few if any clouds. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [November 23, 2016, 12:20am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/29 "2016-11-23T00:20:34Z")
> [@LSLGuy](#): > > Damn those mirrors are bright. Sometimes we get a little too much concentrated fusion power on us and we’re 20 miles way from the darn thing. I’ll bet with a little extra software development on the mirror aiming system, we could turn that into a 2020’s-style death ray. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 23, 2016, 1:04am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/30 "2016-11-23T01:04:57Z")
As an aside, the OP appears to have been the first, and so far only, person to ever use the very apt word “hellpit” to describe this type of design, or at least so suggests Google. So, kudos on that. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 23, 2016, 1:56am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/31 "2016-11-23T01:56:33Z")
> [@Chronos](#): > > As an aside, the OP appears to have been the first, and so far only, person to ever use the very apt word “hellpit” to describe this type of design, or at least so suggests Google. So, kudos on that. Alas, I plagiarized the name from DC Comics fictional planet Apokolips. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 23, 2016, 2:15am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/32 "2016-11-23T02:15:56Z")
In your honor earlier tonight I referred to Venus as a planetary hellpit of boiling sulfuric acid. Seemed apt. It was a very pretty hellpit hanging high in the western sky at dusk. But a hellpit nonetheless. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 23, 2016, 3:14am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/33 "2016-11-23T03:14:52Z")
> [@Dr.Strangelove](#): > > I’ll bet with a little extra software development on the mirror aiming system, we could turn that into a 2020’s-style death ray. It’s already tested and operational: > [@LSLGuy's Wiki link](#): > > biologists working for the state estimated that 3,500 birds died at Ivanpah in the span of a year, many of them burned alive while flying through a part of the solar installment where air temperatures can reach 1,000 degrees Fahrenheit ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [November 23, 2016, 3:42am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/34 "2016-11-23T03:42:09Z")
“Living next to a hellpit has its disadvantages, but you should see when the birds fly over it…” ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 23, 2016, 4:18am UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/35 "2016-11-23T04:18:28Z")
To be clear, I didn’t say you were the only one to use the word “hellpit”. I said that you were the only one to use it for power generation via underground nuclear explosions. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [November 23, 2016, 2:43pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/36 "2016-11-23T14:43:09Z")
> [@LSLGuy](#): > > And it’s \*still \*fusion powered. Rule of Cool yet applies! So are solar panels, wind turbines, hydroelectric, fossil fuels, and all other methods that rely on the current or past output of the sun. (Geothermal and fission rely on the fusion output of earlier generations of stars.) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 23, 2016, 3:46pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/37 "2016-11-23T15:46:46Z")
Spoilsport! 🙂 ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [November 23, 2016, 4:19pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/38 "2016-11-23T16:19:28Z")
> [@Xema](#): > > It’s already tested and operational: [They’re getting better at not incinerating birds in mid-flight.](https://cleantechnica.com/2015/04/26/bird-killing-solar-falls-short-foes-kill-rate-hopes/) ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [November 23, 2016, 4:33pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/39 "2016-11-23T16:33:05Z")
One problem might be the radiated thermal losses from the exposed hot surface of the hellpit. I remember [this thread,](http://boards.straightdope.com/sdmb/showthread.php?t=510861) which discussed the challenges of maintaining a lava-filled moat. One of the respondents calculated an ongoing thermal radiative loss of about 24 kW per square meter of exposed surface. A hellpit comprising a “large lake or small sea” will thus have massive thermal losses; imagine a surface 250 meters square (= 62,500 square meters), and your thermal losses will be a continuous 1.5 gigawatts. Thermal power plant efficiency is on the order of 50%, which means that if you’re generating 1.5 gigawatts of electrical power, you’re already going to have 1.5 gigawatts of waste heat to get rid of; add in the 1.5 gigawatts of thermal loss from the surface of the hellpit, and your overall efficiency drops to 33%. If you can build and deploy thermonuclear bombs fairly cheaply, then maybe the low overall efficiency isn’t a big deal, but I doubt that’s the case. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 23, 2016, 4:47pm UTC](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911/40 "2016-11-23T16:47:44Z")
Looks like the pit will need to be roofed over; maybe just as well to keep radioactive material from boiling out. Speaking of which, it might be a good place to dump the world’s radioactive waste- it isn’t like it would make things any worse. [Previous page](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911.md?page=1) [Next page](https://boards.straightdope.com/t/would-this-work-fusion-power-by-hellpit/448911.md?page=3)