Half a croissant, on a plate, with a sign in front of it saying '50c'
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Solar copper mine

For a place like Timna or Petra
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(+1, -2)
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Instead of installing expensive power lines, crushing digging and mining the ore, and then using wasteful non- renewable energy for melting the ore and creating the copper (or other precious metals) why not just use a "solar furnace" directing and concentrating sunlight from these largely desert areas, directly into the mine or cave, melting the ore directly on its location, and then handling it from there.
pashute, Nov 08 2012

composition of Solar Wind http://sohowww.nasc...ons/compos9_12.html
per an annotation that misinterpreted the title of this Idea. Copper isn't high on the list of common elements in the Solar Wind, but be assured it is there. [Vernon, Nov 09 2012]

Copper extraction techniques http://en.wikipedia...traction_techniques
[spidermother, Nov 10 2012]


       // non- renewable energy //   


       Solar energy is not actually "renewable".   


       Electrolytic refining of copper is actually the most energy-efficient method available.
8th of 7, Nov 08 2012

       If radiation from the sun and the resulting products are not "renewable", then we really are up shits creek without a paddle. "Recycling" is the most energy efficient mechanism for satisfying the demand for copper.
WcW, Nov 08 2012

       Solar radiation isn't renewable. Once a photon from the sun hits you, that photon will never hit you again, and when the sun is all out of photons, that's it. No renewal.   

       Oh, and this idea is Bad Science in more ways than I care to count, though I'm sure others will.
Alterother, Nov 09 2012

       ^^^ Schlee's right. Except that I thought electrolysis was to purify the (already refined) copper. [Edit] (terminology fail) It's typically *smelted* with coke, *reduced* with natural gas, then *refined* electrolytically.   

       Anyway, what they ^ all said. "Just add solar" [-].
spidermother, Nov 09 2012

       //If radiation from the sun and the resulting products are not "renewable", then we really are up shits creek without a paddle.// Now you're getting the hang of it!
spidermother, Nov 09 2012

       //Solar energy is not actually "renewable".//   

       It is definitionally “renewable energy”. If you're talking about some sense of the word “renewable” that cannot be used to describe sunlight, you're no longer referring to the word that is used as part of the phrase “renewable energy”, but rather some homonym of that word.   

ytk, Nov 09 2012

       [Marked-for-Deletion] WKTE   

       Conceptually, at least. The practicalities are far from solved.
MechE, Nov 09 2012

       //It is definitionally “renewable energy”.//   

       That's precisely the problem. People just say "solar's renewable", then drift of into a cloud-cuckoo land where you are no longer required to practice valid accounting - the energy and resources consumed by the solar harvesting project, and the Nth order resources consumed in providing those resources, is simply ignored. Solar may be (and probably sometimes is) less bad than many of the alternatives, but that doesn't grant a license to hide one's head in the sand.
spidermother, Nov 09 2012

       While solar fusion is not, technically, renewable, it can be considered such for two reasons. First, that if we haven't come up with alternatives in the nine billion years before it goes out, it's probably because we aren't around any more (as a species) to care about it. Second, we don't have any way to slow it down or stop it, so it's more wasteful not to use it than to use it.   

       Beyond that is the question of whether harvesting solar energy is renewable. In it's simplest form, the answer is yes. Harvesting food and burning biomass can be 100% renewable.   

       Beyond that, the more sophisticated your harvesting gets, the more difficult that question is to answer. If, however, sufficient power is available, then it becomes possible to completely recycle all components of any solar harvesting system at the end of life. I believe, although I cannot find hard numbers, that the EROI on the latest generation of PV panels is sufficiently high that they do, in fact have a net positive return even if complete recycling is taken into account. (This doesn't mean such recycling will be done, it's still cheaper to mine new.) If it can be done, then yes, the panels are completely renewable.
MechE, Nov 09 2012

       We assert that there is a predictable upper limit to your primary's energy output, calculable directly from its mass and rate of hydrogen conversion, and therefore it is not "renewable"; it is a fixed and time-limited resource.
8th of 7, Nov 09 2012

       [MechE] With those provisos, I agree with you.
spidermother, Nov 09 2012

       Yes, but that's not the meaning of the term “renewable energy”. You're shifting the goalposts here by focusing on an alternative definition of “renewable” that is not the one used in the context of “renewable energy”. “Renewable energy” refers specifically to energy derived directly from resources that are naturally replenished, including sunlight. You seem to be misapplying the term “renewable” to mean “unlimited”.   

       It's like claiming that “antisemitism” doesn't mean hatred of Jews because you're applying an alternative definition of the word “semitic”. That's all well and good, but focusing on a homonym for part of the phrase in order to attack the usage of the entire phrase is a straw man.   

       Don't you try and out-pedant me, [8th]. I am the pit bull of pointless pedantry (say /that/ ten times fast).
ytk, Nov 09 2012

       Example: production of fuel ethanol from purpose-grown maize. The total fossil fuel energy consumed (using deep energy accounting) almost certainly exceeds the ethanol energy delivered to the end user. But if there is any net fossil fuel consumption, the overall process is less than completely renewable. My view is that the goalposts are misplaced in the mainstream definition, which tends to ignore such bedevilled details and say "it's bio-fuel / solar / whatever, therefore it's renewable".
spidermother, Nov 09 2012

       Solar energy is renewable as long as you don't actually mean "renewable".
FlyingToaster, Nov 09 2012

       I will fully agree that corn ethanol is one of the stupidest things anyone ever came up with, but I'm not certain it's EROI is below one. I'm not certain it's above, either.   

       Sugarcane ethanol does better, and is almost definitely well above one, although how far is open for discussion.   

       I'm still hoping that one of the cellulosic ethanol plans will work out, but we shall see.   

       Flat plate solar thermal definitely is, concentrated solar thermal probably is. PV is, I think, and is getting better as greener manufacturing approaches are found.   

       Wind EROI is far above one, as is hydro if sufficient effort is made to avoid damaging the local fish stocks. (Treating those as food that needs to be replaced).   

       Nuclear is wonderful in that respect, at least once we switch over to low waster reactors that reduce the need for thousands or millions of years of care. It's not actually renewable, however.
MechE, Nov 09 2012

       We're kind of missing the point here. “Renewable energy” is a term of art that is defined to encompass solar energy (check Wikipedia—it's in the very first sentence). But beyond that, regarding the non-renewability of the Sun:   

       //We assert that there is a predictable upper limit to your primary's energy output, calculable directly from its mass and rate of hydrogen conversion, and therefore it is not "renewable"; it is a fixed and time-limited resource.//   

       So, you can't think of any way to increase its mass? I suggest a fact-finding mission to the surface of the Sun— and if you go, the Earth thanks you for your contribution to the longevity of its main energy source.
ytk, Nov 09 2012

       Simply because we do not have any influence over the sustainability of the sun doesn't mean that solar fission isn't the most sustainable and most renewable form of energy production available in this universe. No other technique for producing energy from raw materials even comes close to the output of a star for the ability to renew the useful output over time. Is most of the energy wasted? Yes. Does it mater? No. Is it matter? Yes.
WcW, Nov 09 2012

       [WcW], the Sun uses fusion to produce energy, not fission.   

       Anyway, I thought this Idea would be about extracting copper atoms from the Solar Wind....
Vernon, Nov 09 2012

       //Solar energy is not actually "renewable".//   

       All energy is renewable
fishboner, Nov 09 2012


       Sources of negentropy the harvesting of which does not greatly impact their abundance or availability may be loosely regarded as "renewable" sources (although "renewing" would be more technically correct). If they can be harvested in such a way that the abundance or availability of other (non-"renewable") resources is not reduced, then the result may be regarded as sustainable negentropy harvesting.   

       In a non-technical setting, the word "energy" may be used as a short-hand for high grade energy (that is, concentrated negentropy, used or usable by humans).
spidermother, Nov 09 2012

       ^ You just have to shake the flask really really hard.
FlyingToaster, Nov 09 2012

       I played in a D&D game where a character had an item like that. It worked on magic.
Alterother, Nov 10 2012

       As far as I understand, and please just correct me without any snide remarks if I'm wrong, that the smelting stage is done with a source of carbon such as coke fuel and [bold] heat, a lot of heat, at very high temperatures. [/bold]   

       So extraction of iron, copper, silver and other metals from the ore needs a lot of energy, which is usually NOT AVAILABLE at the location, and also is very expensive.   

       Concentrating and sending light deep into a cave seems to me to be anything but "bad science".   

       So, Alterother or any other boner, please spell out the bad science here.   


       This idea was written after a visit to the desert mines of ancient times in Timna, where slaves dug the ore in deep mines, then sent it up to a furnace, where the copper was extracted by heat and charcoal.
pashute, Nov 10 2012

       and c'mon. So call it "clean energy". I didn't think you were all pedantic.
pashute, Nov 10 2012

       I went with WKTE because solar furnaces are an old technology. Several attempts have been made to get them to metal smelting temperatures, and one or two exist, but the practicalities have kept them from being economical so far.
MechE, Nov 10 2012

       Iron needs 1250C. Solar furnaces reach 3500C and more. See wikipedia "solar furnace"
pashute, Nov 10 2012

       Yeah, yeah, smelters are hot, solar furnaces are hot. We all get that. But there's nothing to be gained from heating the ore in the mine. It needs to be extracted ... prepared ... diced! And the heat in a copper smelter comes from the reaction itself - not from some external source. And the difficulty is not that no-one has thought of it - they have - but that it is difficult.
spidermother, Nov 10 2012

       Copper foundries typically heat the metal to between 1900 and 2250 degrees before the pour, and even if the founding process were simply a matter of melting the metal (which it is not; various solid and gaseous additives must be introduced at different stages), the sustained BTU requirements of an industrial copper foundry range into the low millions. The biggest solar furnace I can find on the web cranks out around 700,000 over a six-hour run.   

       Those technical quibbles, however, only apply once you've got the metal to the foundry. Getting it out of the ground, extracted from the ore, and refined into usable form is a much bigger and more complicated task, and only the very last stage (smelting) involves any significant amount of heat, which, as [spidey] pointed out, is not solely generated by an external source. Simply introducing intense heat directly to a chalcocyte deposit accomplishes nothing other than warming up a bit of orange-ish rock.   

       That brings me to my next issue; the site you visited bears little resemblance to the copper mines of today. Nowadays, copper-bearing ores are nearly always mined in open-pit mines or via hillside/hilltop removal, so instead of directing concentrated sunlight into a shaft or tunnel, you'd have to cast it over a very wide area. Assuming your concept were possible, this would require a light collection and concentration appuratus many times larger than the mined area (which themselve can be 50 square miles, sometimes more), and building such an installation would consume so much energy that you could practically never balance it out with the amount of non-renewable energy you'd be 'saving.'   

       Finally, the idea that you could heat even pure metal to melting temp while it's still in the ground strains credulity. The Earth is the biggest heat sink on Earth.   

       The bone isn't mine. I'd much rather mock than bone.
Alterother, Nov 10 2012

       //I'd much rather mock than bone.// But for those of us unable to mock...
pocmloc, Nov 10 2012

       But for Timna and similar places (dark red rock btw, not light orange) this would be fit. Because of the concentration of energy heat loss would be irrelevant. It would act like plasma gasification does with metals (they "leak down" out of the other material).   

       I'm not saying this is the whole process. Its just a cheap way that may do a large part of the process.
pashute, Nov 11 2012


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