Solar cheaper than nuclear
in [Design]
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From: Charlie E. on 13 Aug 2010 14:06 On Tue, 10 Aug 2010 12:51:58 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >On Tue, 10 Aug 2010 11:30:50 -0700, Charlie E. <edmondson(a)ieee.org> >wrote: > >>On Tue, 10 Aug 2010 19:02:15 +0100, Dirk Bruere at NeoPax >><dirk.bruere(a)gmail.com> wrote: >> >>>On 10/08/2010 16:26, Jim Thompson wrote: >> >>>> >>>> The naivete, and ignorance (�), of tree-huggers is stunningly >>>> profound. >>>> >>>> I suspect it's because they're not engineers... they think arm-waving >>>> and warm and cuddly feelings are what make things work. >>>> >>>> ...Jim Thompson >>> >>>So you have some reason for believing that solar panels are going to >>>remain at around $400 per sq m when at least one company is >>>manufacturing them at a third of that price? And that manufacturing cost >>>will never fall below that value? >> >>Dirk, >>Yes, the panels MAY drop in price, by a third or even more. >> >>The mounting hardware and similiar infrastructure won't drop that >>much, if at all. >> >>Installation for them will only go up, at least for a while. >> >>Inverters and other grid tie or other uses SHOULD go down, but they >>haven't yet! >> >>BTW, the trend in industry for residential panels is to include the >>inverter and grid tie equipment ON THE PANEL! That way, the actual >>interconnections are all done as standard electrical connections as >>per NEC, meaning a standard electrician can wire them up without a lot >>of special training. Also makes passing code easier. >> >>But right now, as a home owner, I can't buy Nanosolar panels. They >>are shipping everything they can produce either to Germany or to large >>industrial installations. When their production increases to the >>extent that they can sell to residential installers, MAYBE we will see >>less expensive home panels... >> >>Charlie > >And the benefit/cost ratio is what?? > > ...Jim Thompson That is the point. IFF the cost of the panels << cost of electricity produced, then the whole charade is meaningless! So, assuming Nanosolar is right, and can produce panels at a dollar a watt, so my house needs $3K in panels. Then, someone standardizes inverters, so a 3KW grid tie inverter costs basically its parts cost plus markup, say $1K, then for $4K I can have the hardware to run my home during full sun, plus some for the grid to offset my night use. If my installation and mountings cost less than $4k, then I can have a solar system that pays for itself in electricity costs in four years. If averager system lifespans are 20 years, then I have a decent ROI. If they last 10 years, then an acceptable ROI. If five years or less, then I screwed up royally! Charlie
From: Nobody on 13 Aug 2010 15:47 On Fri, 13 Aug 2010 11:43:33 -0700, Charlie E. wrote: >>That would be about 65 years, then. The half-lives of the waste products >>involved go up to ~700 million years for U-235. >> >>Burying stuff isn't "disposal"; it's "out of sight, out of mind". >> > > Ok, ONE MORE TIME! > > If it has a half life of 700 MYrs, then it AIN'T RADIOACTIVE! U-235 most definitely is radioactive. You're forgetting that it's fissile, which means that it "amplifies" decays (whether of U-235, its decay or fission products, or other radioactive elements in the waste). > If it has a half life of less than 100 years, then USE IT AS A POWER > SOURCE! Nuclear power generation relies upon fission, not spontaneous decay. If it relied upon decay, all of the weapons-grade U-235 in the world wouldn't power a small town. This is why U-238 has negligible radioactivity compared to U-235, in spite of only having a sixfold greater half-life: U-238 isn't fissile.
From: Charlie E. on 13 Aug 2010 17:17 On Fri, 13 Aug 2010 20:47:14 +0100, Nobody <nobody(a)nowhere.com> wrote: >On Fri, 13 Aug 2010 11:43:33 -0700, Charlie E. wrote: > >>>That would be about 65 years, then. The half-lives of the waste products >>>involved go up to ~700 million years for U-235. >>> >>>Burying stuff isn't "disposal"; it's "out of sight, out of mind". >>> >> >> Ok, ONE MORE TIME! >> >> If it has a half life of 700 MYrs, then it AIN'T RADIOACTIVE! > >U-235 most definitely is radioactive. You're forgetting that it's fissile, >which means that it "amplifies" decays (whether of U-235, its decay or >fission products, or other radioactive elements in the waste). > So, if it is radioactive, then it doesn't have a half life of 100 MYrs, now does it! >> If it has a half life of less than 100 years, then USE IT AS A POWER >> SOURCE! > >Nuclear power generation relies upon fission, not spontaneous decay. If it >relied upon decay, all of the weapons-grade U-235 in the world wouldn't >power a small town. > >This is why U-238 has negligible radioactivity compared to U-235, in spite >of only having a sixfold greater half-life: U-238 isn't fissile. Ah, fission IS spontaneous decay. Now, chain-reactions just cause LOTS of fission to occur, and U-235 is a lot less stable in the presense of extra neutrons making chain reactions more probable. And there are plenty of power supplies that rely on spontaneoud decay, esp. for space applications. For a nowhere man, you don't know much, do you? ;-) Charlie
From: Dave Platt on 13 Aug 2010 17:38 In article <p69b6610mg7sno8bhp1db2gqg8k579rn2b(a)4ax.com>, Paul Keinanen <keinanen(a)sci.fi> wrote: >While the simple RTGs are highly inefficient for electricity >production, the heat generation would be sufficient to keep houses >warm in cold climate. > >Pu 238 would be particularly interesting to be kept in a pool of water >in the basement as a part of the central heating system, since the >half life is so long that you would not have to reload it during the >typical life time of a house. At about one-half watt of heat generated per gram, one would need quite a lot of Pu 238. Reportedly (by the Great Dubious Source of All Information a.k.a. Wikipedia), extracting pure Pu 238 from spent reactor fuel for RTGs is not economical - it requires an expensive isotopic separation process. It's possible to manufacture pure Pu 238 for use in RTGs, but this is also rather expensive. >Of course you would have to keep burglars away, since some countries >seem to be interested in Pu238 for other purposes and pay well for >it:-). The fact that plutonium forms hydrides on contact with moisture, which are pyrophoric once dried, would also be a matter that would require careful thought and design before deploying this technology en masse (to say no more!). You *really* wouldn't want to have that basement pool be drained for any reason, since the plutonium heating elements could then catch fire spontaneously. -- Dave Platt <dplatt(a)radagast.org> AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads!
From: Paul Keinanen on 13 Aug 2010 18:37
On Fri, 13 Aug 2010 14:38:43 -0700, dplatt(a)radagast.org (Dave Platt) wrote: >In article <p69b6610mg7sno8bhp1db2gqg8k579rn2b(a)4ax.com>, >Paul Keinanen <keinanen(a)sci.fi> wrote: > >>While the simple RTGs are highly inefficient for electricity >>production, the heat generation would be sufficient to keep houses >>warm in cold climate. >> >>Pu 238 would be particularly interesting to be kept in a pool of water >>in the basement as a part of the central heating system, since the >>half life is so long that you would not have to reload it during the >>typical life time of a house. > >At about one-half watt of heat generated per gram, one would need >quite a lot of Pu 238. Assuming 1-10 kW heating power requirement for a small house, 2-20 kg of Pu 238 would be required. The density of Pu is quite high, so a small bottle would be sufficient to contain it. >Reportedly (by the Great Dubious Source of All Information a.k.a. >Wikipedia), extracting pure Pu 238 from spent reactor fuel for RTGs is >not economical - it requires an expensive isotopic separation process. Why would one require pure Pu 238 for heat production by natural decay? From the heat production point of view, it would be perfectly OK, if the Pu 238 isotope is spread by some filler material. However, there are practical problems with fuel rods recently taken out of a PWR/BWR reactor. These contain a lot of nasty short lived isotopes (half life hours to years). After 30 years of rod storage, the situation would be quite different. >It's possible to manufacture pure Pu 238 for use in RTGs, but this is >also rather expensive. > >>Of course you would have to keep burglars away, since some countries >>seem to be interested in Pu238 for other purposes and pay well for >>it:-). > >The fact that plutonium forms hydrides on contact with moisture, which >are pyrophoric once dried, would also be a matter that would require >careful thought and design before deploying this technology en masse >(to say no more!). You *really* wouldn't want to have that basement >pool be drained for any reason, since the plutonium heating elements >could then catch fire spontaneously. Why would I want 100 % pure Pu 238 for heat production ? Mixing the same amount of 2-20 kg of pure Pu 238 of something else (clay or inactive uranium isotopes) would still produce the same 1-10 kW amount of heat. |