Solar Furnaces are economical ?

Discussion in 'Energy' started by Widdekind, Nov 25, 2012.

  1. Widdekind
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    Widdekind Member

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    According to the National Geographic documentary Known Universe -- Most Powerful Stars, "solar furnaces" can quickly reflect "megawatts per square meter" of (free) solar energy, onto targets, heating & melting computers, aluminum plates, and stainless steel meat cleavers.
    Could not "solar furnaces" heat water, producing steam, that could then drive turbines, per conventional power plants? Solar energy is free (cost zero), so could not inefficient solar power panels be bypassed, in favor of direct reflection of sunlight, onto water targets, to produce vapor, to drive turbines?
     
  2. polarbear
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    polarbear I eat morons

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    That`s all been done for decades. The Themis solar tower has been up and running since 1970
    But You got it all backwards. It`s not reflecting "megawatts" per square meter". It is using an area of almost 12 000 square meters for the mirrors which concentrates it to a ~ 25 square meter focal area.
    And the best peak power flux achieved was 3600 kW per square meter
    [​IMG][​IMG]

    You also got the "(free) solar energy" all wrong. The only thing that`s free is the sunshine, but not the power You want to get from the sunshine.
    The air is free too, but not if You want the oxygen in it!
    [​IMG]

    It cost`s over $ 100 for a re-fill. There is "free" water all around You, but the water coming out of Your faucets is not free either.

    In 1973 when everything was still a lot less expensive as today Themis cost ~ 300 000 000 Francs ( ~ 45 000 000 Euros). Figure out yourself how much less You get for a $ today as compared to 1973.
    Themis was closed in 1986 because it was too expensive to operate.

    The people that make movies like the one You watched (Known Universe) are not engineers. It takes a lot more than just sunshine and heat to make power with a solar furnace. The only places where these work have 1 thing in common, and that is why Themis was abandoned. Themis had 2400 hours of sunshine per year, but You will have a lot of (even more expensive) problems in places that have enough sunshine to engineer the cooling You need for any thermal power plant,...no matter what the power source is.
    These kind of power plants are typically in arid areas like deserts or mountain tops where there is no cooling water available.
    It`s not as simple as just making superheated steam, blasting it into a turbine intake and presto You got power...there is a lot more to it than that what has to happen after that. To get a usable pressure differential between a steam turbine intake and outlet You have to condense the steam in gigantic coolers. You can`t just feed a boiler with "hard" water and vent the steam turbine exhaust into the atmosphere.
    After 2 days the damn thing would be solidly plugged up with Calcium deposits. So You have to condense the steam after the turbine and recycle the soft, mineral free and pH controlled boiler water.
    And that`s the biggest ($$$) problem with solar furnace power plants and was the prime reason why Themis was shut down. With "Solar 2" in the Mojave desert cooling is not a free lunch either:
    [​IMG]

    No matter how You configure it:
    [​IMG]

    Reality and movies are 2 different worlds, even if it was a "national Geographic" movie. Not considering the rest of the not so minor details does`nt make this movie any better than any other Hollywood movie.
    "Renewable" energy is far from "free" matter of fact it`s the most expensive energy of all the alternatives.
     
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    Last edited: Nov 25, 2012
  3. polarbear
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    polarbear I eat morons

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    See daveman that`s what the greenies all have in common. They watch movies like that NatG movie for example where they melted a meat cleaver and that`s supposed to demonstrate how to solve the energy "problem"...a problem that would not even exist were it not for assholes like Michael Mann and the IPCC etc.
    It`s one thing to melt a meat cleaver, but a whole other thing to generate power from "free" solar energy. If You want a melt down even more spectacular than just a meat cleaver all You have to do is shut down the cooling in a nuclear power plant.
    And as far as PV solar is concerned check out how "cheap" it is just for iddy biddy residential components:
    Power Inverters and Solar Inverters for Home and Businesses - The Inverter Store

    $ 1.21 per watt...and a minimum residential power "service" is 200 amps @ 220 Volts = 44000 Watts...= $ 53 000 !! for solar PV. And in a NatG movie they call that "free power".

    We are talking almost $ 1000 just to power up a couple of light bulbs and a washing machine or a cook stove for a few minutes after the sun went down.
    Where I live when people come home from work during the winter it`s already dark and You won`t be able to cook a meal or have a hot shower with what solar has stored in a $1000 deep cycle battery bank during the time when the sun was out.

    The green energy carpet baggers state it like this...(It`s also funny that You have to consult the foreign press to get better details..!!!)...:
    Solar energy sector lights up in California - Features - Al Jazeera English

    Notice the usual "could"...!!!
    Even then You`ld be looking at over $ 40 000 for something that only works during the hours while most people are away at work.
    In California it works just like it did in Germany,...only the well off like my friend the stock broker in Landsberg can afford it and use it because he can do all his business all day long while the sun shines at home in his multi-million $ house. California has no different plans either:
    And I would like to see how that is supposed to work in ND, Minnesota or Montana where it`s already a problem to plow the snow off the roads:
    [​IMG]



    The entire "power plant" would be out of action from the first snowfall in November or December till next year in March or April.
    Wind farms are no different. If You check when they actually do put out power it`s in a very narrow operational envelope between 15 mpH and < than 50 mpH winds. They are way too expensive to risk relying on the automatic feather and yaw mechanism every time a thunderstorm is approaching.
    Most operators yaw them way before a thunderstorm or high winds arrive at the location. During the summer the wind farms in most areas in the prairies and the "wheat belt" are off almost as much as they are in the on-line mode. Just because they are turning does not mean they actually put out usable grid power or what their name plate rating is.

    [​IMG]
    [​IMG]

    So, there is no conflict of interest because we were talking about solar instead of oil...!!!
    It was bad enough during Obama`s first term, Solyndra, Chevy Volt etc...wait how outrageous it`ll get during the second term !
     
    Last edited: Nov 25, 2012
  4. whitehall
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    whitehall Gold Member

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    Nat-Geo is in it for the viewers and the bucks. They can say anything they want to because it is just entertainment. They are half right about the gigantic solar furnace in the sky. The Sun controls weather patterns and life on planet earth but the technology for harnessing the Sun's radiation to produce cheap energy does not exist
     
  5. Widdekind
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    Widdekind Member

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    First, everybody agrees, that "millions of watts per square meter" have been demonstrated, e.g. nearly 4000KW per square meter (according to PB).

    Second, "it's always sunny somewhere"; power could be harvested in one region, and sold to another one day; et vice versa the next day.

    Third, the south-facing flank of a mountain could be mirrored, directing light downhill (southwards) to a collector tower. ~1000m2 would harvest GW of power.

    Fourth, what is so challenging, about harvesting sunlight, streaming to earth, "for free"? Nobody in North America can put together a profitable prospectus?
     
  6. Widdekind
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    Widdekind Member

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    Where on earth is sunnier than the Middle East? Where on earth could solar power potentially be more economical? Honoring an ancient name, Archimedes the Greek managed to manipulate mirrors over 2000 years ago. Oil Wells & Refineries run on solar power would have more petroleum to market. Fearing 'Peak Oil' within the next 10-100 years, solar power could prolong the availability of (evidently) most-cost-effective petroleum for smaller vehicles (cars, trucks, trains, planes). (Whilst also giving trees & plankton more time to consume the CO2 released.) Nobody can figure out how to harvest free sun light?
     
  7. flacaltenn
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    flacaltenn USMB Mod Staff Member Gold Supporting Member

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    Now there's a ECOLOGICALLY SOUND proposal in bold above. Just tear up the entire south side of a mountain, clear the trees, level the ground so that mirrors will accurately line up and blast some water into vapor.. I'm CERTAIN the Sierra Club will cheer this engineering revelation with welcomed relief..

    "It's always sunny somewhere?" --- that's the kind of rigid engineering analysis that will keep your lights on. Just snap your feet 3 times repeating that mantra and see if you end up back in Kansas...
     
  8. PUCrussel
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    PUCrussel Russel W.

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    Of course, it is, in future.
     
  9. whitehall
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    whitehall Gold Member

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    You can't even support all the energy requirements of a single family home with a football field of solar panels. There are no solar furnaces on this planet. If the crap worked we would all be off the grid.
     

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