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Switching off lights (and brains)

  1. Oct 23, 2007 #1

    vanesch

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    Silly "ecology action": a collective of ecologist organisations in France wanted everybody to switch off lights between 19:55 and 20:00, in order to "give a strong signal" to politicians that one is serious concerning measures against climate change.

    Especially in France where about 80% of the electricity is nuclear, and about 10% is hydro, this is a pretty dumb thing to do, as the only effect such a glitch will have, is utilities to start up gas turbines to be ready for the consumption spike.
     
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  3. Oct 23, 2007 #2

    EnumaElish

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    I am not an engineer and I will prove it to you:

    At 19:54:59 there is sufficient nuclear + hydro online generation capacity to meet the demand from 50 million French households. ("To make up a number.")

    At 19:55:00, 1 million households become dark, leading to excess capacity.

    At 20:00:00, the load goes back to 50 million households. If the nuclear + hydro capacity was sufficient at 19:54:59, why is there a need for gas turbines at 20:00:00?
     
  4. Oct 23, 2007 #3

    mgb_phys

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    1, Turn lights on/off to try and blow up power statsion.
    2, Most of France's power is Nuclear.
    3, Most of the power plants are on the channel coast (where the wind blows towards the UK)
    4, It's all a conspiracy!
     
  5. Oct 23, 2007 #4

    EnumaElish

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    Will that create a surge? (I guess it would...)
     
  6. Oct 23, 2007 #5

    Evo

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    :rofl: okay

    I'm at a loss for words.

    Kind of like the "don't buy gasoline on Tuesday because this will cause a serious financial problem for the oil companies". Right, like all of the fools filling up their tanks the day before to make sure they have enough gas is going to hurt the gas companies. :rolleyes: A lot of people actually fell for this joke.
     
  7. Oct 23, 2007 #6

    Ivan Seeking

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    It sounds more like a signal for the politicians than an energy conservation effort - literally flashing the lights to express concern. I don't understand that objection.

    I agree that this sort of thing is a bit silly, but it does bring attention to the effort, thus the reason for the effort.
     
    Last edited: Oct 23, 2007
  8. Oct 23, 2007 #7

    EnumaElish

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    Anyone to tackle my excess capacity question?
     
  9. Oct 23, 2007 #8

    vanesch

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    You can't keep that excess capacity for longer than a few seconds or the voltage of the grid will rise and the generators will speed up! So you have to be able to reduce production in a matter of a few seconds. Utilities have a whole staff trying to predict consumption evolution, and adapt their means of production to the events. As such, when such a glitch is foreseen, they have to power up gaz turbines BEFORE the event and reduce nuclear + hydro a bit, in order to be able to follow the foreseen drop in production with the tubines (the only generators that can follow production in a matter of seconds).

    At that moment, they have to speed up the turbines again, in order to adapt to consumption. Afterwards, they can slow down gaz turbines while speeding up nukes (matter of several minutes) to take over again a smooth consumption pattern.
     
  10. Oct 24, 2007 #9

    vanesch

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    The point is that this is a typical ecologist ideology thing: they want people to "reduce energy consumption because of climate change". But electricity from nuclear doesn't contribute to it, not more than eating vegetables. You can consume as much electricity from nuclear as you want, you won't be contributing to any greenhouse effect and this is something that pisses off ecologists (mostly with anti-nuclear ties), so they want to instore some kind of confusion. So the point is: there is no objective ecological reason to reduce electricity consumption if it comes from nuclear.

    You could just as well have given a "strong signal to politicians to limit climate change" by not eating vegetables for a week.
     
    Last edited: Oct 24, 2007
  11. Oct 24, 2007 #10

    Ivan Seeking

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    You don't sell power? By conserving, can the power saved be sold to countries using dirtier technologies.

    But I do agree that many of these stunts are rather lame.
     
    Last edited: Oct 24, 2007
  12. Oct 24, 2007 #11

    vanesch

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    Well, that's already the case in fact. Maybe France can build 50 more nukes, in order to sell electricity all over Europe, and especially in Germany where they are going to replace nukes by coal power plants (and a few windmills). 26 new brown coal plants have been approved in Germany in march 2007 in order to be ready for their nuclear phaseout, but indeed, maybe France should build enough nukes to "save the planet" in Europe...

    http://www.spiegel.de/international/germany/0,1518,472786,00.html
     
  13. Oct 24, 2007 #12

    Art

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    I think the argument is that the nuclear process produces heat and most of the electricity produced ends up as heat so although no greenhouse gasses are produced according to the ecologists the energy produced still contributes to GW as this heat ends up bouncing around between the atmosphere and the planet. Unfortunately it seems many ecologists are not so interested in clean energy as no energy.
     
    Last edited: Oct 24, 2007
  14. Oct 24, 2007 #13
    Same idiocity here in sweden:mad:. 50% of our electricity is nuclear, the other 50% is hydro. That doesnt stop all environmentalits from whining about the electricity consumption and now some politicians are jumping on the bandwagon aswell.

    Everyone here talks about wind, wind, wind, wind while completely ignoring that our electricity production isnt causing any co2 emissions.
     
  15. Oct 24, 2007 #14

    vanesch

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    :rofl::rofl:

    That's "global warming" taken litterally! We "warm" the earth (with our hands ?).

    This is a totally ridiculous idea, first of all because of the utterly tiny fraction of energy involved in the total energy balance of the earth: GW, if true, is due to changes in the way the sunlight is reflected and/or retained by eventual "barriers" such as greenhouse gasses, not by the direct heat of any human activity which is insignificant in the heat balance of the solar radiation.

    But what is more, is that if this were true, then the warming would be NOW, and not in 20 years or so!

    Hell, if we take the human body to produce 100 W, and we are 6 billion, then our collective body heat is producing the equivalent of 200 nuclear power plants (at 3GWth), which is half of what is installed worldwide. So we should "switch off" immediately half of the human bodies worldwide :devil: as a way to avoid GW.
     
    Last edited: Oct 24, 2007
  16. Oct 24, 2007 #15

    vanesch

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    Wind is nice... as a minority contribution in the power offer, but in order to have a full-scale non-CO2 producing electricity generation, the only option is nuclear.
    The feasibility is shown in the following comparison:
    mid-70ies --> mid-90ies: France became about 80% nuclear
    mid 80ies --> now: Denmark became for about 20% eolean

    and:

    France is a net exporter of electricity, helping their neighbours with shortenings ;
    Denmark needs Germany and Sweden to act as a power buffer for their variable wind energy production.

    This shows the comparison of the two technologies.

    Photovoltaic is for the moment still too expensive, and although less erratic, there is nevertheless the day/night cycle and the summer/winter cycle which makes that photovoltaic will also never be able to be a majority contributor in the electricity production.

    Biofuel is a joke when looking at the total energy balance.
     
  17. Oct 24, 2007 #16

    EnumaElish

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    Thanks for the explanation.
     
  18. Oct 25, 2007 #17

    Ivan Seeking

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    And we haven't even talked about getting rid of petro powered cars. How many plants would it take to go all electric - or say go H2, perhaps H2 combustion in standard internal combustion engines since fuel cells aren't there yet - using electrolysis at the typical 50% efficiency?

    Here in the US, in order to go all nuclear we would have to build about 1200 more plants - ie we need about 13 times the power supplied by the 100 plants operating now - if we ignore the additional losses in the fuel chain [efficiency] as compared to petro. I would expect that this would take about 650 years to do, as a best case. :biggrin:
     
    Last edited: Oct 25, 2007
  19. Oct 25, 2007 #18
    The high temp reactors would be much better suited for hydrogen production than using electrolysis.

    How much hydrogen does a car need? I have seen figures(forgot where) that a car can get 400km on 3kg of hydrogen. I dont know if its right but Il use that number.
    I guess the avarage joe drives about 40km a day or so? So that means 0.3kg hydrogen/day for the avarage car.

    JAEA claims that a 600MWt high temp reactor can produce 130tons/day. Enough for 400 000 cars using the above assumptions.
    General atomics claim a 2400MWt can produce 800 tons/day. Enough for 2,5 million cars.

    If there is 300 million cars running in the us you need anything from 120-800 reactors. So nuclear could have a big impact before 2050.

    Much easier in smal countries, sweden could become independent of gasoline with just 2-3 large reactors or 10 small ones.
     
  20. Oct 25, 2007 #19

    J77

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    In reply to OP:

    ummm....

    The switching off of lights for 5 minutes isn't to save electricity, it's a statement.

    Much like what Gore won his prize for :biggrin:
     
  21. Oct 25, 2007 #20

    vanesch

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    How do you get to that number ? A nuclear power plant, a standard one (PWR, BWR...) costs of the order of 1 billion $. Probably gen IV reactors will be a bit more expensive, say 2 billion $. So in order to build 1000 such reactors, you need 2000 billion $. How much did the Iraq war cost you in how much time ?

    Realistically, we are talking on the scale of 4 decades or so. France built ~60 reactors in ~20 years time. A 6 times bigger economy (US vs. France) can hence build 360 reactors in the same period, or 720 reactors in 40 years time. But the nuclear power building didn't "ruin the country" in France. So an extra effort is possible without difficulties.
     
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