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    • CommentAuthorunderunity
    • CommentTimeJan 16th 2010
     
    Posted By: ping1400
    Posted By: underunitysnip

    Corrections:
    1) Standard commercial HVDC connections nowdays have ± 450 kV (total of 900 kV)
    2) DC has less losses than AC and can transport power cross much larger distances
    Example: NorNed cable connecting Norway and the Netherlands
    http://www.abb.com/cawp/gad02181/8c5558c304d0eb13c1256f77003a33a1.aspx

    The line losses of HVDC is less than AC, but conversion losses are significantly higher. Thats why it only makes sense to use them in long-distance situations.
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      CommentAuthorDerrickA
    • CommentTimeJan 16th 2010
     
    Posted By: Angus
    Posted By: DerrickAA global high voltage DC grid could do wonders for balancing energy supply and demand. For instance, solar power wouldn't need to be stored, if your night-time power comes from the other side of the planet. During the day, your excess capacity would return the favor. As is is always sunny (or windy) somewhere in the world, power would always be available. Of course, as mrflora says, major improvements to the grid would be required. A global DC grid would be an expensive undertaking, involving a high degree of international cooperation.


    Why DC?


    Sounds like you already know the answer. No matter if AC or DC systems are chosen, power conversion will be required to feed the regional AC grids of countries collaborating on an international project. As there are frequency differences between Europe and North America, at some point, DC will be needed to bridge the divide. DC also offers lower losses on long haul transmission lines, and with the advent of high voltage/high power semiconductor switches, DC lines are getting increasingly competitive anyway. DC is also a no brainer for underwater transmission
    lines, though I'm not sure if stringing a line or two across the Bering strait would be worth the cost.
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      CommentAuthorAngus
    • CommentTimeJan 16th 2010
     
    @ping
    Do you have any information about StatKraft's salinity generation experiment in Norway? It was announced open in the autumn but it's really hard to find any info.
    • CommentAuthorjoshs
    • CommentTimeJan 16th 2010
     
    AC transmission exhibits losses that DC transmission doesn't due to coupling to the earth.
    AC transmission requires maintaining phase balance that DC transmission doesn't.
    AC transmission requires synchronization, or double conversion that DC transmission already implements.
    • CommentAuthorjoshs
    • CommentTimeJan 16th 2010
     
    Posted By: underunityThere in lies the problem with HVDC though, getting high voltages is really, really, reaaaaally difficult if I recall correctly. HVDC is still only something 200kV right now, while we've already done 750kV+ AC voltages. What all this means is that while HVDC systems are easier to maintain and don't give migraines like AC systems, they have a higher resistive loss than comparable AC systems.

    But you are right, HVDC systems ARE more economical long-range.

    Underwater HVDC is probably the way to go, to be honest, because IIRC, you can bundle wires together and not worry about capacitance issues.
    You are misinformed.
    • CommentAuthorLakes
    • CommentTimeJan 16th 2010
     
    Loads of windmills being planted in the sea off the Uk coast, but nothing being done with wave or tidal power?, why?

    I agree with the storage thing btw...
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      CommentAuthorThicket
    • CommentTimeJan 16th 2010
     
    Wave and tidal power are still too expensive. There are numerous demonstration plants around the world, but I don't think any are commercially viable yet. Their time may come.
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      CommentAuthormrflora
    • CommentTimeJan 16th 2010
     
    While I am not opposed to nuclear in principle, I think there are major obstacles to expanding fission's share in the electricity mix. It's instructive to read The Future of Nuclear Energy series at The Oil Drum, by Dr. Michael Dittmar of CERN. It appears that it will be difficult to sustain the present nuclear industry using conventional light water reactors and known U sources. Only through a combination of spent fuel recycling (not done in the U.S. anyway), breeder reactors (none currently in commercial service), thorium-fueled reactors (none yet in service) and new U sources such as seawater (not economically feasible at present) could nuclear's share of the electricity mix be expected to grow.

    Regards,
    M.R.F.
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      CommentAuthorAngus
    • CommentTimeJan 16th 2010
     
    Posted By: mrfloraWhile I am not opposed to nuclear in principle, I think there are major obstacles to expanding fission's share in the electricity mix. It's instructive to readThe Future of Nuclear Energyseries at The Oil Drum, by Dr. Michael Dittmar of CERN. It appears that it will be difficult to sustain the present nuclear industry using conventional light water reactors and known U sources. Only through a combination of spent fuel recycling (not done in the U.S. anyway), breeder reactors (none currently in commercial service), thorium-fueled reactors (none yet in service) and new U sources such as seawater (not economically feasible at present) could nuclear's share of the electricity mix be expected to grow.

    Regards,
    M.R.F.


    What - you don't like our dirty oil? We have lots of Uranium for you. Just name your poison.
    Signed
    Mercenary Canadian
    • CommentAuthorenginerd
    • CommentTimeJan 16th 2010
     
    The main limitation to nuclear energy being a bigger, cheaper, better contributor to world enery needs are societal not technical.
    • CommentAuthorjoshs
    • CommentTimeJan 16th 2010
     
    Posted By: Angus
    Posted By: mrfloraWhile I am not opposed to nuclear in principle, I think there are major obstacles to expanding fission's share in the electricity mix. It's instructive to readThe Future of Nuclear Energyseries at The Oil Drum, by Dr. Michael Dittmar of CERN. It appears that it will be difficult to sustain the present nuclear industry using conventional light water reactors and known U sources. Only through a combination of spent fuel recycling (not done in the U.S. anyway), breeder reactors (none currently in commercial service), thorium-fueled reactors (none yet in service) and new U sources such as seawater (not economically feasible at present) could nuclear's share of the electricity mix be expected to grow.

    Regards,
    M.R.F.


    What - you don't like our dirty oil? We have lots of Uranium for you. Just name your poison.
    Signed
    Mercenary Canadian
    Nuclear reactors do not necessarily mean generation of materials suitable for nuclear weapons or high level waste that is active for thousands and thousands of years. The US already has huge stockpiles of thorium that could be used to run inherently safe plants for hundreds of years.
    • CommentAuthorenginerd
    • CommentTimeJan 16th 2010
     
    Although I actually agree with Josh, I must quibble because use of terms like "inherently safe" give rise to misunderstanding and controversy.

    Generation of energy in large amounts is inherently dangerous (like life).
    •  
      CommentAuthorAngus
    • CommentTimeJan 16th 2010
     
    Posted By: enginerdGeneration of energy in large amounts is inherently dangerous


    Somebody should tell the free energy people.
    • CommentAuthorcwatters
    • CommentTimeJan 16th 2010
     
    I hope orbo doesn't release too much heat. There has been at least one paper published that says the heat energy we release maybe significant by 2100. Wind, by removing energy from the air also cools it unlike nuclear.
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      CommentAuthorAngus
    • CommentTimeJan 16th 2010
     
    Posted By: cwattersI hope orbo doesn't release too much heat. There has been at least one paper published that says the heat energy we release maybe significant by 2100. Wind, by removing energy from the air also cools it unlike nuclear.


    pcstru?
  1.  
    "Wind, by removing energy from the air also cools it"

    You have just liquefied my brain. I cannot form a coherent thought. In a moment, I am sure the gray ooze will begin to flow from my earholes as I topple over, making strange croaking sounds in the back of my throat.