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View Diary: Wind power set to decline under Obama? (270 comments)

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  •  Upgrading the national power grid (3+ / 0-)
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    ClaudeB, betson08, papicek

    to allow electricity generated from wind in the plains and rurual areas to be piped into the cities all over the country will also help long term, right?

    •  Yes. (7+ / 0-)

      The main tech being pursued is called "High Voltage Direct Current", or HVDC.  Back during the war of the currents, AC ultimately won out for long-distance power transmission because it's much easier to change it up to a very high voltage, which means low losses during transmission.  However, as tech has advanced, we've become able to do the same with DC.  And high voltage DC is much better than high voltage AC for very long distance power transmission, as there are a variety of energy loss mechanisms in AC that don't exist with DC.  It also takes less wires and you can pump more current over those wires.  Lastly, HVDC links will strongly aid in syncing different AC networks together.

      Another benefit of HVDC is that it allows you to link our hydropower with the rest of the nation.  Dams are basically giant batteries, in that they can store up energy and then let it out as needed.  So they can help even out the loads.  In my view, that's the only good justification for building a big dam these days, given what we know about how destructive damming rivers is for their ecosystems.

      •  Very informative, thanks! =) (1+ / 0-)
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      •  AC is not so bad (1+ / 0-)
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        My local transmission operator has over 7,000 miles of 735/765 kV AC circuits and with regular improvements in serial compensation, they've reduced their loss rate to 5.2%.

        As for large dams, they do make a lot of sense for another reason. Their EROI is 10 times higher than with any other technology.

        •  They don't have 7,000 miles end to end. (0+ / 0-)

          If they did, the loss rate would be way, way more.  They have 7,000 miles, but that's to cover a proportionally small, roughly 2-dimensional area.  The average distance from generator to consumer is small, probably averaging several dozen miles.

          AC transmission losses are about 2.5% per 100 miles.  HVDC losses are about the same for 500 miles.

          •  How about 850 miles? (0+ / 0-)

            I'm talking about them. They've been doing it for the last 30 years :)

            •  I don't know which Hydro Quebec line you're (0+ / 0-)

              talking about that's 850 miles long, and I didn't even know you were talking about Hydro Quebec (which is kind of a special case, as far as utilities go), but even Hydro Quebec is starting to switch from 735kV (abnormally high voltage AC, which they pioneered) to HVDC.  Examples:


              They used extremely high voltage AC back in the 1960s because HVDC was immature then.  But today, it's easily the optimum choice for long-distance power transmission.  Despite their experience with 735kV AC, HydroQuebec's latest long-haul line is an 800-mile long 450kV HVDC line (a 700-mile extension on an older HVDC line that was used for sharing power across the border -- we come back to HVDC's ability to transfer power across unsynced AC networks).

              And no, talking about average losses of the system as a whole but then comparing them to the longest distance in the system still is not an appropriate comparison.

    •  Agree but have to be carefull (1+ / 0-)
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      There was a show on tv about a power company in California wanting to build new transmission lines through parklands. The company green washed it by saying it would be used to carry solar power from the desert. When asked to put in writing that it would carry mainly green power, the company would not.

      Further investigation found out it had lines near the Mexican border  and could easily be used to bring in energy from unregulated Mexican dirty coal plants.

      Need to make sure that the fine print will help promote green technology, not just a ruse by the Power Companies.

      Republicans : Socialism for the rich, capitalism for the poor

      by ctsteve on Wed Jan 28, 2009 at 10:57:55 AM PST

      [ Parent ]

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