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Yeah, we gotta build some of that solar and wind stuff, but lets just look at the savings we realize just by building HVDC trunklines in the US, without renewable energy. An AC transmission line has a 7% transmission loss, DC has a 3% transmission loss.

Lets say we want to move 200 gigawatts of electricity 1000 miles. Using an AC transmission grid we lose 14 gigawatts. DC transmission lines see only a loss of 6 gigwatts. So on paper if we switch from AC to DC in this case we save 8 gigawatts. The Equivalent of 8, 1000Mw nuclear power plants or 8, 1000Mw coal burning plants.

8,000 Mw of coal fired plants equals the carbon footprint of 9.6 million cars.

8,000 Mw of coal fired plants will emit 59.2 million tons of Co2 in a typical year, including 2720 pounds of mercury and 3600 pounds of arsenic.
http://www.sourcewatch.org/...

In this scenario just switching to HVDC saves nearly 60 million tons of Co2, thousands of pounds of mercury and arsenic. Plus its cheaper, it saves money. In 3 years GE might have its new class of offshore wind turbines ready ... in the 10 to 15 MW class. Using MRI type magnets these turbines might make wind th cheapest form of electricity on the planet.

Does this seem absurd to you? There must be a hook to this, right ? HVDC must cost a lot or some part of a HVDC system makes it unpractical. Nope.

As long as the installation is longer than about 50 miles, HVDC transmission lines are cheaper. You've all seen paths cut thru a forest with the towers and wires strung from tower to tower ? AC power is 3 phase, and a ground or neutral, making a total of 4 wires. DC, 2 wires. Where AC needs two sets of towers and 2 sets of wires, DC can transmit the same amount of power thru one set of towers holding 2 wires.
HVDC,wind power,renewable energy,job creation

HVDC is suitable for transmission of as much as 2 gigawatts of electricity, Ultra High Voltage DC as much as 7 gigawatts of electricity. As part of the Euro supergrid undersea HVDC cable will connect the UK, France, Germany and Norway, while providing a undersea backbone for wind power development.

Off the East coast of the US, there is a similar project that should be started in a about a year. A 350 mile long HVDC trunkline from about Sawyerville New Jersey to Virginia Beach Virginia called the Atlantic Wind Connection. The purpose is to allow wind developers to install offshore wind turbines 12 to 18 miles from the shore, out of sight. and not have to build individual transmission systems to move electricity to land.

In 3-4 years GE might have its new class of offshore wind turbines ready ... in the 10 to 15 MW class. Using MRI type magnets and composite materials these turbines might make wind the cheapest form of electricity on the planet.

Atlantic Wind Connection

More on HVDC, Solar, Wind, the Smartgrid
Atlantic Wind Connection, 350 mile, 7kMw offshore wind project

Originally posted to Kosowatt on Wed Sep 07, 2011 at 07:38 PM PDT.

Also republished by DK GreenRoots and SciTech.

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Comment Preferences

  •  Tip Jar (25+ / 0-)

    FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

    by Roger Fox on Wed Sep 07, 2011 at 07:38:30 PM PDT

  •  Which Corporations Presently Stand to Reap the (8+ / 0-)

    profit benefits from HFDC?

    And what's the return compared to financial gambling?

    We are called to speak for the weak, for the voiceless, for victims of our nation and for those it calls enemy.... --ML King "Beyond Vietnam"

    by Gooserock on Wed Sep 07, 2011 at 07:40:18 PM PDT

    •  hVdc !! (4+ / 0-)

      We are called to speak for the weak, for the voiceless, for victims of our nation and for those it calls enemy.... --ML King "Beyond Vietnam"

      by Gooserock on Wed Sep 07, 2011 at 07:40:40 PM PDT

      [ Parent ]

    •  Utility operators (5+ / 0-)

      FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

      by Roger Fox on Wed Sep 07, 2011 at 08:00:00 PM PDT

      [ Parent ]

    •  RE HVDC profitability ... (2+ / 0-)
      Recommended by:
      Wee Mama, Roger Fox

      1.  Obviously, companies who make the wires / systems to support it.

      2.  Construction companies who would be installing the HVDC power lines.

      3.  Centralized power producers who are looking to get power to market over long distances.  (Note, however, that reduced line losses could end up leading to lower electricity prices per mWh and thus could 'cost' them revenue ... thus, a complicated set of items.)

      4. Etc ...

      Re 'financial gambling', point is that this would be done -- in most cases -- at a reasonable, but not outrageous, ROI.  Thus, equity speculators would hate it as they hate project finance. People who want surety about what their money might look like a decade from now would sign up for this.  

      Blogging regularly at Get Energy Smart NOW! for a sustainable energy future.

      by A Siegel on Thu Sep 08, 2011 at 06:10:42 AM PDT

      [ Parent ]

    •  Comparable to Interstate Highways (2+ / 0-)
      Recommended by:
      sewaneepat, Tinfoil Hat

      It's not just corporations who might benefit from building out an HVDC trunkline system.  In many respects, creating an integrated electrical system parallels the building of the interstate highway system.  It certainly facilitates the building of renewable energy systems of all stripes - wind, tidal, solar, you name it - which usually cannot be located co-terminus with a major load or population center.  It offers a tremendous potential for creating the type of jobs which will pay off for the nation for at least fifty years, the type of investments which were made as part of the New Deal eighty years ago.  If such a program were sold on the basis of it being a long-term national investment, akin to a family buying a house via a mortgage, a case could be made understandably to the electorate that it wasn't really deficit spending as some might define it.

      "Love the Truth, defend the Truth, speak the Truth, and hear the Truth" - Jan Hus, d.1415 CE

      by PrahaPartizan on Thu Sep 08, 2011 at 07:32:11 AM PDT

      [ Parent ]

  •  Progress in energy technology will have (8+ / 0-)

    a greater effect on our future than the vast majority of topics discussed by most politicians.

    I just hope there is enough success before the fossil fuel economy hits the edge of the cliff.

    "The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt." Bertrand Russell

    by Thutmose V on Wed Sep 07, 2011 at 07:51:33 PM PDT

  •  Two comments (5+ / 0-)
    Recommended by:
    G2geek, Sandino, A Siegel, PeterHug, Wee Mama

    First, just a peev.  I think you mean to say Gigawatt hours rather than Gigawatts, having had the distinction (the former is potential, the latter is actual power) hammered into me in my own education, it's a small quible that affects how you are taken.  Like people who say wind mills instead of wind turbines.

    Second, as of last year, the race for the new mega turbines for offshore use was one.  In Spain, the Azimut Project is a combined effort of all the native turbine manufacturers to produce the world's first 15 MW turbine for offshore.

    The following graphics come from this book.

    Basically, the economics offshore are different.  Because the non-turbine costs are higher, it makes more sense to have a big turbine.  That's the future.  Azimut is a long term project there. Clipper has been planning to debut a 10MW offshore model for UK offshore contracts, but Clipper has pulled back from this.  They are based out of Iowa, and have an anti-union wrap.  As opposed to Spain based Gamesa which has a very constructive relationship with its workers in the US.

    http://www.economicpopulist.org

    by ManfromMiddletown on Wed Sep 07, 2011 at 08:52:10 PM PDT

    •  Gigawatts. Not Gigawatt-hours. (8+ / 0-)

      The term is used correctly here.
      Wikipedia has a very good breakdown on how the terms should be correctly used:

      A power station would be rated in multiples of watts, but its annual energy sales would be in multiples of watt-hours.- Confusion of Watts

      And that is how we use it in the field. The wind turbine I worked on was a 2MW machine. It produces 2 mega watts of power. Period. You can connect loads rated for up to 2 mega watts cumulatively to the turbine for X amount of time and it works.

      A hair dryer is rated at 1200 Watts.  Not watt-hours.

      A modern single family house needs 7500 Watts of total power on average at any moment in time.

      As the wiki article states you use the "-hours" to describe energy NOT power.  The total amount of energy consumed is metered for many reasons much of it for sales of the power. But energy is not factored into the electrical equations discussed here.

      NO CE/CW. NO UNION BUSTING

      by Aeolos on Wed Sep 07, 2011 at 10:05:13 PM PDT

      [ Parent ]

      •  Ok. So you use GW (1+ / 0-)
        Recommended by:
        Wee Mama

        for transmission, that's good to know.  

        I understand the distinction.  From the things that I study the big issue is that people don't draw the distinction between capacity and electric production.  Which you'll know from your work is some fraction of the rated capacity.

        Which is important in policy  planning because different sources of electricity have different capacity factors. And the variability of wind means that wind turbines are rarely at their nominal capacity. Which means that a 2 MW turbine is rarely pumping out a full 2 MW. If you operate from the assumption that nominal capacity (2 MW) is the capacity factor, that's problematic because it assumes a 100% capacity factor.  Wind tends to be more like 30-40%.  

        In the context of transmission, my point was off, it doesn't matter so much in terms of transmission as why you need to be able to balance loads. Which is why we need a better transmission infrastructure. With HVDC lines, you can do that.   Which means that you can shift power over long distance.  That still doesn't get around the issue with the capacity factor for wind being lower.

        Coal tends to have a 70-80% capacity factor, so about twice that of wind.  Which means in order to get the same number of GWh out of wind you're going to need twice the nominal capacity.  So, in essence, 1000 MW of wind power produces the same number of GwH as 500 MW of coal over the course of a year.

        Improved transmission gets around the variability factor in terms of grid integration, but it doesn't allow the actual capacity factor of individual wind turbines to be increased.

        That was my short version of this, hence why I get peeved when the distinction isn't made.  One slip of a word requires several paragraphs of explanation.  But, you're right the specific way the diary used it I was off in my earlier point.  

        http://www.economicpopulist.org

        by ManfromMiddletown on Wed Sep 07, 2011 at 10:40:05 PM PDT

        [ Parent ]

        •  Yes it's a nominal 2 MW. (3+ / 0-)

          Just a rating of power capacity.

          You've gone another level up in terms of production (energy).  And like you pointed out, Roger's talking about transmission and comparing two different engineering options with how we wire up the circuit itself. Not to specifically increase a wind turbine's capacity but to save a lot of heat losses in the copper from the grid in general.

          NO CE/CW. NO UNION BUSTING

          by Aeolos on Wed Sep 07, 2011 at 11:10:11 PM PDT

          [ Parent ]

        •  Challenge re wind capacity (1+ / 0-)
          Recommended by:
          ManfromMiddletown

          versus transmission is that the 25-40% is rated across time. There are periods (sometimes even extended) where the wind is running at near 100% capacity in an area.

          If we have a 5 mw turbine at 40% capacity factor with 2 mw of transmission capacity, if the average were a perfect reflection that 2 mw would handle everything.  But, if 10% of the time were at 90+% of capacity, 10% at 75-89%, 10 % at 60-75%, and 10% at 41-59%, we would end up losing a sizable percentage of the turbine's production if there weren't some form of storage to balance out the transmission.

          If I understand correctly, wind farms seek to have near 100% transmission capacity from turbine into 'grid' which provides, therefore, an ability to balance an individual turbine / an individual field within a larger system (including traditional production, other renewables, storage (such as Denmark sending electricity into Sweden for hydro storage/balancing), etc ...  

          Blogging regularly at Get Energy Smart NOW! for a sustainable energy future.

          by A Siegel on Thu Sep 08, 2011 at 06:18:10 AM PDT

          [ Parent ]

        •  I see wind capacity as 33% (0+ / 0-)

          DOE proposes 300 gigs of wind, with a 100 gig capacity. Newer-better trubines might improve that figure.

          FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

          by Roger Fox on Thu Sep 08, 2011 at 11:40:00 AM PDT

          [ Parent ]

          •  The number I've (1+ / 0-)
            Recommended by:
            Roger Fox

            seen is 37% nationally, but it varies quite a bit across sites.

            Just to give an (European) example Spain has less installed capacity than Germany but often peaks in front of it in terms of GWh produced annually.  Spain has better wind resources.

            That said, don't buy the hype about shrouded turbines.  A firm by the name of the D'Arcinoff group has tried to sell officials in Upstate NY and Eastern Indiana on the idea that they are going to open factories and pump out enormous number of high efficiency, shrouded, turbines. Never happened.  

            http://www.economicpopulist.org

            by ManfromMiddletown on Thu Sep 08, 2011 at 07:02:00 PM PDT

            [ Parent ]

            •  I can see the blade tip turbulence (0+ / 0-)

              being reduced. Beyond that testing a scale model that small ina wind tunnel is very problematic, boundary layers dont change thickness. This is a problem with small scale radio control airplanes, the boundary layer is the same on a full size P-51 mustang as it is on 1/35th scale model.

              FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

              by Roger Fox on Fri Sep 09, 2011 at 12:03:30 AM PDT

              [ Parent ]

      •  I am learning (0+ / 0-)

        SO I do make novice mistakes sometimes. But I do try to get it right.

        FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

        by Roger Fox on Thu Sep 08, 2011 at 11:36:57 AM PDT

        [ Parent ]

      •  Ohmic losses on a hot summer day (0+ / 0-)

        increase resistance, which causes more loses which causes more heat, etc. Stability can be an issue in those days.

        FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

        by Roger Fox on Thu Sep 08, 2011 at 03:32:19 PM PDT

        [ Parent ]

    •  RE offshore ... (3+ / 0-)
      Recommended by:
      Wee Mama, PrahaPartizan, Roger Fox

      the large is also more viable because it is 'easier' to move the huge systems ... try moving a 200 meter wind turbine blade ashore versus moving it from a port to an offshore location.  As well, the NIMBY aspects are far different 20 miles offshore compared to those in many locations ashore.

      Blogging regularly at Get Energy Smart NOW! for a sustainable energy future.

      by A Siegel on Thu Sep 08, 2011 at 06:12:33 AM PDT

      [ Parent ]

      •  Cape Wind vs AWC (0+ / 0-)

        Cape Wind is nestled between Islands, 2-3 miles south of Hyannis, 12 from Nantucket. In an area with air and sea traffic. AWC is 12 to 18 miles offshore.

        Who has the better model? AWC. I like the thinking behind AWC, its one that should be emulated.

        FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

        by Roger Fox on Thu Sep 08, 2011 at 11:44:35 AM PDT

        [ Parent ]

  •  The beautiful thing about the growing (3+ / 0-)
    Recommended by:
    Creosote, A Siegel, sewaneepat

    use of nature's basic elements for our energy needs is how perfectly it fits redoing our entire infrastructure. Besides just making jobs, it will actually serve in the long term to make the nation more economically viable. (Not to overlook: healthier.)

    Maybe I missed it in this diary, but I'm pretty sure there'd have to be conversion to AC somewhere along the line to the end-user, as that is how we are wired. So is the energy expenditure in the conversion of any great amount?

    PS: I'm guessing HVDC means "High Voltage Direct Current." Wasn't sure right away. It helps the reader if they see what an acronym stands for the first time they see it.


    "Whatever you do, don't mention The War." Basil Fawlty, while mentally impaired.

    by Jim P on Wed Sep 07, 2011 at 09:12:14 PM PDT

    •  Yes - there does have to be conversion to AC (5+ / 0-)

      The local infrastructure, which is all AC based - is too expensive to replace all at once, even if DC were cheaper and more reliable (which it probably isn't except for long distance transmission). And nearly all end-users' equipment (except incandescent light bulbs, which are being banned) runs on AC - you can't afford to force everyone to buy all new everything.

      The conversion efficiencies of inverters (DC to AC converters) can be very high though, which is what makes HVDC practical. I'd really like to see the differences from point of generation to my wall-socket though, not just what happens on the wires.

      If my thought-dreams could be seen, they'd probably put my head in a guillotine

      by badger on Wed Sep 07, 2011 at 11:14:57 PM PDT

      [ Parent ]

    •  Right, modern inverters are smaller cheaper (1+ / 0-)
      Recommended by:
      Jim P

      all the hardware involved in HVDC underwent a sort of renewal maybe 20 years ago. IIRC after about 50 miles HVDC is cheaper to install.

      See the 2 links at end of diary, top one for smartgrid has much info and links for HVDC.

      FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

      by Roger Fox on Thu Sep 08, 2011 at 11:49:04 AM PDT

      [ Parent ]

  •  Thanks, Roger. (3+ / 0-)
    Recommended by:
    marleycat, A Siegel, Roger Fox

    Had no idea of the energy-loss differential between HVDC and (what must be standard - which is dismaying) AC!

    The amount of metal saved by smaller and fewer towers alone would make a huge difference.

    What I don't understand: How and where would the DC current be converted to AC?

    •  There would be (2+ / 0-)
      Recommended by:
      Creosote, A Siegel

      a substation terminating the long-distance transmission line that would convert DC to AC (an inverter) and then distribute it to existing AC substations and the rest of the local grid.

      The "how" is likely electronic circuitry, similar to the kind of inverter you can plug into your car's cigarette lighter socket to get AC power. It would be somewhat larger though :)

      It would likely be many lower power circuits in parallel to achieve the current levels necessary. I really don't know how they handle the extremely high voltages on the front end - lots of lower voltage parts in series perhaps.

      It's not a trivial design problem, and reliability would be a big concern.

      If my thought-dreams could be seen, they'd probably put my head in a guillotine

      by badger on Wed Sep 07, 2011 at 11:23:02 PM PDT

      [ Parent ]

      •  That makes sense. (0+ / 0-)

        "Not a trivial design problem" - but still what a huge efficiency difference.

        •  Did I misunderstand? (1+ / 0-)
          Recommended by:
          Creosote

          HVDC requires NOTHING to be developed. 100% off the shelf.

          FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

          by Roger Fox on Thu Sep 08, 2011 at 12:00:32 PM PDT

          [ Parent ]

          •  Maybe "off the shelf" in terms of the technology (1+ / 0-)
            Recommended by:
            Creosote

            being well-established now, but at megawatt or gigawatt power levels, no equipment is going to be off the shelf - it'll involve some custom design and manufacture (but using standard components). I don't think you can pick this stuff out of a catalog.

            I'm guessing a little here, because power electronics to me is in the kilowatt range - I've never worked with gigawatts and while I have some guesses about how they might do stuff, I really don't know.

            I was saying "not a trivial design problem" in terms of who could accomplish the design, not necessarily in the sense that a lot of R&D is still required - not, for example, like building a commercial fusion reactor tomorrow. It'd take experienced engineers and engineering operations to design and build stuff at these power levels and for the kind of reliability needed.

            If my thought-dreams could be seen, they'd probably put my head in a guillotine

            by badger on Thu Sep 08, 2011 at 05:37:12 PM PDT

            [ Parent ]

          •  Well, my original question (0+ / 0-)

            didn't have to do with development of HVDC (and I'm old enough to have seen lights on in buildings that still had DC current in New York in the big brownout of 1965) -- no blame!

            My thought was that HVDC couldn't just be run into the existent AC lines but would need to be converted, and wondering what sort of processes that would entail, and whether the conversion itself might be energy costly.

            Glad to know more about this area.  

      •  I have one (1+ / 0-)
        Recommended by:
        badger

        Cig lighter to 110 outlet, I used to drive a limo, this came in handy for clients.

        Modern HVDC is off the shelf, utilities and utiliy operators are moving in this direction, market forces are moving it.  Nothing needs to be developed, there are many HVDC projects in the US, for exmpale Long Island to Conneticut, Long Island to NJ are in use right now, see link at end of dairy. And HVDC is a game changer. UHVDC is starting to be installed, transmission capacities of up to 7 gigs=7 nuke power plants.

        SO moving Great Lake wind power on a continental scale is a mtter of just installing the stuff. Detroit to NYC, Green Bay to LA.

        FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

        by Roger Fox on Thu Sep 08, 2011 at 11:59:11 AM PDT

        [ Parent ]

      •  I'm going to ask a silly question. (2+ / 0-)
        Recommended by:
        Roger Fox, badger

        Obviously, they would have to do whatever to lower the power to 110 or whatever, but could they not keep all the  lines DC and install inverters in everyone's house? Would that save money if they did?

        This is all beyond my pay grade (again obviously) but we have an inverter that converts the DC from our solar panels to AC and that seems to work just fine.

        You can't scare me, I'm sticking to the Union - Woody Guthrie

        by sewaneepat on Thu Sep 08, 2011 at 01:16:07 PM PDT

        [ Parent ]

        •  The cost of inverters might be (2+ / 0-)
          Recommended by:
          sewaneepat, badger

          prohibitive. AC is fine for distribution, thats the way utilities envision the smartgrid. HVDC doing the heavy lifting, AC does the distribution.

          FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

          by Roger Fox on Thu Sep 08, 2011 at 02:54:18 PM PDT

          [ Parent ]

        •  There are several stages of step down (1+ / 0-)
          Recommended by:
          sewaneepat

          from transmission voltages at 100s of thousands of volts, to local powerline voltages (13,200 volts is one common voltage, I think) to your house from the transformer on the pole, which is 240v (it's sort of +120v and -120v, so the difference is 240v, which allows 240v for ranges and water heaters, and 120v for everything else).

          The infrastructure to handle AC locally is all in place, so even if DC to DC voltage level shifting were price competitive, it would be very expensive to replace all of the existing infrastructure.

          In addition, local generation is still all AC too, and you have to mix and match with that. The HVDC is basically for transmitting electricity over fairly long distances, where the transmission losses are significant. Locally, the transmision losses are less significant, and DC has less advantage over AC.

          It's only in recent years that doing efficient DC power transmission has been possible - before that AC was considerably more efficient because it's voltage levels could be stepped up and down cheaply. That was difficult to do with DC, and for efficient transmission, you need to use higher voltages.

          If my thought-dreams could be seen, they'd probably put my head in a guillotine

          by badger on Thu Sep 08, 2011 at 05:27:40 PM PDT

          [ Parent ]

  •  Good ideas - republished. (1+ / 0-)
    Recommended by:
    Roger Fox

    Thanks!

    Is it true? Is it kind? Is it necessary? . . . and respect the dignity of every human being.

    by Wee Mama on Thu Sep 08, 2011 at 07:26:17 AM PDT

  •  Interesting discussion. No cost estimates on (1+ / 0-)
    Recommended by:
    Roger Fox

    $s per mile? Costs in general?

    Here is one from ABB, a huge manufacturer of HVDC components and power plant controls for nukes, wind, solar and coal:

    http://www.ieee.org/...

    Costs per mile, one citation, is here: http://www.aep.com/... which shows about $2.6 million per mile. Thus, a 1000 mile HVDC line run at 750kv is $.2,600,000,000.

    The Chinese, the only country that is implementing both HVDC, UHVDC AND advanced HVAC lines, is where to look. They are running HVDC from their largest producers. HVDC runs best where generation is densest, which for China means three sources: hydro (think Three Gorges Dam at 18GWs), nuclear (built in "parks" of 4 or more reactors" and coal plants, clustered all over the place.

    HVDC is always considered for placement of nuclear there, which it's a rapidly growing dense form of energy. Thus feed in from the AC generators to the DC are cost effective. With spreading out wind...as it's diffuse...into the highly centralized HVDC system would be costly. So expect a lot of normal AC transmission or, if the wind is producing DC directly, DC transmission lines (over 150kv should be considered as 'transmission'). The costs would be far greater per KWhr (kilowatt HOUR) for wind than, say, hydro, nuclear or gas turbine.

    This is not to say HVDC for wind doesn't make sense. If you "anchor", as the Chinese are doing right now, their UHVDC lines to large hydro and nuclear, then tie in their massive amount of stranded wind in between this makes sense so long as you put your capacity for the transmission lines at total 100% capacity for wind.

    BTW...the average wind capacity in the US for land based wind energy is 25%, not "30% to 45%". It is expected to stay that way.

    Just a few thoughts.

    Dr. Isaac Asimov: "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny ...'"

    by davidwalters on Thu Sep 08, 2011 at 08:49:15 AM PDT

    •  The DOE uses the 30% to 45% (0+ / 0-)

      Right- currently is about is 25%. IIRC direct drive might be closer to 30-33%.

      Newer turbines do better with border line optimal wind, no? And if the next gen lowers the minimal wind speed from 16 mph, to 10 mph (pulling that number from a a hat), that means improved capacity, generation over more hours per day, another plus.

      FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

      by Roger Fox on Thu Sep 08, 2011 at 12:06:35 PM PDT

      [ Parent ]

    •  Expected to stay that way? I doubt that (0+ / 0-)

      Going from gearboxes to direct drive means greater efficiency, wind doesnt have to move the gears, composite blades bring the same. Reducing rotating mass is a big deal.

      Jerome Paris has written about this, 25% is expected to become 30%

      Yes, the average wind capacity in the US for land based wind energy is 25%. But that includes some very old designs, and do not account for the new direct drive turbines.

      FDR 9-23-33, "If we cannot do this one way, we will do it another way. But do it we will.

      by Roger Fox on Thu Sep 08, 2011 at 04:48:27 PM PDT

      [ Parent ]

  •  4 Wires vs 2 (0+ / 0-)

    I think this is a little misleading.  You understand that only 3 of the 4 3 phase wires are transmitting power? For a balanced load their is no current flowing in the neutral. For an unbalanced load the neutral carries the difference. The neutral is there primarily as a reference.

    That being the case for a given wire size the correct equivalence is 4 wires AC to 6 wires DC.

    Re: inverters. Not positive but I don't think there are inverters available at the megawatt size. Yes you could series/parallel devices to achieve but the inefficiency goes up accordingly. Even then might not be feasible. I think high power inverters are usually implemented as dynamotors. Not an expert here, I'm a solid state guy.

  •  The limiting factor (0+ / 0-)

    Is the cost of the conversion equipment.  You need to convert generated AC to HVDC for transmission using expensive power electronics.  At this time it is only cost effective for transmitting large blocks of power over long distances.

    Dave B
    Power Engineer

    When the power of love overcomes the love of power, the world will know peace. Jimi Hendrix

    by Dave B on Sat Sep 10, 2011 at 10:28:56 AM PDT

  •  yeah, but how many exajoules have ever (0+ / 0-)

    been transmitted over HVDC in the US?

    EXAJOULES!!!! IT'S ALL ABOUT EXAJOULES!!!!

    To put the torture behind us is, inevitably, to put it in front of us.

    by UntimelyRippd on Sat Sep 10, 2011 at 01:12:29 PM PDT

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