Thomas Edison Will Win Tranmission Of D.C. In Your Future

Discussion in 'Off-Topic' started by loosewire, Dec 28, 2011.

  1. loosewire

    Thread Starter AAC Fanatic!

    Apr 25, 2008
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    The news says that Edison will win,they will using more D.C.
    transmission in the next 20- 50 years.There a lot of investment
    now,enough to compare Edison and Tesla again after all this time.
     
  2. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    I don't see why they would do this. DC is much more dangerous at mains voltages, and causes rapid heating of conductors. Back during the Battle of the Currents, many homes were burnt down because of DC mains that caused fires within the walls of a house. It is also very inefficient. In order for it to work as well as AC transmission, the conductors (power wires) would need to be 3-4 inches in diameter, and a generator (which is very noisy and expensive to run) would be required every mile or so. The costs would increase dramatically, and it is a fire and electrocution hazard. I honestly can't understand why they would want to go back to DC. The only thing I can think of is that there is a new technology that allows for efficient transmission, but I think that would be extremely unlikely. Is the article online? I'd like to read it. Perhaps there's something we're missing.
     
  3. loosewire

    Thread Starter AAC Fanatic!

    Apr 25, 2008
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    See if you can find the story on reuters new service,you would like the picture
    of Tesla they have.Full page story.
     
  4. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    Ah, I believe I found it. Here's the link, to those of you who are interested:

    http://www.reuters.com/article/2011/12/20/us-power-acdc-idUSTRE7BJ0PW20111220

    After reading through it, I see what they are talking about. Wind turbines and solar panels produce DC rather than AC, so if renewable energy (like wind or solar power) becomes more popular, so will the use of DC. However, I still don't think it will go to DC so easily. As I mentioned before, to transmit DC would require substations or generators very close to each other, and huge conductors. The heating would be immense, and would cause all sorts of problems. Although the generators create DC, and many household appliances run on DC, transmission is the main factor. I believe that DC transmission will never be as efficient as AC transmission, and that alone will make up for the issues produced by the appliances turning AC back to DC. Sure, rectifiers may waste some energy and, therefore, money, but I think that the money put into the creation and repair of so many generators and substations, and huge conductors, etc will far exceed that which is wasted by semiconductors. Personally, I don't see the method of power transmission changing much in the next 50 years (unless some incredible new technology comes along that makes it safer and more efficient to transmit DC). I can't say for sure, but in my honest opinion, I believe people will still be using AC in 50 years.
     
  5. amilton542

    Active Member

    Nov 13, 2010
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    If I had it my way and we had the money, I would connect off-shore wind turbines on to a superconducting transmission system.

    I'm not a fan of the nuclear program associated with power generation, nor am I a fan of renewable energys that take up our fields to grow crops.
     
  6. steveb

    Senior Member

    Jul 3, 2008
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    It's not clear why you are doubting the ability to transmit DC efficiently. There have been major advancements in semiconductor technology and computer control technology which allows high voltage DC to be generated and transmitted.

    The major loss mechanism is the I^2R heating loss in the cable resistance. The only way around this is to use high voltage and low current. This works for either AC or DC. In the old days, transformers were the most practical method of generating high voltage, which required AC.

    There are actually more disadvantages to AC in terms of transmission efficiency. Capacitive coupling can loose some power AC power, and there are other effects.

    Local distribuition costs can also be much less with DC. Further, even our old standby technology based on induction motors has done a complete reversal. Wereas AC was needed in the old days to drive an induction motor, modern day vector control allows precision control of indcution machines by using a DC bus and an inverter with variable frequency output. All roads seem to be leading to DC, and it seems reasonable to anticipate that a change may occur in the future.

    However, change is a very difficult thing to institute and it may be a long time. Perhaps you are right and even 50 years is not enough. Or, we may all be surprised and see changes happen much faster than we thought. It's really hard to tell sometimes.

    http://www.solarec-egypt.com/resources/Larruskain_HVAC_to_HVDC.pdf
     
  7. steveb

    Senior Member

    Jul 3, 2008
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    Since Edison was primarily a businessman, and since he is dead now, it's hard to say he will be a winner in this battle. He won many battles and even won the war since he died rich and famous, while Telsa died poor, lonely and is now a hero only to those of us here that understand something about real substance. But when it comes to this so called "battle of the currents", Edison lost, and ain't nothing gonna change that !!! :p

    As an analogy, the South could rise again and defeat the North, but General Robert E. Lee would not be named a victor.

    However, on the issue of future power systems, whether it is DC conversion or renewable energy systems, the real winners will be those of us here that recognize the coming opportunities and capitalize on them.
     
  8. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    They're working on that one already :D
     
  9. Adjuster

    Well-Known Member

    Dec 26, 2010
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    High voltage DC transmission is already being used for specialised purposes such as underwater power links. With the development of increasingly efficient high power electronics this looks set to continue, and may take over more long-distance transmission applications, as well as being used in relation to wind and other variable speed generators as already mentioned.

    It is possible that in time this could lead to the establishment of high - level DC networks, which could benefit from some advantages such as freedom from the need for synchronisation. There would however be definite disadvantages, particularly in the area of switching and fault protection: basically, powerful DC arcs are harder to extinguish than AC.

    What is not so clear is how readily domestic supplies and local distribution could be shifted over to DC. The switching and protection problems would be more widespread, and there would be the problem of incompatibility with all the existing hardware. The system would have to offer clear advantages to persuade people to make such an investment.

    That is however not quite beyond the bounds of imagination. For instance, think of what might happen such things as fuel cells or much better storage battery technologies ever become economically viable. Local power generation with storage against temporary outages might then become more attractive, at least in remote locations where extending grid power is costly.

    At that point it may be more attractive for these rural set-ups to avoid the difficulties involved in converting kilowatts of DC into AC, some of which would anyway have to be rectified again within various appliances. Perhaps if a niche market could be established for such DC appliances, like modern versions of grandfather's 32 volt Farm Radio, this could in time allow them to be more widespread.
     
  10. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Fisher and Paykel from New Zealand is already doing this for home appliances. Even though most are run by AC they use BLDC motors that operate from the AC but can also run from a DC source. Any appliance from washers and dryers to refrigerators.
     
  11. Adjuster

    Well-Known Member

    Dec 26, 2010
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    That doesn't really surprise me. I expect this sort of thing to be most attractive initially in areas with a low population densities, but reasonably high standards of living. Perhaps there are still quite a few isolated farms and even small communities dependent on "off-grid" electricity in both New Zealand and Australia.

    Presumably though the days of the pedal radio ended some time back?
     
  12. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    HVDC has been "in the works" ever since the IGBT was perfected.

    It makes total sense, now that switching supply losses are less than the transformer losses. Also, there's no power factor to worry about, that's an "in house loss" if they need to use a few cabinets of IGBT to create the 3 phase they use.

    I'm sure it will be tried on a developing country, the savings in copper for the low frequency transformers alone makes it attractive.
     
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