View Full Version : a dc electric grid?!?!
June 27th, 2008, 5:51 PDT
I was reading an article on energy in the economist and they were describing the need we have for a smarter energy grid, one thats DC based because its more suited for traveling long distances compared to AC. excuse me but is that right? i always thought it was the opposite! ive seen myself trying to run a DC line from my batts to my office to power a pc (as was documented here a couple yrs ago, thanks!) : i was getting too much voltage drop and the pc wouldnt run without jumping through hoops. i had to switch to AC, problems disappeared.
clearly this must be a mistake right? or is there some transmission achritectiure that would make dc grids better under certain conditions??
June 27th, 2008, 7:14 PDT
Check this article out. I was wrong too, I though A\C was the only way to go for long runs: http://en.wikipedia.org/wiki/High-voltage_direct_current
June 27th, 2008, 9:35 PDT
ohhhhh, so it's all about the high voltage, pretty cool, thanks for confirmation
June 27th, 2008, 9:44 PDT
Actually, it is about the AC--alternating current--charging and discharging the lines against the natural capacitance of the line.
And buried or underwater cables have even more capacitance per foot/mile/km...
Even though there is no direct energy lost when charging or discharging the capacitors--there is an I^2 * R loss because of the extra currents needed to charge and discharge the parasitic capacitance of the transmission line.
There are also long distance DC transmission lines in the US (typically from hydro power dams up north to the southern California/US.
The issue is the costs and power losses of a pair of ACtoDCtoAC conversion plants vs the larger wire and higher losses of a pure AC transmission line.
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