High Voltage Direct Current

We were discussing generating with windpower in the central plains of this country during our last meeting. One of the problems with that is how to ship the power from the central plains to the populated coastal areas where it is needed. I brought up high voltage DC power transmission and no one seemed to have hear of it.

The distance from Wichita, KS to NYC is about 1300 miles. Interestingly, there is already high voltage direct current transmission over that distance from near the border of Washington and Oregon (hydroelectric energy, I guess) to Los Angeles. The project was commissioned by JFK and built in the sixties. You can read about it at http://en.wikipedia.o...

According to Wikipedia, transmission losses using HVDC are only about 5% every 1000 miles http://en.wikipedia.o... , so that would be something like 6.5% for power shipped from Kansas to New York. Average losses in the existing grid, which consists most of high voltage AC transmitted over much shorter distances, are about 7.2% for the whole USA http://en.wikipedia.o...

It seems to me that HVDC would have an advantage over HVAC in that a steady current, unlike an alternating one, would have a constant, rather than a changing, magnetic field, and therefore wouldn't induce currents in anything near the transmission lines that conducts electricity. You can also use a smaller conductor, because HVDC is always at peak current, while HVAC is at less than peak current most of the time, yet still needs a conductor big enough to handle peak current. Another advantage is that it is difficult to sync up the phases of alternating voltages over a grid distributed over great distances, a problem that completely disappears when you go to DC.

Wind just is NOT feasible in most parts of the United States.

Even though we can TECHNICALLY ship the power from KS to NYC, look at New York. We just had 3/4 of our new windfarms in upstate New York shut down because they only were able to produce about 1/3 the time they were supposed to produce, and then overproduced when they were producing.

Could you clarify that a bit? What exactly does "overproducing" mean? Could you provide a URL to the news story?

Also, I have the impression wind power produces energy proportional to the cube or at least the square (I think it's the cube) of wind speed, meaning that if you set it up in a place that's not really windy enough, it's hopeless. I'm really not sure upstate NY is a good place for wind power, Kansas might be a lot better.

Wind Turbines do not produce proportional to the amount of wind. Depending on the exact style, size, etc;... Most wind turbines work best with a constant 15-35mph wind. Short bursts of wind will not do the turbines any good.

Overproducing means that there is too much electricity in the given area that is not being used. Most of the good locations for Wind production are in the middle of nowhere, such as Kansas. If you put a windfarm in Kansas, the area will have too much electricity.

Sure, you can try to calculate voltage drop and run a thick enough, long enough wire to try to get the electricity to a city that can use it, but the voltage drop would be huge. Voltage drop changes with the weather, so you would have to gauge the wire size to allow for a huge voltage drop during the summer. Due to the inconsistant winds and amount of electricity getting to this said town, you would need a plant to provide the power the rest of the time, so you're not really accomplishing anything.


http://www.nytimes.co...

You totally didn't read what I said. With high voltage DC, which has been around since the '60's and unlike the high voltage AC that most of our grid is built around, we could transmit wind power from Kansas to New York with very acceptable grid losses of around 6.5%. Generating wind power in New York, compared to doing it in Kansas or the Dakotas, is a joke. The difference in performance between optimal and suboptimal locations for generating wind power is huge. Wind power increases at least with the square of wind speed, I think actually the cube of wind speed (force == drag == lift is proportional to speed squared, energy is force times distance, speed is distance over time, force times speed == force times distance over time == energy over time == power ), putting wind power at proportional to wind speed^3.
As for overproduction, it seems to me that it would be pretty simple to build windmills whose blades can be feathered if the energy isn't wanted.
On another thread, I reported a news story that the federal senate is acting to clear the way for the badly needed federal long distance grid.