Page 71 of the January 14th issue of The Economist had an article discussing the building of high voltage direct current electric transmission lines (HVDC). (Article can be found here) As discussed in the article, HVDC is an efficient way to deliver large amounts of power over long distances, and the need for these lines will be greater as the development of renewable generation increases. To help give an idea of the transmission situation in the US, I created a map showing all of the US and Canadian transmission lines over 500kV.
Source: SNL
The lines in red are above 750kV, with the 500-750kV lines in black. The map doesn’t differentiate between AC and DC lines, but you can definitely see that there is a big gap in bulk transmission in the center of the country, which could create investment opportunity. Most of the best sources for wind power are located in the middle of the country, and there is no way for this resource to connect to the most efficient power lines. The Economist article discusses a big project called the Plains and Eastern Line, that will deliver up to 4,000MW of power from Oklahoma to Tennessee. (The project’s website can be found here, and has lots of details about the project and about HVDC lines.) Here is a video from the Plains and Eastern Line website that provides more information about what HVDC lines do.
Source: Clean Line Energy Partners
To find out where some of these HVDC projects are located throughout the world, there is a page you can check out on Wikipedia. (see here)
There was one important issue around transmission lines that was not discussed in The Economist’s article. This is the difficulty in lining up the right-of-way to build the lines. The NIMBY issues in creating a line that travels hundreds of miles create huge headaches that can sabotage a long distance project before it is even started. As the article states there are substantial benefits for society in getting these projects built, but it is really political and property issues that are the big hurdle to getting these projects done.