Long Topped By AC, DC is Key to Renewable Energy

Trabish talks with Aftab Khan, Vice President and General Manager of U.S. Grid Systems, about why DC will be a big part of the country's smart grid:

"Power on a DC line is completely controlled. If you say, 'I want to bring power from point A to point B and I want exactly this many megawatts on that line,'" Khan said, "the power goes." Theoretically, he added, AC lines can do the same. But in an AC system, "you don't have the ability to manage the power flow from point A to point B directly."

High-voltage direct current (HVDC) lines are currently in use in China, delivering hydroelectric current from remote resources.