Intermittency and the HVDC Supergrid

May 22, 2011 - Howard Silverman - peopleandplace.net

Smart grid or supergrid? Although the terms are sometimes used interchangeably, distinguishing them can be useful.

A smart grid uses digital communications networks to manage and monitor advanced electrical functions: integrating large quantities of distributed generation, shifting and scheduling demand loads, and dynamically pricing electrical delivery. 

A supergrid uses high-voltage, direct current (HVDC) transmission lines to send electricity over long distances.

Certainly, the technologies are complementary. Both would be incorporated in large-scale concepts like a SuperSmartGrid across Europe, North Africa and West Asia, or a Unified Smart Grid across the U.S. or North America.

Still, they assume different strategies for dealing with intermittency: the periodic availability of renewable energy resources like wind and solar.

A smart grid would use supply and demand management and pricing to smooth the intermittent availability of renewables. A supergrid would rely on a long-distance footprint, covering a portfolio of sources and availabilities.

A supergrid could also be built in stages, link-by-link transmitting from where energy is generated to where its needed. Dozens of HVDC projects have been developed around the world. Last December, 10 European countries signed an agreement on a North Sea supergrid to take advantage of offshore wind. Offshore proposals along the U.S. East Coast are also under discussion ("Offshore Wind Power Line Wins Backing," NYT).

One can't help but notice the discrepancy in media coverage between the smart and super grids. Plenty of attention to smart grids, which are in initial phases of development. Little attention to supergrids, segments of which have been around for decades.