Debating and debunking AC vs. DC

June 28, 2013 | By Barbara Vergetis Lundin

Approximately 80 percent of the power loads in commercial and residential structures are now direct current, including those electricity loads being served by alternating current power grids, according to Navigant Research.

The market for DC distribution networks is not a single, cohesive sector but consists of several disparate opportunities, including data centers, green telecommunication towers, DC subsystems within grid-tied commercial buildings, and off-grid military networks. Some industry players conclude that due to broad political and policy support for inverter-based native DC power sources it makes inherent sense to reduce DC-AC-DC conversion losses and integrate DC distribution networks into the power supply infrastructure. That is the argument for DC, but there is much more to the story.

"There is heated debate about the advantages and disadvantages of DC, and several myths that still need to be debunked in order for this class of power distribution equipment to become mainstream," said Peter Asmus, principal research analyst with Navigant Research. "One misconception is that DC is only 1 percent or 2 percent more efficient than AC grids. In fact, research by Lawrence Berkeley National Laboratory shows that medium voltage DC networks are 7 percent to 8 percent more efficient than AC."

Currently, the majority of progress in developing DC-based technologies has occurred at either the high-voltage (more than 1,000 V) or low-voltage (less than 100 V) level of electricity service. Since microgrids typically operate at medium voltage, more work needs to be done to bridge this voltage innovation gap, according to Asmus.

For more:
- see this bulletin

http://www.fierceenergy.com/story/debating-and-debunking-ac-vs-dc/2013-06-28