The electric power loads being served by today’s alternating current (AC) power grids are increasingly natively direct current (DC), at the end-use level. In fact, according to some estimates, about 80 percent of the electric power loads in commercial and residential structures are now DC.
Along with the broad political and policy support for inverter-based native DC power sources, this is leading many industry players to conclude that it makes inherent sense to reduce DC-AC-DC conversion losses and integrate DC distribution networks into the power transmission and distribution infrastructure.
“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,” says 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.”
At present, the majority of progress in developing DC-based technologies has occurred at either the high-voltage (more than 1,000V) or low-voltage (less than 100V) level of electricity service. Since microgrids typically operate at medium voltage (~380-400V), more work needs to be done to bridge this voltage innovation gap. This is the focus of technology companies such as ABB, Intel, Johnson Controls Inc., Emerson Network Power, and others.