Case Studies: Enhancing Reliability and E fficiency Using Locally Generated DC Power— The Hybrid Building

Abstract

Since Edison’s day alternating current (AC) and direct current (DC)
have co-existed by necessity: AC to make the trip from the generating
plant and DC to power electronic loads. This has resulted in billions of
electrical compromises in the form of the ubiquitous power supply, or
a rectifier, that must stand in front of DC loads to convert AC to DC.
As Arthur Rosenfeld a California Energy Commissioner calls them, our
“Energy Vampires.”
But now, many buildings are generating power of their own, usu-
ally direct current energy. Is this wasteful back-and-forth conversion
really necessary? Just as the automobile industry has advanced to the
hybrid car, buildings can use multiple sources of power to achieve dra-
matic increases in ef ficiency