January 10th, 2018
Article Summary: Use of Direct Current (DC) to Power Commercial Buildings
In the article “DC, Come Home”, Patterson argues for the need to integrate direct current (DC) energy systems as sources to power commercial buildings, alongside the current widely used alternating current (AC)-power distribution systems (60). Highlighting such a need, as argued by the author, are the inefficiencies of the centralized ac-power systems, and the environmental impact of energy wastage that arises in converting ac to dc for use in many appliances and equipment used in such buildings and data centers. Additionally, the clamor for Zero-Net-Energy Buildings (ZEBs), as argued by Patterson, establishes dc as the modality through which buildings can serve as energy generation and storage sites (e.g. by installing equipment to harness solar and wind energy), instead of being net consumers of energy from centralized ac-distribution plants (62).
The article first highlights the need for a future powered by ac-dc hybrid power system, providing the preliminary work by Emerge Alliance (EA), a non-profit consortium leading efforts for establishment of distributed dc-based microgrids connected to a “smart” ac macro-grid to form an “enernet” comparable to the Internet. Afterwards the author introduces the concept of ZEBs and the role of DC microgrids in such buildings, i.e., enabling generation and storage of energy within the building site, while allowing for interconnection with the smart grid to get power in times of shortfall. In such a way, the buildings are not subject to power disruptions that occur when a fault in one area affects all areas served by a centralized ac-based distribution approach. Additionally, use of dc microgrids can enable saving on wastages currently experienced in converting ac to dc for use in most appliances, data center systems, and lighting in such buildings. Subsequently, the article discusses topologies for integrating such microgrids in the buildings’ architectural designs. Further, the author discusses the need for standards and codes to facilitate the development of hybrid ac-dc power distribution systems, noting areas (e.g. alternative energy sources and storage technology) where progress has been made through concerted efforts by organizations under EA.
Finally, the article presents the factors challenging increased use of DC power systems in buildings, some of these being absence of standards on dc power distribution equipment and application, limited knowledge on dc distribution at the building level, and variance in use of and specifications for safety and power protection equipment. Other challenges are underdeveloped ecosystem to support dc-powered electrification at the building level and ambiguity concerning how the development from an ac-centered distribution approach to a dc-inclusive approach will proceed. Through the discussions presented, Patterson is able to present a succinct case for the integration of dc power distribution systems in buildings to reap the benefits envisaged in the areas of energy efficiency and environmental impacts of energy use.
Patterson, Brian T. “DC, Come Home.” IEE Power & Energy Magazine November/December (2012): 60-69. Web. 10 March 2013.