Green Circuits, a distribution-efficiency initiative led by the Electric Power Research Institute (EPRI), focuses on T&D efficiency and opportunities for investments in infrastructure that can improve overall energy efficiency and energy conservation. The project involves participation from utilities around the world to analyze and actually demonstrate energy savings resulting from distribution system investments.

The Northwest Energy Efficiency Alliance work reported in the February 2010 issue of Transmission & Distribution World provided an indication that significant savings were possible through voltage optimization. The EPRI Green Circuits initiative has continued to evaluate this potential as well as other distribution- efficiency measures, with a larger sample of distribution systems.

The Green Circuits collaborative project was initiated following a series of industry workshops held from December 2007 through March 2008 in which more than 30 electric utilities explored issues related to distribution system efficiency. The conclusions from the series of workshops formed the main objectives for the project:

• Develop and demonstrate a consistent method to quantify losses

• Compile credible data to quantify the costs, benefits and risks of using energy efficiency and loss mitigation as part of distribution planning

• Report on actual field demonstrations where options for efficiency improvement have been implemented and validate the corresponding realized efficiency gains.

EPRI is now working with more than 24 utilities to characterize 85 circuits across 33 states and four countries, identify existing circuit losses and prioritize potential options for efficiency improvement. The initiative will result in developing a comprehensive database to improve the understanding of the technical, economic and implementation issues with various distribution system efficiency measures.

Preliminary results show that distribution losses can be reduced by 5% to 10% over the next 10 to 15 years by using more-efficient components for system upgrades. Overall efficiency can be improved by reducing unbalance and providing more continuous control of circuit power factor and var flows. Besides reducing distribution losses, there are significant opportunities to reduce customer energy use through control of the voltage on the distribution system, referred to as voltage optimization.

Partners in this collaborative research include: American Electric Power, CenterPoint Energy, CPS Energy, Consolidated Edison, Consumers Energy, Dominion Power, Duke Energy, Entergy, ESB Networks, Électricité de France, FirstEnergy, Kansas City Power & Light, New York Power Authority, Northeast Utilities, Pacific Gas & Electric, Public Service Electric & Gas, Salt River Project, Southern California Edison, Southern Company, Tennessee Valley Authority, United Illuminating and Xcel Energy. Additionally, the National Rural Electric Cooperative Association and the New York State Energy Research and Development Authority are also partners in this effort.