Modeling Interregional Transmission Congestion in the National Energy Modeling System

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Historically, major blackouts seem to have brought calls for upgrading the U.S. transmission system. More recently, the chorus is stronger and more constant. The lack of investment in the grid is widely deplored as a leading cause of poor reliability and increasing congestion. While extremely complicated to fully comprehend, analysis of national grid capability is becoming a vital policymaking need. A common indicator of an economically inadequate grid is congestion, which by definition implies the cheapest availably supply cannot be used; therefore a less-congested system can lead to lower electricity prices and less frequent power outages. To help reduce transmission grid congestion, the Department of Energy's (DOE) Energy Efficiency and Renewable Energy (EERE) Program supports many potentially helpful technologies. Some of these include microturbines, combined heat and power, fuel cells, photovoltaics, and energy efficient appliances. These technologies offer the ability to reduce system load, site generation close to load, and thereby expand effective grid capacity. These benefits may be significant, particularly with respect to lowered congestion costs, generation costs, and system investments. To begin evaluating the benefits of reduced congestion, Berkeley Lab has tried to use the transmission and congestion modeling in the Energy Information Administration's (EIA) National Energy Modeling System (NEMS) including exploration of a promising new approach to better represent interregional transfers of electric power. This complex task is divided into three parts: understanding how the existing North American transmission system operates, understanding how NEMS represents interregional transfers of electric power, including how the generation construction logic inherent in NEMS limits its ability to consider significant changes in interregional transfers, and, finally, given all this, assessing how how to measure benefits of technologies that affect transmission congestion. Berkeley Lab expects to eventually measure benefits by correlating scenarios with less congestion with lower electricity prices and less transmission investment and failure. At the present time, neither NEMS, in its official configuration, nor NEMS, as enhanced by Berkeley Lab, can fully capture these impacts. These limitations, there sources, and possible ways to address them, are the subject of this report. . As far as reliability benefits, less congestion can be indicative of less stress on the electric grid. NEMS was not designed to capture this impact and it is not the subject of this report.

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