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Transmission |
The transmission grid conveys electricity over a system of high-voltage electric lines extending between electric generators and distribution companies. Proper coordination and planning of the transmission system is critical to maintaining electricity reliability and the ability to provide adequate power supplies at reasonable prices. The map on page 7 illustrates the extent of Maryland’s existing transmission network.
FERC regulates the interstate transmission of electricity, natural gas, and oil in the United States. FERC’s responsibilities with respect to the electric industry include regulating the transmission system and wholesale sales of electricity in interstate commerce; ensuring the reliability of high-voltage interstate transmission systems; and monitoring and investigating energy markets. For more information see: www.ferc.gov.
The federal Energy Policy Act of 2005 authorized the North American Electric Reliability Corporation (NERC), an independent organization, to create mandatory and enforceable reliability standards for the interstate transmission system. At present, FERC has approved 83 of these mandatory reliability standards. Eight regional reliability councils, including the Reliability First Corporation (RFC), which covers Maryland and most of the PJM geographic footprint, are charged with assessing compliance with these standards.
The FERC-regulated PJM Interconnection dispatches and coordinates the flow of bulk power across the District of Columbia and all or parts of 13 states: Kentucky, Tennessee, North Carolina, Virginia, West Virginia, Maryland, Delaware, New Jersey, Pennsylvania, Ohio, Indiana, Illinois, and Michigan. PJM consolidates the regional system’s transmission needs into a single coordinated plan to ensure bulk power electric supply adequacy. PJM creates 5-year plans to undertake transmission system upgrades, as well as a 15-year plan for upgrades to high-voltage circuits (i.e., 230 kV and above).
Transmission congestion describes a situation in which lower cost power cannot reach its intended market because the transmission system is not able to carry the electricity. Typically occurring during periods of peak demand, congestion results from a constraint along the transmission line – either a physical, electrical, or operational limit. PJM electricity prices are called Locational Marginal Prices (LMPs) and vary across PJM according to zone. Transmission congestion can have a significant impact on these location-specific prices of electricity in the wholesale markets. Generators selling electricity in a zone with transmission congestion may be able to obtain higher prices than a generator with comparable operating costs located in a zone that is not subject to transmission congestion.
| LMP differentials between PJM regions are mainly due to congestion between the Western Region, where abundant low-cost generation is located, and the Mid-Atlantic Region, where the large load centers are. PJM estimates that congestion added approximately $57.7 million in costs for BGE in 2007 and $66.6 million for Delmarva Power – the distribution utilities serving most of Central and Eastern Maryland. To reduce congestion and improve system reliability, a number of new transmission projects are being proposed, three of which would affect Maryland: the Trans Atlantic Interstate Line (TrAIL), the Potomac-Appalachian Transmission Highline (PATH), and the Mid-Atlantic Power Pathway (MAPP) (see map on page 8). |
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