When the first two units were brought online in 1951, Edge Moor was the first major steam station in the Delmarva Power & Light electrical system.  Those units have since been retired.  Currently in operation are units 3, 4, 5 and 10.  Unit 3 began commercial operation in 1954, Unit 10 in 1963, Unit 4 in 1966, and Unit 5 in 1973.

 When Calpine acquired the 725 MW facility in 2010 as part of its purchase of the Conectiv Energy assets, the company discontinued burning coal at the site.  Calpine’s decision to run Edge Moor primarily using natural gas is in keeping with its corporate philosophy to produce power in an environmentally sensitive fashion.  Currently, the plant uses state-of-the-art technologies, installed in early 2009, to control emissions.

 Unit 10 is a combustion turbine unit that uses low-sulfur diesel.