COLUMBUS, Ohio, May 24, 2021 /PRNewswire/ -- Cardinal Operating Company (COC) on behalf of AEP Generation Resources Inc. (AEPGR), an unregulated wholly owned subsidiary of AEP Energy Supply, LLC, is seeking bids for the supply of coal to Cardinal Power Plant Units 1, 2, and 3. AEP Energy Supply, LLC, which owns Cardinal Unit 1, is a wholly owned subsidiary of American Electric