 Several notable energy companies are headquartered in the state , including American Electric Power , Columbia Gas of Ohio , <unk> Inc . , Marathon Petroleum Company , American Municipal Power , Inc . , Cliffs Natural Resources , Murray Energy , FirstEnergy , Oxford Resource Partners LP , AB Resources , American Hydrogen Corporation , and IGS Energy . Rolls @-@ Royce North America 's Energy Systems Inc . , a subsidiary of United Kingdom @-@ based Rolls @-@ Royce plc , is headquartered in Mt . Vernon , specializing in gas compression , power generation , and pipeline technologies . Ultra Premium Oilfield Services and V & M Star Steel operate steel production facilities in the state , which cater to energy exploration . 
