Relationship between radio transmitter output power and its input electrical power?
The efficiency of typical RF trasmitter is between 20...30% for AM transmitters, and 40...70% for FM transmiters. It means, the transmitter expects on main power 2...4x greater than output power. 

For your example, 100,000W = 100kW on RF output means needs about 200...400kW of mains.