At the start, "The Seabolt" is shown as the newest invention of Dr. Seabolt. The Energy Cradle was supposed to be only a test. Later, it is said that The Seabolt: Unstable. Will self-destruct. Build the Energy Cradle before it's too late. Further, the player will keep using The Energy Cradle.
The Energy Cradle is Empires and Allies' equivalent of the Wind Farm in Cityville.