The country's largest electricity company is on alert for cyberattacks that aim to hamper the critical flow of power and is listening to U.S. intelligence agencies about potential threats, the Duke Energy Corp. executive heading electronic protection efforts said. Duke Energy manages dams, nuclear power plants and other types of electricity-generating plants - three of the 16 types of infrastructure critical to American life that the U.S. is focused on protecting from criminal hackers and hostile governments.