You made a correct assertion initially "power (1.5 gigawatts) and energy (power over time)," but then failed to use it correctly. 1.5 gigawatts is a rate, of 1.

You made a correct assertion initially "power (1.5 gigawatts) and energy (power over time)," but then failed to use it correctly. 1.5 gigawatts is a rate, of 1.5 billion joules per second.