>> Do they mean 1.5 gigawatts per hour? or per day? or per year? 1.5 gigawatts is 1.5 billion joules per second. If you sustain that power for 2 hours it will

>> Do they mean 1.5 gigawatts per hour? or per day? or per year? 1.5 gigawatts is 1.5 billion joules per second. If you sustain that power for 2 hours it will produce 3 gigawatt-hours of energy. 1 watt-hr is 3600 joules because 1J/s for 3600 seconds.