The lightning strike lasts for $30$ microseconds. Does this mean that you get $100$ TW of energy in just $30$ microseconds?
You are confused about units. Watt is a unit of power (energy/time), Watt-hour is a unit of energy. 16TW is an estimate of the continuous average power usage of the world - which is about 140,000 TWh each year. If the lightning has a peak power of 1TW for 30 microseconds, this corresponds to an energy content of about 8000 Watt-hours.