1000 watts
Joules are a measure of energy; Watts are a measure of the rate of energy generated or consumed. A Watt is defined as one joule per second. So if your 1000 Joules flowed in one second, the power would be 1000 Watts or 1 kW. But if it took 1000 seconds for the 1000Joules to flow, the power would be 1 Watt.