Our sun produces more energy every second than 1 billion major cities would produce in one year. Our galaxy produces 20 billion times more. In numbers, the energy output of our galaxy is 4x10^58 watt-second every second. The estimated output of the observable universe is 4X10^69 watt-second.
Sources:
Lisle, Jason. Taking Back Astronomy. Green Forest, AR: Master, 2006. Print.
http://en.wikipedia.org/wiki/Orders_of_magnitude_%28energy%29