Images: Black holes extremely energy-efficient

The particles in the gas discharge move at close to the speed of light. The amount of energy being discharged is almost equal to the amount of energy consumed in making them. As a result, black holes appear to be incredibly efficient. "If a car was as fuel-efficient as these black holes, it could theoretically travel over a billion miles on a gallon of gas," Christopher Reynolds, an astronomer of the University of Maryland, said in a prepared statement.