The Railpower GG20B Green Goat is a low-emissions diesel hybrid switcher locomotive built by Railpower Technologies Corp. It is powered by a single Caterpillar C9 six cylinder inline engine developing 300 horsepower (224 kW), which is also connected to a large battery bank where both sources combine for a total power output of 2,000 horsepower (1,490 kW). To date, there have been more than 50 GG20B diesel-electric hybrid switchers manufactured since their first introduction in 2004.