Technical Abstract: Switchgrass was managed as a biomass energy crop in field trials on marginal cropland on ten farms in three states to determine net energy based on inputs and yields. Net energy averaged 43.5 GJ ha-1 y-1. Switchgrass produced 540% more renewable energy than nonrenewable energy consumed. Greenhouse gas emissions from switchgrass were 94% and 76% lower than gasoline or corn ethanol, respectively. Switchgrass managed for high yield had equal or greater net energy than low input perennial polycultures and can produce 350% more liquid fuel per hectare. Improved switchgrass genetics and agronomics will enhance net and total energy yields.