What is renewable energy?
(EERE Biomass Program - http://www.eere.energy.gov/biomass/bioma..._faqs.html)
Energy derived from resources that are regenerative or for all practical purposes can not be depleted. Types of renewable energy resources include moving water (hydro, tidal and wave power), thermal gradients in ocean water, biomass, geothermal energy, solar energy, and wind energy. Municipal solid waste (MSW) is also considered to be a renewable energy resource.
What are energy crops?
(EERE Biomass Program - http://www.eere.energy.gov/biomass/bioma..._faqs.html)
Energy crops are crops that are grown for the specific purpose of producing energy (electricity or liquid fuels) from all or part of the resulting plant. Switchgrass, alfalfa, willow, poplar and eucalyptus are examples of plants that can be grown as energy crops.