Biomass is biological material from living or recently living organisms that can be used as an energy source. Examples of biomass include wood, trees, shrubs, crops, grasses, algae, and animal and food waste. Biomass is a renewable source of energy because it comes from sunlight that plants absorb to grow, and biomass can be regrown as it is used. Biomass is burned in boilers to produce steam that turns turbines and generates electricity.