Biomass is probably our oldest source of energy. For thousands of years, people have burned wood to heat their homes and cook their food. Biomass gets its energy from the sun.
All organic matter contains stored energy from the sun.
During a process called photosynthesis, sunlight gives plants the energy they need to convert water, carbon dioxide, and minerals into oxygen and sugars. Biomass is a renewable energy source because its supplies are not limited. We can always grow trees and crops, and people will always produce garbage. Usually we burn wood and use its energy for heating. Burning, though, is not the only way to convert biomass energy into a usable energy source.