Biomass cofiring refers to the simultaneous combustion of a biomass fuel and a base fuel to produce energy, usually electrical power. The most common base fuel is coal. The most common sources of biomass fuel include low-value wood from forestry activities, crop residues, construction debris, municipal waste, storm debris, and dedicated energy crops, such as switchgrass, willow, and hybrid poplar. Most biomass feedstocks must undergo significant processing before they can be utilized for cofiring. The shape, size, and moisture-content of feedstock particles need to be adjusted to meet specifications.