An Introduction to Biomass Thermochemical Conversion - NREL

Basic Definitions
Biomass is plant matter such as trees, grasses, agricultural
crops or other biological material. It can be used as a solid fuel, or
converted into liquid or gaseous forms for the production of
electric power, heat, chemicals, or fuels.
Black Liquor is the lignin-rich by-product of fiber extraction
from wood in Kraft (or sulfate) pulping. The industry burns black
liquor in Tomlinson boilers that 1) feed back-pressure steam
turbines supplying process steam and electricity to mills, 2)
recover pulping chemicals (sodium and sulfur compounds) for
reuse.