Logs, wood chips, brush clippings, and grasses can all serve as woody biomass -- renewable fuels suitable for producing heat and power.
Burning wood logs in a fireplace once helped heat homes. These days, traditional fireplaces serve more for ambiance than heating, because they allow cold air inside and pollute the air. Modern designs of wood stoves (for burning logs) and pellet stoves (for burning compressed biomass pellets) produce less air pollution and are more energy efficient than traditional fireplaces.
On a larger scale, woody biomass can fire boilers that heat schools, offices, institutions, and manufacturing facilities. The largest wood-powered facilities typically produce both heat and electricity at the same time; such thermal and electric power “cogeneration” systems are most energy efficient.
Like any power source, woody biomass has its benefits and challenges.