Wood-fired steam boilers convert water into steam and are fueled by wood. While these systems are not as popular as other types of boilers, they offer some advantages, such as cost savings.
Oil or gas delivery can be expensive, so people in remote regions sometimes rely on wood-fired boilers. In addition, carbon released from burned wood was absorbed from the atmosphere while the tree was growing, making wood a carbon-neutral fuel, according to some calculations.
However, wood-fired boilers release more particulate matter than gas and oil boilers, and their overall efficiency is significantly lower. Burned wood leaves behind a significant amount of ash, which must be disposed of safely.