Sustainable Firewood: Recycling Atmospheric Carbon

Published Feb 9 2010 by The Wood Heat Organization Inc.
by John Gulland

Wood is a renewable fuel because young trees grow up to replace those harvested for fuel. That’s a simple enough statement, but there is much more to consider when you look into the details.

The use of wood as a heating fuel does not contribute to global warming and climate change the way fossil fuels do. When oil, gas and coal are burned, the carbon they contain (which was absorbed from the atmosphere by plants millions of years ago) is oxidized to carbon dioxide (CO2), the main greenhouse gas. In effect, the combustion of fossil fuels releases ancient carbon, thereby increasing the atmospheric concentration CO2.

Wood is about half carbon by weight but its use as a fuel releases a far smaller net amount of carbon dioxide per unit of heat than the fossil fuels. This is because trees absorb CO2 as they grow so that much of the carbon released in combustion is absorbed by young trees. When trees mature, die and fall in the forest and decompose there, about the same amount of CO2 is emitted as would be released if they were burned for heat. In other words, decomposition (rot) is a slow form of oxidation whereas combustion in a wood stove or furnace is fast oxidation, with heat as a by-product. KEEP READING >>