Spring 2000 Volume 9, Number 1
UNCLE BOB'S WOOD DIATRIBES
by Bob Mayer, Consulting Forester
Athough the popularity of burning wood has decreased since the passing of the "energy crisis" wood as an energy source continues to be a popular topic for industrial and municipal applications. In the north and northeastern regions of the US, fossil fuel energy costs remain relatively high and residential wood burning likewise remains popular. The primary use of wood on the planet earth is for fuel to cook food. Fuelwood use has increased approximately 22% from 1980 to 1997. In developing nations 80%of the total round wood consumption is for fuel. Many nations feel fuelwood needs will decline when their nations become more affluent. They feel their use of fossil fuels will increase, negating the need for wood as a fuel.
From a political and sociological green standpoint, residential wood burning wears both a white and a black hat. As we are all aware, a segment of our society continues to view cutting trees as "bad" and also generally views burning wood as environmentally "dirty". While residential wood fueled space heaters can be "dirty" from a particulate emission standpoint, the newer models on the market are amazingly clean. The introduction of the catalytic combustor not only increased wood stove efficiency by 10% to 25%, but additionally reduced overall wood heat appliance air pollution by as much as 80%. Today's wood pellet stoves provide a preview of just how clean residential and industrial wood burning can be.
On a positive side, wood burning hits all the right terms for today's society. First off, if you are burning wood you are conserving fossil fuels. The following discussion may be somewhat rhetorical, but conversely may be of use in discussions with your "green" associates. As a tree grows, it absorbs sunlight, carbon dioxide (CO2) and soil nutrients to create wood fiber, while producing oxygen (02) in the process. When a tree is burned it makes heat, consumes 0-2, and releases its nutrients in the form of ash. It will make the identical amount of C02 during combustion as it absorbed during growth. If that same tree is land filled or decays on the forest floor, it will decompose into identical chemicals and produce the same volume of heat, albeit more slowly. Ever feel your compost pile heatup?
If you do not burn wood to obtain the heat that the fiber contains, the wood will decompose (oxidize) into C02, heat, and ash anyway. If you burn oil, gas or coal (electricity) to make the heat you need, you give Mother Earth a double dose of C02 ... once from the wood waste composting and a second dose from the combustion of fossil fuels. Maybe there is a lesson here: Wood waste is not waste unless it is wasted.
You can (and should) easily look at a tree as an inexpensive, self-repairing, oxygen producing, self-aligning, renewable solar collector that stores energy until you want it. All you have to do is bum it. (There are other ways of getting this some tree energy though) If we did not burn fossil fuels there would be no "greenhouse effect" today. White Hat.
An Addendum ... not wholly relevant, but perhaps good grist for your select green acquaintances...
If you are a recycled product advocate, be mindful of the true content of post consumer material contained in available recycled products. Be especially careful to see that non-renewable, recycled plastic or metal products contain minimally 30% post consumer material. The point is this: Plastics (derived from oil) and metals have a high-embodied energy content (read: oil/cool/nuclear energy used in the extraction, manufacture & transport processes). Remember that wood fiber has been recycling itself for a billion years or so ... we have brought about practices to limit its use by prohibiting its entry into landfills and chemically preserving wood. As referenced above, wood is manufactured with solar energy, as such; its low energy conversion (sawing/drying/planing) makes it far lower in embodied energy content than most recycled non-renewables. White Hat II.
Lastly, lots of folks wish to use wood chips or bark mulch as landscaping mulch. While one can certainly mulch the shrubs with the industrial by-products, a little composting may be beneficial. Wood fiber alone is not the best ground cover as it hosts insects including termites, and robs the soil to a degree of available nitrogen. Woodchips have an 800:1 carbon to nitrogen ratio. However, composed with sludge, or simply composted over time perhaps with the addition of nitrogen amendments, it is an excellent soil humus additive. The wood fiber provides carbon and oxygen, sludge or nitrogen amendments provide the nitrogen. The ideal carbon to nitrogen ratio is about 40:1. Compost treatment encourages natural vegetation restoration and inhibits the uptake of heavy metals in edible plants.
Bob Mayer is a consulting forester focusing on forest industries, as well as traditional forestry. The Mayer family is entering their 23rd year of winter heating freedom from fossil fuels.