Is Wood Heat Green?
The scientific method follows a rigid methodology. Ask a question. Do background research. Construct a hypothesis. Test the hypothesis. And then, communicate the results.
So what is the question? Are the fires in our homes bad because they add to global warming? Release carbon dioxide into the air? Pollute the atmosphere with soot and particulate matter? All of the above?
Where is the research?
To answer these questions, and to analyze whether wood heat is green or not, we must consider the three impacts heating with wood has on the environment.
- Air pollution from the smoke (smog).
- The impact on air quality inside the wood heated dwelling.
- Impact wood collection/harvesting has on our forests.
Fortunately there is data available, even though the Air Quality Control Board chooses to ignore it. Letâ€™s consider these points one by one:
According to an EPA report in 1993 (EPA-453/R-93-036), wood smoke is comprised of some fifty noxious and lethal sounding chemicals whose names bureaucrats like to toss around to frighten us. But in point of fact these fifty odd chemicals A) are only produced by a smoldering fire (the kind of fire an airtight outdoor wood stove typically produces), B) of the fifty, only a few are carcinogenic, and C) in most rural environments the smoke blows away before it can bother anyone; only in some areas are there inversion layers that cause the smoke from airtight stoves to become a health problem.
Secondly, new high-efficient outdoor wood stoves donâ€™t smoke at all! The emissions from these stoves are only slightly higher than from an oil fired furnace. And the gases are far less complex. Basically carbon dioxide, some carbon monoxide and a number of other gases, water vapor and some not quite completely oxidized bits of hydrocarbons. In more intelligent air quality jurisdictions these EPA approved high-efficiency outdoor wood stoves are permitted where regular stoves and fire places are otherwise banned.
Another valid question is: Does wood smoke contribute to global warming?
The answer is no. Heating with wood is technically carbon neutral. If you factor in the fossil fuels that are burned in its production (chain saw gas, wood splitters, trucks to haul it, etc.) itâ€™s not quite neutral, but still â€” studies done in Canada show that the amount of carbon dioxide released into the atmosphere to produce a given amount of heat from wood is about fifty percent (50%) less that the amount released by fuel oil to produce the same amount of heat,even factoring in the fossil fuels burned to â€œmakeâ€ that wood!
About 50% of the content of wood is carbon that the tree has absorbed from the atmosphere over its lifetime. If the dead wood is allowed to decay (oxidize) in the forest, that carbon is re-released into the atmosphere as carbon dioxide (CO2) over time. If the wood is burned it is released quickly. This is why, in fact, wood turns black when it burns. The non-carbon constituents (volatile oils, cellulose, etc.) burn off fairly quickly leaving only the carbon. The carbon contains more heat and thus burns more slowly, giving off CO2 gas. But itâ€™s the same amount of CO2.
By heating our homes with wood we are simply tapping into the natural carbon cycle flow of CO2 from the atmosphere to the forest and back again.
Fossil fuels, on the other hand, introduce new carbon to the atmosphere, thus throwing the whole natural balance out of whack. Do it long enough, which we have, and the result is the greenhouse effect weâ€™re now beginning to experience.
And as for the end result of smelly old wood smoke: As particles go, wood smoke that you can see is really big, really gooey, and really heavy. It travels only a short distance (relatively speaking) before falling to the ground where it becomes part of the mix of new, rich loam. Soil for new growth.
This is mostly a matter for each home owner. Obviously, breathing wood smoke isnâ€™t good for you. And like all smog, itâ€™s hardest on young children and the elderly. But choosing a outdoor wood stove that doesnâ€™t smoke every time you open the door is the responsibility of the buyer. Obviously cheaper (or older) airtights are more likely to smoke than newer, more expensive models. High-efficiency outdoor stoves donâ€™t smoke at all when you open the door.
In the United States â€œfuel woodâ€, as itâ€™s called, normally comes from two sources: A)Hardwoods harvested as part of normal logging operations that are then purchased by firewood vendors, or B) dead fall removal from U.S. Forest Service via the Forest Serviceâ€™s long standing fuel wood permit program.
While the former may, or may not be sustainable (depending on ones view of any particular logging operation) the latter is a venerable program that allows citizens and commercial firewood sellers to remove only dead and downed wood from the National Forest. Each load must be tagged and logged onto the permit form by the collector for inspection by the Forest Ranger. In the thirty or so years this program has been in operation there has been no apparent deleterious effects to the forests from this very ancient firewood collection practice.
So yes, properly managed and harvested, wood heat is green and is good for the planet. One of the only nearly universal sources of heat for cooking, heating water and our homes available to mankind that can make that claim. The Bay Area Air Quality Management District needs to cop a clue!
Article from Michael Matsonâ€™s Alternative Building Services.
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