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. Let’s consider these points one by one:
Wood Smoke
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 don’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.) it’s not quite neutral, but still — 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 “make” that wood!
Why?
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 it’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 we’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.
Air Quality
This is mostly a matter for each home owner. Obviously, breathing wood smoke isn’t good for you. And like all smog, it’s hardest on young children and the elderly. But choosing a outdoor wood stove that doesn’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 don’t smoke at all when you open the door.
Forest Impacts
In the United States “fuel wood”, as it’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 Service’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 Matson’s Alternative Building Services.
The choice to burn wood is a solid economic and environmentally friendly decision which is supported by a the fact that it is a naturally renewable fuel. Energy generated by both outdoor wood furnaces and wood pellet stoves in a clean combustion system, benefits both industry and the environment.
Energy produced from wood strengthens all industries by reducing dependence on foreign fossil fuels, which produce higher amounts of CO2 (greenhouse gas), and decreases the amount of wood burning waste in landfills.
Carbon Dioxide, CO2, naturally exists in the planet’s atmosphere and is an important part of supporting life. Most plants and trees use carbon dioxide in the atmosphere to promote their growth through a process known as photosynthesis. At the end of a plants or trees life cycle they rot in the forest or can be burned by man to create energy. When either of these happen they release the same amount of carbon back into the planet’s atmosphere creating what is called a carbon neutral process.
Jun. 25 – Alternative biomass fuels like wood chips are starting to compete with conventional coal and gas heating systems in the UK.
Companies and public authorities are starting to think about cleaner ways to heat their offices and other buildings.
Chris Burns reports for Reuters
© Reuters 2007. All rights reserved.
2. FUEL USED: Only those listed fuels recommended by the manufacturer of your unit.
Never use the following: trash, plastics, gasoline, rubber, naphtha, household
garbage, material treated with petroleum products (particle board, railroad ties and
pressure treated wood), leaves, paper products, and cardboard.
3. LOADING FUEL: For a more efficient burn, pay careful attention to loading times and
amounts. Follow the manufacturer’s written instructions for recommended loading
times and amounts.
4. STARTERS: Do not use lighter fluids, gasoline, or chemicals.
5. LOCATION: It is recommended that the unit be located with due consideration to the
prevailing wind direction.
• Furnace should be located no less than 100 feet from any residence not served by
the furnace.
• If located within 100 feet to 300 feet to any residence not served by the furnace, it
is recommended that the stack be at least 2 feet higher than the peak of that
residence.
6. Always remember to comply with all applicable state and local codes.
Provided by the Hearth, Patio and Barbecue Association (HPBA), Outdoor Furnaces Manufacturers Caucus.
Initially the power station will burn forest residue – sawdust, branches and offcuts from a local sawmill. “If this residue wasn’t burnt then it would just rot down and produce carbon dioxide anyway. We can speed this process up by burning it and producing heat and power at the same time,” says Reay. The power station not only reduces reliance on fossil fuels, it will harness energy from something that would otherwise be left lying around.
Eventually, when all the forest residue has been used up, E.ON hopes to encourage local farmers to start producing a fast-growing willow, which can be burned in the power plant.
“Growing crops to feed the biofuel plant has a few caveats,” says Reay. “If the wood has to be trucked in from a long way away, or if fallow land is specially cultivated to grow the crops, then you lose the carbon neutral benefit.” You have to be careful which biofuels you grow. “Some, like sugar-cane, produce greenhouse gases while growing.” But overall a wood-burning power station is likely to be a positive environmental step.
Kate Ravilious / Saturday October 15, 2005 / The Guardian