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Is burning wood for heat carbon neutral?

Post in 'The Green Room' started by Dune, May 31, 2011.

  1. allhandsworking

    allhandsworking Feeling the Heat

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    [quote author="btuser" date="1307075733"]I'd have to say no. A lot of wood is just going to rot in place, therefor release the carbon anyway so look at it that way. Wood fermenting in a forest stew will produce methane which is a lot worse than CO2.[/quote
    That's right and burning that local wood is displacing the fossil fuel that would have been burned! Most wood burners use standing dead, fallen, or trimmed timber that would have rotted or been transported to a land fill.

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  2. allhandsworking

    allhandsworking Feeling the Heat

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    Sorry redundant.
  3. tom in maine

    tom in maine Minister of Fire

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    Interesting thread.
    Burning wood is one hell of a lot more carbon neutral than any fossil fuel.

    Here in Maine, in-growth per acre per year is about 1/2-1 cord.
    It is not anywhere near as efficient as a solar thermal collector but it still is solar heat and it is what I consider the
    "current" carbon cycle. It is not carbon that was sequestered millions of years ago that when released is going to contribute to
    global warming.

    As long as it is burned in something efficient and is produced in a sustainable way, it is a way station
    for us as we transition to solar and/or zero energy buildings.

    I will burn wood or pellets rather than fossil fuels anywhere I can.
    It is not perfect, just better.
  4. Seasoned Oak

    Seasoned Oak Minister of Fire

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    ditto on the re-purposed pine, 2/3 s on the wood i burn would have gone to the landfill. Oak floorboards ,floor joists,,wall studs,lathe boards ,most 100 years old or so.
  5. Dune

    Dune Minister of Fire

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    Thanks.
  6. GaryGary

    GaryGary Feeling the Heat

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    Hi,
    Sorry I missed your post -- better late than never :)

    Heating Degree Days are a way of accumulating the heating load over a time period like a whole heating season.
    Basically if the average outside temperature for a day is 10F lower than than the inside temperature, then that is 10 heating degree days accumulated.
    To getting the total heating degree days for the whole season, you just add up each day's heating degree days.
    So, when it says a 6000 Heating Degree Day (HDD) season, it means that the adding up all the daily HDDs for the whole season gives you a total of 6000 Heating Degree Days. Here in Bozeman our season is about 8100 HDD.

    The seasonal HDD's are published for hundreds of locations -- some sources here:
    http://www.builditsolar.com/References/Calculators/InsulUpgrd/HDDhelp.htm
    There is a little more to it than explained above, but is covered at the link.

    To turn HDD into how much heat a house will use, you have to know the heat loss of the house.

    First start with just the hourly heat loss through an example wall:
    If you have an R15 wall that is 100 sqft, and its 20F outside and 70F inside, then the heat loss per hour is:

    HL = A * (Tin -Tout)/Rvalue = (100sqft)*(70F - 20F)/R15 = 333 BTU/hr

    The HDD number lets you turn that hourly estimate into a whole season estimate -- the formula becomes:

    HL = A * HDD * 24 / Rvalue = (100 sqft)*(6000 HDD)*(24hr/day)/R15 = 960,000 BTU

    Its the same formula as the hourly loss with HDD*24 substituted for the temperature difference.
    The 24 comes from 24 hours per day.

    So, it says that in a 6000 HDD climate, that wall would lose 960,000 BTU over the full winter.
    If it was Fairbanks with a 14000 HDD winter, it would 2.2 million BTU.

    You don't have to do this all by hand, there are calculators out there that will do most of the work -- this is mine:
    http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

    I got the heat loss for the 2000 sf house using this calculator.

    Gary
  7. GaryGary

    GaryGary Feeling the Heat

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    I guess -- The whole thing could still be carbon neutral if you plant a few more trees each year than you harvest.

    But, even if you don't, I think its a pretty impressive saving -- burning 10 gallons of tractor fuel to harvest your firewood is a hundred times less carbon than burning a thousand gallons of home heating oil to heat your house the usual way.



    Gary
  8. barkeatr

    barkeatr Member

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    Upstate NY
    its hard not to "plant" as many trees as you cut. It happens automatically! As soon as you open the canopy the new available light triggers seed growth and massive growing of all the understory biomass. think about it, now the sun is hitting a much larger surface area than before the mature tree (that had optimized collecting the sun) came down.

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