25 Matching Annotations
  1. Aug 2021
  2. Oct 2020
  3. Nov 2019
    1. To grow, trees photosynthesize and turn water and carbon dioxide (pulled from the air), into hydrocarbons. A living tree sucks carbon dioxide from the air and locks it into wood as it grows. Even when the tree dies (unless we burn it), the carbon is still locked up in the wood

      Cycle of tree's life

    2. For a wood fire, ash is primarily composed of metal carbonates and oxides (such as Calcium Carbonate, and Potassium Carbonate), from the compounds in the original wood

      Ash - compounds that did not burn

    3. As long as there is a source of fuel (and oxygen), the fire will burn

      Oxygen keeps the fire alive

    4. As the fire gets hotter, more complete combustion occurs, less smoke is produced, and the flames lose the yellow color, turning more blue

      As the fire gets hotter:

      • more complete combustion
      • less smoke
      • yellow colour turns into blue
    5. yellow flames seen in a fire are the result of incomplete combustion

      Yellow flames - incomplete combustion

    6. smoke produced (early stages of fire) is unburned carbon

      Smoke - unburned carbon

    7. It is the volatile compounds that out-gas from the wood, and eagerly react with oxygen, that are burning, and generate the flames we see

      Generation of flames - volatile compounds eagerly reacting with oxygen

    8. When the temperature of wood is increased (through application of heat), first the water is driven off. This occurs up to about 200°C. Between approximately 200°C–280°C the heat starts to break down the hemicellulose compounds into Carbon Monoxide, Carbon Dioxide, Acetic Acid, (and more water vapour); these are driven out. Between 280°–500° decomposition of the longer cellulose and lignin begins and produces light tars and Methyl Alcohol

      Burning process:

      1. < 200°C - water is driven off
      2. 200°C-280°C - heat breaks down the hemicellulose compounds into Carbon Monoxide, Carbon Dioxide, Acetic Acid, and more water vapour
      3. > 280°C - hydrogen is still produced. Oxygen reacts directly with the Carbon left in the wood exothermically (process happening in the glowing embers)
    9. A couple of hundred intermediate products (organic acids, ketones, esters, aldehydes …) have been identified as being produced by the pyrolysis of wood

      Output from wood pyrolysis

    10. The pyrolysis of wood is an incredibly intricate and complex process that is not completely mapped out and the exact output depends of many variables

      Pyrolysis is complex and relies on lots of variables (type of wood, temperature...)

    11. The correct term to describe what is going on when we ‘burn’ wood is Pyrolysis

      Pyrolysis (from Greek) - correct term for "burning" wood (thermal decomposition)

    12. The chemical composition of wood varies from species to species, but is approximately 50% carbon, 42% Oxygen, 6% Hydrogen, 1% Nitrogen, and 1% other elements (mainly Calcium, Potassium, Sodium, Magnesium, Iron, and Manganese) by weight

      Chemical composition of wood. Mainly:

      • 50% carbon
      • 42% oxygen
      • 6% hydrogen
    13. Wood is the hard-fibrous material that comes from the trunk, stems, roots, and branches of a once living tree

      What is wood

  4. May 2019
  5. Sep 2018
  6. Jan 2018
  7. Nov 2017
  8. Aug 2017
  9. Apr 2017
  10. Feb 2016
    1. He expects that the logging project near Quimby’s land will likely generate about $755,250 at the state’s average sale price, $50.35 per cord of wood. The land has about 1,500 harvestable acres that contain about 30 cords of wood per acre, or 45,000 cords, but only about a third of that will be cut because the land is environmentally sensitive, Denico said. The Bureau of Parks and Lands expects to generate about $6.6 million in revenue this year selling about 130,000 cords of wood from its lots, Denico said. Last year, the bureau generated about $7 million harvesting about 139,000 cords of wood. The Legislature allows the cutting of about 160,000 cords of wood on state land annually, although the LePage administration has sought to increase that amount.
  11. Dec 2015
    1. from plantations. If that were to increase to 75 percent, the logged area of natural forests could drop in half.” Meanwhile the consumption of all wood has leveled off---for fuel, buildings, and, finally, paper. We are at peak timber.
  12. Sep 2015