Btu's One Pound of Wood Could Produce

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Estimate the amount of Btu's one pound of wood will produce depending on moisture content and the efficiency rating of the unit your are using to burn the wood.

Btu's

All species of wood generate similar heat, Btu's on a per pound basis with a slightly higher amount for high resinous species of trees.

It is said that under ideal conditions one pound of wood @ 0% MC can produce 8600 Btu's. Species that contain a high amount of resin can produce as much as 9000 + Btu's/pound.

Loss due to moisture from the combustion of hydrogen reduces the amount of potential Btu's by about 6% .
This will reduce the potential 8600 Btu's to 8084 Btu's and the 9000 Btu's figure to 8460 Btu's

8600Btu's (=100%) - 6% = 100% - 6% = 94% = 8600 * (94% / 100) = 8600 * 0.94 = 8084 Btu's
9000Btu's (=100%) - 6% = 100% - 6% = 94% = 9000 * (94% / 100) = 9000* 0.94 = 8460 Btu's

Use 8084 Btu's for your calculation and if your firewood has a high resinous content start of with 8460 Btu's

Moisture

Burning wood with a high moisture content is a waste of energy. Wood that is dried to a low moisture content produces a cleaner, hotter fire with less smoke and it also generates more Btu's than wood with a high moisture content.

Btu's at various moisture content(MC):
@ 65% MC-- 8084 * 0.606 (lbs/dried wood)= 4899 Btu's.
@ 30% MC-- 8084 * 0.769 (lbs/dried wood)= 6217 Btu's.
@ 20% MC-- 8084 * 0.833 (lbs/dried wood)= 6734 Btu's.

To see where value of 0.606 (lbs/dried wood) comes from look here!

Heat value * efficiency:

How you are burning your wood will further effect the amount of Btu's per pound. When wood is burned not all the energy (heat) will be available to you. If the wood burning fireplaces that we placed in homes in the old days were rated for efficiency, you would be lucky if it was over 10% efficiency. If your burning unit has an efficiency rating of 60% it will reduce the Btu's by 40% and the 6734 Btu's @ 20% MC will be reduced to 4040 Btu's per one pound of wood containing 20% moisture

Moisture Content %
Btu's Btu/pound
Efficiency %

Results:

Btu's Reduced by MC of Wood Btu's/lb
Final Heat Value per Pound of Wood Btu's/lb

The Calculation

  1. Moisture content of wood (percentage)
  2. Btu's per pound of wood (Btu's per pounds you wish to calculate for)
  3. Efficiency (percentage heating efficiency)

Results

  1. Btu's one pound will produce @ your MC%.
  2. Btu's one pound will produce reduced by the efficiency rating of your burning unit.


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