lbs/cu.ft. x (cu.ft./cord) = (lbs/cord)(lbs/cord) x (btu/lb) = (btu/cord) |

57 lbs/cu.ft. x (cu.ft./cord) = (lbs/cord)(lbs/cord) x (btu/lb) = (btu/cord) |

57 lbs/cu.ft. x 85 (cu.ft./cord) = 4845 (lbs/cord)4845 (lbs/cord) x (btu/lb) = (btu/cord) |

Oxygen Bomb Calorimeter | + | Wood at 0% Moisture Content | = | 8660 btu/lb(Absolute Heat Value of Fuel Wood) |

Well, we're not going to use that number. While useful in analyzing theoretical problems, the absolute fuel value of wood does not reflect real-world available heat.

100% Efficient Stove | + | Fuel Wood at 20% Moisture Content | = | 6928 btu/lb(Theoretical Heat Value of Fuel Wood) |

We're not going to use that number either. The graphic formula shown above, while mathematically accurate, still doesn't reflect a real-world situation, because it is not possible for a wood stove to extract 100% of the Heat Value to the room. The explanation is twofold:

Real Stove w/ 350° Exhaust | + | Fuel Wood at 20% Moisture Content | = | 6200 btu/lb(Available Heat Value of Fuel Wood) |

Voila! Here's what we get when we plug in the Available Heat Value to finish our formula for Osage Orange:

57 lbs/cu.ft. x 85 (cu.ft./cord) = 4845 (lbs/cord)4845 (lbs/cord) x 6200 (btu/lb) = 30 (mbtu/cord) |

Now, let's run the formula for Willow. On the Engineering Toolbox list, Willow at 20% moisture content weighs 27 pounds per cubic foot:

27 lbs/cu.ft. x 85 (cu.ft./cord) = 2295 (lbs/cord)2295 (lbs/cord) x 6200 (btu/lb) = 14.2 (mbtu/cord) |

So you see, if your wood-seller is offering a cord of Osage Orange or a cord of Willow at the same price, you want to jump on the twice-as-heavy Osage Orange.

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