Firewood
From Wikipedia, the free encyclopedia
Firewood was the primary source of fuel until the 1800s, when it was displaced by coal and later by oil. Firewood is a renewable resource, provided the consumption rate is controlled to sustainable levels. Today firewood is usually obtained from timber or trees unsuitable or unwanted for building or construction. In the United States, firewood is sold by the cord, and is therefore also called cordwood.
Of all of the renewable resources, only biomass, including wood, and geothermal need to be carefully managed in order to prevent depletion.[1] The shortage of suitable firewood in some places has seen local populations damaging huge tracts of bush thus leading to further desertification. On the other hand, proper forestry practices applied to firewood allow the usage of a carbon-neutral, or even carbon-negative, energy source, since the carbon dioxide released by the burning of the firewood was previously absorbed from the ambient atmosphere through photosynthesis. Because of this, firewood can be considered to be a form of solar energy.
Contents |
[edit] Harvesting firewood
Some firewood is harvested in "woodlots" managed for that purpose,[2] but in heavily wooded areas it is more usually harvested as a byproduct of natural forests. Deadfall that has not started to rot is preferred, since it is already partly seasoned. Standing dead timber is considered better still, as it is both seasoned and has less rot. Harvesting this form of timber reduces the speed and intensity of bushfires. Harvesting timber for firewood is normally carried out by hand with chainsaws. Thus, longer pieces - requiring less manual labour, and less chainsaw fuel - are less expensive and only limited by the size of their firebox. Prices also vary considerably with the distance from wood lots, and quality of the wood. Buying and burning firewood that was cut only a short distance from its final destination prevents the accidental spread of invasive tree-killing insects and diseases.[3] Generally speaking, a distance of 50 miles (83km) from cut site to final burning site is considered the longest distance that firewood should be moved.
Normally wood is cut in the winter when trees have less sap so that it will season more quickly. Most firewood also requires splitting, which also allows for faster seasoning by exposing more surface area. Today most splitting is done with a hydraulic splitting machine, but it can also be split with a splitting maul.
[edit] Measurement of firewood
[edit] Cord
In the metric system, firewood was normally sold by the stère (= 1 m³ = ~0.276 cords). Currently it is also sold to consumers by the kilogram.
In the United States, firewood is usually sold by the cord, 128 ft³ (3.62 m³), corresponding to a woodpile 8 ft (2.4 m) wide × 4 ft (1.2 m) high of 4 ft-long logs. The cord is legally defined by statute in most states.
[edit] 1/3rd cord ("face cord" or "rick")
It is also common to see wood sold by the "face cord" or "rick," which is usually not legally defined, and varies from one area to another. For example, in one state a pile of wood 8 feet (2.4 m) wide × 4 feet (1.2 m) high of 16"-long logs will often be sold as a "face cord" or "rick," though its volume is only one-third of a cord. In another state, or even another area of the same state, the volume of a face cord may be considerably different. Hence, it is risky to buy wood sold in this manner, as the transaction is not based on a legally enforceable unit of measure.
In Australia, it is normally sold by the tonne.
[edit] Heat Value of Firewood Types
The amount of heat energy provided by firewood when burned varies by the species of the wood.[4]
| Wood Species | Heat Value |
|---|---|
| Tamarack | 22.3 MBTU/Cord |
| Birch | 21.3 MBTU/Cord |
| Red Fir | 20.6 MBTU/Cord |
| White Fir | 16.7 MBTU/Cord |
MBTU/Cord = Million BTU per Cord
[edit] How to buy firewood
The only measurement of firewood that is regulated is a cord. All other measurements including 1/3 cord, half cord, and truckloads are not regulated. Also, firewood can either be seasoned or unseasoned and that can affect the price. Kiln dried firewood, although more expensive, burns very well and is not a potential risk for the unintentional transport of tree-killing insects and diseases. This makes kiln-dried wood the only commonly available form of firewood that is safe to move over long distances.
Firewood is classed as either hardwood such as Apple, Cherry, Maple, Oak or Walnut, or softwood such as Fir, Hemlock, Pine or Spruce. Both classes of wood has its own characteristics. Hardwoods tend to have a higher heating value than softwoods, but are harder to split and ignite than softwoods. Softwoods tend to burn more quickly with a crackling sound and produce more residue than hardwoods. Exceptions to these rules are the hardwoods Alder and Birch, which burn like hardwoods but split like softwoods.
[edit] Seasoned firewood
Firewood needs to be seasoned for 8 months[citation needed], so the best time to buy firewood would be in the spring. It is also the cheapest time to buy firewood. The term seasoned is not regulated, so a reseller can claim that they are selling seasoned firewood, but it may not be seasoned for a full 8 months.
Using 4 mil plastic it is possible to create a greenhouse effect and decrease the amount of time needed to season the firewood. See the link below.
The energy content of a cord of wood depends on the type and moisture content of the wood, and ranges from 15.5 to 32 million Btu per cord.[5]
[edit] How to stack firewood
There are several methods for stacking firewood.
Under a roof: Here are no concerns about the wood being subjected to rain, snow or run-off. The methods for stacking depend on the structure and layout desired. Whether split, or in 'rounds' (flush-cut and unsplit segments of logs), the wood should be stacked lengthwise, which is the most stable and practical method.
Outdoors: Firewood should be stacked with the bark facing upwards. This allows the water to drain off, and standing frost, ice, or snow to be kept from the wood. When possible, a tarp or water-proof cover may be placed over the top of the pile. This can be a large piece of plywood or an oiled canvas cloth, although cheap plastic sheeting may also be used.
A Holz hausen, or "wood house", is a circular method of stacking wood which results in accelerated drying and a small footprint. A traditional holz hausen has a 10 foot diameter, stands 10 feet high, and holds about 6 cords of wood. The walls are made of pieces arranged radially, and tilted slightly inward for stability. The inside pieces are stacked on end to form a chimney for air flow. The top pieces are tilted slightly outward to shed rain and are placed bark side up. If constructed correctly, this method of stacking can produce seasoned firewood in as little as three months.[6]
[edit] See also
[edit] References
- ^ Brown, Lester, Flavin, Christopher, Postel, Sandra, Saving the Planet: How to Shape an Environmentally Substainable Global Economy 1991 ISBN 0393030709 pg. 57
- ^ Where does firewood come from?
- ^ Dontmovefirewood.org
- ^ Energy Content of Firewood
- ^ Preparing your fuel supply
- ^ How to construct a Holz Hausen
