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Firewood
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Firewood is any wood like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form.
Firewood is a so called renewable resource. However, demand for this fuel can outpace its ability to regenerate on local and regional level. For example in some places in the world and through history, the demand has led to desertification. Good forestry practices and improvements in devices that use firewood can improve the the local wood supplies.
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Firewood is any wood like material that is gathered and used for fuel. Generally, firewood is not highly processed and is in some sort of recognizable log or branch form.
Firewood is a so called renewable resource. However, demand for this fuel can outpace its ability to regenerate on local and regional level. For example in some places in the world and through history, the demand has led to desertification. Good forestry practices and improvements in devices that use firewood can improve the the local wood supplies. As a Biofuel, some consider firewood to be a form of solar energy and to be relatively carbon neutral.
Firewood terms
Since firewood has been used by humans for a long time, there are many terms and concepts to describe it.
North America
Firewood can either be seasoned (dry) or unseasoned (green). It can be classed as hardwood or softwood. In most of the United States, the standard measure of firewood is a cord or 128 cubic feet. However, firewood can also be sold by weight, when the moisture content is established. The BTU value can have an impact upon the price.
Harvesting firewood
Harvesting or collecting firewood varies by the region and culture. Some places have specific areas for firewood collection. Other places may integrate the collection of firewood in the cycle of preparing a plot of land to grow food as part of a field rotation process. Collection can be a group, family or an individual activity. The tools and methods for harvesting firewood are diverse.
North America
Some firewood is harvested in "woodlots" managed for that purpose, 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. 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.
Preparing firewood
In most parts of the world, firewood is only prepared for transport at the time it is harvested. Then it is moved closer to the place it will be used as fuel and prepared there. The process of making charcoal from firewood can take place at the place the firewood is harvested.
Storing firewood
There are many ways to store firewood. These range from simple piles to free-standing stacks, to specialized structures. Usually the goal of storing wood is to keep water away from it and to continue the drying process.
Stacks: The simplest stack is where logs are placed next to and on top of each other, forming a line the width of the logs. The height of the stack can vary, generally depending upon how the ends are constructed. Without constructing ends, the length of the log and length help determine the height of a free-standing stack.
Wood wants to absorb water. It is a good idea to place a stack on something or cover it if moisture or water is anticipated.
There are many ways to create the ends of a stack. In some areas, creating a crib end by alternating pairs of logs helps stabilize the end. A stake or pole placed in the ground is another way to end the pile. A series of stacked logs at the end, each with a cord tied to it and the free end of the cord wrapped to log in the middle of the pile, is another way.
Under a roof: There 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.
Storing 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.
Round stacks can be made many ways. Some are piles of wood with a stacked circular wall around them. Others like the American Holz Hausen are more complicated.
- 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.
Heat Value Firewood
The moisture content of firewood determines how it burns and how many BTUs are available for heating. Unseasoned (green) wood moisure content varies by the species, anywhere from 50% to over 100%. Typically, seasoned (dry) wood has between 25% to 20% moisture content.
The energy content of a measure of wood depends on its species. For example, it can range from 15.5 to 32 million BTUs per cord. The higher the moisture content, the more BTUs that must be used to evaporate(boil) the water in the wood before it will`burn. Dry wood delivers more BTUs for heating than green wood of the same species.
Here are some examples of BTU content of several species of wood:
| Wood Species | Heat Value |
|---|
| Tamarack | 22.3 MMBTU/Cord | | Birch | 21.3 MMBTU/Cord | | Red Fir | 20.6 MMBTU/Cord | | White Fir | 16.7 MMBTU/Cord |
MMBTU/Cord = Million BTU per Cord
The Sustainable Energy Development Office (SEDO), part of the Government of Western Australia states that the energy content of wood is 4.5 kWh/kg or 16.2 gigajoules/tonne (GJ/t).
Measurement of firewood
Usually firewood is sold by volume. While a specific volume term maybe used, there can be a wide variation in what this means and what the measure can produce as a fuel. For example, a "cord" which is made from 4 foot logs, will not be a cord when it is cut into 1 foot logs and these split so each piece will fit through a 3 inch circle. A measure of green unseasoned wood with 65% moisture contains less usable BTUs than when it has been dried to 20%. Regardless of the term, firewood measurement is best thought of as an estimate.
Metric
In the metric system, firewood was normally sold by the stère (= 1 m³ = ~0.276 cords). It can also be sold to consumers by the kilogram.
United States measures
In the United States, firewood is usually sold by the cord, 128 ft³ (3.62 m³), corresponding to a woodpile wide × high of 4 ft-long logs. The cord is legally defined by statute in most states.
- A "Face cord" is a stack of wood that is 4 feet by 8 feet and is only the length of the logs in the stack.
- A "Rick" is another regional name for a face cord.
- A "Load" refers to some mutually agreed upon amount that will fit into a carrying device.
European
- Faggot a bundle of small pieces of wood.
See also
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