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Wood fuel (or fuelwood) is a fuel such as firewood, charcoal, Woodchips, sheets, wood pellets, and sawdust. The particular form used depends upon factors such as source, quantity, quality and application. In many areas, wood is the most easily available form of fuel, requiring no in the case of picking up dead wood, or few tools, although as in any industry, specialized tools, such as and hydraulic wood splitters, have been developed to mechanize production. Sawmill waste and construction industry also include various forms of lumber tailings. About half of wood extracted from forests worldwide is used as fuelwood.
The discovery of how to make fire for the purpose of burning wood is regarded as one of humanity's most important advances. The use of wood as a fuel source for heating is much older than civilization and is assumed to have been used by . Today, combustion of wood is the largest use of energy derived from a solid fuel biomass. Wood fuel can be used for cooking and heating, and occasionally for fueling and steam turbines that generate electricity. Wood may be used indoors in a furnace, stove, or fireplace, or outdoors in furnace, campfire, or bonfire.
In permanent structures and in caves, were constructed or established—surfaces of stone or another noncombustible material upon which a fire could be built. Smoke escaped through a smoke hole in the roof.
In contrast to civilizations in relatively arid regions (such as Mesopotamia and Egypt), the Greeks, Romans, Celts, Britons, and Gauls all had access to forests suitable for using as fuel. Over the centuries there was a partial deforestation of climax forests and the evolution of the remainder to coppice with standards woodland as the primary source of wood fuel. These woodlands involved a continuous cycle of new stems harvested from old stumps, on rotations between seven and thirty years.
One of the earliest printed books on woodland management, in English, was John Evelyn's "Sylva, or a discourse on forest trees" (1664) advising landowners on the proper management of forest estates. H. L. Edlin, in "Woodland Crafts in Britain", 1949 outlines the extraordinary techniques employed, and range of wood products that have been produced from these managed forests since pre-Roman times. And throughout this time the preferred form of wood fuel was the branches of cut coppice stems bundled into faggots. Larger, bent or deformed stems that were of no other use to the woodland craftsmen were converted to charcoal.
As with most of Europe, these managed woodlands continued to supply their markets right up to the end of World War Two. Since then much of these woodlands have been converted to broadscale agriculture. Total demand for fuel increased considerably with the Industrial Revolution but most of this increased demand was met by the new fuel source coal, which was more compact and more suited to the larger scale of the new industries.
During the Edo period of Japan, wood was used for many purposes, and the consumption of wood led Japan to develop a forest management policy during that era.Diamond, Jared. 2005 Collapse: How Societies Choose to Fail or Succeed. Penguin Books. New York. 294–304 pp. Demand for timber resources was on the rise not only for fuel, but also for construction of ships and buildings, and consequently deforestation was widespread. As a result, forest fires occurred, along with floods and soil erosion. Around 1666, the shōgun made it a policy to reduce logging and increase the planting of trees. This policy decreed that only the shōgun, or a daimyō, could authorize the use of wood. By the 18th century, Japan had developed detailed scientific knowledge about silviculture and plantation forestry.
The metal stove was a technological development concurrent with the Industrial Revolution. Stoves were manufactured or constructed pieces of equipment that contained the fire on all sides and provided a means for controlling the draft—the amount of air allowed to reach the fire. Stoves have been made of a variety of materials. Cast iron is among the more common. Soapstone (talc), tile, and steel have all been used. Metal stoves are often lined with refractory materials such as firebrick, since the hottest part of a woodburning fire will burn away steel over the course of several years' use.
The Franklin stove was developed in the United States by Benjamin Franklin. More a manufactured fireplace than a stove, it had an open front and a heat exchanger in the back that was designed to draw air from the Basement and heat it before releasing it out the sides. The heat exchanger was never a popular feature and was omitted in later versions. So-called "Franklin" stoves today are made in a great variety of styles, though none resembles the original design.
The 1800s became the high point of the cast iron stove. Each local foundry would make their own design, and stoves were built for myriads of purposes—parlour stoves, box stoves, camp stoves, railroad stoves, portable stoves, cooking stoves and so on. Elaborate nickel and chrome edged models took designs to the edge, with cast ornaments, feet and doors. Wood or coal could be burnt in the stoves and thus they were popular for over one hundred years. The action of the fire, combined with the causticity of the ash, ensured that the stove would eventually disintegrate or crack over time. Thus a steady supply of stoves was needed. The maintenance of stoves, needing to be blacked, their smokiness, and the need to split wood meant that oil or electric heat found favour.
The airtight stove, originally made of steel, allowed greater control of combustion, being more tightly fitted than other stoves of the day. Airtight stoves became common in the 19th century.
Use of wood heat declined in popularity with the growing availability of other, less labor-intensive fuels. Wood heat was gradually replaced by coal and later by fuel oil, natural gas and propane heating except in rural areas with available forests.
After the 1967 Oil Embargo, many people in the United States used wood as fuel for the first time. The EPA provided information on clean stoves, which burned much more efficiently.
The magazine "Wood Burning Quarterly" was published for several years before changing its name to "Home Energy Digest" and, subsequently, disappearing.
The mess of wood, bark, smoke, and ashes is kept outside and the risk of fire is reduced. The boilers are large enough to hold a fire all night and can burn larger pieces of wood, thus less cutting and splitting is required. There is no need to retrofit a chimney in the house. However, outdoor wood boilers emit more wood smoke and associated pollutants than other wood-burning appliances. This is due to design characteristics such as the water-filled jacket surrounding the firebox, which acts to cool the fire and leads to incomplete combustion. Outdoor wood boilers also typically have short stack heights in comparison to other wood-burning appliances, contributing to ambient levels of particulates at ground level. An increasingly popular alternative is the wood gasification boiler, which burns wood at very high efficiencies (85-91%) and can be placed indoors or in an outbuilding.
There are numerous ways to process wood fuel, and wood is still used today for cooking in many places, either in a stove or an open fire. It is also used as a fuel in many industrial processes, including smoking meat and making maple syrup. As a sustainable energy source, wood fuel also remains viable for generating electricity in areas with easy access to forest products and by-products.
In the United States and Canada, firewood is usually sold by the cord, 128 ft3 (3.62 m3), corresponding to a woodpile 8 ft wide × 4 ft high of 4 ft-long logs. The cord is legally defined by statute in most U.S. states. A "thrown cord" is firewood that has not been stacked and is defined as 4 ft wide × 4 ft tall × 10 ft long. The additional volume is to make it equivalent to a standard stacked cord, where there is less void space. It is also common to see wood sold by the "face cord", which is usually not legally defined, and varies from one area to another. For example, in one state a pile of wood 8 feet wide × 4 feet high of 16 inch-long logs will often be sold as a "face cord", 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, firewood is normally sold by the tonne, but is commonly advertised as sold by the barrowload (wheelbarrow), bucket ( of a 1 m3 bucket of a typical skid-steer), ute-load or bag (roughly 15–20 kg).
The Sustainable Energy Development Office (SEDO), part of the Government of Western Australia states that the energy content of wood is 16.2 megajoules per kilogram (4.5 kWh/kg).
According to The Bioenergy Knowledge Centre, the energy content of wood is more closely related to its moisture content than its species. The energy content improves as moisture content decreases. (includes a range of calculators, including one for calculating the energy content of wood, taking into account the moisture content)
In 2008, wood for fuel cost $15.15 per 1 million BTUs (0.041 EUR per kWh).
One by-product of wood burning is wood ash, which in moderate amounts is a fertilizer (mainly potash), contributing minerals, but is strongly alkaline as it contains potassium hydroxide (lye). Wood ash can also be used to manufacture soap.
Smoke, containing water vapor, carbon dioxide and other chemicals and aerosol particulates, including caustic alkali fly ash, which can be an irritating (and potentially dangerous) by-product of partially burnt wood fuel. A major component of wood smoke is fine particles that may account for a large portion of particulate air pollution in some regions. During cooler months, wood heating accounts for as much as 60% of fine particles in Melbourne, Australia. Environment Protection Authority (2002) Wood heaters, open fires and air quality. Publication 851 EPA Victoria. Significant quantities of volatile organic compounds are released from the combustion of Firewood. Large quantities of smaller oxygenate species are released during the combustion process, as well as organics formed from the Depolymerization reaction of lignin such as phenolics, and furanones. The combustion of Firewood has also been shown to release many organic compounds into the aerosol phase. The burning of Firewood has been shown to release organic components over a range of volatilities, over effective saturation concentrations, C*, from 101-1011 μg m−3. The emissions from Firewood samples collected from the Delhi area of India were shown to be 30 times more reactive with the Hydroxyl radical radical than emissions from liquefied petroleum gas. Furthermore, when comparing 21 polycyclic aromatic hydrocarbons emitted from the same Firewood samples from Delhi, emissions from fuel wood were around 20 times more toxic than emissions from liquefied petroleum gas.
In some of the most efficient burners, the temperature of the smoke is hot enough to burn itself (e.g. for igniting carbon monoxide gas). This may significantly reduce smoke hazards while also providing additional heat from the process. By using a catalytic converter, the temperature for obtaining cleaner smoke can be reduced. Some U.S. jurisdictions prohibit sale or installation of stoves that do not incorporate catalytic converters.
The technique of compressing wood pulp into pellets or artificial logs can reduce emissions. The combustion is cleaner, and the increased wood density and reduced water content can eliminate some of the transport bulk. The fossil energy consumed in transport is reduced and represents a small fraction of the fossil fuel consumed in producing and distributing heating oil or gas.Manomet Center for Conservation Science. 2010. Biomass sustainability and Carbon Policy Study: Report to the Commonwealth of Massachusetts Department of Energy Resources.[2]
Some firewood is harvested in "" managed for that purpose, but in heavily wooded areas it is more often harvested as a byproduct of natural . 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 . Harvesting timber for firewood is normally carried out by hand with . Thus, longer pieces - requiring less manual labor, 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. Firewood usually relates to timber or trees unsuitable for building or construction. Firewood is a renewable resource provided the consumption rate is controlled to sustainable levels. The shortage of suitable firewood in some places has seen local populations damaging huge tracts of bush possibly leading to further desertification.
In an attempt to provide quantitative information about the relative output of CO2 to produce electricity or domestic heating, the United Kingdom Department of Energy and Climate Change (DECC) has published a comprehensive model comparing the burning of wood (wood chip) and other fuels, based on 33 scenarios. The model's output is kilogram of CO2 produced per megawatt-hour (MWh) of delivered energy. Scenario 33 for example, which concerns the production of heat from wood chips produced from UK small roundwood produced from bringing neglected broadleaf forests back into production, shows that burning oil releases of CO2 while burning woodchips releases of CO2 per MWh of delivered energy. However, in scenario 32 of that same reference, which concerns the production of heat from wood chips that would otherwise be made into particleboard, showed that only of CO2 per MWh was released. Therefore, the relative greenhouse effects of biomass energy production are dependent on the usage model.
The intentional and controlled charring of wood and its incorporation into the soil is an effective method for carbon sequestration as well as an important technique to improve soil conditions for agriculture, particularly in heavily forested regions. It forms the basis of the rich soils known as Terra preta.
Wood burning advocates claim that properly harvested wood is carbon-neutral, therefore off-setting the negative impact of by-product particles given off during the burning process. In the context of forest wildfires, wood removed from the forest setting for use as wood fuel can reduce overall emissions by decreasing the quantity of open burned wood and the severity of the burn while combusting the remaining material under regulated conditions. On March 7, 2018, the United States House of Representatives passed a bill that would delay for three years the implementation of more stringent emission standards for new residential wood heaters.
Many lower- and middle-income countries rely on wood for energy purposes (notably cooking). The largest producers are all in these income groups and have large populations with a high reliance on wood for energy: in 2021, India ranked first with 300 million m ³ (15 percent of total production), followed by China with 156 million m3 and Brazil with 129 million m ³ (8 percent and 7 percent of global production).
In the United States, wood fuel is the second-leading form of renewable energy (behind hydro-electric).
Species used as sources of firewood include:
In 2013, the main pellet consumers in Europe were the UK, Denmark, the Netherlands, Sweden, Germany and Belgium, as U.E.'s annual report on biofuels states. In Denmark and Sweden, pellets are used by power plants, households and medium scale consumers for district heating, compared to Austria and Italy, where pellets are mainly used as small - scale private residential and industrial boilers for heating. The UK is the single largest consuming market for industrial wood pellets, in large part due to its major biomass-fueled power stations such as Drax, MGT and Lynemouth.
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