Environmental aspects of wood energy use are diverse. They range from local land use to global climate change, and from applications in smoky kitchens to electricity generation in large-scale power stations. Consequently environmental impacts of wood energy use and production can be both positive and negative, and an assessment of these impacts should always be part of wood energy policy making.
When talking about wood energy and environment, many people think of deforestation. Cutting wood for fuelwood and charcoal has often been cited as a major cause of deforestation. This idea was largely based on the "fuelwood gap theory" formulated in the seventies, that assumed that all woodfuels came from forest resources and that woodfuel consumption would increase at the same rate as population. It ignored the substantial supply of wood from non-forest areas and responses of woodfuels users to scarcities, such as fuel switching, changing cooking habits and developing alternative supply sources.
Now it is widely accepted that the major cause of deforestation is the conversion of forest land into agricultural land and urban areas, due to the growing population and growing demand for food. Although in some areas woodfuel use may contribute to localized deforestation and forest degradation, it is no longer considered a major cause. In fact, commercial woodfuel trade can lead to the improvement of the local environment, because it provides incentives to landowners and farmers and traders to plant trees, as is the case in Cebu, the Philippines.
Nevertheless, wood energy policies and programs are still largely based on this idea (and other misconceptions), which leads to ineffective and even obstructing interventions, such as prohibiting woodfuel gathering from forests, restricting the transportation of woodfuels and cookstove programs that solely aim to reduce woodfuel consumption. (link to flows and conservation pages)
In recent years, serious environmental concerns like global climate change related to the use of fossil fuels, have revived the interest in wood energy as a renewable, sustainable and environmentally benign energy source. Wood energy is renewable, and if sustainably used and produced it is carbon neutral. Wood emits CO2 while burning or decomposing naturally, but trees absorb carbon from the atmosphere through photosynthesis. Natural decomposition also emits methane, which doesn't occur when the wood is burned completely, so from an environmental point of view burning wood residues from logging and processing is beneficial. In addition, woodfuel does not emit SO2, unlike coal and oil.
Therefore, wood energy can be used to reduce greenhouse gas emissions related to energy use, by replacing fossil fuels. For this reason, modern wood energy applications are becoming more and more competitive with conventional applications. Other benefits of modern wood energy are employment generation, saving on foreign exchange due to reduced oil import, and the upgrading of barren and deforested areas by energy plantations.
Most woodfuels in Asia are used by households which mostly use traditional stoves. These stoves have low efficiencies and often burn wood incompletely, leading to the emission of pollutants such as carbon monoxide, methane and nitrogen oxides. These pollutants can have serious health impacts and they also contribute to greenhouse gas emissions. This doesn't mean that wood is a dirty fuel and should be replaced but that traditional technologies are inadequate and need improvements. In addition to focusing on fuel conservation, improved cookstove programs should also focus on aspects of health and convenience for users.
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