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Nitrous oxide Sources - Biomass Burning

burning wodBiomass burning, largely resulting from the activities of man, accounts for around half a million tonnes of nitrous oxide-N emission each year. Nitrous oxide emissions arising from biomass burning are a result of incomplete combustion and significant amounts can be produced during large scale burning of woodlands, savanna and agricultural waste.

In savanna regions of the world, burning is often carried out every few years to promote regeneration of the vegetation. An important biomass burning related source of nitrous oxide emission is that of crop residue burning.

The high nitrogen and water contents of many crop residues mean that the burning of such material can produce a relatively high percentage (around 1 percent) emitted as nitrous oxide.

Human Impact

Though fires caused by lightning strikes have, and still do, account for some large biomass burning events, the activities of man in the last 100 years have dwarfed nitrous oxide emissions from such natural biomass burning. Huge areas of woodland and grassland are now periodically burned for land clearance and agricultural land-use.

Burning of agricultural waste also produces significant amounts of nitrous oxide due to its generally high water content. Additionally, wood burning as a domestic fuel source and for charcoal production can release significant amounts of nitrous oxide on a global scale.

Potential for control

Reductions in crop residue burning give a direct route for reductions in biomass burning related nitrous oxide emissions. Similarly, careful management of any necessary crop residue burning to ensure emissions of nitrous oxide are kept to a minimum may help to reduce the strength of this nitrous oxide source. On a large scale, the uncontrolled way in which most biomass burning happens means that the only real route to reducing emissions from this source is to reduce the amount of burning itself.

Some biomass burning is required if environments such as the savanna are to be retained, but it is the large scale destruction of forest areas for cash crop agriculture and urban spread which stand out as areas to be tackled. Biomass burning is currently being developed as an alternative to traditional fossil fuel energy production methods, with power stations fuelled by wood chips and the like already a reality.

By making use of a renewable resource, like pine wood chips, and avoiding uncontrolled and incomplete combustion, these biomass power stations are able to have a much reduced net greenhouse gas impact compared to equivalent coal, oil and gas fired power stations.


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