Producing Biomass Fuel

Although there are many types of biomass fuels available for combustion, the two main sources are from the forest industries and from agriculture;

Forestry Industry

There are lots of low value forest outputs that can be suitable for the woodfuel market if they can be extracted at a sensible cost, both financial terms and environmental.  These are typically branches, small round wood (SRW), thinnings and poorly formed wood, in some situations even the stumps and brash can be harvested for fuel. 

High quality timber butts/stems will continue to be sold on for processing by sawmills for other industries, principally for construction and furniture.  The processing itself leaves useful off cuts, bark and sawdust which can also be converted to a fuel.

For further information about the any of the following topics, click on the links below to the Biomass Energy Centre website:

Forestry

Arboriculture

Sawmills

Energy crops

Agricultural residues

Industrial waste and co-products;

Untreated wood  and  Waste Incineration Directive (WID)

Supplying Woodfuel

Supplying woodfuel might at first glance seem like a very simple matter.   Whilst in essence the physical process of supplying logs or chipping wood is simple, problems arise when no thought has been given to the end user and the boiler installed.  There are many different boiler and chipping systems on the market, whilst many boilers will burn a fairly standardised fuel, some are more fussy, and some more lenient on what you put in them.  Some burners are designed to burn green chips (not been pre dried).  For a basic overview of woodfuel, click on woodfuel basics, for information on present standards click on standards.

The general rules for supplying good fuel are that there are no long slivers over a certain size as they can get stuck/bridge in fuel feeding systems and cause blockages.  On the other end of the scale you don’t want too many fines (small particles), as these can build up in fuel feed systems and compact over a period of time, again leading to blockages.  And vitally important for efficiency is supplying fuel of the right moisture content, most boilers will require fuel below 35% moisture content.  Always check with the boiler installer what size chip or pellets are compatible and what the ideal moisture content should be, and that you can get a local supplier!

Other things to be aware of are excessive ash building up, which is often due to high proportions of bark or leaves in the chip.  Avoid contaminated sources of wood as they can lead to excessive levels of heavy metals, alkali, sulphur or chloride.  Contamination from soil and stones is also to be avoided when handling and storing fuel.  Any form of contaminated or inappropriate fuel can lead to combustion problems and over a long period of time can cause damage to the boiler units, thus reducing efficiency and life expectancy. 

For further information about the any of the following topics, click on the links below to the Biomass Energy Centre website:

Supplying wood chips

Supplying wood pellets

Supplying firewood logs

Chippers ;  Disk chippers ;  Drum chippers ;  Screw chippers

Drying Biomass

Storing Biomass

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