Wood Fuel and Supply Chain

Wood pellets and chips are the two most suitable fuels for automatically fired heating systems in large buildings.


Wood fuels (pellets/chips)

Wood pellets and chips are the two most suitable fuels for automatically fired heating systems in large buildings. The bio-fuels to be used in this programme should comply with I.S. CEN / TS 14961:2005 or equivalent. Post consumer wood waste is not acceptable as a fuel for this programme.

The following table includes the typical characteristics of pellets and chips.

Table_characteristics of dry chips

Moisture content of wood has a significant impact on the calorific or energy value of the fuel. The diagram below shows the relationship between moisture content and energy content.

Moisture content v energy content

It is important that the moisture content of the wood chip is compatible with the boiler in which it is being used.

Pellets and chips have various advantages and disadvantages that have to be weighed up. Which fuel is used will depend very much on local conditions. Preferably systems should be installed, that can use both fuels and can therefore respond flexibly to the future market situation. Such boilers have an electronic control system that adjusts the combustion parameters to the selected fuel. It is important that the feed system is suitable for handling both fuels. As chips (unlike pellets) are not generally blown in, the store should be designed to enable the fuel to be delivered by tipper truck if chips are expected to be used. The advantage of above ground silos for pellets is their lower cost. The following table highlights the advantages of the two fuels and compares them.

Local availabilityAvailability generally is not local
Favourable effect on the local job marketLess favourable for the local economy
Cheaper than pelletsHigher fuel costs
Large storage space requiredSmaller fuel store
Uniform fuel quality not standardisedStandardised fuel, greater reliability
More work required for system maintenanceLess work for service and maintenance
Wood fuels are generally delivered by truck or tractor trailer that tips the fuel into the opening in the store. Pellets are usually delivered in tankers. As 1 cubic metre of pellets has four times the calorific value of 1 cubic metre of dry chips, the frequency of deliveries is much lower than for chips. As a result, pellet heating systems may be a better solution in urban areas where the traffic plays an important role. There should be enough room for the delivery vehicle to turn.

The size of the fuel store depends on many factors: anticipated fuel requirements, fuel type, reliability of deliveries, space available, delivery vehicle capacity etc. In existing buildings adjusting the fuel delivery intervals to the available storage space is cheaper in most cases than putting in a new store outside the building.

More information on Wood Pellets and Wood Chips can be found here on the website.

Wood Energy Supply Chain

For more information about the supply chain of wood energy please visit www.woodenergy.ie. This website is owned and managed by COFORD, the National Council for Forest Research and Development with content contribution by wood energy consultant, Pieter D. Kofman.

Woodenergy.ie is dedicated to bringing you information on using wood biomass as a carbon neutral, renewable energy source. Information is given on wood fuel quality and all aspects of the wood fuel supply chain, such as harvesting, storage, transportation and handling.

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