Chip or Pellet?

RES has established a nationwide quality assured wood chip and pellet fuel supply network which enables RES to enter into long term fuel supply contracts for non-domestic sites. For more information, visit www.res-fuels.com.

A main consideration is the type of wood fuel that is to be used; specifically whether to employ a boiler system designed to run on wood chip fuel or wood pellet fuel. Wood chips can be made from a variety of sources (sawmill residues, round wood from forestry management etc.). Wood pellets are generally made from compressed sawdust.

The key factors which will determine the best solution for a particular site will be economic (cost of equipment and fuel costs); technical and local fuel availability.

Wood chip boilers can operate on both wood chip and pellet. Pellet boilers can only operate on pellet, so a wood chip boiler provides flexibility allowing the operator to use the most cost effective fuel available. Should the price or availability of a particular biomass fuel change in the future the customer can switch fuels and continue to enjoy high efficiency biomass heat.

Wood pellets

Wood chips

However, wood chip fuel is generally much lower cost than wood pellet fuel on an equivalent energy basis; often less than half the cost. Furthermore, wood pellet production is currently localised to a number of regions in the UK and therefore, in certain areas, wood pellets would have to be brought in, sometimes from considerable distances. In contrast wood chip fuel would in almost all cases be delivered from within say a 10 mile radius of the site and hence would always be local, keeping the economic benefit within the local community.

Comparison of Fuel Costs

A typical wood chip cost for small scale installations is around 1.5p/kWh (based on a delivered price for wood chip of £56/tonne at 25% moisture content). This compares with a wood pellet price of typically £150/tonne delivered, corresponding to a unit energy cost of 3.0p/kWh. A typical small primary school would be expected to have an annual heat usage of 50,000kWh per year, corresponding to £1500/year for wood pellets and £750/year for wood chip fuel. Therefore, the fuel costs of a 25 year period would be;