A GLASU PROJECT GEO20
The aim of the project was to determine whether satisfactory fuel pellets could be made from non-wood biomass with a view to expanding the range of raw materials that could be utilised as fuel. Evaluations of the availability of resource and the economic viability of converting into pellets were also carried out.
|
Straws (wheat, oat,
oilseed rape)
Garden clippings
Hemp (hemcore)
Bracken
Miscanthus
Rushes
Apple pulp
|
Woody materials:
Landfill timber
Plywood
Willow
Oilseed cake
Wheat grains (whole)
|
They were first put through a Dragon Machinery shredder with, 4mm screen (Pencader, Carmarthenshire, 01559 384303) then pelleted in a Farm Feed Systems (Cinderford, 01594 825106) 10 HP small scale mill. |
We were able to produce pellets from all of the materials tested
Some were easy and made very good pellets whilst others were harder, needing some vegetable oil or water but made poorer pellets.
What was notable was that the addition of oilseed cake could greatly facilitate the formation of good quality pellets particularly when using waste wood material
Success with the alternative materials will depend on the material, its moisture content, its form and consistency and the type of die in the mill as well as additives such as vegetable oil or oilseed cakes, etc – the optimum conditions for producing a pellet from the chosen material (and a pellet that complies with standards) would need to be determined
The combustion properties of the pellets were tested in a room heater pellet burner and professionally by Richard Marsh, Dept Engineering, Cardiff University (02920 876586). By and large the pellets burned well. However:
The pellets tended to produce much larger amounts of ash than those made
from wood (up to 25 times more)
Ash from some materials, for example miscanthus, tended to fuse into a slag.
Some pellets had relatively high sulphur levels (chloride was not tested)
It will be crucial to ensure that the heating appliance is able to
handle high ash content, clinker and any corrosive products from combustion.
The following table outlines many of the results.
The potential to produce pellets from alternative materials also depends on the manufacturing cost of producing the pellets. Capital and running costs, particularly of small scale pelleting equipment can be fairly high so it may be important to be able to source low cost raw materials to ensure that the pellet prices are competitive. Prices of farm commodities are currently rising sharply in part because of competing demands for energy biomass. On the other hand, the market price of wood pellets tends to be high in comparison to other wood fuel. Some materials such as bracken, generally of no value, could be a low cost raw material.
Material |
Cost - Ease of Pelleting |
Ash |
Sulphur |
Pellet Potential
|
Landfill timber
|
Could be low or negative cost
Hard to moderate |
Low |
V. Low |
Very cheap but may need rape cake to improve pellet quality. Risk of contamination? |
Bracken
|
Low cost, mowing and baling probably cost up to £15/tonne
Moderate to easy |
Med/High |
Low |
Low cost, may be reasonable amount available, low sulphur. Ash (high potash) OK for organic crops. |
'Garden waste'
|
Low
Easy |
Med |
Low but may vary |
May be too mixed and unpredictable but low cost, suitable for power stations? |
Hemcore
|
High-good markets in animal bedding
Moderate |
Med |
Low |
Probably too expensive due to competing uses (animal bedding, insulation) |
Lavender
|
Cutting and baling costs only - may already be done
Easy |
Med/High |
ND |
France only - low cost, large quantities, good potential |
Miscanthus
|
£45/odt but may need to be higher to attract growers
Moderate |
Low/Med |
Low |
May need to be expensive to encourage production potential for high production. Ash and slagging may be a problem |
Oilseed rape cake
|
£90/tonne |
Med/High? |
High |
Expensive, competing markets forcing price up, but may be good as a blend to facilitate use of other materials |
Oilseed rape straw
|
Baling cost only?
Hard to moderate |
High |
High |
Tends to be ploughed in? Could be a good material, low cost, but ash and sulphur high |
Rushes
|
Mowing and baling cost only, up to £15/tonne
Easy |
Med/high |
Med |
Low cost but may not be large quantities. A niche market? |
Wheat straw
|
Locally about £45/tonne delivered but can be much higher
Hard to moderate |
Very High |
Med |
High ash, high price variability, may be other demands when needed |
Wheat grain
|
£95/tonne + delivery
Easy |
Med |
ND |
Expensive but best used as a binder |
Willow
|
£45/odt but probably nearer £90/odt to attract growers
Hard to moderate |
Low/Med |
ND |
Need to dry (drying costs?). May be expensive as need high price to encourage production. However, potential for high production. |
Coed Cymru, The Old Sawmill,
Tregynon, Newtown,
Powys SY16 3PL
Tel 01686 650 777
|
