Wood processing machinery for biomass: four machines and what they decide

A biomass fuel line has four main machines. Get one wrong and the cost per ton changes for the whole line. Here is what each does and what the decision rests on.

The four machines

Chipper. Turns logs and offcuts into chips at a set size. The first point that determines whether the output is consistent. Blunt blades tear rather than cut, producing excess fines.

Hammer mill. Used when making pellets. Grinds chips fine enough to press. Screen size sets the fineness.

Dryer. Brings moisture from roughly 40–50% down to about 10% before pressing. The heaviest energy consumer on the line, and the reason pellets cost several times more than chips.

Pellet mill. Presses wood powder through a die under high pressure. Friction heat softens the lignin in the wood, which binds the pellet without any added glue.

Why chips cost so much less than pellets

Count the stages.

Chips: screen → chip → ship.

Pellets: screen → chip → mill → dry → press → cool → grade → ship.

Drying alone consumes enormous energy, because tens of percent of water has to be evaporated. That is why pellets carry a higher price per ton — not because the feedstock differs. It is the same feedstock.

Chips against pellets

	Wood chips	Rubberwood pellets
Calorific value	~2,200 Kcal/Kg	~4,000 Kcal/Kg
Moisture	~43%	~9%
Density	Low, needs yard space	High, easy to store and ship
Production stages	3	8
Suits	Boilers and power plants with yard space	Tight space, automatic feeding

For the decision criteria in detail see wood chips versus pellets.

What pellet-line investors most often get wrong

Underestimating feedstock moisture. ROI modelled on 30% wood when 45% is what actually arrives. The dryer works harder than designed and output never reaches target.

Forgetting the cost of screening. If the feedstock carries soil, blades and screens wear far faster than the vendor's figures suggest.

Comparing machine price instead of cost per ton. A cheap machine that draws heavily and stops for repairs costs more across its life than an expensive one that runs.

Ask before investing

We run this line ourselves in Trang every day and are not an equipment dealer, so we can advise from feedstock screening through to machine specification. Call +66 92 392 2292.

Read on: why deciding too fast costs more