How are pellets made? From wood waste to sustainable fuel
Pellets have become increasingly popular in recent years as a sustainable alternative for fossil fuels. But how are pellets actually made? In this article, we take you step by step through the production process of wood pellets, we discuss what raw materials are used, and explain why these small cylindrical pellets are so efficient as fuel.
What exactly are pellets?
Pellets are small, compressed grains usually made from wood waste, such as sawdust, wood chips and shavings. They are mainly used as fuel in pellet stoves, biomass boilers and industrial plants. Their high energy density and low moisture content make them an efficient and environmentally friendly source of energy.
Types of pellets
- Wood pellets: Made from pure wood waste, with no additives.
- Agricultural pellets: Made from agricultural waste such as straw or corn stalks.
- Industrial pellets: Often coarser in texture and intended for large-scale applications.
The production process: how are wood pellets made?
Making wood pellets is a multi-step process. Below, we discuss the complete production process, from raw material to finished product.
1. Raw material selection and supply
The first step in the production process is collecting the right raw materials. This usually involves:
- Sawdust
- Shavings
- Wood chips
- Forest residues
These materials often come from sawmills or wood processing industries. The use of residual materials makes the process extra sustainable.
2. Drying of the material
Before the raw materials can be pressed into pellets, they must first be dried. The moisture content must be reduced to around 10%. This is usually done in large drum dryers operating on hot air.
3. Ground into fine fibres
After the material is dry, it is ground to a fine consistency using hammer mills or rollers. This ensures that the fibres are suitable for pressing.
4. Pressing into pellets
During this step, the finely ground material is pressed through a die under high pressure. This creates cylindrical grains, usually 6 or 8 mm in diameter. The pressure releases lignin from the wood, which acts as a natural binding agent.
5. Cooling and sieving
After the pellets come out of the press, they are still warm and soft. They are therefore cooled with air currents to harden them. They are then sieved to remove dust and broken pellets.
6. Packing or storage
Finally, the finished pellets are packed in bags (usually of 15 kg) or stored in bulk containers for transport to distributors or end-users.
Quality and certification of wood pellets
Quality is essential when using wood pellets, especially if you use them in a modern pellet stove or boiler. There are several labels indicating that the pellets meet strict requirements:
- ENplus certification (A1/A2)
- DINplus certification
- SBI label (for Scandinavian countries)
Quality pellets have high efficiency, produce little ash and provide clean combustion without much smoke or soot formation.
Sustainability: why choose wood pellets?
Renewable energy sources are playing an increasing role in our society. Wood pellets offer numerous advantages:
- Low CO₂ emissions: Burning only releases as much CO₂ as the tree absorbed during its lifetime.
- Circular use: Pellets use waste streams from the wood industry.
- Locally produced: Reduces transport emissions when produced and used locally.
Moreover, with a pellet stove, households can save significantly on their energy costs compared to gas or fuel oil.
Applications of wood pellets
Pellets are used not only at home, but also on an industrial scale:
- Pellet stoves for domestic use
- Central heating via biomass boilers
- Power plants switching to biomass (such as coal-fired plants)
- Animal bedding in stables (due to good absorption capacity)
Cost and availability of pellets
The price of wood pellets varies depending on factors such as raw material prices, transport costs and seasonal influences. On average, a 15 kg bag costs between €4 and €6 (prices vary by region). Bulk prices are lower per kilo but require storage space such as a silo or bunker.
Sustainable future: innovation in pellet production
Today, there is plenty of innovation within the pellet industry to produce even more sustainably:
- Torrefaction: A process in which biomass is thermally treated to increase energy content.
- Less energy consumption: New presses consume less electricity per tonne of pellets produced.
- Local forest management: Provides renewable supply without deforestation.
Synthetic alternatives: not just wood anymore?
Some companies are experimenting with alternative feedstocks such as elephant grass (miscanthus), grape seeds or coffee grounds to develop new types of biomass pellets. These innovations could contribute to even more circular solutions within the energy transition.
Pallets versus Pellets: often misunderstood terms!
Make sure you do not get confused between "pellets" (fuel pellets) and "pallets" (transport platforms). These words are similar but have completely different meanings!
Frequently asked questions on how pellets are made (FAQ)
- What are pellets made of?
- Pelllets are usually made from residual wood such as sawdust, wood chips or shavings from sawmills and wood processing plants.
- Are there chemicals in wood pellets?
- No, quality wood pellets contain no chemical additives; lignin from the wood acts as a natural binding agent during pressing.
- Are all pellets suitable for pellet stoves?
- No, only certified A1 wood pellets are suitable for domestic pellet stoves because of their low ash content and high calorific value.
- Are harmful substances released during combustion?
- Provided it burns correctly in an approved stove, emissions are very low; therefore, maintenance is crucial for optimal operation.
- Are there alternatives to wood as a raw material?
- Yes, experiments are underway with agricultural residues such as straw, elephant grass or coffee grounds for alternative biomass pellets.
