Knowing how to measure pellet moisture is the first step towards quality production. Accurate moisture control affects not only how pellets form, but also logistics and combustion. In this article we explain why moisture matters so much at every stage of the process and which tools Marrari offers to control it.
The role of moisture control in biomass production
Ensuring top quality in biomass production is a complex challenge, but it is vital to avoid wasting money and resources. In energy applications, efficient moisture management is even more important, as it is directly linked to energy production costs and operational efficiency.
Hygroscopicity in pellets and biomass
Hygroscopicity is a physical property shared by pellets and biomass: they absorb and release water depending on contact with liquids or with air humidity. Water molecules bind to biomass components such as cellulose and hemicelluloses, mainly through hydrogen bonds, until the material reaches equilibrium with its surroundings.
How water affects product properties
Water in the biomass structure does more than cause simple physical changes: it alters chemical and mechanical properties. Accurate moisture control is a decisive factor for maximum efficiency in pellet production and use.
Material compression and moisture
When the material is compressed to form pellets, moisture helps by making particles bind together. But the balance is delicate: excessive moisture, above 20%, can compromise pellet stability, while moisture close to 5% impairs particle adhesion. In practice, feedstock is usually pelletized at around 10% to 15% moisture.
Ideal moisture varies between biomasses
There is no single, universal ideal moisture content: it varies between biomasses, including agri-food and forest residues. That is why investment and rigorous control are essential to find the ideal production point for each raw material.
Logistics impact: moisture and transport costs
Logistics in the pellet supply chain is heavily influenced by moisture control. Moisture content is directly linked to loading costs, since wetter biomass weighs more, which directly increases transport costs: you are paying to haul water.
How to measure pellet moisture
Constant moisture monitoring matters not only to manufacturers but also to end consumers. Transparency in production, including effective techniques for measuring pellet moisture, builds consumer trust and ensures high-quality products.
The reference method is oven drying (gravimetric): the sample is weighed, dried at 105 ± 2 °C to constant mass (ISO 18134) and weighed again. It is accurate but slow. For day-to-day control, portable meters give readings in seconds, and in-line moisture meters track the material continuously on the conveyor, so drying can be adjusted in real time.
Impact on combustion
Water in pellets is not just a production issue; it also harms combustion. Part of the energy released is spent evaporating the water, which lowers the fuel’s useful calorific value and means more material is needed to produce the same amount of heat. That is why quality standards for energy pellets, such as ENplus, limit final product moisture to 10%.
Drying control: costs and product value
Moisture in pellets is a multifaceted factor, which makes effective control during drying essential. This stage not only keeps production costs down but also adds value to the final product, ensuring the customer receives a high-quality product.
Marrari solutions for moisture measurement and control
For these challenges, Marrari offers a broad range of solutions. Its meters, sensors and controllers simplify pellet moisture control and bring efficiency and reliability to customers and suppliers.
Author: Frederico Ramon Machado Teixeira, Industrial Wood Engineering student (UFPR), Umilab laboratory at Marrari Automação
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