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A Look at Pellet Production in Chile

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Fernando Muñoz Sáez, Forestry Engineer, PhD, Faculty of Forest Sciences, University of Concepción

The use of native firewood for thermal energy generation is traditional in southern Chile. However, in recent years, demand for another biofuel—pellets—has increased due to greater consumer acceptance and the Pollution Mitigation and Conversion Plans from wood-burning stoves to pellet-burning stoves, promoted by the government in several southern Chilean cities. Currently, this biofuel is produced using byproducts from sawmills and processing plants.

Pellets are solid, homogeneous, cylindrical biofuels with low moisture content and higher energy density compared to firewood. Their production occurs through biomass extrusion in a perforated steel matrix, where the holes typically range between 6–12 mm in diameter, under an internal pressure of approx. 300 MPa from the cylinders that help force the material through the holes at an approximate temperature of 100°C. In most cases, pellet formation occurs without the need for adhesives due to the cohesive capacity of lignin, resulting in a renewable, economical, simple, safe, and highly convenient biofuel for transport and storage.

In Chile, pellet production has increased in recent years, reaching a total of 117,460 tons in 2018, with Pinus radiata being the most commonly used species due to its agglomeration properties and light color, which makes it attractive to the market. Pellets are produced in plants integrated with sawmills and wood processing centers, using dry chips and sawdust as raw materials. However, the availability of dry chips and sawdust for pellet production is limited, as only 9.9% of sawmills dry their wood artificially.

On the other hand, high atmospheric pollution in the regions between O'Higgins and Aysén, caused by inefficient burning of wet firewood and outdated equipment, has led the Ministry of the Environment to support the replacement of wood heaters with pellet heaters due to their low PM 2.5 emissions. By 2019, 40,403 units were replaced annually. Emissions can be reduced by up to 94% when switching from firewood to pellets in old double-chamber heaters. Additionally, private purchases of pellet heaters are estimated at 8,050 heaters and 128 residential boilers annually, increasing pellet demand in the residential sector by 24,106 tons per year.

Nearly all pellet production is based on Pinus radiata biomass, with a smaller proportion from other species. Pellet production using native wood is low, approx. 3,700 tons per year, representing no more than 3.2% of total national production in 2018.
Pellet quality can vary considerably depending on moisture content, calorific value, gas emissions, and ash generated during combustion. Another important variable is durability, which relates to mechanical stresses affecting pellets during transport and handling, potentially leading to fine particle formation that complicates their use. This is mainly influenced by lignin content, a key parameter that aids particle binding.

Another determining factor is biomass moisture, as high moisture levels hinder compaction, resulting in brittle or crumbly pellets. Reducing pellet moisture improves quality by preventing swelling and disintegration due to high hygroscopicity, limiting microbial activity during storage, and avoiding reductions in calorific value.

Chemical parameters are important, particularly chlorine content in pellets, sulfur levels that may affect combustion equipment (stoves), and the amount of ash produced from combustion.
Additionally, biomass availability for pellet production is tied to plantation ownership and residues generated in log processing centers (chips, shavings, sawdust), creating an entry barrier for companies seeking to purchase raw materials without agreements with large suppliers.

The challenge, therefore, is to incorporate raw materials from other sources in the coming years. A recent study conducted by the Faculty of Forest Sciences at the University of Concepción used 5-year-old Pinus radiata trees, discarded from thinning and including bark, to produce pellets that met usage standards.

Demand for pellets as a residential and semi-industrial fuel (bakeries, public buildings, etc.), especially in southern Chile, will continue in the future due to environmental benefits and ease of use. Other raw material sources must be incorporated, more production plants established, and quality controls improved to prevent the use of non-compliant pellets.