R&D for Eucalyptus Wood Pellet Production

By:Dominic Meng
Position:Project Sales Director
Jul 24, 2023
Eucalyptus, which is native to Australia, Indonesia, the Philippines, and other nations, is the world's fastest growing tree species, growing one meter in a month and up to ten meters in a year. Eucalyptus has a wide adaptability, high resistance, rapid growth, good dry form, drought endurance, and widespread application. It grows in a variety of habitats, from the tropics to temperate zone, coastal to interior, plains to mountains. Eucalyptus has applications in pulp and paper, wood-based panels, and building industries. It can also be utilized to produce biomass fuel and forest byproducts such as eucalyptus oil and polyphenols.
Eucalyptus are well adapted to dry, infertile sites such as degraded land no longer suitable for agriculture. They can also contribute to the protection of biodiversity, water and soil systems:
Around the world, pressure is being placed on natural forests due to demand for fuel wood and timber. Eucalypts are a fast-growing alternative to native species, which are often difficult to establish. Eucalypts can save biodiversity by preventing the destruction of natural forests.
Careful management of hydrological impacts is important for any landuse. Forested catchments reduce water yield compared to non-forested catchments. However, forests regulate water flow, preventing extremes. The effect of eucalypts in reducing water yield is probably less than that of pine and greater than that of other broad leaved species. One important aspect of eucalypts is water use efficiency, which is much greater than other tree species, meaning that per unit of water consumed, eucalypts produce more biomass than alternative plantation species. Eucalypt plantations can improve the infiltration capacity of the soil to reduce run-off and to activate the soil water charging, filtering and cycling process. Practices to improve interception and infiltration include retention of litter, development of an understory or of a compatible native ground cover; development of a nitrogen fixing compatible ground cover, and in water short areas lower tree stocking to reduce water consumption.
Eucalypts specifically do not cause soil erosion and if managed correctly can sustain or improve the condition of the soil on a site. Eucalypts are well suited to degraded soils and will often grow where native species will not grow. For this reason, eucalypts can be used to restore damaged forest ecosystems where natural regeneration is not possible in the short term. Eucalypt foliage and bark contains a large amount of nutrients, so when plantations are harvested it is a good management practice to retain these on site to maintain the nutrient status of the soil. Application of fertilizer can be used to add nutrients to the soil. Allelopathy of eucalypts has not been shown, which is supported by the ability to grow many crops in intercropping agroforestry systems. The use of soil conservation techniques combined with nutritional management results in eucalypt plantation being able to be sustained on the same site for many rotations without degradation of the soil.

In May 2023, one of SIMEC clients entrusts us to take a series of pelletizing tests using eucalyptus wood wastes. To make wood pellets is an important solution to upgrade the value of eucalypts. The client is an European based company with its own plywood mill, sawmill, processing facilities and plantations. They are the earliest foreign direct investment company in Lao PDR and have an extensive knowledge of Lao PDR and a wide regional network. They have planted 6,000 ha and have signed land concessions for 68,000 ha of plantable land in Lao PDR. As well, they have been responsible for establishing and managing some of the most cost efficient plantations in Brazil exceeding more than 300,000 ha. The company is committed to managing and developing the business in a sustainable manner. They rely on the developed management techniques, strong research and development programs to manage their eucalypt plantations. They incorporate Agroforestry which is a land-use system in which crops or pasture are grown amongst trees into its industrial plantations, combining food and fiber production, to create a more diverse, productive, profitable and ecologically sound landscape. And it shows that high stocking, low thinning and early final harvest favors production of biomass or pulp logs, while lower stocking, high thinning and late final harvest favors the production of saw logs. It also provides an abundant, renewable source of raw materials for their diverse industries. As well, it helps their industries conform to FSC certifications in Lao PDR.
As agreed, 20 kgs of eucalyptus wood waste sample in three packages were delivered from Lao PDR and arrived at SIMEC R&D center in May 2023.    
Description of Sample _ As received:
Status: Original Eucalyptus wood chips sample, Pretreated by pulverizing and drying before delivery to SIMEC office.
Moisture: Below 10%.
Size: Maximum 65*50*3mm.
Based on the above parameters, it’s preliminarily judged that the sample of eucalyptus wood chips needs further size reduction process before pelletizing.
Description of Sample _ After size reduction:
Status: Ground wood particles
Moisture: Below 10% (6.9%~7.6%)
Size: Smaller than 10mm.
Based on the above parameters and our experience, the moisture needs to be adjusted before pelletizing.
Due to eucalyptus wood is a kind of tropical hard woods, there are some Needle-like wood chips which need to be further grinded. Otherwise, it may reduce the efficiency of pelletization process. Thus, we adopted fine pulverizing process to avoid its impact on the next pelletizing process.
Description of Sample _ After Fine Pulverizing:
Status: Fine pulverized wood chips
Moisture: below 10%
Size: Smaller than 5mm. Diameter of the needle-like wood chips 2-3mm, still very hard.

The result presents there is some certain ratio of big size needle-like wood chips after fine pulverizing.
In an initial pelleting test, the wood chips mixed with the fine powder and adhere to the grooves of roller shell. As a result, the press rollers of pellet mill slipped, thus there was no longer any pressure generated to drive the material that remains in the ring die hole out. In the light of this, SIMEC R&D team worked out a solution to ripen and soften the pulverized eucalyptus wood chips. It significantly helps to activate the action of lignin and decreases resistance while pressing. The wood chips became much easier to pass through the holes of ring die. The eucalyptus wood chips combine to pellet form under the effect of pressure and lignin which is the natural binder. 
Analysis result of Eucalyptus Wood Pellets produced in the test:
 Description of Goods: Solid Biomass Fuel (Eucalyptus Wood Pellet, Diameter: 8mm)
 Parameter  Test Method  Value
 Total moisture (Wet basis)  CEN/TS 14774  5.77%
 Ash (Dry basis)  CEN/TS 14775-2004  1.38%
 Volatile matter (Dry basis)  CEN/TS 15148-2005  81.17%
 Fixed carbon (Dry basis)  ISO 17246:2005  17.52%
 Sulphur (Dry basis)  CEN/TS 15408  0.041%
 Gross calorific value (Dry basis)  CEN/TS 14918  4642 Kcal/kg
 Density (Dry basis)  CEN/TS 15103-2005  684 kg/m3
 Total carbon (Dry basis)  GB/T 476-2008  44.53%
*The test results and parameters of sample pellets are valid for the received and tested sample only.
Based on the testing findings and samples, SIMEC client is full of confidence for the commercial eucalyptus wood pellet project, and can lock in potential pellet purchasers and extend the market in advance. We also outlined the essential processes and experiences to help guide commercial projects.

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