Citation: Ismail, R.I.; Khor, C.Y.; Mohamed, A.R. Pelletization Temperature and Pressure Effects on the Mechanical Properties of Khaya senegalensis Biomass Energy Pellets. Sustainability 2023, 15, 7501. https:// doi.org/10.3390/su15097501 Academic Editor: Paris Fokaides Received: 9 February 2023 Revised: 13 March 2023 Accepted: 28 April 2023 Published: 3 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). sustainability Article Pelletization Temperature and Pressure Effects on the Mechanical Properties of Khaya senegalensis Biomass Energy Pellets Ras Izzati Ismail 1, * , Chu Yee Khor 1, * and Alina Rahayu Mohamed 2 1 Faculty of Mechanical Engineering & Technology, Universiti Malaysia Perlis, UniCITI Alam Campus, Sungai Chuchuh, Padang Besar 02100, Perlis, Malaysia 2 Faculty of Chemical Engineering & Technology, Universiti Malaysia Perlis, UniCITI Alam Campus, Sungai Chuchuh, Padang Besar 02100, Perlis, Malaysia * Correspondence: rasizzati@unimap.edu.my (R.I.I.); cykhor@unimap.edu.my (C.Y.K.) Abstract: Biomass pellets are one of the most crucial feedstocks for bioenergy production on a global scale due to their numerous advantages over raw biomass resources. Pellets provide improved energy density, bulk density, moisture content, and homogeneity thereby reducing storage, handling, and transportation costs. To produce high-quality solid fuel, it is necessary to comprehend the properties of wood fuel. This study explored the potential of Khaya senegalensis (khaya) as a dedicated energy crop (DEC) for the production of green energy. It thrives in less-than-ideal conditions and grows rapidly. The low durability of energy pellets raises the risk of dust and fire during handling and storage. In addition, the potential for fines and dust formation is strongly correlated with the mechanical strength of materials. Due to this necessity, the current study examines the effects of pelletization factors, including temperature and pressure, on pellet properties, particularly on its mechanical properties. The durability and compressive strength of pellets were determined using a sieve shaker and a universal testing machine, respectively. The highest mechanical durability was observed at 3 tons of pressure and 75 degrees Celsius, each with a value of 99.6%. The maximum axial compressive strength was measured at 57.53 MPa under 5 tons of pressure. When pelletized at 125 ◦ C, the axial compressive strength increased by 13.8037% to 66.06 MPa compared to the strength obtained at 5 tons of pressure. Pelletizing Khaya feedstocks at 4 tons of pressure, on the other hand, produced a slightly lower diametral compressive strength of 7.08 MPa compared to 7.59 MPa at 125 ◦ C. The experimental results revealed that the aforementioned factors significantly affect the mechanical properties of pellets. The elucidation of wood biomass, solid fuel qualities and pelletization parameters of this potential energy crop may facilitate the production of high-quality pellets from Khaya senegalensis wood to meet the increasing local and worldwide energy demands. Keywords: biomass; densification; pelletization; biomass pellet; solid fuel; fuel pellets; pellet quality; mechanical properties 1. Introduction Fossil fuel depletion has resulted in the recent increasing demand for substitution of heat and power generation to cater the industrial and residential consumption. The increasing demand for biomass as a source of green energy requires intensive research of several factors contributing to the high quality of biomass feedstock. Dedicated energy crops (DEC) have been extensively utilized in developed countries as a renewable energy feedstock resource for green energy generation. Many exciting results have been reported, indicating its potential as green energy feedstock [1,2]. It is noticed that the research to date has focused on producing biomass fuels from wastes, such as agricultural wastes, munic- ipal solid wastes, food processing waste, and yard waste which include tree trimmings. However, most of the studies in the open literature did not examine the use of dedicated Sustainability 2023, 15, 7501. https://doi.org/10.3390/su15097501 https://www.mdpi.com/journal/sustainability