Abstract¬¬-PLA is one of the most promising bio-compostable and bio-degradable thermoplastic made from renewable sources. In the literature, the technique mainly developed for ring opening polymerization (ROP) of Lactide is based on metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts in suitable solvent [1]–[3]. However, the PLA synthesized using such catalysts may contain trace elements of the catalyst which causes hazard and toxicity. Reactive extrusion experiments using stannous octoate Sn(Oct)2 and tri-phenyl phosphine (PPh)3 were considered to perform ROP of lactide monomer using ultrasounds as an alternative energy (AE) source for activating and/or boosting the polymerisation. Mathematical model of ROP of PLA was developed to estimate the impact of reaction kinetic and AE source on the polymerisation process. Ludovic® software was used for the simulation of continuous reactive extrusion of PLA. Experimental and simulated results schematic were developed to validate Figure 1. In this work we also investigated the usefulness and drawbacks of most conventional metal catalysts as well as effect of alternative energies on reaction mechanism and future aspects for safer and efficient bulk PLA production. Keywords: alternative energy, bio-degradable, Extrusion, metal catalyst, poly lactic acid (PLA), ring opening polymerization (ROP) [1] P. Dubois, C. Jacobs, R. Jerome, and P. Teyssie, “Macromolecular engineering of polylactones and polylactides. 4. Mechanism and kinetics of lactide homopolymerization by aluminum isopropoxide,” Macromolecules, vol. 24, no. 9, pp. 2266–2270, Apr. 1991. [2] Y. Yu, G. Storti, and M. Morbidelli, “Ring-Opening Polymerization of l,l-Lactide: Kinetic and Modeling Study,” Macromolecules, vol. 42, no. 21, pp. 8187–8197, Nov. 2009. [3] I. Banu, J.-P. Puaux, G. Bozga, and I. Nagy, “Modeling of L-lactide Polymerization by Reactive Extrusion,” Macromol. Symp., vol. 289, no. 1, pp. 108–118, 2010.