Literature Review: Characteristics of Briquettes from Palm Oil Shell Waste and LDPE Plastic as Alternative Fuels

Abstract

The increasing global energy demand and the depletion of fossil fuel reserves have driven the search for renewable alternative energy sources. Indonesia, as the world's largest palm oil producer, generates abundant palm oil shell waste, while plastic waste, particularly Low-Density Polyethylene (LDPE), poses a significant environmental challenge. Briquettes made from palm oil shell waste and LDPE plastic offer a dual solution: waste valorization and alternative fuel production. This literature review synthesizes findings from five experimental studies investigating the physical, mechanical, thermal, and emission characteristics of palm oil shell and LDPE plastic briquettes. The reviewed studies examined the effects of starch adhesive composition (0.5–3.5 g), briquetting pressure (30–80 N/m²), LDPE content (0%–9%), and particle size (40–100 mesh) on briquette properties. Key findings indicate that optimal adhesive content of 2 g yields the best overall quality (calorific value 6,840 cal/g), optimal briquetting pressure of 40–70 N/m² enhances mechanical strength, addition of 9% LDPE increases calorific value up to 6,058 cal/g, and 80 mesh particle size combined with 70 N/m² pressure produces the highest ultimate strength (4.81 MPa). Briquettes with less than 10% LDPE addition and appropriate combustion chamber design meet Indonesian emission standards. All reviewed briquette formulations satisfied SNI 1683:2021 standards for moisture content, volatile matter, and fixed carbon, though ash content requires further optimization. This review identifies research gaps including the need for long-term combustion performance studies, economic feasibility analysis, and scaling up production.