Pengaruh Pembersihan Biogas Menggunakan Larutan NaOH terhadap Performa Motor Bensin: Studi Komparatif RPM, Torsi, Konsumsi Bahan Bakar, dan Emisi Gas Buang

Abstract

Biogas merupakan sumber energi terbarukan yang menjanjikan untuk aplikasi motor bakar, namun kandungan kontaminan seperti CO₂ (25-45%), H₂S (10-40 ppm), dan H₂O mengurangi nilai kalor dan dapat merusak komponen mesin. Penelitian ini menganalisis pengaruh pembersihan biogas menggunakan larutan NaOH terhadap performa motor bensin 4-tak. Pengujian dilakukan pada motor bensin dengan variasi konsentrasi NaOH (0%, 10%, 20%, 30%) untuk pembersihan biogas. Parameter yang diukur meliputi RPM, torsi, konsumsi bahan bakar spesifik (KBBS), suhu gas buang, dan emisi gas (CO, CO₂, HC, O₂). Hasil penelitian menunjukkan bahwa konsentrasi NaOH optimal sebesar 20% dapat menurunkan kandungan CO₂ hingga 71,9% dengan peningkatan kemurnian CH₄ mencapai 87,76%. Performa motor dengan biogas terproses menunjukkan stabilitas putaran yang lebih baik, torsi meningkat 8-12%, dan emisi CO₂ turun 15-22% dibandingkan biogas tanpa pembersihan. Efisiensi konsumsi bahan bakar dengan biogas terproses mencapai 144,625 g/kW.jam, lebih efisien dibanding bensin premium. Penelitian ini memberikan rekomendasi praktis untuk optimalisasi pemanfaatan biogas sebagai bahan bakar alternatif ramah lingkungan.This study investigates the effect of biogas purification using sodium hydroxide (NaOH) solution on the performance of a four-stroke gasoline engine. Biogas is a promising renewable energy source, but the presence of contaminants such as CO₂, H₂S, and water vapour reduces its calorific value and can cause corrosion in engine components. In this research, biogas is purified using NaOH solution with four concentration levels (0%, 10%, 20%, and 30%), and then supplied to a gasoline engine as an alternative fuel. The measured parameters include engine speed (RPM), torque, brake specific fuel consumption (BSFC), exhaust gas temperature, and exhaust emissions (CO, CO₂, HC, O₂) under several load conditions. The results indicate that a NaOH concentration of 20% is optimal, reducing CO₂ content by about 70% and significantly increasing CH₄ purity, which leads to an improvement in torque by approximately 8–12% and a reduction in BSFC compared to untreated biogas. Furthermore, the purified biogas lowers CO and HC emissions and slightly reduces CO₂ emissions relative to raw biogas, demonstrating better combustion quality and environmental performance while maintaining engine operation that is comparable to gasoline fuel