Energy and exergy analysis of SNG production from syngas derived from agricultural residues in Bolívar, Colombia

Abstract

Synthetic natural gas (SNG) production from biomass residues represents a promising strategy to reduce greenhouse gas emissions and enhance energy security in regions with abundant agricultural waste. This study evaluates the thermodynamic performance of SNG synthesis from rice husk (RH) and empty fruit bunches (EFB) bio-oils, major residues in the department of Bolívar, Colombia. The process was simulated in Aspen Plus®, integrating syngas data and methanation under equilibrium conditions at 320 °C and 30 bar, complemented by hydrogen injection via alkaline electrolysis to maintain an H2/CO ratio above 3. Energy and exergy analyses were performed to quantify efficiencies and irreversibilities. Results indicate carbon conversion rates of 48.3% for EFB and 47.4% for RH, producing SNG with 96% CH4 suitable for grid injection. Energy efficiencies reached 71.9% and 71.0%, while exergy efficiencies were 87.2% and 82.9%, respectively, aligning with or surpassing literature benchmarks. The main irreversibilities occurred in methanation and CO2 removal, highlighting thermal integration and gas recycling as key improvement strategies. These findings demonstrate the potential of leveraging local biomass for clean energy production and support the development of Power-to-Gas systems in Colombia.