Biodiesel production using various methanol sources and catalytic routes: A techno-environmental analysis

The primary objective of this research is to investigate the biodiesel production via the transesterification reaction between triolein and methanol in the presence of a basic and acidic catalysts, namely sodium hydroxide and sulfuric acid, using CHEMCAD simulation software as a process modelling and simulation tool. Methanol, one of the raw-materials used in biodiesel manufacturing, was synthesized using reforming technology applied to: i) coke oven gas and carbon dioxide, and ii) glycerol that represents an important by-product of the biodiesel synthesis. Four different cases were developed and compared, with detailed operating parameters and equipment designs for each of the investigated scenarios. The production capacity was set to 1000.00 kg/h of biodiesel and a purity higher than 98 % was registered in all investigated cases. Based on the material and energy balances derived from modelling and simulation section, an environmental analysis using the Life Cycle Assessment methodology was performed with the aid of the GaBi software. Ten environmental impact categories (i.e., Global Warming Potential, Fossil Depletion Potential, Human Toxicity, Water Depletion, etc.) are generated and relevant discussions about the sub-processes that exhibit the highest influence are given. The environmental evaluation shows that the most environmentally friendly scenario consists of the methanol production using coke oven gas and carbon dioxide, and its subsequent utilization for the biodiesel production following the alkali catalysis. A scenario analysis regarding several electric and thermal energy sources (i.e., natural gas, biogas, biomass, grid mix) was performed. According to this scenario analysis, while evaluating the synthesis of biodiesel through the alkali catalysis pathway, using biomass as a renewable source improves the environmental performances across certain impact categories.