Techno-economic Analysis And Comprehensive Evaluation Model On Biodiesel Production Process

Recent concerns over diminishing petroleum fuel supplies and adverse environmental impacts from the use of fossil fuel have prompted considerable interest in research and development of green and renewable energy resources. Biodiesel is one of the most attractive alternative energy sources because of its good combustion properties, renewable and environment-friendly features. There are a number of choices with regard to biodiesel production technology, raw materials and byproduct utilization patterns, making it difficult to evaluate the production process objectively and comprehensively. So there still lacks systematic research in this area. From this perspective, technology applicability, economic feasibility and environmental impact using different raw materials and production processes were studied in this paper. And a comprehensive evaluation model was established.A detailed description of four typical processes, including homogeneous base-catalyzed transesterification using rapeseed oil, homogeneous base-catalyzed transesterification with a pretreatment unit, solid acid-catalyzed transesterification, and supercritical methanol transesterification using waste oil were carried out. Plants capable of producing 8000 tons/yr biodiesel were calculated for the material and energy balance. On this basis, four processes were technically assessed, they were all feasible that can achieve high quality of biodiesel and byproduct glycerin under possible operating conditions. However, each process had its limitation. In contrast, the solid acid-catalyzed method is relatively simple in equipments and operation, which is a more promising approach.A economic feasibility assessment of each process is also presented with the technological economics theory and methods, as well as the uncertainty analysis. The economic indexes consisted of static payback period, dynamic payback period, financial net present value and return on investment. The results showed that, in our current tax and price system, the ROI of four projects were -170.21%, -25.55%, 70.3%, 5.33%, respectively. Only the solid acid-catalyzed project can be profitable without any subsidies, and other projects were not economically viable. Raw material cost constituted 75-82% of the total manufacturing cost. Preliminary sensitivity analysis showed that variations on price of raw material had the biggest influence over the breakeven price and return on investment, prompting people to use lower cost raw materials and the corresponding process. To some extent, the increase of price and production scale both can improve the profitability and ability to resist risks. At the same time, government subsidies played an important role.A comprehensive evaluation model according to the Analytic Hierarchy Process (AHP) was set up, and three evaluation criteria and eight indicators were brought out. The conclusion showed that the weights of environmental pollution and supply of resources were the greatest, and product quality, equipment and technology and economic benefits weighed lower. Solid acid-catalyzed process obtained the highest scores. Therefore, future biodiesel should be clean, low-power, while seeking for stable, inexpensive source of raw materials.The conclusion of this study laid the foundation for technical improvement, optimization, and further development of biodiesel industry.