Life Cycle Assessment (LCA) And Data Quality Analysis Of Vehicle Fuel From Biomass

With global energy crisis and environmental pollution becoming increasingly serious, the production of vehicle fuels, as an alternative for traditional fossil fuels from clean and renewable biomass, can not only alleviat the energy crisis, but also reduce greenhouse gases. However, there exist some problems, such as environment pollution, resource consumption, economy cost, etc. during the utilization of biomass energy. Therefore, it is essential to carry out the life cycle integrated evaluation for clean and efficient utilization of biomass.Firstly, the integrated evaluation model was established based on life cycle assessment (LCA) and analytic hierarchy process (AHP). The integrated performance of environment, resource, and economy for two processes, which were vehicle fuel production from biomass fast pyrolysis with hydroprocessing (Bio-FPH) and Fischer-Tropsch synthesis technology (Bio-FTL) using corn stalks as biomass feedstock, was studied. The results are shown as follows. (1) The total environmental impact loads are 0.30-0.46 person annual for one ton fuel and 0.33-0.54 person annual for one ton fuel at different perspectives, following the decreasing order of globality, equality, regionality and locality. And the environmental performance of Bio-FPH is better than that of Bio-FTL. For biomass conversion process, the main environmental impact categories are global warming (GWP), acidification (AP) and photochemical ozone formation (POF) accounting for 80%?95%, whereas the contributions of these environmental impact categories are varied from different perspectives. The contributions of stages are also different and the primary pollutants in the system were derived from the biomass growth stage and production stage. (2) The resource performance of Bio-FPH is superior to Bio-FTL, in which the resource consumption for Bio-FPH and Bio-FTL are 0.04 and 0.05 person annual for one ton fuel, respectively. The main resource consumption occurs at production stage with electricity consumption. (3) The economic performance of Bio-FPH is also better than Bio-FTL, and the economic costs for Bio-FPH and Bio-FTL are approximately 7800 RMB/t and 8830 RMB/t, respectively. The main economic costs of Bio-FPH and Bio-FTL are biomass feedstock costs and depreciation charges, which accounted for 44.6%?47.3% and 13.9%?15.7% of total costs separately. (4) The indexes of integrated performance of the two biomass conversion processes were obtained using the range transform method. The integrated performance for Bio-FPH and Bio-FTL are about 0.22?0.34 and 0.26?0.40, furthermore, the integrated performance of Bio-FPH has an advantage over Bio-FTL. The indicators affecting the integrated performance are in the order of economic cost>environmental impact>resource consumption. (5) Sensitivity analysis shows that the environmental performance and resource performance are more sensitive to the biomass consumption ratio and electricity consumption in the production stage, and the sensivities of economic costs caused by biomass consumption ratio and fixed cost are more significant. Moreover, biomass consumption ratio, electricity consumption and fixed cost are the key factors to influence the integrated performance. (6) Compared with petroleum diesel, the greenhouse warming and resource consumptions during of Bio-FPH and Bio-FTL are reduced and Bio-FPH exhibits a more remarkable effect. However, the opposite tendency could be observed for economy.Secondly, the model of the data quality assessment was established based on data quality indicators matrix and uncertainty, and the relative standard deviation (RSD) was proposed to quantify the LCA indicators of Bio-FPH and Bio-FTL. In addition, the key raw data with high uncertainty and sensitivity in LCA could be identified, which indicated the "hot spot" for data quality improvement. The results are as follows. (1) For Bio-FPH and Bio-FTL, the uncertainties(Uh) of total environmental impact loads, from different perspective, are 6.2%-7.0%. The uncertainty of EP is far greater within the range of 15.8%to 15.9% and the uncertainty of other environmental impact category indicators are less than 8.5%. (2) The uncertainty of resource consumption and economic cost, varying in the range of 6.7%to 6.8%and 8.0%to 8.3%, respectively, meet the data quality requirement as well. (3) As for GWP, AP, solid waste (SW) and abiotic depletion potential (ADP), the key data with high uncertainty and sensitivity for data quality improvement are biomass and electricity consumption in the production stage. Besides, the biomass consumption and HC emission during fuel utilization stage are key data for POF. Moreover, the electricity consumption and NOx emission during utilization stage are more significant of human toxicity (HTP). Furthermore, the data quality improvement for eutrophication (EP) lies on biomass and N fertilizer consumption. For economic cost, biomass purchase price, biomass consumption and fixed cost are important data.Finally, based on the assessment model of integrated performance, the integrated LCA software for biomass conversion processes is developed using Visual Basic 6.0 as software development platform, Microsoft Access as database management system (DMS), and active data objects (ADO) to operate the DMS. The LCA software can carry out basic information inquire, life cycle evaluation and analysis of environment, resource and economy. In addition, the software is user-friendly, simple, practical and extensible.