Ecological-based Life Cycle Assessment Methodology And The Application To Energy-chemical Processes

The energy-chemical industries are parts of the foundation of social development. They provide varieties of essential products and services to the economy and people’s living. Yet the serious problems of consumption and pollution in energy-chemical industries also bring harms to human health, community safety and ecosystems quality. With the awareness of sustainability development strengthening, researches which only focus on the production phase and industrial supply chains of products do not meet the requirements of decision-making any more. All the ecological supply chains and industrial supply chains of products need to be further investigated. However, current methodology of process system engineering are mostly restricted to processing units, products’ life cycle, or the economic scale. Research on sustainability of energy-chemical processes on the ecological scale is relatively blank. This research creates a methodology for sustainability assessment which could simultaneously integrate the resources, economic, and environmental factors of energy-chemical processes on the ecological scale.Firstly, limitations of existing methods including industrial Cumulative Exergy Consumption analysis and Emergy accounting for sustainability researches of energy systems are revealed. To establish the measurement base of resource consumption in energy-chemical systems, the Ecological Cumulative Exergy Consumption(ECEC) is introduced. It combines both the strengths of the Cumulative Exergy Consumption and the Emergy, while avoids their corresponding weaknesses. By such ECEC analysis, the ecological cost of different kinds of resources consumption could be assessed and compared on a consistent base.Economic investment and environmental pollution are also significant factors of sustainability of energy-chemical systems. This research further expands the ECEC analysis to quantify purchased resources and pollutant impacts. By that, an extended ECEC model is established, covering the resources, economic, and environmental factor of energy-chemical processes. Such model establishes the common base on which different resources consumption, different economic investment, and different pollutants could be compared for sustainability. And it provides a measurement of the ecological burden exerted by industrial systems, which could be informative for industrial optimization.Moreover, to further apply the extended ECEC model to different industrial decision-making, the Ecological Life Cycle Cost(ELCC) is put forward as an indicator of sustainability by using currency as its unit. The relationships among ELCC, ECEC, and traditional economic costing are revealed. Accordingly, the theoretical framework of Ecological-based Life Cycle Assessment(Eco-LCA) is defined. It could be used to investigate the ecological influence and sustainability of different process systems through their resources, economic, and environmental factor, so that provides scientific guides for decision-making on energy-chemical systems.At last, this research applies the Eco-LCA method to the comparing assessment among different transportation fuels production. The results reveal that the ELCC of Biomass-to-Liquid fuel is only 1/3 of that of conventional fuel. BTL could be remarkably beneficial to the sustainability development of fuel industries. The pecuniary gain by Coal-to-Liquid fuel, however, does not match its loss in the resource and environmental aspects. The ELCC of CTL is twice of conventional fuel and technical improvement is of urgency. This research offers explicit guides on ecological scale for the development of transportation fuel industries.