Sustainability assessment of power generation in combination with lng evaporation: A comparison of lca methods and exergy analysis

Several options exist for power generation, but it is difficult to determine which option is the most sustainable. When assessing the sustainability of an option or system, it is important to consider the environmental, economic and social aspects of sustainability and to take a life-cycle point of view. According to literature, a relationship exists between exergy and sustainability, but it is not common use to apply exergy analysis for improving sustainability. In this research, three options for power generation in combination with LNG evaporation are assessed, i.e. using the waste heat from a coal-fired power plant for LNG evaporation, integrating an oxy-fuel power plant with an air separation unit and an LNG terminal, and a separate power plant plus an LNG terminal combined with an Organic Rankine Cycle. The results of environmental LCA, environmental Life Cycle Costing, social LCA and the Cumulative Exergy Loss (CExL) method of the three options have been compared. The oxy-fuel option is preferred according to the results of the environmental, economic and exergetic assessment methods. The difference in the outcomes of the social assessment is too small to choose between the three options. From studying the three options in more detail, it became clear that the processes that contribute most to the overall score of a method are different. E.g., the natural gas production process is responsible for about 70 per cent of the LCA score, but causes only 2 to 3 per cent of the CExL