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Production activities of modern economies are ultimately sustained by depletion of non-renewable fossil fuels. In the perspective of non-renewables displacement, an accurate evaluation of energy embodied in goods and services is crucial in order to select among alternative products or policies. Economic-based Input-Output models are widely used for this purpose: however, due to the increasing amount of international trades of products, definition of appropriate methods to account for the energy embodied in trades is nowadays crucial. In this paper, international trades treatment methods in Input-Output analysis are comprehensively formalized and applied to a case study based on the World Input-Output Database (WIOD). Energy embodied in final demand and in detailed products of key national energy sectors have been evaluated for the WIOD countries according to Single-Region and Multi-Regional models. It is found that an inappropriate use of international trades treatment models may produce very inaccurate estimations of numerical values of embodied energy. Three country groups has been identified, characterized by different ranges of fractions of imported/exported primary fossil fuels: Single-Region method A returns best results for countries of Group 1, with high values of fossil exports and low values of fossil imports; Multi-Regional method C is to be preferred for countries of Group 2, with high values of fossil imports and low values of fossil exports; finally, Single-Region method B returns lower deviations compared to other methods for countries of group 3, with low values of fossil imports and exports. This paper aims at supporting researchers in the field of Life Cycle Assessment in the application of Environmentally extended Input-Output analysis, finding the best trade-off between the efforts due to data collection and the accuracy of results. [ABSTRACT FROM AUTHOR]

Abstract The production of Liquefied Natural Gas (LNG) from natural gas reservoirs with high content of acidic compounds is expected to be a strategic and crucial issue for the development of the natural gas market in future decades. Therefore, the identification of alternative suitable processes for the synergistic natural gas purification and LNG production, when the amount of CO 2 in the raw gas feed is high, and their comparative thermodynamic assessment, is necessary to foster a cleaner and efficient production of LNG. In this paper, the energy intensity of the classical chemical absorption units using aqueous solutions of Methyldiethanolamine (MDEA) and the novel Dual Pressure Low-Temperature Distillation process (DPD) operating in different national contexts is assessed by means of the Net Equivalent Methane analysis and the Energy Life Cycle Assessment. These methods return respectively the equivalent methane and the embodied non-renewable energy invoked by the two alternative processes in one operating year. In general, the primary energy required by the construction phases of both the systems results negligible compared to the operation phase, and most of the latter is due to the consumption of energy utilities, which is strongly dependent by the considered national context. According to the results obtained by means of both the methodologies, the DPD process is generally less energy intensive compared to MDEA: the DPD process results to be an efficient and promising technique to perform the synergistic natural gas purification and LNG production. Highlights • Exploitation of acidic natural gas reserves and LNG production will play key role in future decades. • Two alternative processes for acid natural gas purification and LNG production are introduced. • Net Equivalent Methane method and Energy LCA of the processes are comparatively applied. • Both the methods confirm that Dual Pressure Low-Temperature Distillation has the lowest energy intensity. [ABSTRACT FROM AUTHOR]