Comparison Between Traditional Methodologies and Advanced Exergy Analises for evaluating efficiency and externalities of energy system

The majority of the studies available in Oil and Gas Industry literature is often related to the downstream impact of the process chain, while less attention is given to the upstream side. In this frame, efficiency improvements in the sector would provide relevant contributions to the issue of the impact of the oil chain on environment and society. In industrial sector, environmental impact and efficiency of energy systems are assessed through traditional methodologies (Environmental Impact Assessment, Life Cycle Assessment, Risk Analysis).Several innovative methodologies of analysis have been developed to evaluate the overall impacts of complex systems in terms of exergy consumption. These methodologies underline the tendency to extend the evaluation of the impact including the life time of the energy system by considering the exploitation of the involved resources (Cumulative Exergy Consumption, Exergetic Life Cycle Assessment), and including the interaction with the space around the system, by assessing the externalities from the environmental and the economic point of view (Thermoeconomics, Extended Exergy Accounting). The purpose of this paper is to compare the different methodologies commonly used in the industrial sector to assess the environmental impact and the efficiency related to oil and gas sector with the methodologies based on advanced exergy analysis. To perform the comparison a decision model from multi-attribute methods is developed and a hierarchical analysis based on the Analytic Hierarchy Process is performed. Methodologies are compared through a range of criteria based on input-output approach and declined in thirteen indicators concerning integrated assessment and environmental assessment. This paper is part of a wider work aiming to develop a new approach to integrate the different peculiarities of the methodologies to reduce the environmental impact while increasing the technical and economic efficiency of the upstream chain of Oil and Gas sector, by analysing energy and exergy flows, material and waste flows and externalities of the global system.