Minimization of local impact of energy systems through exergy analysis

For the acceptability of energy systems, environmental impacts are becoming more and more important. One primary way for reducing impacts related to processes is by improving efficiency of plants. A key instrument currently used to verify such improvements is exergy analysis, extended to include also the environmental externalities generated by systems. Through exergy-based analyses, it is possible indeed to evaluate the overall amount of resources consumed along all the phases of the life cycle of a system, from construction to dismantling. However, resource consumption is a dimension of the impact of a system at global level, while it may not be considered a measure of its local impact. In the paper a complementary approach named Combined Risk and Exergy Analysis (CRExA) to assess impacts from major accidents in energy systems is proposed, based on the combination of classical exergy analysis and quantitative risk analysis (QRA). Impacts considered are focused on effects on human health. The approach leads to the identification of solutions to minimize damages of major accidents by acting on the energy system design

Exergy as a measure of oil well potential

The growing problem of non-renewable resources scarcity led analysts and researchers to deepen Second Law analysis methods in order to optimize the consumption of resources in energy systems and related supply chains. Since little focus has been made so far on the second law analyses applied to the upstream of Oil & Gas supply chains, in this paper a theoretical exergy model for the evaluation of oil streams potential is presented. The model is applied to two multiphase multi-component oil streams, using field data. The objective of the model is to determine the net exergy of a generic oil stream, bringing it from the well head conditions to a defined dead state through a series of reversible processes. The ideal process is modeled using a modular representation, where each step represents a single thermodynamic transformation to equilibrium towards the dead state (Pressure and Temperature, Species Separation and Chemical composition). Some of the contributions are positive (work may be extracted from the stream) other are negative (work is required to complete the transformation). The net exergy of the stream is the algebraic sum of such contributions. This ideal value can be assumed to assess the ideal energetic potential of the oil stream