Sustainable Power Production Research Articles

Exergy Sustainability Indicators as a Tool in Industrial Ecology

Abstract: Life‐cycle assessment is an established tool for industrial ecology. An analysis of the energy use in the chemical and other energy‐intensive industries is still under discussion in this field. We argue that the concept of exergy can play a role in industrial ecology, using a recent Norwegian power production policy question as illustration. The question is whether to build a standard natural gas‐ or a hydrogen‐fired gas‐turbine combined‐cycle power plant to meet increased needs for electricity in Norway. Several indicators are relevant for this discussion, and we calculate three based on exergy calculations, as proposed in the literature. The indicators are exergy renewability, exergy efficiency, and environmental compatibility. We show how these indicators can be used to evaluate paths for sustainable power production in two gas‐fired combined‐cycle power plants. We found that the two plants in question were equivalent, as judged by their exergy renewability and their environmental compatibility, but not by their exergy efficiency. This indicator favored the standard power plant, possibly in combination with carbon dioxide (CO2) sequestration in a depleted gas reservoir. The analysis suggested that the present situation for power production in gas‐fired combined‐cycle power plants is such that one may have to choose in general between power production with a high exergy efficiency, but low renewability indicator, or the opposite, low exergy efficiency and high renewability indicator. The general importance of exergy analysis was demonstrated by this example. It enables communication between different professional groups. The technological details, understood by the engineers, can be transposed to meaningful aggregated indicators for decision makers.

Multiphysics Simulation of Wave Energy to Electric Energy Conversion by Permanent Magnet Linear Generator

The possibility to use three-phase permanent magnet linear generators to convert sea wave energy into electric energy is investigated by multiphysics simulations. The results show a possibility, which needs to be further verified by experimental tests, for a future step toward a sustainable electric power production from ocean waves by using direct conversion. The results suggest that wave energy can have an impact on tomorrow's new sustainable electricity production, not only for large units, but also for units ranging down to 10 kW. This gives wave power a larger economical potential than previously estimated. The study demonstrates the feasibility of computer simulations to give a broad, and in several aspects a detailed, understanding of the energy conversion. The simulation results also give a useful starting point for future experimental work.