Wells turbine for wave energy conversion : a review

In the past twenty years, the use of wave energy systems has significantly increased, generally depending on the oscillating water column (OWC) concept. Wells turbine is one of the most efficient OWC technologies. This article provides an updated and a comprehensive account of the state of the art research on Wells turbine. Hence, it draws a roadmap for the contemporary challenges which may hinder future reliance on such systems in the renewable energy sector. In particular, the article is concerned with the research directions and methodologies which aim at enhancing the performance and efficiency of Wells turbine. The article also provides a thorough discussion of the use of computational fluid dynamics (CFD) for performance modeling and design optimization of Wells turbine. It is found that a numerical model using the CFD code can be employed successfully to calculate the performance characteristics of W-T as well as other experimental and analytical methods. The increase of research papers about CFD, especially in the last five years, indicates that there is a trend that considerably depends on the CFD method

Pareto-Improving Water Management over Space and Time: The Honolulu Case

We model welfare gains from efficient allocation of groundwater over space and time relative to the status quo policy of financial cost recovery. In order to promote political feasibility, an intertemporal compensation plan is devised that renders the reform Pareto-improving. Gainers from the reform finance the compensation in proportion to their benefits through a block-pricing scheme. For the Honolulu case, only 7% of the $441 million in gains to winners is needed to compensate losers from the reform. Future winners from the reform also repay the deficit created by the compensation package, much as state and local governments finance capital improvements. Copyright 2009, Oxford University Press.