Oscillating-water-column wave energy converters and air turbines: A review

"Comprehensive Renewable Energy" is the only multi-volume reference work of its type at a time when renewable energy sources are seen increasingly as realistic alternatives to fossil fuels. As the majority of information published for the target audience is currently available via a wide range of journals, seeking relevant information (be that experimental, theoretical, and computational aspects of either a fundamental or applied nature) can be a time-consuming and complicated process. "Comprehensive Renewable Energy" is arranged according to the most important themes in the field (photovoltaic technology; wind energy technology; fuel cells and hydrogen technology; biomass and biofuels production; hydropower applications; solar thermal systems: components and applications; geothermal energy; ocean energy), and as such users can feel confident that they will find all the relevant information in one place, with helpful cross-referencing between and within all the subject areas, to broaden their understanding and deepen their knowledge. It is an invaluable resource for teaching as well as in research. Available online via SciVerse ScienceDirect and in print. Editor-in Chief, Professor Ali Sayigh (Director General of WREN (World Renewable Energy Network) and Congress Chairman of WREC (World Renewable Energy Congress, UK) has assembled an impressive, world-class team of Volume Editors and Contributing Authors. Each chapter has been painstakingly reviewed and checked for consistent high quality. The result is an authoritative overview which ties the literature together and provides the user with a reliable background information and citation resource. The field of renewable energy counts several journals that are directly and indirectly concerned with the field. There is no reference work that encompasses the entire field and unites the different areas of research through deep foundational reviews. "Comprehensive Renewable Energy" fills this vacuum, and can be considered the definitive work for this subject area. It will help users apply context to the diverse journal literature offering and aid them in identifying areas for further research. Research into renewable energy is spread across a number of different disciplines and subject areas. These areas do not always share a unique identifying factor or subject themselves to clear and concise definitions. This work unites the different areas of research and allows users, regardless of their background, to navigate through the most essential concepts with ease, saving them time and vastly improving their understanding. There are more than 1000 references from books, journals and the internet within the eight volumes. It is full of color charts, illustrations and photographs of real projects and research results from around the world. The only reference work available that encompasses the entire field of renewable energy and unites the different areas of research through deep foundational reviews. Allows readers, regardless of their background, to navigate through the most essential concepts with ease, saving them time and vastly improving their understanding.

Comprehensive Renewable Energy

This paper describes the present status of the art on air turbines, which could be used for wave energy conversion. The air turbines included in the paper are as follows: Wells type turbines, impulse turbines, radial turbines, cross-flow turbine, and Savonius turbine. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been compared by numerical simulation and sea trial. As a result, under irregular wave conditions it is found that the running and starting characteristics of the impulse type turbines could be superior to those of the Wells turbine. Moreover, as the current challenge on turbine technology, the authors explain a twin-impulse turbine topology for wave energy conversion.

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Air Turbines for Wave Energy Conversion

https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1767&context=etdr

Optimal control of wave energy converters

A novel radial self-rectifying air turbine for use in wave energy converters

A twin unidirectional impulse turbine topology for OWC based wave energy plants – Experimental validation and scaling

The near shore Oscillating Water Column (OWC) based Indian wave energy plant was operated with several conceptually different power modules. These include a tapered chord Wells' turbine, a linked guide vane (LGV) impulse turbine and a fixed guide vane (FGV) impulse turbine, while using the same grid connected induction generator. The turbine efficiency is calculated for a wide range of pneumatic power on a cycle to cycle basis. The behaviour of the turbines at various flow coefficients is compared with reported steady state measurements under laboratory conditions. The cycle by cycle analysis of the turbines clearly shows the behaviour under real conditions. The overall comparison shows that among the turbines tested, the FGV is the better choice.

Analysis of Power Modules in the Indian Wave Energy Plant

Pneumonia has been labeled as the single largest cause of child mortality for the children under five in developing countries around the world. We propose a novel method to continuously monitor parameters like Respiration Rate, Heart Rate, Blood Oxygenation (SpO2) and Body Temperature in a noninvasive and nonobtrusive manner behind the ear. The data is streamed using WiFi to the parent's smartphone or a smart gateway device which uploads it to a server. This paper also explores the opportunities for presenting patient vital signs from such a device to the remote health care workers and doctors. A prototype named Raksh was developed and various sensors were evaluated. The final bill of material cost of the device would be 23 US dollars.

A wearable diagnostic device to combat children's pneumonia

The near shore oscillating water column (OWC) wave energy plant at Vizhinjam, India had twin 1 m Well’s turbines and 1 m linked guide vane impulse turbines as power modules. Performance analysis of the observed records during operation yield significant insight on the dimensioning of the turbine with respect to the caisson. A cycle by cycle analysis of energy capture clearly identifies stalling behavior of the Well’s turbine. Similarly, the performance degradation of the linked guide vane due to mechanical problems could be identified. Such analysis is possible as the electrical machine is an induction generator and the moment of inertia of the system is relatively small. It is clear that optimum dimensioning of the turbine is a must with an OWC based wave energy plant.

Performance Comparison of Power Modules In the Indian Wave Energy Plant

Results from near-shore bottom standing Oscillating Water Column (OWC) based wave energy plants in Japan and India have now been available for about a decade. The most complete and detailed experimental results with near shore OWC plants are possibly from the one at Sakata port, Japan. Experience in Europe is mostly with shoreline devices as evidenced in the LIMPET and other similar plants. The plant in India is the longest standing device since its commissioning in 1991. It is unique in that several power modules with different turbines have been tested. Recently a proposal has been made to use twin unidirectional turbines in lieu of traditional bidirectional turbines promising very significant improvements in the power module efficiency. However, as experience has shown, the overall efficiency is also dependent on matching the power module to the OWC. In this work we review the principal design features that were initially considered for the Indian wave energy plant in the light of recent developments. We suggest methods for optimizing the overall performance in order to design the next generation OWC plant. The work will also be useful for planning newer installations. The influence of the power module on the overall efficiency will be clearly highlighted. As an example we estimate the performance of the Sakata port design with proposed twin unidirectional impulse turbines instead of twin 1.337 m Wells turbines using the experimentally observed hydrodynamic efficiencies. We show the performance of a wave energy plant designed for Indian conditions based on a comparison of the two designs for a plant with an overall width of 10m. The calculation is done for both monsoon and non monsoon conditions and the significant conclusions are highlighted. Cost estimates for two different plant sites, one island and one mainland, are also provided.

K. Mala

Papers

A twin unidirectional impulse turbine topology for OWC based wave energy plants – Experimental validation and scaling

Analysis of Power Modules in the Indian Wave Energy Plant

A wearable diagnostic device to combat children's pneumonia

Performance Comparison of Power Modules In the Indian Wave Energy Plant

Techno-Commercial Study of Twin Unidirectional Turbine Based Wave Energy Plants