Maria Kartezhnikov and Thomas M. Ravens – Renewable Energy, Volume 66, June 2014
A simple technique to estimate the far-field hydraulic impacts associated with the deployment of hydrokinetic devices is introduced. The technique involves representing hydrokinetic devices with an enhanced Manning (bottom) roughness coefficient. The enhanced Manning roughness is found to be a function of the Manning roughness, slope, and water depth of the natural channel as well as device efficiency, blockage ratio, and density of device deployment. The technique is developed assuming simple open channel flow geometry. However, once the effective bottom roughness is determined, it can be used to determine the hydraulic impact of arbitrary device configurations and arbitrary flow situations.
Mark J. Kaiser and Brian F. Snyder – Ships and Offshore Structures, February 2014
Decommissioning requirements for offshore renewable energy facilities in US federal waters requires that all facilities be removed and the seafloor be cleared of all obstructions at the end of the life of the lease. Before construction activities are permitted, developers are required to post a bond based on the estimated cost of decommissioning to ensure that the federal government is protected in case of company default. The purpose of this note is to provide weight algorithms of offshore wind farm components to estimate the lift requirements in decommissioning, the scrap value of material, and disposal cost. Weight algorithms are calibrated and compared with North Sea project data and examples illustrate the procedures. The component weights at the Cape Wind farm offshore Massachusetts are estimated.
J. Vaughn Barrie and Kim W. Conway – Continental Shelf Research, October 2013
An inventory of Canada’s marine renewable energy resources based on numerical modeling of the potential tidal, wave and wind energy has been published that identifies areas with maximum resource potential. However, the inventory does not consider the seabed geological conditions that will control the safe development of seabed installations and cable corridors. The Geological Survey of Canada (Natural Resources Canada) has therefore undertaken an assessment of seafloor geological characteristics and physical environmental parameters that will be encountered during any extensive deployment of marine renewable energy systems for the Pacific offshore of Canada. Here we present an overview of seabed characterization for key sites for each of the three energy types. Continue reading
Wei-Haur Lam and Aalisha Bhatia – Renewable and Sustainable Energy Reviews, December 2013
Research and development of tidal current turbines has undergone significant growth since the past decades. The trials and errors have led to the improvements for various aspects of tidal current turbines. One of the remaining problems of tidal current turbines is the difficulties in transportation and installation. The concept of folding tidal turbine was proposed to provide a solution for the ease of transportation and installation in 2010. Folding tidal turbine has the foldable parts of blades, shaft, connecting rods and outer box compared to the rigid structure of a conventional turbine. The current study discusses the components of folding turbine, rigidity of structure, performance, working concept, efficiency, material, electrical aspects, environmental impacts and prevention of marine corrosion. Previous works proposed the costs for transportation and installation of a conventional tidal turbine were 30% of the total cost. Folding tidal turbine is estimated to reduce 20% of the total cost with a shorter installation time.