S. Spain – Technical Report submitted to DOE EERE Wind & Water Power Program, March, 2012
HDR has completed a study of the technical, regulatory, and economic feasibility of installing hydrokinetic turbines under the Morrison, Broadway, and Sellwood bridges. The primary objective of installing hydrokinetic turbines is a demonstration of in-stream hydrokinetic technologies for public education and outreach. Due to the low gradient of the Lower Willamette and the effects of the tide, velocities in the area in consideration are simply not high enough to economically support a commercial installation. While the velocities in the river may at times provide enough energy for a commercial turbine to reach capacity, the frequency and duration of high flow events which provide suitable velocities is not sufficient to support a commercial hydrokinetic installation. We have observed that over an 11 year period, daily average velocities in the Lower Willamette exceeded a nominal cut-in speed of 0.75 m/s only 20% of the time, leaving net zero power production for the remaining 80% of days. Continue reading
(American Chemical Society) Combining the secrets that enable water striders to walk on water and give wood its lightness and strength yielded an amazing material so buoyant that, in everyday terms, a boat made from 1 pound of it could carry five kitchen refrigerators, about 1,000 pounds. One of the lightest solid substances in the world, it was among the topics of a symposium here today at the 243rd National Meeting & Exposition of the American Chemical Society.
W Yang, PJ Tavner, R Court – Mechanical Systems and Signal Processing, March 2012
► The technique is informative and reliable in comparison of existing methods. ► The criteria are effective in detecting both mechanical and electrical faults. ► Stator and rotor winding faults can be discriminated with the aid of the criteria. ► The proposed criteria are simple in calculation, thus suited for online use.
S Salter-Oxford Tidal Energy Workshop, March 2012
There were many possible options for onshore wind turbines but the three-bladed axialflow horizontal-axis design with a mono-tube tower is now universal. It is therefore not surprising that nearly all of the proposals for tidal-stream turbines use horizontal-axis axial-flow. The widely separated rotors are the equivalent of leaky pipes in a hydro-electric scheme. This paper attempts to show that, despite its widespread popularity, the transfer from wind technology is wrong and that a cross-flow design  with rotation about a vertical axis  is better.
JA Oskamp, HT Özkan-Haller-Renewable Energy, September 2012
► Power calculations were performed for one year of hourly spectral wave data for a non-resonating wave energy converter. ► Passive tuning was considered over time scales of hours to a year. Optimal tuning coefficients varied greatly. ► The annual power output declined only 3% when tuning was performed annually rather than hourly. ► An array of four interacting WECs placed 10 diameters apart produced 5% less annual power than equivalent individual WECs.
L Lazauskas, BK Kirke- Renewable Energy, September 2012
► Modeling of passive variable pitch Darrieus hydrokinetic turbines predicts. ► High starting torque. ► Peak efficiency 50% higher than for fixed pitch turbines. ► Optimization reduces shaking to 1/3 that for fixed pitch turbines.
JCC Henriques, MFP Lopes, RPF Gomes, LMC Gato, AFO Falcão- Renewable Energy, September 2012
► Time-domain modelling of a two-body wave energy converter with latching control. ► Annual energy absorption maximization regarding a wave climate. ► Optimum mass ratio between the floater and the submerged body. ► New high-order numerical method for the solution of the Cummins equations. ► Continuous polynomial approximation of the solution using the least-squares method
S Benelghali, M Benbouzid JF Charpentier – Revue des Energies Renouvelables, March 2012
Emerging technologies for marine current turbine are mainly relevant to works that have been carried out on wind turbines and ship propellers. It is then obvious that many electric generator topologies could be used for marine current turbines. As in the wind turbine context, doubly-fed induction generators and permanent magnet generators seems to be attractive solutions to be used to harness the tidal current energy. In this paper, a comparative study between these two generators type is presented and fully analyzed in terms of generated power, maintenance and operation constraints. This comparison is done for the Raz de Sein site (Brittany, France) using a multi physics modeling simulation tool. This tool integrates, in a modular environment, the resource model, the turbine hydrodynamic model and the generators models.
I Colak, S Sagiroglu, M Yesilbudak- Renewable Energy, October 2012
► A literature review including data mining and wind power prediction is presented.► The data mining models which are able to give better performance are specified. ► Many different data mining applications used in wind energy systems are summarized.► Many deficiencies in the literature are revealed and many solutions are proposed.
A. Weinstein, D. Roddier, K. Banister, Technical Report submitted to DOE EERE Wind & Water Power Program, March, 2012
The main challenge for offshore floating renewable energy devices remains to build a structure capable of withstanding the highly energetic ocean environment in such a way that costs are competitive in global energy markets. Due to technological similarities to onshore wind energy and continually growing demand for better wind resources close to load, in certain parts of the world the offshore wind industry is developing quickly. Principle Power, Inc.’s (PPI) WindFloat is a floating foundation for multi-megawatt wind turbines. The WindFloat is a three column semi-submersible platform designed to harvest wind energy in water depths of 45 meters and deeper, where fixed offshore turbines cease being economical. The present WindFloat deploys an industry standard horizontal axis wind turbine at the top of a tower, on one of the three columns and is suitable to accept any other wind turbines configurations as maybe chosen by an end user. In this configuration, the WindFloat has enough deck space for additional equipment.
Principle Power Inc. and National Renewable Energy Lab (NREL) have completed a contract to assess the technical and economic feasibility of integrating wave energy converters into the WindFloat, resulting in a new concept called the WindWaveFloat (WWF).