J. Mar. Sci. Eng.2014, 2(3), 551-567; doi:10.3390/jmse2030551 - published online 2 July 2014 Show/Hide Abstract
Abstract: Physical model tests with the scale of 1:36 are carried out in the Near-Shore Wave Basin (NSWB) at Tainan Hydraulics Laboratory (THL) with the jacket-type offshore wind turbine foundation (jacket-type foundation) and the combination of hard or soft scour protection in the test area. Scouring around the jacket-type foundation exposed to wave and current was conducted in the NSWB with a mobile bed experiment. Two locations (a water depth of 12 m and 16 m) of the foundations are separately simulated in this study. Based on the analysis from the former NSWB experimental results, one traditional hard scour protection usually used in Taiwan with four layers around the foundation is proposed for the mitigation of scouring. From the experimental results, a four-layer scour protection is tested and found to be effective in preventing scouring around the jacket-type foundation. Besides the hard scour protection countermeasure, the scour protection effect of an integrated offshore wind turbine and cage net aquaculture facility as a soft countermeasure for scour protection of the jacket-type foundation is further evaluated in this study. Meanwhile, a detailed analysis for stakeholders’ opinions on the integration of offshore wind farms and coastal aquaculture is also considered to obtain important experience and knowledge; and furthermore, to understand the real demand for adjusting the feasibility of this soft countermeasure.
J. Mar. Sci. Eng.2014, 2(3), 534-550; doi:10.3390/jmse2030534 - published online 1 July 2014 Show/Hide Abstract
Abstract: Blue whale (Balaenoptera musculus) movements are often driven by the availability of their prey in space and time. While globally blue whale populations undertake long-range migrations between feeding and breeding grounds, those in the northern Indian Ocean remain in low latitude waters throughout the year with the implication that the productivity of these waters is sufficient to support their energy needs. A part of this population remains around Sri Lanka where they are usually recorded close to the southern coast during the Northeast Monsoon. To investigate inter-annual variability in sighting locations, we conducted systematic Conductivity-Temperature-Depth (CTD) and visual surveys between January–March 2011 and January–March 2012. In 2011, there was a notable decrease in inshore sightings compared to 2009 and 2012 (p < 0.001). CTD data revealed that in 2011 there was increased freshwater in the upper water column accompanied by deeper upwelling than in 2012. We hypothesise that anomalous rainfall, along with higher turbidity resulting from river discharge, affected the productivity of the inshore waters and caused a shift in blue whale prey and, consequently, the distribution of the whales themselves. An understanding of how predators and their prey respond to environmental variability is important for predicting how these species will respond to long-term changes. This is especially important given the rapid temperature increases predicted for the semi-enclosed northern Indian Ocean.
J. Mar. Sci. Eng.2014, 2(2), 506-533; doi:10.3390/jmse2020506 - published online 10 June 2014 Show/Hide Abstract
Abstract: Located on the northwestern of Taiwan, the Matsu archipelago is near mainland China and comprises four islands: Nangan, Beigan, Juguang, and Dongyin. The population of Matsu totals 11,196 and is chiefly concentrated on Nangan and Beigan. From 1971 to 2000, Matsu built five oil-fired power plants with a total installed capacity of 47 MW. However, the emissions and noise generated by the oil-fired power plant has caused damage to Matsu’s environment, and the cost of fuel is high due to the long-distance shipping from Taiwan. Developing renewable energy in Matsu has therefore been a fervent topic for the Taiwan government, and tidal power is considered to be of the highest priority due to Matsu’s large tidal range (4.29 m in average) and its semidiurnal tide. Moreover, the islands of Nangan and Beigan are composed of granite and have natural harbors, rendering them ideal places for coastal engineering of tidal power plants. This paper begins with a renewable energy reserves assessment in Matsu to determine the amount of tidal energy. Next, a tidal turbine type of the lowest cost is chosen, and then its dynamic characteristic, performance, and related design are analyzed. Finally, the coastal engineering condition was investigated, and a conceptual design for tidal power plant is proposed.
J. Mar. Sci. Eng.2014, 2(2), 493-505; doi:10.3390/jmse2020493 - published online 4 June 2014 Show/Hide Abstract
Abstract: Liquid Natural Gas (LNG) processing facilities typically are located on ocean shores for easy transport of LNG by marine vessels. These plants use large quantities of water for various process streams. The combined wastewater effluents from the LNG plants are discharged to the coastal and marine environments typically through submarine outfalls. Proper disposal of effluents from an LNG plant is essential to retain local and regional environmental values and to ensure regulatory and permit compliance for industrial effluents. Typical outfall designs involve multi-port diffuser systems where the design forms a part of the overall environmental impact assessment for the plant. The design approach needs to ensure that both near-field plume dispersion and far-field effluent circulation meets the specified mixing zone criteria. This paper describes typical wastewater process streams from an LNG plant and presents a diffuser system design case study (for an undisclosed project location) in a meso-tidal coast to meet the effluent mixing zone criteria. The outfall is located in a coastal and marine ecosystem where the large tidal range and persistent surface wind govern conditions for the diffuser design. Physical environmental attributes and permit compliance criteria are discussed in a generic format. The paper describes the design approach, conceptualization of numerical model schemes for near- and far-field effluent mixing zones, and the selected diffuser design.
J. Mar. Sci. Eng.2014, 2(2), 477-492; doi:10.3390/jmse2020477 - published online 26 May 2014 Show/Hide Abstract
Abstract: A point absorbing wave energy converter (WEC) is a complicated dynamical system. A semi-submerged buoy drives a power take-off device (PTO), which acts as a linear or non-linear damper of the WEC system. The buoy motion depends on the buoy geometry and dimensions, the mass of the moving parts of the system and on the damping force from the generator. The electromagnetic damping in the generator depends on both the generator specifications, the connected load and the buoy velocity. In this paper a velocity ratio has been used to study how the geometric parameters buoy draft and radius, assuming constant generator damping coefficient, affects the motion and the energy absorption of a WEC. It have been concluded that an optimal buoy geometry can be identified for a specific generator damping. The simulated WEC performance have been compared with experimental values from two WECs with similar generators but different buoys. Conclusions have been drawn about their behaviour.
J. Mar. Sci. Eng.2014, 2(2), 437-476; doi:10.3390/jmse2020437 - published online 19 May 2014 Show/Hide Abstract
Abstract: Numerical simulations of the storm tide that flooded the US Atlantic coastline during Hurricane Sandy (2012) are carried out using the National Weather Service (NWS) Sea Lakes and Overland Surges from Hurricanes (SLOSH) storm surge prediction model to quantify its ability to replicate the height, timing, evolution and extent of the water that was driven ashore by this large, destructive storm. Recent upgrades to the numerical model, including the incorporation of astronomical tides, are described and simulations with and without these upgrades are contrasted to assess their contributions to the increase in forecast accuracy. It is shown, through comprehensive verifications of SLOSH simulation results against peak water surface elevations measured at the National Oceanic and Atmospheric Administration (NOAA) tide gauge stations, by storm surge sensors deployed and hundreds of high water marks collected by the U.S. Geological Survey (USGS), that the SLOSH-simulated water levels at 71% (89%) of the data measurement locations have less than 20% (30%) relative error. The RMS error between observed and modeled peak water levels is 0.47 m. In addition, the model’s extreme computational efficiency enables it to run large, automated ensembles of predictions in real-time to account for the high variability that can occur in tropical cyclone forecasts, thus furnishing a range of values for the predicted storm surge and inundation threat.