Gabriel Alsenas

A 20 KW open ocean current test turbine

Florida is faced with an energy crisis with respect to capacity, supply, cost, emissions, and stability. The untapped energetic waters of the Florida Current could provide a clean, reliable, base-load local renewable energy source for Florida. To facilitate the successful commercial harvesting of this hydrokinetic resource, Florida Atlantic Universitys Center for Ocean Energy Technology is designing, fabricating, deploying, and operating an experimental small-scale turbine. This 20 kW Ocean Current Turbine Testbed (OCTT) is an open-blade axial-flow horizontal underwater turbine driven by a 3 m diameter 3-blade rotor. It is intended to operate in the open ocean near the core of the Florida Current, offshore Ft. Lauderdale, for long periods of time. This turbine is not intended to be a scaled prototype of a commercial model, but it is intended to be an experimental system to assess technology, identify gaps, investigate and collect data about potential environmental impacts, and provide a foundation for commercial and policy development.

Florida's Center for Ocean Energy Technology

The Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) is a timely State of Florida initiative for the research and development of ocean current and ocean thermal energy technologies. The Center is a synergistic partnership among academic, industry, and government organizations focused on developing knowledge, understanding, infrastructure, technology, and policy towards a low-environmental-impact extraction of ocean energy. The Center is a hub that bridges the gap between concept and commercial implementation by fostering the research, design, development, implementation, testing, and commercialization of cutting-edge, clean, and innovative ocean energy technology. It brings together a broad range of unique, enabling, and accessible expertise and physical assets.

Response characteristics and maneuverability of a small twin screw displacement hull vessel in seas

Abstract This paper presents the response characteristics and maneuverability of a small twin screw displacement hull vessel quantified through a series of full-scale trials conducted in different environmental conditions. The 20-m test vessel is instrumented with actuator, environmental, and motion sensors. Several different maneuvers are performed at different speeds, including steady maneuvers with constant control input and transient maneuvers with varied control input to quantify and characterize the response of small vessels to aid in automatic controller and simulation development. Straight-line runs are performed in both forward and reverse over the entire operating range of the test vessel to investigate the relationship between throttle position, RPM, and surge velocity. Turning maneuvers are conducted over the achievable rudder deflection range to quantify the vessels turning radius and the relationships with surge, sway, and rotational speed. Other maneuvers include stationary rotation with the engines operating in opposite gears, and transient tests when the vessel is rapidly accelerated and decelerated. These actuator tests not only quantify the response of the actuators, but also set guidelines for the minimum dwell times that should be observed when shifting gears. These data found using a comprehensive sensor suite provide valuable benchmarks for several maneuvers that can be used for simulation validation and the actuator response information provides valuable set points and performance characteristics/limitations that should be considered in control development. The data from these tests were repeatable from run to run and thus, with sufficient instruments, at sea maneuvers can be used to collect a comprehensive set of data that can expand on data collected in tow tests.

Automation of the SHIELD methodology for system hazard analysis and resilient design

The System Hazard Indication and Extraction Learning Diagnosis (SHIELD) methodology was developed as a novel method to perform system hazard analysis and resilient design. In an earlier paper we described SHIELD conceptually and outlined the details necessary to conduct the analysis manually. This approach integrates state space examination into the analysis process in order to facilitate efficient and comprehensive identification of undiscovered risks and hazard scenarios. SHIELD requires that three phases be performed serially to achieve a system hazard evaluation: decomposition, evaluation and prescription. The first phase of SHIELD, decomposition, breaks the system down hierarchically and recursively into smaller components so that the state space associated with each component is more manageable for the user. In the evaluation phase experts analyze the associated state space and transitions for each component, recursively, bottom-up. The prescription phase applies a set of heuristics to the results from the preceding phase to reduce system hazard. The main contribution of this paper is the automation of the methodology to reduce the effort used for analysis without sacrificing accuracy or overlooking hazardous state combinations. We describe in detail our automation concept and preliminary tests with the prototype.

Marine animal classification using UMSLI in HBOI optical test facility

Environmental monitoring is a critical aspect of marine renewable energy project success. A new system called Unobtrusive Multistatic Serial LiDAR Imager (UMSLI) has been prepared to capture and classify marine life interaction with electrical generation equipment. We present both hardware and software innovations of the UMSLI system. Underwater marine animal imagery has been captured for the first time using red laser diode serial LiDAR, which has advantages over conventional optical cameras in many areas. Moreover, given the scarcity of existing underwater LiDAR data, a shape matching based classification algorithm is proposed which requires few training data. On top of applying shape descriptors, the algorithm also adopts information theoretical learning based affine shape registration, improving point correspondences found by shape descriptors as well as the final similarity measure. Within Florida Atlantic University’s Harbor Branch Oceanographic Institute optical test facility, experimental LiDAR data are collected through the front end of the UMSLI prototype, on which the classification algorithm is validated.

Undersea LiDAR imager for unobtrusive and eye safe marine wildlife detection and classification

Marine hydrokinetic (MHK) projects are composed of undersea power generating equipment that converts energy of waves, tides, or ocean currents into electricity. Of primary interest when deploying MHK devices is gaining an understanding of potential harmful interactions between marine animals and equipment at proposed development sites. Therefore, a high priority regulatory expectation exists to observe marine life interaction with such devices. Underwater video observation of MHK scenes is typically accomplished with optical or acoustical cameras. Traditional optical cameras are most effective when significant ambient light is present and in low turbidity. Even the most sophisticated commercially-available underwater camera technologies require artificial white light to illuminate low light scenes. This approach is not desirable for MHK monitoring because artificial light can alter the behavior of the animals being monitored. For example, it has been observed that marine life are attracted to light-emitting sources of wavelengths within their visual light frequency range. However, unlike active acoustic solutions, the primary advantage of using optical approaches is high resolution contrasted scene descriptions essential for object classification and detailed observations. Because red laser illuminators can be configured below the maximum permissible exposure (MPE) limit for humans, which is conservative with regard to marine wildlife due to the lower visual acuity of the eye, and also beyond the wavelength range that is visible to marine wildlife, such systems can be designed to be eye-safe, unobtrusive, and allow for 24/7 operations.

Ocean Current Energy Conversion

Ocean currents in tidal flows and at the western boundaries of the ocean basins, as well as currents in rivers, can have as much potential for power production as the wind. With increased interest in sources of renewable energy, realizing this potential has undergone a renaissance in recent years. This chapter provides an introduction to ocean current energy conversion by emphasizing the contrasts between winds and currents and discussing some of the unique challenges associated with this untapped renewable energy source.

Efficient link management for the wireless communication of an ocean current turbine testbed

We describe a wireless link management framework for an ocean platform-to-shore communication system that uses time series forecasting to predict the available link capacity using ocean platform sensor data metrics to boost link robustness and to efficiently manage quality of service. Based on the predicted link capacity the OCTT Wireless Link (OWL) manager coordinates transmission scheduling of XML/HTTP sensor data at the web service layer and controls queue management for IP packet routing. To validate our framework, we developed a link management tool, the OCTT Wireless Link (OWL) manager to ensure optimal throughput and quality of service (QoS) for the wireless communication system linking ocean-based instrumented platforms with users on the shore. OWL applies sensor fusion to the platform attribute data which is then used to forecast the throughput of the wireless link in the harsh and rapidly fluctuating oceanic environment. OWL continually sends this forecast to the Queue Manager (QM) and when the signal power is forecast to drop outside the ideal range, using Linux networking tools, OWL provides bandwidth provisioning at the IP layer over each of the wireless radios in the network. This article describes our work on this project and experimentation with the OWL manager applied to sensory data collected from early stage OCTT platform testing.

Fatigue analysis of composite turbine blades under random ocean current

Design, analysis and lifetime prediction of a horizontal axis ocean current turbine (OCT) composite blade has been investigated. Loading on a turbine blade under the Gulf Stream in South Florida location (26° 4.3N 79° 55W) at 25 meter depth is calculated and evaluated by using AeroDyn. Static analysis is performed by using NuMAD and ANSYS. Accumulated fatigue damage modeling is employed as a damage estimation rule based on the material fatigue property in DOE/MSU Composite Material Fatigue Database. During its service life, OCT blades are subjected to a large number of cyclic loads and random ocean current loads. The blades experience repeating and alternating stresses leading to fatigue loading. These loads are weighted by its rate of occurrence using the histogram measured by the SNMREC.

Design and Analysis of Composite Ocean Current Turbine Blades Using NREL Codes

Ocean current energy is at an early stage of development — a vital component in that is the design and analysis of turbine blades that would be used to generate the power. The ocean current turbine (OCT) is similar in function to wind turbines, capturing energy through the processes of hydrodynamic, rather than aerodynamic, lift or drag. OCT operates on many of the same principles as wind turbines and share similar design philosophies. NREL (National Renewable Energy Laboratory) has extensively investigated the design of wind turbine blades over the years and many codes have been developed. It is meaningful and prudent to take advantage of those codes and use them in the design of OCT blades. Currently available codes such as FoilCheck, PreComp, BModes, AeroDyn, FAST, etc. provides an excellent dynamic analysis of hollow composite wind turbine blades. Since OCT blades have PVC foam as core materials inside the skin, NREL codes could not be used directly. These core materials for the blade were necessary to fulfill the buoyancy requirement at ocean depth. A set of methods was therefore developed to design and analyze OCT blades where most of NREL codes could be utilized. The methods are as follows: DesignFOIL was first used to generate hydrofoil geometry (coordinates), and lift and drag coefficients for selected blade sections. FoilCheck was then used to calculate hydrofoil data for the entire range of ±180°. FoilCheck output files were later used as input for AeroDyn. In the next step, PreComp computed the section properties for the hollow composite OCT blade. Section properties of the core material such as extensional stiffness, flexural rigidity, and torsional rigidity were calculated separately and added to the properties computed by PreComp. Mode shapes and frequencies of OCT blades were computed using BModes. AeroDyn calculated the hydrodynamic lift and drag forces for the hydrofoil sections along the blade. In AeroDyn input file, kinematic viscosity, density and velocity were set to the values of seawater @ 1.05×10−6 m2/sec, 1025 kg/m3, and 1.7 m/s, respectively. Finally, FAST was used to obtain the dynamic response of three-bladed, conventional, horizontal-axis OCT. However, this analysis did not provide any stress calculations. In order to perform stress analysis, NuMAD code developed by Sandia National Laboratory was incorporated in the method. This allowed us to create ANSYS input files. Loads calculated by AeroDyn were then transported to ANSYS and a complete stress analysis was performed. Critical regions of stress concentration were identified — opening up an opportunity for materials failure and fatigue analysis. In summary, coupling of NREL codes, NuMAD, and ANSYS revealed a path way to achieve comprehensive design and analyses of OCT blades.Copyright