scholarly journals Tribological design constraints of marine renewable energy systems

Author(s):  
Robert J. K. Wood ◽  
AbuBakr S. Bahaj ◽  
Stephen R. Turnock ◽  
Ling Wang ◽  
Martin Evans

Against the backdrop of increasing energy demands, the threat of climate change and dwindling fuel reserves, finding reliable, diverse, sustainable/renewable, affordable energy resources has become a priority for many countries. Marine energy conversion systems are at the forefront of providing such a resource. Most marine renewable energy conversion systems require tribological components to convert wind or tidal streams to rotational motion for generating electricity while wave machines typically use oscillating hinge or piston within cylinder geometries to promote reciprocating linear motion. This paper looks at the tribology of three green marine energy systems, offshore wind, tidal and wave machines. Areas covered include lubrication and contamination, bearing and gearbox issues, biofouling, cavitation erosion, tribocorrosion, condition monitoring as well as design trends and loading conditions associated with tribological components. Current research thrusts are highlighted along with areas needing research as well as addressing present-day issues related to the tribology of offshore energy conversion technologies.

2021 ◽  
Vol 9 (8) ◽  
pp. 810
Author(s):  
Francisco X. Correia da Fonseca ◽  
Luís Amaral ◽  
Paulo Chainho

Ocean energy is a relevant source of clean renewable energy, and as it is still facing challenges related to its above grid-parity costs, tariffs intended to support in a structured and coherent way are of great relevance and potential impact. The logistics and marine operations required for installing and maintaining these systems are major cost drivers of marine renewable energy projects. Planning the logistics of marine energy projects is a highly complex and intertwined process, and to date, limited advances have been made in the development of decision support tools suitable for ocean energy farm design. The present paper describes the methodology of a novel, opensource, logistic and marine operation planning tool, integrated within DTOceanPlus suite of design tools, and responsible for producing logistic solutions comprised of optimal selections of vessels, port terminals, equipment, as well as operation plans, for ocean energy projects. Infrastructure selection logistic functions were developed to select vessels, ports, and equipment for specific projects. A statistical weather window model was developed to estimate operation delays due to weather. A vessel charter rate modeling approach, based on an in-house vessel database and industry experience, is described in detail. The overall operation assumptions and underlying operating principles of the statistical weather window model, maritime infrastructure selection algorithms, and cost modeling strategies are presented. Tests performed for a case study based a theoretical floating wave energy converter produced results in good agreement with reality.


2020 ◽  
Vol 8 (4) ◽  
pp. 253 ◽  
Author(s):  
Yapo Wang ◽  
Lixian Zhang ◽  
Constantine Michailides ◽  
Ling Wan ◽  
Wei Shi

Due to the energy crisis and greenhouse effect, offshore renewable energy is attracting increasing attention worldwide. Various offshore renewable energy systems, such as floating offshore wind turbines (FOWTs), and wave energy converters (WECs), have been proposed and developed so far. To increase power output and reduce related costs, a combined marine energy structure using FOWT and WEC technologies has been designed, analyzed and presented in the present paper. The energy structure combines a 5-MW braceless semisubmersible FOWT and a heave-type WEC which is installed on the central column of the semisubmersible. Wave power is absorbed by a power take-off (PTO) system through the relative heave motion between the central column of the FOWT and the WEC. A numerical model has been developed and is used to determine rational size and draft of the combined structure. The effects of different PTO system parameters on the hydrodynamic performance and wave energy production of the WEC under typical wave conditions are investigated and a preliminary best value for the PTO’s damping coefficient is obtained. Additionally, the effects of viscous modeling used during the analysis and the hydrodynamic coupling on the response of the combined structure are studied.


Author(s):  
Dilara Gulcin Caglayan ◽  
Severin Ryberg ◽  
Heidi Heinrichs ◽  
Jochen Linßen ◽  
Detlef Stolten ◽  
...  

Renewable energy sources will play a central role in the sustainable energy systems of the future. Scenario analyses of such hypothesized energy systems require sound knowledge of the techno-economic potential of renewable energy technologies. Although there have been various studies concerning the potential of offshore wind energy, higher spatial resolution, as well as the future design concepts of offshore wind turbines, has not yet been addressed in sufficient detail. Here, we aim to overcome this gap by applying a high spatial resolution to the three main aspects of offshore wind potential analysis, namely ocean suitability, the simulation of wind turbines and cost estimation. A set of constraints is determined that reveal the available areas for turbine placement across Europe’s maritime boundaries. Then, turbine designs specific to each location are selected by identifying turbines with the cheapest levelized cost of electricity (LCOE), restricted to capacities, hub heights and rotor diameters of between 3-20 MW, 80-200 m and 80-280 m, respectively. Ocean eligibility and turbine design are then combined to distribute turbines across the available areas. Finally, LCOE trends are calculated from the individual turbine costs, as well as the corresponding capacity factor obtained by hourly simulation with wind speeds from 1980 to 2017. The results of cost-optimal turbine design reveal that the overall potential for offshore wind energy across Europe will constitute nearly 8.6 TW and 40.0 PWh at roughly 7 €ct kWh-1 average LCOE by 2050. Averaged design parameters at national level are provided in an appendix.


Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5048
Author(s):  
Zachary Barr ◽  
Jesse Roberts ◽  
William Peplinski ◽  
Anna West ◽  
Sharon Kramer ◽  
...  

The marine renewable energy (MRE; renewable energy captured from waves, tides, ocean currents, the natural flow of water in rivers, and marine thermal gradients, without building new dams or diversions) industry has a vital role in the U.S. clean energy strategy as we progress to meet U.S. electricity and blue economy needs with renewable, domestic energy sources. However, a thorough assessment of the U.S. marine energy permitting process from the viewpoints of both developers that propose projects and regulators that permit them has not been performed. Sharing practical experiences in this new industry is vital to increase the efficiency and effectiveness of the permitting process, identify data and information gaps, develop lessons learned, and advance the industry. This paper is a case study of qualitative findings, lessons learned, and recommendations from guided discussions, workshops, and webinars with both marine renewable energy developers and state and federal regulators that have experience in the permitting process in the U.S.


Electronics ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 237 ◽  
Author(s):  
Silvio Simani ◽  
Stefano Alvisi ◽  
Mauro Venturini

The interest in the use of renewable energy resources is increasing, especially towards wind and hydro powers, which should be efficiently converted into electric energy via suitable technology tools. To this end, data-driven control techniques represent viable strategies that can be employed for this purpose, due to the features of these nonlinear dynamic processes of working over a wide range of operating conditions, driven by stochastic inputs, excitations and disturbances. Therefore, the paper aims at providing some guidelines on the design and the application of different data-driven control strategies to a wind turbine benchmark and a hydroelectric simulator. They rely on self-tuning PID, fuzzy logic, adaptive and model predictive control methodologies. Some of the considered methods, such as fuzzy and adaptive controllers, were successfully verified on wind turbine systems, and similar advantages may thus derive from their appropriate implementation and application to hydroelectric plants. These issues represent the key features of the work, which provides some details of the implementation of the proposed control strategies to these energy conversion systems. The simulations will highlight that the fuzzy regulators are able to provide good tracking capabilities, which are outperformed by adaptive and model predictive control schemes. The working conditions of the considered processes will be also taken into account in order to highlight the reliability and robustness characteristics of the developed control strategies, especially interesting for remote and relatively inaccessible location of many plants.


2019 ◽  
Vol 7 (2) ◽  
pp. 22 ◽  
Author(s):  
Francisco Francisco ◽  
Jan Sundberg

Techniques for marine monitoring have been greatly evolved over the past decades, making the acquisition of environmental data safer, more reliable and more efficient. On the other hand, the marine renewable energy sector has introduced dissimilar ways of exploring the oceans. Marine energy is mostly harvested in murky and high energetic places where conventional data acquisition techniques are impractical. This new frontier on marine operations brings the need for finding new techniques for environmental data acquisition, processing and analysis. Modern sonar systems, operating at high frequencies, can acquire detailed images of the underwater environment. Variables such as occurrence, size, class and behavior of a variety of aquatic species of fish, birds, and mammals that coexist within marine energy sites can be monitored using imaging sonar systems. Although sonar images can provide high levels of detail, in most of the cases they are still difficult to decipher. In order to facilitate the classification of targets using sonar images, this study introduces a framework of extracting visual features of marine animals that would serve as unique signatures. The acoustic visibility measure (AVM) is here introduced as technique of identification and classification of targets by comparing the observed size with a standard value. This information can be used to instruct algorithms and protocols in order to automate the identification and classification of underwater targets using imaging sonar systems. Using image processing algorithms embedded in Proviwer4 and FIJI software, this study found that acoustic images can be effectively used to classify cod, harbour and grey seals, and orcas through their size, shape and swimming behavior. The sonar images showed that cod occurred as bright, 0.9 m long, ellipsoidal targets shoaling in groups. Harbour seals occurred as bright torpedo-like fast moving targets, whereas grey seals occurred as bulky-ellipsoidal targets with serpentine movements. Orca or larger marine mammals occurred with relatively low visibility on the acoustic images compared to their body size, which measured between 4 m and 7 m. This framework provide a new window of performing qualitative and quantitative observations of underwater targets, and with further improvements, this method can be useful for environmental studies within marine renewable energy farms and for other purposes.


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