Showing papers on "Marine energy published in 2019"

Development of multi-oscillating water columns as wave energy converters

Abstract: Wave energy development continues to advance in order to capture the immense ocean energy available globally. A large number of wave energy conversion concepts have been developed and researched to date but we are still not able to see a convergence of technologies. This provides the requirement and additional opportunity for further research. This paper provides a review and discusses the development of the OWC concept of wave energy converters in general and the evolved variation of the M-OWC more specifically. The review outlines the increased potential of the M-OWC concept and its current state through its advancement in recent years. Although still under development the M-OWCs have the potential to provide promising results, through the various innovative concepts under consideration, and support the progression and further development of wave energy as another serious contender in the renewables energy mix.

Control Strategies Applied to Wave Energy Converters: State of the Art

Abstract: Wave energy’s path towards commercialization requires maximizing reliability, survivability, an improvement in energy harvested from the wave and efficiency of the wave to wire conversion. In this sense, control strategies directly impact the survivability and safe operation of the device, as well as the ability to harness the energy from the wave. For example, tuning the device’s natural frequency to the incoming wave allows resonance mode operation and amplifies the velocity, which has a quadratic proportionality to the extracted energy. In this article, a review of the main control strategies applied in wave energy conversion is presented along their corresponding power take-off (PTO) systems.

Capture and simulation of the ocean environment for offshore renewable energy

Abstract: The offshore renewable energy sector has challenging requirements related to the physical simulation of the ocean environment for the purpose of evaluating energy generating technologies. In this paper the demands of the wave and tidal energy sectors are considered, with measurement and characterisation of the environment explored and replication of these conditions described. This review examines the process of advanced ocean environment replication from the sea to the tank, and rather than an exhaustive overview of all approaches it follows the rationale behind projects led, or strongly connected to, the late Professor Ian Bryden. This gives an element of commonality to the motivations behind marine data acquisition programmes and the facilities constructed to take advantage of the resulting datasets and findings. This review presents a decade of flagship research, conducted in the United Kingdom, at the interfaces between physical oceanography, engineering simulation tools and industrial applications in the area of offshore renewable energy. Wave and tidal datasets are presented, with particular emphasis on the novel tidal measurement techniques developed for tidal energy characterisation in the Fall of Warness, Orkney, UK. Non-parametric wave spectra characterisation methodologies are applied to the European Marine Energy Centre's (EMEC) Billia Croo wave test site, giving complex and highly realistic site-specific directional inputs for simulation of wave energy sites and converters. Finally, the processes of recreating the resulting wave, tidal, and combined wave-current conditions in the FloWave Ocean Energy Research Facility are presented. The common motivations across measurement, characterisation, and test tank are discussed with conclusions drawn on the strengths, gaps and challenges associated with detailed site replication.

Evolution of Ocean Heat Content Related to ENSO

Abstract: As the strongest interannual perturbation to the climate system, El Nino–Southern Oscillation (ENSO) dominates the year-to-year variability of the ocean energy budget. Here we combine ocean...

Renewable Hybridization of Oil and Gas Supply Chains

Abstract: The oil and gas sector is not only a major energy producer but also a major consumer of energy. Energy requirements in the form of heat, power, or shaft work during onshore/offshore production, enhanced recovery operation, transportation, processing, and upgrading are mainly provided by fossil-fuel-based conventional technologies. Adaptation of sustainable and eco-friendly renewable energies such as hydropower, photovoltaics, solar thermal energy, wind power, biomass, geothermal energy, and wave power in different industries including the oil and gas sector is now globally examined with some successful stories. Renewable hybridization of the conventional oil and gas sector would reduce energy costs as well as greenhouse gas (GHG) emissions. This chapter investigates recent developments in the integration of renewable energy resources with the oil and gas industry and highlights the prospects.

State of the Art and Perspectives of Wave Energy in the Mediterranean Sea: Backstage of ISWEC

Abstract: According to the European Commission, sea waves have a great potential as renewable energy source. Despite wave energy technology is a field in continuous development, it is not yet competitive with the other renewables, due to the small quantities of devices sold, most of them being prototypal solutions at level. So far, various Wave Energy Converter concepts have been developed and some of them tested in full scale. The most recurrent test environment is the North Atlantic Ocean, which possesses high energy potential. The Mediterranean Sea on the other hand is less energetic, but also possesses less dangerous extreme conditions. It represents a favourable starting point to develop technologies that later will be scaled up to more powerful sites. This article illustrates the wave energy potential of the Mediterranean and analyses the wave energy converters engineered according to sea states characteristic of the Mediterranean Sea. Focus is brought to the Inertial Sea Wave Energy Converter (ISWEC) technology, which is one of the few Mediterranean concept to have reached Technology Readiness Level (TRL) 7. The article will document the deployment and the following open sea test campaign of a full scale prototype off the shore of Pantelleria Island, Italy.

Potential for power generation from ocean wave renewable energy source: a comprehensive review on state-of-the-art technology and future prospects

Abstract: This study presents a comprehensive review of the ocean wave technology and prospects of the wave energy penetration to cater to clean global energy demand. An ocean wave is a remarkable energy resource, but it presents a very small share in the global energy mix because of various challenges and limitations encountered to unleash its potential. This study evaluates intensively the complex barriers to the ocean energy technology deployment. The existing and prospective major wave energy projects are extensively examined to identify the learned lessons and optimise possible technological solutions to close the gap in the energy market. Furthermore, limiting and motivating factors to foster the global wave energy potential growth are deeply discussed to ignite new research directions and promising solutions. In particular, the wave energy converters as the underpinning enabling technology are fully investigated regarding their technical readiness, reliability, competitiveness and critical challenges. To complete the power equation, possible energy conversion stages, grid connection and integration issues are dealt with in a broad view of the wave energy power system. Eventually, this study aims at providing an updated ocean wave technology review and progress while introducing new research gap to fast-track contributions in the global energy mix.

Global renewable energy resources and use in 2050

Abstract: The main forms of renewable energy (RE) used today are biomass energy, hydroelectricity, wind energy, solar energy, and geothermal energy. Although several other RE sources have been extensively discussed, including various forms of ocean energy, these five are likely to still be dominant in 2050. In assessing the probable future of each RE type, it is important to know what factors will tend to enhance or decrease their future output. These include: their energy return on input energy; their technical potential; the impacts that future land use, climate, and other environmental changes will have on their availability; and alternatively, the effects of RE production on the environment.

Combined Exploitation of Offshore Wind and Wave Energy in the Italian Seas: A Spatial Planning Approach

Abstract: The opportunity to co-locate wind and wave energy exploitation is analysed in the Italian seas grounding on the rationale that benefits are greater when un-correlated resources are combined. The study shows that, although waves and winds are generally strongly correlated, in some conditions their correlation is lower and the combined energy harvesting more interesting. As spatial conflicts of sea use and demand for maritime space are increasingly growing, the development of the marine renewable energy sector needs to be evaluated in the perspective of the complex framework of existing uses, pressures and foresees developments. The early prediction of the areas of potential conflicts creates in fact the ground for mitigation actions or early negotiations between stakeholders. In this study the opportunity of co-locating offshore wind turbines and wave energy converters is analysed through a spatial planning approach. Both the potential for combining different renewable technologies, and the impact associated to such development was considered in the context of the existing pressures (e.g. naval traffic; mariculture activities; submarine cables routes; dredg spoils dumping; offshore activities; windfarms and ocean energy projects) and vulnerabilities (Marine Protected Areas, Key habitat presence) through quantitative indicators. The western coast off Sardinia island, the southern areas of Pantelleria island and the Tunisian coastal waters appear to be the most suitable sites. The study shows how quantitative spatial planning methods may support the selection of the sites of potential interest for the marine renewable energy sector in the perspective of cost-effectiveness and environmental impact minimization.

Ocean Energy Systems Wave Energy Modelling Task: Modelling, Verification and Validation of Wave Energy Converters

Abstract: The International Energy Agency Technology Collaboration Programme for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modelling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modelling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude–Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier–Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.

Life Cycle Assessment of Ocean Energy Technologies: A Systematic Review

Abstract: The increase of greenhouse gases (GHG) generated by the burning of fossil fuels has been recognized as one of the main causes of climate change (CC). Different countries of the world have developed new policies on national energy security directed to the use of renewable energies mainly, ocean energy being one of them. The implementation of ocean energy is increasing worldwide. However, the use of these technologies is not exempt from the generation of potential environmental impacts throughout their life cycle. In this context, life cycle assessment (LCA) is a holistic approach used to evaluate the environmental impacts of a product or system throughout its entire life cycle. LCA studies need to be conducted to foster the development of ocean energy technologies (OET) in sustainable management. In this paper, a systematic review was conducted and 18 LCA studies of OET were analyzed. Most of the LCA studies are focused on wave and tidal energy. CC is the most relevant impact category evaluated, which is generated mostly by raw material extraction, manufacturing stage and shipping operations. Finally, the critical stages of the systems evaluated were identified, together with, the opportunity areas to promote an environmental management for ocean energy developers.

On the Marine Energy Resources of Mexico

Abstract: The Atlantic and Pacific coasts of Mexico offer a variety of marine energy sources for exploitation. Although the Mexican government has made important efforts to reduce its dependence on fossil fuels, national participation in clean energies is still limited in terms of electricity production. This paper presents a practical theoretical assessment of marine energy sources around Mexico, with the aim of identifying potential zones for subsequent, more detailed, technical evaluations and project implementations. The energy sources considered are ocean currents, waves, salinity, and thermal gradients. Using global databases, the percentages of energy availability for the defined thresholds were computed to establish the prospective regions with the most persistent power availability. This approach proved to offer more meaningful information than simple averaged values. Moreover, some environmental and socio-economic factors to be considered for future ocean energy resource assessments in Mexico were also discussed. The results show that the wave energy potential is highest in the northwest of Mexico (~2–10 kW/m for more than 50% of the time), and that there is a constant source of ocean current energy off Quintana Roo state (~32–215 W/m2 for more than 50% of the time). The thermal gradient power is more persistent in the southwest and southeast of the country, where ~100–200 MW can be found 70% of the time. The salinity gradient energy is strongest in the southeast of Mexico. The practical approach presented here can be extended to perform preliminary resources assessments in regions where information is scarce.

Current status of electricity generation in the world and future of nuclear power industry

Abstract: It is well known that electrical power generation is the key factor for advances in industry, agriculture, technology, and the standard of living. Also, strong power industry with diverse energy sources is very important for a country's independence. In general, electrical energy can be generated from: (1) nonrenewable energy sources such as coal, natural gas, oil, and nuclear; and (2) renewable energy sources such as hydro, biomass, wind, geothermal, solar, and marine power. Today, the main sources for electrical energy generation are: (1) thermal power—primarily using coal and secondarily using natural gas; (2) “large” hydroelectric power plants; and (3) nuclear power. The balance of the energy sources is from using oil, biomass, wind, geothermal and solar, and has visible impact just in a few countries. This chapter presents the current status of electricity generation in the world, various sources of industrial electricity generation, role of nuclear power with a comparison of nuclear energy systems to other energy systems.

Comparative analysis of European grid codes relevant to offshore renewable energy installations

Abstract: The purpose of this paper is to highlight the most demanding aspects of grid interconnection of marine energy installations while at the same time providing an updated overview and comparative analysis of the connection requirements of eight European Grid Codes. Therefore, the major issues related to marine energy installations will be summarized as well as the requirements of this type of generation. Besides, the extent to which current Grid Codes include marine energy technologies will be analysed jointly with the need of harmonization of different Grid Codes into a generalised European grid code. Apart from this, several future trends of marine energy technology and its interconnection will be provided for the final discussion.

Wave Energy in Tropical Regions: Deployment Challenges, Environmental and Social Perspectives

Abstract: The harnessing of renewable sources of marine energy has become a promising solution for a number of problems, namely satisfying the increasing demand for electricity, the reduction of greenhouse gas emissions, and the provision of energy to regions unconnected to a national grid. Tropical countries have an interesting dichotomy: Despite their varied potential sources of marine energy, their environmental and social conditions impose severe constraints on the development of a renewable energy industry. Moreover, the exploitation of these opportunities is limited by national economies’ reliance on fossil fuels, political and social restraints, and technological immaturity. The present work addresses challenges and opportunities common to wave energy implementation in tropical nations, as a first approach to a regional diagnosis. The motivation for this work is to encourage research on wave energy policies in the Tropics. Technical, environmental, and social challenges to be overcome in wave energy projects are discussed. The technical challenges are grouped into development, deployment, and operation stages of wave energy converters; environmental challenges are divided into biodiversity, cumulative effects, and monitoring aspects, whilst social issues include population growth and energy access matters. The Mexican strategy for developing sustainable technology throughout the wave energy production chain is also presented.

Wave-induced real-fluid effects in marine energy converters: Review and application to OWC devices

Abstract: The performance assessment of industrial marine energy converters involves the integrated treatment of their hydrodynamic design and the optimization of their device hulls. Nowadays, such tasks require extensive experimental work and simulation plans, consuming considerable resources and time. In this comprehensive review of integrated approaches to numerical and experimental testing, the advantages and disadvantages of existing tools, from full-scale prototype and wave tank models to Computational Fluid Dynamics (CFD) and potential flow simulations, are all analysed. Likewise, current challenges such as experimental scale effects, numerical viscosity, and turbulence treatment are all studied. The novelty of this research is an integrated approach that employs experimental wave tank tests to validate a numerical wave tank model based on CFD that serves to calibrate a fast potential flow solver with Morison's correction terms. The model allows running, on tight resources, the necessary simulation for the design and optimisation of marine energy converters under multiple sea state conditions. Given the operating regimes of conventional marine energy converters, the results show that the influence of turbulence may be small, due to the unsteady nature of the oscillatory boundary layer flows.

Small-scale Experimental Testing of a Novel Marine Floating Platform with Integrated Hydro-pneumatic Energy Storage

Abstract: Co-locating energy storage within the floating platform of offshore renewable energy systems is an effective way of reducing the cost and environmental footprint of marine energy storage devices. However, the development of suitable, non-hazardous technologies, and the influence of the marine environment on their efficiency remains an open problem. Research at the University of Malta has culminated in the Floating Liquid-piston Accumulator using Seawater under Compression (FLASC) concept, a solution involving hydro-pneumatic energy storage tailored for offshore renewables. A small-scale prototype was deployed at a sheltered marine location in the Maltese Islands, in the central Mediterranean Sea. The aim of the experimental campaign was to measure the performance of the energy storage system, and to quantify the effects of different system parameters along with the surrounding meteorological conditions. Results from selected charging-discharging cycles are presented, these include different scheduling schemes and pressure ranges. Overall, results indicate that the experimental system consistently demonstrated a high thermal efficiency (> 93%) across hundreds of charging cycles. Operating pressure range and charging schedule play a limited role on the hydro-pneumatic process, whereas seasonal temperature changes play a more significant role, in that such changes can slightly alter the effective storage capacity of the system. Results from this experimental work provide a practical proof-of-concept for hydro-pneumatic marine energy storage, and can enable key conclusions to be drawn providing a basis to numerous ongoing developments in fluid-based energy storage systems for offshore implementation.

Dynamic optimization of synthesis, design and operation of marine energy systems:

Abstract: In order to cover the overall energy demands of a vessel (e.g. mechanical, electrical and thermal), energy systems onboard ships are required to produce energy of several forms while at the same ti...

Current Policy and Technology for Tidal Current Energy in Korea

Abstract: As global energy consumption continues to increase, the negative impact of global warming also grows. Therefore, eco-friendly energy policy is being established all over the world. Korea’s energy consumption problems are further complicated by the country’s high dependence on energy sourced overseas. Korean energy policy is evolving rapidly to address these problems. Korea has begun to phase out nuclear power and is focusing on developing new sources of renewable energy. So there has been substantial interest in the development of ocean energy. Of all ocean energy technologies, tidal current energy is the closest to the commercialization. Especially, the southwestern coast of Korea is the most promising candidate site for the development of tidal current energy owing to the abundant tidal current energy resource. Meanwhile, ocean energy policy is an important factor in determining the development of ocean energy. Thus, this paper presents the overview of the current status of policy and technology for the tidal current energy system in Korea. These policies explained in this paper can provide significant interest and motivation for the use of tidal current energy resources.

Design, Modeling, and Experiments of the Vortex-Induced Vibration Piezoelectric Energy Harvester with Bionic Attachments

Abstract: Since the energy demand increases, the sources of fluid energy such as wind energy and marine energy have attracted widespread attention, especially vortex-induced vibrations excited by wind energy. It is well known that the lock-in effect in vortex-induced vibration can be applied to the piezoelectric energy harvester. Although numerous researches have been conducted on piezoelectric energy harvesting devices in recent years, a common problem of low bandwidth and harvesting efficiency still exists. In order to increase the response amplitude and decrease the threshold wind speed of vortex-induced vibration, a bionic attachment structure is proposed based on the experimental method. In the present work, twelve models are designed according to the size of pits and hemispheric protrusions which are added to the surface of a flexible smooth cylinder. Compared with the smooth cylinder which is taken as a carrier, the harvester with the bionic structure shows stronger energy capture performance on the whole. As the threshold speed decelerates from 1.8m/s to 1 m/s, the bandwidth, on the contrary, increases from 39.3% to 51.4%. Particularly, for the 10 mm pits structure with 5 columns, its peak voltage can reach 47 V, and its peak power can reach 1.21 mW with a resistance of 800 kΩ, 0.57 mW higher than that of the smooth cylinder. Comparatively speaking, the hemispherical projections structure figures with a much more different energy capturing characteristic. Starting from the column, the measured voltage of the hemispherical bionic harvester is much smaller than that of the smooth cylinder, with a peak voltage less than 15 V and a reducing bandwidth. However, compared with the smooth cylinder, hemispheric projections with 3 columns have a better energy capture effect with a measured voltage of 35V, a resistance of 800kΩ, and a wind speed of 3.097 m/s. Besides, its output power also enhances from 0.48 to 0.56 mW.

The Study of a Multicriteria Decision Making Model for Wave Power Plant Location Selection in Vietnam

Abstract: With about a 7% average annual economic growth rate in Vietnam, the demand for electricity production is increasing, and, with more than 3000 km of coastline, the country has great potential for developing wave energy sources to meet such electricity production. This energy source, also known as renewable energy, comes from tides, wind, heat differences, flows, and waves. Both wind and wave energy are considered to have the most potential for energy sources in Vietnam. Just as hydropower projects are controversial due to depleting water resources and regulating floods, nuclear power projects cause safety concerns. To overcome this problem, Vietnamese scientists are considering using abundant wave energy resources for electricity. Nowadays, the ocean energy sector offers many new technologies to help minimize carbon dioxide emissions (CO2) in the living environment. Further, many countries already have wave power plants. In this research, an integrated model, combining the fuzzy analytical network process (FANP) and the technique for order of preference by similarity to ideal solution (TOPSIS), is proposed for wave energy plant location selection. As a result, Con Co (SITE3) is determined the best site for wave energy production. The primary aim of this study is to provide insight into site selection problems for renewable energy investments of Vietnam. The contribution of this research is to propose a fuzzy multiple-criteria decision-making (MCDM) model for site selection in the renewable energy sector. The proposed model also can address different complex problems in location selection; it is also a flexible design model for considering the evaluation criteria; further, it is applicable to site selection of other renewable energies in the world.

What about Marine Renewable Energies in Spain

Abstract: Renewable energies play a fundamental role within the current political and social framework for minimizing the impacts of climate change. The ocean has a vast potential for generating energy and therefore, the marine renewable energies are included in the Sustainable Development Goals (SDGs). These energies include wave, tidal, marine currents, ocean thermal, and osmotic. Moreover, it can also be included wind, solar, geothermal and biomass powers, which their main use is onshore, but in the near future their use at sea may be considered. The manuscript starts with a state-of-the-art review of the abovementioned marine renewable energy resources worldwide. The paper continues with a case study focused on the Spanish coast, divided into six regions: (I) Cantabrian, (II) Galician, (III) South Atlantic, (IV) Canary Islands, (V) Southern Mediterranean, and (VI) Northern Mediterranean. The results show that: (1) areas I and II are suitable for offshore wind, wave and biomass; (2) areas III and V are suitable for offshore wind, marine current and offshore solar; area IV is suitable for offshore wind, ocean wave and offshore solar; (3) and area VI is suitable for offshore wind, osmotic and offshore solar. This analysis can help politicians and technicians to plan the use of these resources in Spain.

Reducing variability in the cost of energy of ocean energy arrays

Abstract: Variability in the predicted cost of energy of an ocean energy converter array is more substantial than for other forms of energy generation, due to the combined stochastic action of weather conditions and failures. If the variability is great enough, then this may influence future financial decisions. This paper provides the unique contribution of quantifying variability in the predicted cost of energy and introduces a framework for investigating reduction of variability through investment in components. Following review of existing methodologies for parametric analysis of ocean energy array design, the development of the DTOcean software tool is presented. DTOcean can quantify variability by simulating the design, deployment and operation of arrays with higher complexity than previous models, designing sub-systems at component level. A case study of a theoretical floating wave energy converter array is used to demonstrate that the variability in levelised cost of energy (LCOE) can be greatest for the smallest arrays and that investment in improved component reliability can reduce both the variability and most likely value of LCOE. A hypothetical study of improved electrical cables and connectors shows reductions in LCOE up to 2.51% and reductions in the variability of LCOE of over 50%; these minima occur for different combinations of components.