Ocean Energy Research Articles

Autonomous sensor suite for evaluating fish-turbine interactions and environmental impacts in marine renewable energy and hydropower.

Marine renewable energy (MRE) harnesses ocean-based resources such as waves, tides, currents, and thermal or salinity gradients for sustainable power generation. It has the potential to complement existing renewable resources, support remote communities, and contribute to decarbonization efforts. However, understanding the hydrodynamic forces created by MRE devices and their impacts on marine life is critical for responsible deployment. To address these concerns, advanced sensor devices, including the Marine Sensor Fish (MSF), Sensor Fish Mini (SF Mini), and Flexible Sensor Fish (FSF), were developed to measure interactions between aquatic organisms and MRE systems. This paper details the design, manufacturing, calibration, and field deployment of these sensor suites, highlighting their ability to capture key physical stressors such as shear forces, pressure changes, and collision impacts. The MSF successfully evaluated turbine interactions at a tidal turbine in the Salish Sea, capturing data on turbulence, collision impact, and pressure gradients. The SF Mini validated hydrodynamic conditions in scaled hydraulic models, supporting computational fluid dynamics simulations. The FSF, with its flexible silicone body, measured species-specific impacts in turbulent environments. This research demonstrates the potential of Sensor Fish technology to advance sustainable marine energy systems by reducing biological impacts and informing environmentally sustainable designs.

Multi-directional reconfigurable ultra-low frequency vibration energy harvester

Abstract Converting vibrational energy from the environment into electrical energy more efficiently has been one of the key research topics of this century. The majority of vibrations observed in the natural environment occur at low frequencies and are not fixed in direction. This work presents a design of a piezoelectric vibration energy harvester supported by an elastic rod (R-PVEH), which allows for multidirectional responses to capture vibrational energy. The distinctive configuration of the structure allows for a reduction in vibration attenuation in the presence of low-frequency, unstable excitation. Further, in instances where a complex vibration source is present, multiple units can be reconfigurable to achieve a higher and more stable voltage output. The device can output an average voltage of 15.2 V in response to horizontal low-frequency vibrations of 0.3 Hz, representing a 193.3% increase compared to the conventional cantilever beam structure. The device is expected to be employed in multidirectional low-frequency scenarios such as ocean wave energy harvesting.

Examining future changes in coastal low-level jet properties offshore California through dynamical downscaling

Abstract The coastal low-level jet, or CLLJ, is a synoptically-forced meteorological feature frequently present offshore the western United States (U.S.). Characterized by a wind speed maximum that resides at the top of the marine boundary layer, the CLLJ is largely controlled by the location and strength of the North Pacific High (NPH) as well as the coastal geometry. Considering the rich wind resource available in this offshore region, the Bureau of Ocean Energy Management identified wind energy lease areas offshore California and supported the deployment of two U.S. Department of Energy wind lidar buoys near Morro Bay and Humboldt. Despite our relatively good understanding of the fundamental mechanisms responsible for large-scale CLLJ properties offshore the western U.S., future changes in CLLJ characteristics are less clear. To address this research challenge, and ultimately to better inform future wind turbine deployments, we use simulations driven by three global climate models (GCMs). We apply self-organizing maps to the model outputs for a historical and two future climate periods to show the range of NPH regimes that support CLLJ conditions during the warm seasons, as well as the subtle contribution from land-falling cyclones approaching the mainland during the cold seasons. Compared to the historical period, the three GCM-driven simulations agree that CLLJ conditions will become more (less) prevalent from central California northward (southward). They agree less with respect to future changes in maximum CLLJ wind speeds and CLLJ heights. However, after considering model biases present during the historical period, wind speeds between the models are actually more similar during the 2070-2095 period than during the historical period. The potential combination of more frequent CLLJ conditions characterized by relatively consistent wind speeds occurring at lower heights across northern California suggests that the Humboldt lease area may be ideal for a long-term wind turbine deployment.

Methodology for the development of neuro-fuzzy automatic control systems with a function for identifying the parameters

The article discusses a methodology for developing neuro-fuzzy automatic control systems (ACS) for marine steam turbine installations (MSTI) with a parameter identification function during their operation. The proposed methodology includes stages of MSTI dynamic modeling, the development of parameter identification algorithms based on neural networks, and their integration with fuzzy logic for decision-making. An analysis of the proposed approach's capabilities regarding the enhancement of reliability and stability of marine power plants has been conducted. The results obtained demonstrate that such a system can adjust model parameters in real-time, ensuring control accuracy and reducing the risk of emergency situations. The methodology can be implemented in real marine power systems that require automated control of complex processes.

Localized Negatively Charged Interfaces for Seawater Electrolyte‐Based Zinc‐Air Batteries

AbstractSeawater electrolyte‐based zinc‐air batteries (S‐ZABs) are considered the promising choice for highly efficient marine power supply, owing to their high specific energy, low cost, and eco‐friendliness. However, the air‐cathode suffers from the sluggish oxygen reduction reaction (ORR) kinetics together with the severe adsorption of Cl− in seawater electrolytes, which severely limits the service life and efficiency of S‐ZABs. Herein, precisely decorating axially coordinated Cl ions (Cl−) on Fe atomic sites (Cl‐FeSA/NC) to construct a local negatively charged interface to inhibit the adsorption of Cl− is proposed, which exhibits a desirable ORR activity, and good stability with almost no loss in electrocatalytic performance after long‐term stability test. Moreover, the assembled battery achieves a peak power density of 208.0 mW cm−2, which is 1.45 times higher than commercial Pt/C‐based S‐ZABs. Density functional theory calculations reveal that the axially coordinated Cl− not only constructs a local negatively charged interface to inhibit the corrosion and poisoning of Fe active sites by Cl−, but also regulates the electronic states of Fe active sites to optimize adsorption/desorption energy of intermates, thus improving the electrocatalytic activity and stability of Cl‐FeSA/NC.

Intensification of Hurricane Idalia by a river plume in the eastern Gulf of Mexico

Abstract Hurricane Idalia formed on 26 August 2023 and three days later rapidly intensified from a Category 1 to Category 4 strength storm in less than 24 h over the west Florida shelf. On August 30, it made landfall along Florida’s Big Bend area as a Category 3 hurricane. Strikingly, despite Idalia’s moderate intensity and favorable vortex structure, neither upper ocean thermal energy nor environmental vertical wind shear conditions were as favorable during its intensification from Category 2 to Category 4 as earlier in its path, raising the question of what external factors contributed to its extreme intensification during this phase. Using satellite data, underwater glider observations, and numerical model outputs, this study reveals that, in addition to the 2023 marine heatwave, an extensive riverine plume in the eastern Gulf of Mexico, extending from the Mississippi-Alabama-Florida shelf to the Straits of Florida, produced a ∼20 m thick low-salinity layer (∼34–34.5 psu) and a corresponding warm upper ocean (>29 °C, ∼25–30 m thick). This defined a 10–20 m thick strongly stratified barrier layer below the surface layer with buoyancy frequencies exceeding 10−3 s−1 that suppresses vertical mixing and became a critical factor contributing to Idalia’s rapid intensification under the relatively less than favorable thermal and wind field environments. Therefore, incorporating the river plume in future forecast models appears to be essential to improve the accuracy of intensity predictions, especially in the areas affected by the plume, where stratification plays an important role in the intensification dynamics.

Numerical modelling and performance analysis of closed ocean thermal energy conversion cycles in the South China sea

Numerical modelling and performance analysis of closed ocean thermal energy conversion cycles in the South China sea

Enhancement of wave energy harvesting performance by wave concentration with vertical cylinders

The performance of ocean wave energy harvesting can be enhanced by optimizing the design and operation of wave energy converters (WECs). In this experimental study, we investigate the wave interaction produced by installing additional structures to augment the power and efficiency of a WEC. Four circular cylinders are arranged in a square within a large-scale ocean engineering basin, and a duck-type rotor WEC is placed at the center of the cylinders. Several incident wave conditions are generated by varying the wavelength and wave height for a fixed wave steepness. In the absence of the rotor, the waves scattered by the cylinders become concentrated at the center of the array, increasing their amplitudes. With the rotor, wave heights in front of the rotor increase under all wave conditions from the case without the cylinders. The wave concentration produced by the cylinder array contributes positively to the power and efficiency of the rotor. The maximum power output of the rotor within a cycle improves in the entire range of the wavelength, and its efficiency over a cycle increases significantly for small wavelengths. These results are primarily attributable to changes in the temporal profile of the rotor angular velocity by the cylinder array.

Vortex-driven nanogenerators for marine energy harvesting and flow velocity sensing

Vortex-driven nanogenerators for marine energy harvesting and flow velocity sensing

Advances in TENGs for Marine Energy Harvesting and In Situ Electrochemistry.

The large-scale use of ample marine energy will be one of the most important ways for human to achieve sustainable development through carbon neutral development plans. As a burgeoning technological method for electromechanical conversion, triboelectric nanogenerator (TENG) has significant advantages in marine energy for its low weight, cost-effectiveness, and high efficiency in low-frequency range. It can realize the efficient and economical harvesting of low-frequency blue energy by constructing the floating marine energy harvesting TENG. This paper firstly introduces the power transfer process and structural composition of TENG for marine energy harvesting in detail. In addition, the latest research works of TENG on marine energy harvesting in basic research and structural design are systematically reviewed by category. Finally, the advanced research progress in the power take-off types and engineering study of TENG with the marine energy are comprehensively generalized. Importantly, the challenges and problems faced by TENG in marine energy and in situ electrochemical application are summarized and the corresponding prospects and suggestions are proposed for the subsequent development direction and prospects to look forward to promoting the commercialization process of this field.

Innovations in Wave Energy: A Case Study of TALOS-WEC’s Multi-Axis Technology

The technologically advanced learning ocean system—wave energy converter (TALOS-WEC) project addresses the urgent need for sustainable and efficient energy solutions by leveraging the vast potential of wave energy. This project presents a pioneering approach to wave energy capture through its unique multi-axis and omnidirectional point absorber design. Featuring a fully enclosed power take-off (PTO) system, the TALOS-WEC harnesses energy across six degrees of freedom (DoFs) using an innovative internal reaction mass (IRM) mechanism. This configuration enables efficient energy extraction from the relative motion between the IRM and the hull, aiming for energy conversion efficiencies ranging between 75–80% under optimal conditions, while ensuring enhanced durability in harsh marine environments. The system’s adaptability is reflected in its versatile geometric configurations, including triangular, octagonal, and circular designs, customised for diverse marine conditions. Developed at Lancaster University, UK, and supported by international collaborations, the TALOS-WEC project emphasises cutting-edge advancements in hydrodynamic modelling, geometric optimisation, and control systems. Computational methodologies leverage hybrid frequency-time domain models and advanced panel codes (WAMIT, HAMS, and NEMOH) to address non-linearities in the PTO system, ensuring precise simulations and optimal performance. Structured work packages (WPs) guide the project, addressing critical aspects such as energy capture optimisation, reliability enhancement, and cost-effectiveness through innovative monitoring and control strategies. This paper provides a comprehensive overview of the TALOS-WEC, detailing its conceptual design, development, and validation. Findings demonstrate TALOS’s potential to achieve scalable, efficient, and robust wave energy conversion, contributing to the broader advancement of renewable energy technologies. The results underscore the TALOS-WEC’s role as a cutting-edge solution for harnessing oceanic energy resources, offering perspectives into its commercial viability and future scalability.

Mapping out the scenarios of ocean energy scale-up based on the development of offshore wind

Background Our oceans remain one of the last untapped large sources of renewable energy. The predictability and reliability of marine energy technologies could contribute significantly to the global energy transition. By 2022, marine energy, and in particular wave and tidal energy have reached a pre-commercial phase in their development. Methods This study investigates the potential progression of the wave and tidal energy sector in the next three decades based on the offshore wind sector in the past three decades. Two different models were developed from the yearly capacity increase of offshore wind in Europe and applied to the wave and tidal energy sector. Results According to both models, the 40 GW 2050 target for marine energy set by the European Commission in 2020 could be reached if European coastal countries, including countries associated to the EU-27, adopt supportive policies for both technologies immediately. A sensitivity analysis shows further that a small delay right now will have tremendous negative impacts on fulfilling the EU goals and the contribution of marine energy to the energy transition. Conclusions The ocean energy sector shows a strong growth potential and is capable of supporting the European and global climate targets substantially by 2050. Lessons learned from the offshore wind sector can help scope and support the growth of marine energy technologies.

Regulating Contact Electrification and Charge Retention Capability With Metal–Organic Frameworks in Triboelectric Nanogenerator for Self‐Powered Sewage Treatment

AbstractThe harvesting of ocean wind energy for triboelectric nanogenerators (TENGs) is greatly influenced by the contact electrification (CE) capability, charge retention characteristics, and harsh marine environment. In this work, four highly water‐stable metal–organic frameworks, including MIL‐101(Cr), UiO‐66, ZIF‐8, and MOF‐303, are doped into PVA/Ta layers to modulate their CE capability, charge retention, and resistance to harsh marine environments. The CE capability is compared at multiple scales including electronic, atomic, and molecular levels using DFT calculation. The combined effect of the pyrazole ring and ─COO─ group contributes to the highest tribopositivity of PVA/Ta/MOF‐303. Besides, the reduced HOMO–LUMO gap and the increased HOMO level make it easier for electrons in PVA/Ta/MOF‐303 to transfer. Meanwhile, MOF‐303 with high charge capture capability located in deep layers can serve as charge traps to reduce charge dissipation rate. Hence, the charge density of PVA/Ta/MOF‐303‐based TENG (PTM‐TENG) at 90% RH reaches to 361.43 µC m−2. Hydrogen bonding, coordination effects, and electrostatic interactions endow PVA/Ta/MOF‐303 with excellent mechanical, anti‐swelling, and anti‐aging properties. Finally, PTM‐TENG is assembled into a self‐powered sewage treatment system, and the generation of ·OH and ·O2− enables PTM‐TENG to realize a high water sterilization rate (99.99%) and efficient organic pollutant degradation (>95%) within 20 min.

Ocean wave-driven covalent organic framework/ZnO heterostructure composites for piezocatalytic uranium extraction from seawater

Piezoelectric catalysis possesses the potential to convert ocean wave energy into and holds broad prospects for extracting uranium from seawater. Herein, the Z-type ZnO@COF heterostructure composite with excellent piezoelectric properties was synthesized through in situ growth of covalent organic frameworks (COFs) on the surface of ZnO and used for efficient uranium extraction. The designed COFs shell enables ZnO with stability, abundant active sites and high-speed electron transport channels. Meanwhile, the interface electric field established in the heterojunctions stimulates electron transfer from COFs to ZnO, which break the edge shielding effect of the ZnO’s metallic state. Additionally, the polarization of ZnO is enhanced by heterogeneous engineering, which ensures the excellent piezocatalytic performance. As a result, ZnO@COF achieves an ultra-high efficiency of 7.56 mg g−1 d−1 for uranium extraction from natural seawater driven by waves. In this work, we open an avenue for developing efficient catalysts for uranium extraction from seawater.

Gyro‐Multigrid Triboelectric Nanogenerator via Topological Defects Strategy for Efficiently Harvesting Low‐Grade Wave Energy

AbstractWave energy is a promising sustainable energy yet to be fully exploited due to the low frequency and broad‐banded wave fields, so much so that difficult to capture, resulting in low efficiency and limited power output from current many wave energy harvesters. Here, a topological defect gyro‐multigrid triboelectric nanogenerator (TD‐GM‐TENG) is proposed that harnesses the mechanical energy of ocean waves to generate electricity and promotes the accumulation of triboelectric charge on the basis of realized from low to high rotation speed under the precession and gravitation acceleration effects. It benefited from topological defect strategy, TD‐GM‐TENG offers a charge transfer rate of 3.1 µC s−1 that when can reach to a speed of nearly 1000 rpm at the wave frequency of 1 Hz. Furthermore, the charge density reaches 90 µC m−2 in a cycle of 0.06 s, which is 1.6 times higher than the same kind of spherical‐TENGs in the field of ocean energy harvesting. Finally, TD‐GM‐TENG unit outputs a peak power of 3.7 mW at the simulated water wave environment of 1 Hz and demonstrates its applicability and feasibility of being used as a distributed emergency power supply in the offshoring observation and early warning services.

Mitigating anthropogenic climate change with aqueous green energy

Reaching net zero emissions and limiting global warming to 2 °C requires the widespread introduction of technology-based solutions to draw down existing atmospheric levels and future emissions of CO2. One such approach is direct air CO2 capture and storage (DACCS), a readily available, yet energy-intensive process. The combination of DACCS and ocean thermal energy conversion (OTEC) allows for independently powered carbon capture plants to inject concentrated carbon into deep marine sediments where storage is generally safe and permanent. OTEC is a form of electricity production that exploits the temperature difference between deep and shallow ocean waters, and can power DACCS on floating platforms at a price competitive with coal-generated electricity. Here we highlight the scale of the challenge facing society. We show that a safe and sustainable level of OTEC-generated electricity powering DACCS for 70 years could result in up to a 35% decrease in the relative global mean temperature warming compared to a business-as-usual emissions scenario.

Optimising the Design of a Hybrid Fuel Cell/Battery and Waste Heat Recovery System for Retrofitting Ship Power Generation

This research aims to assess the integration of different fuel cell (FC) options with battery and waste heat recovery systems through a mathematical modelling process to determine the most feasible retrofit solutions for a marine electricity generation plant. This paper distinguishes itself from existing literature by incorporating future cost projection scenarios involving variables such as carbon tax, fuel, and equipment prices. It assesses the environmental impact by including upstream emissions integrated with the Energy Efficiency Existing Ship Index (EEXI) and the Carbon Intensity Indicator (CII) calculations. Real-time data have been collected from a Kamsarmax vessel to build a hybrid marine power distribution plant model for simulating six system designs. A Multi-Criteria Decision Making (MCDM) methodology ranks the scenarios depending on environmental benefits, economic performance, and system space requirements. The findings demonstrate that the hybrid configurations, including solid oxide (SOFC) and proton exchange (PEMFC) FCs, achieve a deduction in equivalent CO2 of the plant up to 91.79% and decrease the EEXI and the average CII by 10.24% and 6.53%, respectively. Although SOFC-included configurations show slightly better economic performance and require less fuel capacity, the overall performance of PEMFC designs are ranked higher in MCDM analysis due to the higher power density.

A Fuzzy Logic Technique for the Environmental Impact Assessment of Marine Renewable Energy Power Plants

A Fuzzy Logic Technique for the Environmental Impact Assessment of Marine Renewable Energy Power Plants

Spectral Flux Decomposition in a Wind‐Driven Channel Flow With Near‐Inertial Waves

AbstractIn recent years it has become evident that the spatiotemporal distribution of oceanic kinetic energy (KE) is strongly influenced by the interactions between oceanic mesoscale eddies, submesoscale currents, and near‐inertial waves (NIWs). However, the proposed interaction mechanisms remain difficult to evaluate and quantify in complex oceanic numerical simulations. To address these difficulties we introduce an analysis framework that combines spectral KE flux computations across horizontal wavenumbers with temporal filtering and a Helmholtz decomposition, and apply it to idealized, high‐resolution, baroclinic channel solutions consisting of eddies, fronts, and filaments in the Rossby parameter regime. By comparing solutions with and without NIW forcing we are able to demonstrate that externally forced NIWs lead to a reduction in the inverse KE cascade of the low‐passed eddying flow, and to an enhancement in its forward cascade. These stimulated cascades are associated with the interactions between rotational and divergent eddy motions, characteristic of mesoscale eddies and submesoscale currents, respectively. Additionally, we demonstrate that at larger spatial scales the forward KE cascade of NIWs is accomplished through wave scattering and direct extraction by rotational eddy motions, whereas at smaller spatial scales it is also dominated by wave‐wave interactions. The caveats of our framework, its suitability to investigate eddy‐NIW interactions in realistic oceanic simulations and the disparities between the spectral KE flux and the coarse‐graining methods are also discussed.

Social Acceptance of Green Infrastructure Adoption in Lithuania

Lithuania aims to have entirely renewable energy sector in the future, which will increase demand for sustainable infrastructure that integrates wind, solar, hydro, bio, geothermal, ocean, and hydrogen energy sources. This study uses demographic data to assess public acceptance of green infrastructure. While older, lower-income, rural, and less educated groups are more sceptical, younger, wealthy, urban, and highly educated people exhibit greater acceptance. These observations highlight the need of taking demography into account when trying to achieve broad acceptability and a successful transition to sustainability.