• Energy Research
• 13. Climate action close
• 12. Responsible consumption close

Underwater acoustic sensor networks (UWA-SNs) are envisioned to perform monitoring tasks over the large portion of the world covered by oceans. Due to economics and the large area of the ocean, UWA-SNs are mainly sparsely deployed networks nowadays. The limited battery resources is a big challenge for the deployment of such long-term sensor networks. Unbalanced battery energy consumption will lead to early energy depletion of nodes, which partitions the whole networks and impairs the integrity of the monitoring datasets or even results in the collapse of the entire networks. On the contrary, balanced energy dissipation of nodes can prolong the lifetime of such networks. In this paper, we focus on the energy balance dissipation problem of two types of sparsely deployed UWA-SNs: underwater moored monitoring systems and sparsely deployed two-dimensional UWA-SNs. We first analyze the reasons of unbalanced energy consumption in such networks, then we propose two energy balanced strategies to maximize the lifetime of networks both in shallow and deep water. Finally, we evaluate our methods by simulations and the results show that the two strategies can achieve balanced energy consumption per node while at the same time prolong the networks lifetime.

After being neglected for a long time, in the last years, ships have been recognized and studied as sound emitters. The sound energy they generate impacts the outside, but it can also affect the indoor quality of life if the environments are not properly designed. In fact, acoustic comfort plays a pivotal role, particularly in recreational crafts. In the present work, room acoustics and acoustic camera measurements were performed, inside a 50 m length overall yacht, chosen as a case study in order to evaluate the acoustic comfort. The Italian classification procedure UNI 11367:2010 for buildings was applied, and results have been compared to other international comfort classes. However, all of these are based on prescription for standard buildings, and the present work highlights that they do not account for the effective ship’s acoustic issues: sound energy transfer from impacts over ceilings and sound energy leakage. While attention of shipbuilders in acoustic comfort is shown in the measured good reverberation times, the acoustic camera revealed sound energy leakages corresponding to hidden escape ways that have been poorly insulated. This compromises the standardized sound difference between contiguous compartments and also the thermal insulation, as leakage involves air passages. The present work attempts to evolve the classification procedure by also including, for the first time, the reverberation time, but future studies focused on finding correct standardized impact level noise for ship cases are needed. In fact, their values were very high and not comparable with those measured in actual buildings and for which reference values have been designed.

Increasing levels of anthropogenic underwater noise have caused concern over their potential impacts on marine life. Offshore renewable energy developments and seismic exploration can produce impulsive noise which is especially hazardous for marine mammals because it can induce auditory damage at shorter distances and behavioural disturbance at longer distances. However, far-field effects of impulsive noise remain poorly understood, causing a high level of uncertainty when predicting the impacts of offshore energy developments on marine mammal populations. Here we used a 10-year dataset on the occurrence of coastal bottlenose dolphins over the period 2009-2019 to investigate far-field effects of impulsive noise from offshore activities undertaken in three different years. Activities included a 2D seismic survey and the pile installation at two offshore wind farms, 20-75 km from coastal waters known to be frequented by dolphins. We collected passive acoustic data in key coastal areas and used a Before-After Control-Impact design to investigate variation in dolphin detections in areas exposed to different levels of impulsive noise from these offshore activities. We compared dolphin detections at two temporal scales, comparing years and days with and without impulsive noise. Passive acoustic data confirmed that dolphins continued to use the impact area throughout each offshore activity period, but also provided evidence of short-term behavioural responses in this area. Unexpectedly, and only at the smallest temporal scale, a consistent increase in dolphin detections was observed at the impact sites during activities generating impulsive noise. We suggest that this increase in dolphin detections could be explained by changes in vocalization behaviour. Marine mammal protection policies focus on the near-field effects of impulsive noise; however, our results emphasize the importance of investigating the far-field effects of anthropogenic disturbances to better understand the impacts of human activities on marine mammal populations. Echolocation detectors (CPODs; Chelonia Ltd) were deployed between 2009 and 2019 to investigate the variation in dolphin detections in relation to the impulsive noise from three energy developments: a seismic survey for oil and gas exploration and the installation of foundation piles for two offshore wind farms (Beatrice Offshore Wind Farm and Moray East Offshore Wind Farm). Data on the timing of the seismic survey and piling operations were provided by the developers (Oil and Gas UK Ltd., COWRIE, Beatrice Offshore Wind Ltd. and Moray Offshore Wind Farm East). Data consist of 7 files and include the datasets and R code required to repeat all the analyses. A full description of the files provided in the Readme.txt file: OFB_FarField_DPH.csv OFB_FarField_BOWL.csv OFB_FarField_MEOW.csv OFB_FarField_BACI_Obtain_DPH_Dataset.R OFB_FarField_DPH_for_BACI.csv OFB_FarField_BACI_DPH_Models.R OFB_FarField_Readme.txt

The acoustic waves produced and received by a multi array transducer allows the detection of buried targets in marine sediments or the determination of their geoacoustic parameters. In this study sea data obtained in situ and artificial sediment are used to modelise the focalization acoustic wave. The characteristics of the sediment and the interface taken into account for a model. These acoustic parameters (celerity and attenuation of the longitudinal waves ― acoustic impedance of sediments) affect the form, the dimensions of the focal point and the performances of the process. A large wave attenuation enables the emission of energy focalization and troubles the treatment of the signal of reception (the energy level of the longer distances are too low). In the paper results from artificial sediments are also presented. They are used to quantify acoustic parameters relative to an artificial site representing the natural behaviour of the sea. Furthermore these parameters define the performances of array transducers La detection d'objets enfouis dans les sediments marins ou la determination de certaines de leurs caracteristiques geotechniques peut se faire a partir d'ondes acoustiques generees et captees par des antennes multielements. Les auteurs se proposent d'appliquer des donnees, acquises en mer et a partir de sediments artificiels, a un modele numerique permettant de prevoir le comportement de la focalisation d'ondes en fonction de parametres geoacoustiques des fonds marins. L'influence du sol sera prise en compte: 1) au niveau de l'interface, 2) dans le sediment

This study was conducted to determine whether a low-powered sound source could be effective at deterring gray whales from areas that may prove harmful to them. With increased interest in the development of marine renewal energy along the Oregon coast the concern that such development may pose a collision or entanglement risk for gray whales. A successful acoustic deterrent could act as a mitigation tool to prevent harm to whales from such risks. In this study, an acoustic device was moored on the seafloor in the pathway of migrating gray whales off Yaquina Head on the central Oregon coast. Shore-based observers tracked whales with a theodolite (surveyor’s tool) to accurately locate whales as they passed the headland. Individual locations of different whales/whale groups as well as tracklines of the same whale/whale groups were obtained and compared between times with the acoustic device was transmitting and when it was off. Observations were conducted on 51 d between January 1 and April 15, 2012. A total of 143 individual whale locations were collected for a total of 243 whales, as well as 57 tracklines for a total of 142 whales. Inclement weather and equipment problems resulted in very small sample sizes, especiallymore » during experimental periods, when the device was transmitting. Because of this, the results of this study were inconclusive. We feel that another season of field testing is warranted to successfully test the effectiveness of the deterrent, but recommend increasing the zone of influence to 3 km to ensure the collection of adequate sample sizes. Steps have been taken to acquire the necessary federal research permit modification to authorize the increased zone of influence and to modify the acoustic device for the increased power. With these changes we are confident we will be able to determine whether the deterrent is effective at deflecting gray whales. A successful deterrent device may serve as a valuable mitigation tool to protect gray whales, and other baleen whales, in the event that marine energy development poses a collision or entanglement risk.« less

Penetration of intermittent renewable energy sources into the power grid requires large-scale energy storage to ensure grid stability. Pumped Hydro Energy Storage (PHES) is among the most mature, environmentally friendly, and economical energy storage technologies, but has traditionally only been feasible at sites with large natural topographic gradients. ALPHEUS addresses this by developing reversible pump-turbines efficient at low heads, that operate between an enclosed inner basin (that functions as the upper or lower reservoir) and a shallow sea or lake.

There are many developments for offshore renewable energy around the United Kingdom whose installation typically produces large amounts of far-reaching noise, potentially disturbing many marine mammals. The potential to affect the favorable conservation status of many species means extensive environmental impact assessment requirements for the licensing of such installation activities. Quantification of such complex risk problems is difficult and much of the key information is not readily available. Expert elicitation methods can be employed in such pressing cases. We describe the methodology used in an expert elicitation study conducted in the United Kingdom for combining expert opinions based on statistical distributions and copula-like methods.

Wireless Sensor Networks (WSNs) has become increasingly important in the Oil and Gas industry. Despite the various advantages WSN has compared to the wired counter parts, it also faces some critical challenges in the oil fields; one of them is the power supply. The periodic replacement of batteries for the WSN in the downhole environments has been economically inconvenient and the enormous cost induced by the maintenance has turned people's attention to the energy harvesting technology, hoping for a more sustainable solution. Power supply is only half of the problem. To retrieve the data recorded by the various sensors in the downhole environments, a reliable way of wireless communication is required. A new approach utilizing acoustic communication was proposed. This thesis presents an Archimedean Screw Turbine (AST) based energy harvester that takes advantage of the abundant flow energy in the upper stream section of the oil production cycle, especially in the water injection wells and oil extraction wells, with the goal of providing power supply to Wireless Sensor Networks (WSNs) and underwater acoustic modems deployed in the various locations in the downhole environments. Parametric study on the number of blades, screw length, screw pitch, and rotational speed was conducted through CFD analysis using Ansys Fluent in order to determine the optimal geometry and operating conditions. The relationship between power generation and AST geometries, such as AST length and AST pitch, were discovered and the optimal rotational speed was revealed to be solely dependent on the screw pitch. Experiments were conducted in the lab environment with various flow rates and various external resistive loads to verify and determine the maximum power generation of the designed harvester. FEA analysis was conducted using the Acoustic and Structural Interaction Module of COMSOL MULTIPHYSICS to determine the attenuation characteristics of acoustic waves propagating in the water-filled pipes buried in soil. Experiments with and without the harvester integrated in the pipe system were conducted in lab environment using a pair of under water acoustic modems to determine the acoustic communication capability. The impact of the integrated harvester on the acoustic communication was tested. Combining energy harvesting technology and underwater acoustic communication together, this system can potentially achieve real-time monitoring and communication in the oil downhole environment. Master of Science Oil and Gas industry has been the primary energy source provider for our society for hundreds of years. As this industry evolves with new technologies, it also faces new challenges. One of the main challenges is the power supply problem in the oil field because of the limited lifespan of traditional batteries used in the oil production process. This study present a novel energy harvesting device that can replace the traditional batteries. By taking advantage of the constant fluid flow in various wells at oil field, the device can provide power for electronic devices, including but not limited to wireless sensors, communication modules, at the oil extraction sites, without needing additional power supply. This novel energy harvesting device can also be integrated with communication modules that uses acoustic wave to achieve wireless acoustic communication between underground and the surface. In this study, the harvester design, optimization, tests, and integration with acoustic modems were presented. With the help of such energy harvesting device, Oil and Gas industry will be one step closer to achieving true wireless, and real-time monitoring and communication. This will not only reduce maintenance cost but also greatly improve the production efficiency.