• Energy Research
• 13. Climate action close

This work experimentally investigates the performance of solar still with induced turbulence (SWIT) which operates with a novel approach for improved productivity. A metal wire net has been submerged in basin water of still and direct current vibration micro motor has been used to develop small intensity vibrations in wire net. These vibrations serve to induce turbulence in basin water and also break the thermal boundary layer between still surface and water to enhance the evaporation. The energy-exergy-economic-environment analysis of SWIT has been performed and compared with conventional solar still (CS) of identical size. The overall heat transfer coefficient of SWIT is found to be 66% more in comparison of CS. The SWIT provided 53% increase in yield and it is 55% more thermally efficient than CS. The average exergy efficiency of the SWIT is found to be 76% higher than that of CS. The cost of water from SWIT is 0.028 $ with a payback period of 0.74 years and the carbon credit gained by SWIT is found to be 105 $. The productivity of SWIT has also been compared for intervals of 5, 10, and 15 min between the induced turbulence to find suitable interval duration.

Due to their large and increasing size and the corrosive nature of salt water and high wind speeds, offshore wind turbines are required to be more robust, more rugged and more reliable than their onshore counterparts. The dynamic characteristics of the blade and its response to applied forces may be influenced dramatically by rotor rotational speed, which may even threaten the stability of the wind turbine. An accurate and computationally efficient structural dynamics model is essential for offshore wind turbines. A comprehensive model that takes the centrifugal stiffening effect into consideration could make rapid and accurate decisions with live data sensed from the structure. Moreover, this can enhance both the performance and reliability of wind turbines. When a rotating blade deflects in its plane of rotation or perpendicular to it, the centrifugal force exerts an inertia force that increases the natural frequencies and changes the mode shapes, leading to changes in the dynamic response of the blade. However, in the previous literature, studies of centrifugal stiffening are rarely found. This study investigates the influence of centrifugal stiffening on the free vibrations and dynamic response of offshore wind turbine blades. The National Renewable Energy Laboratory (NREL) 5 MW blade benchmark was considered to study the effect of angular speed in the flap-wise and edge-wise directions. The results demonstrate that the angular speed directly affects the modal features, which directly impacts the dynamic response. The results also show that the angular velocity effect in the flap-wise direction is more significant than its effect in the edge-wise direction.

AbstractEnergy harvesting induced from flowing fluids (e.g., air and water flows) is a well-known process, which can be regarded as a sustainable and renewable energy source. In addition to traditional high-efficiency devices (e.g., turbines and watermills), the micro-power extracting technologies based on the flow-induced vibration (FIV) effect have sparked great concerns by virtue of their prospective applications as a self-power source for the microelectronic devices in recent years. This article aims to conduct a comprehensive review for the FIV working principle and their potential applications for energy harvesting. First, various classifications of the FIV effect for energy harvesting are briefly introduced, such as vortex-induced vibration (VIV), galloping, flutter, and wake-induced vibration (WIV). Next, the development of FIV energy harvesting techniques is reviewed to discuss the research works in the past three years. The application of hybrid FIV energy harvesting techniques that can enhance the harvesting performance is also presented. Furthermore, the nonlinear designs of FIV-based energy harvesters are reported in this study, e.g., multi-stability and limit-cycle oscillation (LCO) phenomena. Moreover, advanced FIV-based energy harvesting studies for fluid engineering applications are briefly mentioned. Finally, conclusions and future outlook are summarized.

Anthropogenic activities directly contacting the seabed, such as drilling and pile-driving, produce a significant vibration likely to impact benthic invertebrates. As with terrestrial organisms, vibration may be used by marine species for the detection of biotic and abiotic cues, yet the significance of this and the sensitivities to vibration are previously undocumented for many marine species. Exposure to additional vibration may elicit behavioral or physiological change, or even physical damage at high amplitudes or particular frequencies, although this is poorly studied in underwater noise research. Here we review studies regarding the sensitivities and responses of marine invertebrates to substrate-borne vibration. This includes information related to vibrations produced by those construction activities directly impacting the seabed, such as pile-driving. This shows the extent to which species are able to detect vibration and respond to anthropogenically-produced vibrations, although the short and long-term implications of this are not known. As such it is especially important that the sensitivities of these species are further understood, given that noise and energy-generating human impacts on the marine environment are only likely to increase and that there are now legal instruments requiring such effects to be monitored and controlled.

Significant increase in the demand for freight and passenger transports by trains pushes the railway authorities and train companies to increase the speed, the axle load and the number of train carriages/wagons. All of these actions increase ground-borne noise and vibrations that negatively affect people who work, stay, or reside nearby the railway lines. In order to mitigate these phenomena, many techniques have been developed and studied but there is a serious lack of life-cycle information regarding such the methods in order to make a well-informed and sustainable decision. The aim of this study is to evaluate the life-cycle performance of mitigation methods that can enhance sustainability and efficacy in the railway industry. The emphasis of this study is placed on new methods for ground-borne noise and vibration mitigation including metamaterials, geosynthetics, and ground improvement. To benchmark all of these methods, identical baseline assumptions and the life-cycle analysis over 50 years have been adopted where relevant. This study also evaluates and highlights the impact of extreme climate conditions on the life-cycle cost of each method. It is found that the anti-resonator method is the most expensive methods compared with the others whilst the use of geogrids (for subgrade stiffening) is relatively reliable when used in combination with ground improvements. The adverse climate has also played a significant role in all of the methods. However, it was found that sustainable methods, which are less sensitive to extreme climate, are associated with the applications of geosynthetic materials such as geogrids, composites, etc.

Debris flows have become a common disaster in Taiwan in recent years since the impacts of extreme weathers has been aggravated. To protect people from the debris-flow disasters, a monitoring and warning system was developed by Soil and Water Conservation Bureau (SWCB) in Taiwan. The rainfall-based criteria are used in Taiwan for debris flow warning. Different to rainfall measurement, the ground surface vibrational signal from a debris flow has been studied more widely in recent years. Sensors of geophone (short period seismograph) and broadband seismograph are commonly used for debris flow monitoring. In this paper, the signal analysis of debris flows was performed by calculating the vibrational energy. The comparison of the analysis results indicated that when the energy ratios of at least two of the axes are greater than 1.12, a debris flow is highly likely to occur. The starting point in the increasing trend of vibrational energy implied the possible warning time point for debris flow. Vibration examples of debris flow and earthquakes were also compared in this paper.

The widespread and increasing consumption of fossil-based fuels as an energy source causes a rapid decrease of these natural sources, as well as an increase of pollution in the atmosphere. Fuel oil, one of the products of fossil fuels, is today the commonly used energy source for transportation. The importance of contributing to the fuel economy and of increasing environmental consciousness have necessitated certain measures in the automotive sector, as well as in other industrial sectors. Therefore, the technological developments recently carried out in the automotive sector aim to reduce the consumption of fossil fuels, for example by recovering waste energy in vehicles. In this direction, efforts have been centered upon the development of energy harvesting systems that provide energy recovery from dynamic parts of the vehicles, such as suspensions. Moreover, the regenerative braking systems that recover some amount of kinetic energy of the vehicles slowing down have been developed and have been in use long since. In this study, research studies on providing the recovery of the vehicles’ waste energy are reviewed with their comparisons.

The roads we travel daily are exposed to several energy sources (mechanical load, solar radiation, heat, air movement, etc.), which can be exploited to make common systems and apparatus for roadways (i.e., lighting, video surveillance, and traffic monitoring systems) energetically autonomous. For decades, research groups have developed many technologies able to scavenge energy from the said sources related to roadways: electromagnetism, piezoelectric and triboelectric harvesters for the cars’ stress and vibrations, photovoltaic modules for sunlight, thermoelectric solutions and pyroelectric materials for heat and wind turbines optimized for low-speed winds, such as the ones produced by moving vehicles. Thus, this paper explores the existing technologies for scavenging energy from sources available on roadways, both natural and related to vehicular transit. At first, to contextualize them within the application scenario, the available energy sources and transduction mechanisms were identified and described, arguing the main requirements that must be considered for developing harvesters applicable on roadways. Afterward, an overview of energy harvesting solutions presented in the scientific literature to recover energy from roadways is introduced, classifying them according to the transduction method (i.e., piezoelectric, triboelectric, electromagnetic, photovoltaic, etc.) and proposed system architecture. Later, a survey of commercial systems available on the market for scavenging energy from roadways is introduced, focusing on their architecture, performance, and installation methods. Lastly, comparative analyses are offered for each device category (i.e., scientific works and commercial products), providing insights to identify the most promising solutions and technologies for developing future self-sustainable smart roads.