Energy Harnessing Research Articles

Co-Digestion of Household Black Water with Kitchen Waste for a Sustainable Decentralized Waste Management: Biochemical Methane Potential and Mixing Ratios Effects

The generation of anthropogenic wastes, such as household human feces and kitchen waste, has resulted in a severe environmental impact. Sustainable management approaches to address disposal challenges and harness potential nutrient and energy values are urgently needed. This investigation assessed the anaerobic co-digestion of food waste and black water to identify the biochemical methane potential. The household kitchen waste showed improved performance at a dilution ratio of 50% with biochemical methane potential of 265 mL CH4/g volatile solid (VS), and that of the black water was 220 mL CH4/g VS without dilution. This trend indicates their easy biodegradation/digestibility and potential for energy recovery. The kitchen waste equal mix ratio of 50% v/v with the black water had the highest biochemical methane potential of 295.13 mL CH4/g VS when co-digested. High performance was due to the comparative balance in substrate concentrations that offered robust methanogenic activities without inhibitions. The effluent total chemical oxygen demand reduction of ∼90% and other physicochemical parameters showed that the codigestion treatment (kitchen waste and black water 50:50% v/v) was efficient. The codigestion route could offer a decentralized wastewater management system for energy recovery.

Erosion Mapping of Through-Thickness Toughened Powder Epoxy Gradient Glass-Fiber-Reinforced Polymer (GFRP) Plates for Tidal Turbine Blades

Erosion of tidal turbine blades in the marine environment is a major material challenge due to the high thrust and torsional loading at the rotating surfaces, which limits the ability to harness energy from tidal sources. Polymer–matrix composites can exhibit leading-blade edge erosion due to marine flows containing salt and solid particles of sand. Anti-erosion coatings can be used for more ductility at the blade surface, but the discontinuity between the coating and the stiffer composite can be a site of failure. Therefore, it is desirable to have a polymer matrix with a gradient of toughness, with a tougher, more ductile polymer matrix at the blade surface, transitioning gradually to the high stiffness matrix needed to provide high composite mechanical properties. In this study, multiple powder epoxy systems were investigated, and two were selected to manufacture unidirectional glass-fiber-reinforced polymer (UD-GFRP) plates with different epoxy ratios at the surface and interior plies, leading to a toughening gradient within the plate. The gradient plates were then mechanically compared to their standard counterparts. Solid particle erosion testing was carried out at various test conditions and parameters on UD-GFRP specimens in a slurry environment. The experiments performed were based on a model of the UK marine environment for a typical tidal energy farm with respect to the concentration of saltwater and the size of solid particle erodent. The morphologies of the surfaces were examined by SEM. Erosion maps were generated based on the result showing significant differences for materials of different stiffness in such conditions.

Exploiting the rooftop solar photovoltaic potential of a tropical island state: case of the Mascarene Island of Mauritius

Mauritius relies heavily on fossil fuel imports to satisfy the energy requirements of its population. Urged by policies to address climate change at the national and international levels, the government is committed to promote sustainable development, with emphasis laid on reducing greenhouse gas emissions. Consequently, we provide an assessment of rooftop PV potential at the national level. A sampling strategy is used to acquire reduction coefficients, which are thereafter applied to energy-based equations. The result suggests that the rooftop PV potential at the country-scale is estimated at 20.04 GW with an annual energy output of 32,512 GWh. A novel architectural layout for a Solar City to be located at an identified optimum site is proposed. A shading analysis is conducted to verify the appropriateness of the city’s structural design to harness energy from the sun. An energy analysis performed, reveals that the Solar City has a solar power potential of 13.55 MW and an annual energy generation capacity equivalent to 21.99 GWh. Construction of the Solar City would help avert the emissions of 13,744 tons of CO2 annually.

NpTrack: A n-Position Single Axis Solar Tracker Model for Optimized Energy Collection

The single axis solar tracker based on flat panels is used in large solar plants and in distribution-level photovoltaic systems. In order to achieve this, the solar tracking systems generally need to work by tracking the sun’s position with dozens, maybe hundreds of movements along the day with a maximal known tracking error within the specifications. A novel model is proposed along this work based on the control of the angle deviation within a (polar) single axis configuration. This way an optimization of the harnessing of solar energy can be achieved with as few panel displacements as possible in order to decrease the wear in the mechanical parts of the equipment and the energy consumed by it. This tracking approach was implemented with as few as seven positions along the day and got an estimated theoretical value of 99.27% of the total collected energy in a continuous tracking system. Regarding an annual average basis, it would be about 96.5% of a dual axis system according to the proposed model. The novelty of the model is related to a tradeoff between the gain with the simplicity of a single axis n-position tracking and the solar energy loss associated.

Photocatalytic water splitting for solving energy crisis: Myth, Fact or Busted?

• Practicality of photocatalytic water splitting is assessed from various aspects. • Employments of unrealistic labscale investigation are pointed out. • Intrinsic limitations of photocatalytic water splitting are summarized. • Energy and economy analysis of photocatalytic water splitting are performed. • H 2 energy generation from photocatalytic water splitting is not industrially viable. Reaping hydrogen energy by utilising eternal sunlight offers a good fit to the theme of popularly-hype sustainable and carbon-free energy future. Contrary to that belief, this review unveils the impracticality of photocatalytic water splitting (solar energy for H 2 energy) to fuel global advancement. Despite some success with idealized laboratory-scale studies, the past research works also mutually evinced an extreme low solar-to-hydrogen efficiency (STH < 1.0%). Hitherto, multifarious endeavours, such as advanced reactor design, facilities to eliminate diffusional restrictions, advanced photocatalyst design and an inclusion of sacrificial reagents, are incapable to raise STH efficiency to the practical threshold of STH > 10%. Regardless of the epitome and modifications of photocatalysts, the intrinsic limitation of charges recombination remains a sturdy obstacle, leading to an appreciable energy losses and low STH. For consequential solar-driven H 2 production, the bandgap energy of photocatalyst employed must stay below 2.36 eV. Meanwhile, most photocatalysts are capped by the theoretical maximum STH of 18%, even with the assumption of 100% quantum yield of corresponding spectrum. Nonetheless, the theoretical maximum STH is unattainable at this juncture due to the inevitable solar energy dissipation associated to the scattering effects of reactor and water. From economy standpoint, H 2 production via photocatalytic water splitting is pricey at 10.36 $/kg with exorbitant upfront costs, which is far beyond the practicable price range of 2 – 4 $/kg. In conclusion, we assert that the H 2 production from solar-driven photocatalytic water splitting is an industrially impractical pathway for solar energy harnessing, despite technically-feasible.

Modelling of a Flow-Induced Oscillation, Two-Cylinder, Hydrokinetic Energy Converter Based on Experimental Data

The VIVACE Converter consists of cylindrical oscillators in tandem subjected to transverse flow-induced oscillations (FIOs) that can be improved by varying the system parameters for a given in-flow velocity: damping, stiffness, and in-flow center-to-center spacing. Compared to a single isolated cylinder, tandem cylinders can harness more hydrokinetic energy due to synergy in FIO. Experimental and numerical methods have been utilized to analyze the FIO and energy harnessing of VIVACE. A surrogate-based model of two tandem cylinders is developed to predict the power harvesting and corresponding efficiency by introducing a backpropagation neural network. It is then utilized to reduce excessive experimental or computational testing. The effects of spacing, damping, and stiffness on harvested power and efficiency of the established prediction-model are analyzed. At each selected flow velocity, optimization results of power harvesting using the prediction-model are calculated under different combinations of damping and stiffness. The main conclusions are: (1) The surrogate model, built on extensive experimental data for tandem cylinders, can predict the cylinder oscillatory response accurately. (2) Increasing the damping ratio range from 0–0.24 to 0–0.30 is beneficial for improving power efficiency, but has no significant effect on power harvesting. (3) In galloping, a spacing ratio of 1.57 has the highest optimal harnessed power and efficiency compared with other spacing values. (4) Two tandem cylinders can harness 2.01–4.67 times the optimal power of an isolated cylinder. In addition, the former can achieve 1.46–4.01 times the efficiency of the latter. (5) The surrogate model is an efficient predictive tool defining parameters of the Converter for improved energy acquisition.

Design and analysis of upstream air deflectors for increasing wind-turbine efficiency

The objective of the present work is to increase the effectiveness of the wind turbine explicitly without changing the design parameters of the existing wind turbines. Deflectors which will deflect the air from outer region into the region where wind turbines harness energy are employed. By doing so the flow gets accelerated and this in turn increases the mass flow rate. This reduces the cut in speed for the wind turbine setup. The present work focuses on simulation for flow over the deflector to study the nature of this setup. The simulation was performed for different angle of deflector and at different velocities and the results are presented. Results highlight the significance of such deflectors in improving entire efficiency of the system.

Energy Harvesting and Storage with Soft and Stretchable Materials.

This review highlights various modes of converting ambient sources of energy into electricity using soft and stretchable materials. These mechanical properties are useful for emerging classes of stretchable electronics, e-skins, bio-integrated wearables, and soft robotics. The ability to harness energy from the environment allows these types of devices to be tetherless, thereby leading to a greater range of motion (in the case of robotics), better compliance (in the case of wearables and e-skins), and increased application space (in the case of electronics). A variety of energy sources are available including mechanical (vibrations, human motion, wind/fluid motion), electromagnetic (radio frequency (RF), solar), and thermodynamic (chemical or thermal energy). This review briefly summarizes harvesting mechanisms and focuses on the materials' strategies to render such devices into soft or stretchable embodiments.

Feasibility of marine renewable energies in African coastal countries

Africa has 38 coastal countries with a population of 895,609,564 persons with potential to harness energy from ocean. These coastal countries are: Madagascar, South Africa, Mozambique, Angola, Namibia, Mauritius, Republic of Congo and Democratic Republic of Congo in Southern Africa with 25.31% population; Somalia, Eritrea, Tanzania, Sudan, Kenya, Seychelles, Comoros and Djibouti in Eastern Africa with 17.58% population; Egypt, Morocco, Libya, Tunisia and Algeria in Northern Africa with 20.96% population; Cape Verde, Gabon, Nigeria, Mauritania, Liberia, Ghana, Senegal, Cote d’Ivoire, Cameroon, Sierra Leone, Guinea Bissau, Guinea, Equatorial Guinea, Sao Tome and Principe, Benin, Gambia and Togo with population of 35.15%. Offshore wind, offshore solar, Tidal power, Wave energy, Salinity gradient, Ocean Thermal Energy Conversion (OTEC) are discussed with opportunities and challenges.

Operation and design analysis of an interleaved high step‐up DC–DC converter with improved harnessing of magnetic energy

SummaryIn this paper, a new interleaved DC–DC converter based on a coupled and a single input inductor is proposed. The suggested high step‐up converter utilizes various inductive and capacitive methods to transfer magnetic energy more efficiently. The output voltage is regulated with the switches' duty cycle and the coupled inductor (CI) turns ratio, which provide a wide output voltage range. Interleaving improves the converter reliability, employs both the first and third areas of CI's B‐H plane, cancels DC component of the CI, and reduces the input current ripple of the proposed converter with twice switching frequency. Utilization of two output ports for voltage stress and ripple reduction in each port, recycling the stored energy of inductances in both forward and flyback mechanisms, alleviation of switch voltage spikes, operation without circulating current, high power density, independency of switch voltage stress to the CI turns ratio, and continuous input current can be mentioned as other features. In this paper, continuous and discontinuous conduction modes' steady‐state analytics, power loss calculations, and design procedure of the proposed converter are followed with comprehensive comparisons to evaluate the capabilities. Eventually, experimental results are presented to validate theoretical calculations.

The effect of wave response motion on the insolation on offshore photovoltaic installations

Offshore photovoltaic energy is possibly the most important future step in the harnessing of solar energy. Since no long-term offshore photovoltaic installation exists to date, various unknowns are still present, creating a research gap. For instance, floating structures will have some type of response to incoming waves. This response is highly dependent on the design of the floating structure. This response will have some effect on the insolation on offshore photovoltaic systems installed on floating structures. This research presents a simulation tool that would allow an offshore system designer to assess this effect in order to minimize it and thus, optimize the energy yield of the system. Furthermore, this simulation tool was verified with an experimental setup simulating sinusoidal wave responses and the results are presented in this research. Finally, a parametric analysis was performed taking days close to the 21st of each month of the year for photovoltaic installations facing south with fixed inclinations of 30 ° and 5 ° This research will improve the design of offshore floating platforms used for photovoltaic installations.

Current Status and Possible Future Applications of Marine Current Energy Devices in Malaysia: A Review

Malaysia has a great potential to harness energy in water due to its long coastline within the South China Sea and the Straits of Malacca. Malaysia's energy mix could be improved using marine current energy devices (MCEDs) to replace fossil fuel and it is predictable energy compare to hydropower, solar photovoltaic (PV), and biomass. However, MCEDs is not been fully developed in Malaysia. The objectives of this paper are to provide a useful background for policymakers or researchers in the types of MCEDs and potential sites location of MCEDs that are applicable in Malaysia. This review also discusses the issues and challenges of MCEDs in Malaysia. Five types of MCEDs were discussed including tidal range device, tidal stream turbine, wave energy converter, ocean thermal energy conversion, and salinity gradient energy. These MCEDs are compared for their suitability of application in Malaysia. Among all MCEDs, tidal stream turbine is identified as high potential and commercially viable in Malaysia. However, ocean characteristics in Malaysia are low kinetic energy-flux density, low current speed, low tide, and shallow water; only fulfill the minimum requirement of tidal stream turbine making the tidal stream energy resources not significant enough to contribute to the nation's energy mix. Therefore, using diffuser augmented tidal stream turbines to increase the flow velocity should be studied thoroughly.

PRELIMINARY ASSESSMENT OF WAVE ENERGY IN SRI LANKA

Preliminary results of a numerical model developed to detail spatial and temporal assessment of theoretically available near shore wave energy, and potential wave energy extracting sites, along the Sri Lankan coast is presented in this paper. Wave energy is estimated applying Danish Hydraulic Institute's Mike 21 Spectral Wave (SW) module. The model is developed and applied covering an area along the coast line of entire country extending from 315000 to 640000 mE, and 602000 to 1164000 mN. Model was run with boundary inputs of wind and wave, based on long term measured, and long term hindcast directional wave data available at seven locations, which are well distributed around the country. Model calibration and validation are carried out based on long term measured directional wave data at Colombo, Sri Lanka. Based on the estimated wave energy density maps, and spatial and temporal energy variations, Hambantota, in South East coast is identified as the most feasible location for wave energy harnessing. Annual and seasonal availability of the wave energy, for Hambantota area, at 25 m depth, were looked into in detail. In the above area, mean annual energy potential was estimated as 10 kW/m at 25 m depth, whereas maximum annual potential energy was estimated as 36 kW/m. During South West monsoon, where high waves are present, the mean energy potential is estimated as 15 kW/m.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/dPa9istaB7A

Stability assessment and robust controller design of grid interactive offshore wind farm and marine current farm with STATCOM and BFCL

ABSTRACT In the context of larger renewable energy harnessing, combining offshore wind farm (OWF) and marine current farm (MCF) at the same location is often found suitable in terms of geographical conditions and economic reasons. However, stochastic nature of wind speed and marine current speed with increased penetration level significantly affects the system stability, grid voltage and raises some control and stability problem; furthermore, the parametric uncertainty of generators brings additional challenges under grid voltage distortion. Therefore, in this article, we present a consolidated application of STATCOM and BFCL in the context of stability assessment of integrated system. Consequently, a robust H∞ loop-shaping controller has been proposed in the presence of parametric uncertainties. In this context, optimizing controller performance with respect to the undesired parametric uncertainties and external disturbances has been proposed. The control effort is initiated by formulating the robust H∞ loop-shaping controller in the context of evaluating the controller parameters and gain with respect to desired robust stability margin. The efficacy of the proposed control scheme is measured through different case studies in real time digital simulation (RTDS) environment. The comparative analysis of simulation results demonstrates the effectiveness of the proposed control strategy in the context of integrated system stability and reliability.

An Active FTC Strategy Using Generalized Proportional Integral Observers Applied to Five-Phase PMSG based Tidal Current Energy Conversion Systems

In recent years, multi-phase permanent magnet synchronous generators (PMSGs) have become attractive in the field of tidal current energy conversion systems (TCECS) due to their high-power density, reliability, and availability. However, external disturbances and malfunctions in power conversion chains will bring challenges to achieving stable and continuous tidal current energy harnessing. Using generalized proportional integral observers, an active fault-tolerant control (AFTC) strategy is therefore proposed for a five-phase PMSG based TCECS that is subjected to an open switch fault (OSF) in the generator side converter. This proposed AFTC strategy is applied into q-axis current control loops, which contain fault detection and compensation. The fault compensator will be smoothly activated using a sigmoid function once the OSF is detected. Finally, a small-scale power experimental platform emulating the TCECS is established in order to verify the feasibility and efficiency of the proposed FTC strategy. Experiment results show that this AFTC strategy can detect faults rapidly and effectively attenuate torque ripples in the post-fault operation mode.

Harnessing Energy from Wind Induced Vibrating Structures

This paper focuses on the harnessing of energy from fluid induced vibrations of bluff bodies due to the phenomenon of vortex shedding. Vortex shedding causes oscillating drag and lift forces due to which the bluff body in question experiences transient forces causing it to vibrate. An experiment has been conducted to investigate the potential of such vibrations and its probable usefulness. Maximum achievable efficiency of the system has been calculated and techniques to convert this mechanical energy into electrical energy have been discussed. In this experiment the bluff body used is a simple circular cylinder. The model developed works on the phenomenon of vortex shedding and resonance. The innovation of the setup is that the natural frequency of the structure can be easily altered by changing the relative distance between two of the mounting springs or by simply using springs of a different stiffness, as a result it can be ensured that the natural frequency of oscillation of the structure is always nearly matched to the frequency of vortex shedding for a wide range of wind velocities thereby ensuring a near resonance condition always.

A thorough performance assessment of solar chimney power plants: Case study for Manzanares

Solar chimney power plants (SCPPs) are promising systems for clean energy generation. SCPPs are ideal for the large-scale harnessing of solar energy. They operate efficiently without auxiliary energy and do not cause any environmental pollution. There are several theoretical, numerical and experimental attempts to date for performance assessment of SCPPs, however, there are still contradictions in the findings, and a thorough performance evaluation is still missing. Therefore, in this study, a novel three-dimensional axisymmetric computational fluid dynamics (CFD) approach is proposed by considering the pioneer plant in Manzanares region. For a realistic approach, actual geometric parameters of the pilot plant are utilised in the CFD model, and the performance assessments are done regardless of time. Pressure, temperature and velocity distributions within the SCPP from collector inlet to chimney outlet are numerically modelled with respect to changes in solar radiation and atmospheric temperature. For model validation, the numerical findings are compared with the typical experimental findings performed in pilot plant, and a good agreement is obtained. For a certain value of solar radiation (1000 ​W/m 2 ), maximum air velocity in the pilot plant is found to be 14.24 ​m/s, which is compatible with the experimental data of 15.00 ​m/s. Static pressure is found to sharply decrease from chimney ground to turbine inlet, and then steadily rises to the chimney outlet. Minimum static pressure is observed to be −100.18 ​Pa ​at 21.92 ​m from the ground. Output power of SCPP linearly increases with the solar intensity whereas it steadily reduces with ambient temperature. Available power is determined to be 49059 ​W for the case of 1000 ​W/m 2 , and the atmospheric temperature of 293 ​K. • Manzanares pilot plant is analysed in terms of performance parameters. • For G ​= ​1000 ​W/m 2 , V m is found to be 14.24 ​m/s. • Minimum static pressure is −100.18 ​Pa ​at a height of 21.92 ​m from the ground. • Temperature rise in collector is found to be 20.4 ​°C for G ​= ​1000 ​W/m 2 . • P o is 49663 ​W for T a of 290 ​K while it is 41274 ​W for 320 ​K.

Synergistic Flow-Induced Oscillation of Multiple Cylinders in Harvesting Marine Hydrokinetic Energy

Abstract Flow-induced oscillations/vibrations (FIO/V) of cylinders in tandem can be enhanced by proper in-flow spacing to increase hydrokinetic energy harnessing. In a farm of multiple cylinders in tandem, the effect of interference on harnessing efficiency arises. Three years of systematic experiments in the Marine Renewable Laboratory (MRELab) of the University of Michigan, on an isolated cylinder, and two and three cylinders in tandem have revealed that synergistic FIO can enhance oscillations of cylinders in close proximity. Two cylinders in tandem can harness 2.5–13.5 times the hydrokinetic power of one isolated cylinder. Three cylinders in tandem can harness 3.4–26.4 times the hydrokinetic power of one isolated cylinder. Negative impact on the harnessed energy by multiple cylinders, such as the shielding effect for the downstream cylinder/s, is possible. Specifically for the three-cylinder configuration, at a certain flow speed, the decrease in the power of the middle cylinder can be overcome by adjusting its stiffness and/or damping.

Wind Energy Harnessing in a Railway Infrastructure: Converter Topology and Control Proposal

Long distances in the vicinities of railways are not exploited in terms of wind energy. This paper presents a scalable power electronics approach, aimed to harness the wind potential in a railway infrastructure. The key aspect of this proposal relies on both using the wind energy in the location, and the displaced air mass during the movement of a train along the railway, in order to produce electrical energy. Vertical Axis Wind Turbines (VAWT) are used in order to take advantage of the wind power, and widely used and well-known power converter techniques to accomplish the goal, showing MPPT techniques, parallelization of converters and power delivery with a Solid State Transformer (SST). Results are shown according simulations of the whole system, with and without train activity, resulting that 30.6 MWh of the energy could be generated without the train, and the energy generated with the assistance of the train could reach 32.3 MWh a year. Concluding that almost the 10% of the energy could be provided by the assistance of the train.

A review on passive methods for thermal performance enhancement in parabolic trough solar collectors

SummaryAmong the diverse renewable energy sources available, solar energy harnessing has become very common in most countries. Various collectors were developed, built and checked to work in various temperature ranges. The parabolic trough solar collector is found to be the most common among the other collectors in applications such as the distribution of process heat and the production of steam. The heat collector part known as receiver tube is one of the key practical devices of parabolic trough solar collector. Numerous research studies have centered on receiver tube to raise its thermal potential. The usage of passive techniques such as provision of inserts in the receiver tube and geometrical changes of receiver tube are efficient strategies for increasing thermal performance. Detailed review of the numerical and experimental studies conducted on heat transfer enhancement strategies that rely on the use of inserts with the use of different working fluids in a parabolic trough solar collector's receiver tube is described in this article. Additionally heat transfer enhancement due to geometrical modification of receiver tube is also presented. Further, on the basis of literature survey, a comparison among various strategies is outlined. These studies show that future work in this area, that is, usage of passive techniques in parabolic trough solar collector will offer further growth.