scholarly journals Urban Wind Resource Assessment: A Case Study on Cape Town

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1479 ◽  
Author(s):  
Gough ◽  
Lotfi ◽  
Castro ◽  
Madhlopa ◽  
Khan ◽  
...  
Keyword(s):  
South African ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Cape Town ◽  
Economic Benefits ◽  
Electricity Demand ◽  
Small Scale ◽  
Levelized Cost Of Electricity ◽  
Demand Profile ◽  
Power Curves

As the demand for renewable energy sources energy grows worldwide, small-scale urban wind energy (UWE) has drawn attention as having the potential to significantly contribute to urban electricity demand with environmental and socio-economic benefits. However, there is currently a lack of academic research surrounding realizable UWE potential, especially in the South African context. This study used high-resolution annual wind speed measurements from six locations spanning Cape Town to quantify and analyze the city’s UWE potential. Two-parameter Weibull distributions were constructed for each location, and the annual energy production (AEP) was calculated considering the power curves of four commonly used small-scale wind turbines (SWTs). The two Horizontal Axis Wind Turbines (HAWTs) showed higher AEP and capacity factors than Vertical Axis Wind Turbine (VAWT) ones. A diurnal analysis showed that, during summer, an SWT generates the majority of its electricity during the day, which resembles the typical South African electricity demand profile. However, during winter, the electricity is mainly generated in the early hours of the morning, which does not coincide with the typical load demand profile. Finally, the calculation of Levelized Cost of Electricity (LCOE) showed that SWT generation is more expensive, given current electricity market conditions and SWT technology. The study provides a detailed, large-scale and complete assessment of UWE resources of Cape Town, South Africa, the first of its kind at the time of this work.

scholarly journals Power Quality Investigation of Distribution Networks Embedded Wind Turbines

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
A. Elsherif ◽  
T. Fetouh ◽  
H. Shaaban
Keyword(s):  
Power Systems ◽  
Wind Energy ◽  
Electric Power ◽  
Power Quality ◽  
Wind Turbines ◽  
Distribution System ◽  
Renewable Energy Sources ◽  
Distribution Networks ◽  
Small Scale ◽  
Distributed Resources

In recent years a multitude of events have created a new environment for the electric power infrastructure. The presence of small-scale generation near load spots is becoming common especially with the advent of renewable energy sources such as wind power energy. This type of generation is known as distributed generation (DG). The expansion of the distributed generators- (DGs-) based wind energy raises constraints on the distribution networks operation and power quality issues: voltage sag, voltage swell, voltage interruption, harmonic contents, flickering, frequency deviation, unbalance, and so forth. Consequently, the public distribution network conception and connection studies evolve in order to keep the distribution system operating in optimal conditions. In this paper, a comprehensive power quality investigation of a distribution system with embedded wind turbines has been carried out. This investigation is carried out in a comparison aspect between the conventional synchronous generators, as DGs are widely in use at present, and the different wind turbines technologies, which represent the foresightedness of the DGs. The obtained results are discussed with the IEC 61400-21 standard for testing and assessing power quality characteristics of grid-connected wind energy and the IEEE 1547-2003 standard for interconnecting distributed resources with electric power systems.

Numerical Investigation to Assess an Optimal Blade Profile for the Drag Based Vertical Axis Wind Turbine

2013 ◽  
Author(s):  
Sukanta Roy ◽  
Ujjwal K. Saha
Keyword(s):  
Renewable Energy ◽  
Wind Energy ◽  
Wind Turbines ◽  
Energy Demand ◽  
Computational Study ◽  
Flow Behavior ◽  
Renewable Energy Sources ◽  
Vertical Axis ◽  
Small Scale ◽  
Vertical Axis Wind Turbine

Rapid depletion rate of fossil fuels with an increasing energy demand and their high emission are imposing the evolution activities in the arena of renewable energy. To meet the future demands of renewable energy sources, wind energy is a very promising concept. In this feature, the drag based vertical axis wind turbines (VAWTs) are suitable for small scale wind energy generation for decentralized locations. However, these turbines have low power and torque coefficients as compared to other wind turbines. Numerous blade shapes have been proposed till now to improve the performance of these turbines. In the present paper, a computational study has been performed to simulate the air-flow over different blade profiles using shear stress transport (SST) k–ω turbulence model. The results obtained are validated with the available experimental data. In the dynamic simulations, the power and torque coefficients are calculated considering the blade arc angle as the variable shape parameter. The effects of drag and lift forces on the variable blade shapes are also studied in static simulations at various angular positions. The present paper tries to demonstrate an effective computational methodology to predict the flow behavior around a drag based VAWT. Through this study, it has been found possible to select an optimal blade shape from the point of its aerodynamic performance.

Experimental Methodologies for the Measurement of Wind Turbines Performance

2010 ◽  
Author(s):  
Carlo Romano` ◽  
Vincenzo Orlando ◽  
Giuliana Mattiazzo ◽  
Ermanno Giorcelli
Keyword(s):  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Operative Procedure ◽  
Angular Speed ◽  
Small Scale ◽  
Electric Generator ◽  
Research Activities ◽  
Wide Range ◽  
Load Cells ◽  
Physical Quantities

Wind Turbines are one of the most promising technologies to exploit renewable energy sources, and maybe the one which is the closest to achieve grid parity. Many modeling and experimental research activities are carried out in order to continuously improve devices performance. Another promising sector is small scale turbines, below 100kW installed power, for small installation, domestic use, and to be installed on ships. Moving within this scenario, a 1,5 kW turbine was tested inside a wind tunnel, and the following were measured: forces applied to the tower, angular speed, electric power output, mechanical power involved, and stress induced on the blades. Moreover, the cut in rotor speed and the turbine’s efficiency came as outputs of the activity. After some simple forecast calculations, to establish expected maximum values of physical quantities, the experiment was designed. The method used for acquiring all the values at one time involves a wi-fi device, attached to the rotor, in order to acquire signals coming from strain-gauges placed on the blades, avoiding long and cumbersome transmission lines towards the DAQ, coupled to anemometers, load cells, and a wattmeter. Coordination of operators during the tests had a crucial role in carrying out the procedure correctly. Since the main objects of study were blades, rotor and electric generator, the tower has been replaced with a robust support structure, designed to host and protect load cells and signal conditioners from accidental damage, thus permitting a correct measurement of axial force applied to the rotor and reacting momentum of the generator. The wi-fi device was linked to the rotor, in order to affect its mass and inertia characteristics as less as possible. This required the design of a proper linking structure, which was light and well balanced despite being mechanically resistant. Measured quantities are useful to evaluate the turbine’s performance (efficiency, power curve, cut in speed), and also to validate some fem and multi physics predictive models, that are currently under development, as possible tools for general wind turbines design. The outputs of these tests satisfy the need for a wide range of experimental data. This way of designing tests, the physical quantities involved and the schedule of experiments can be suggested as a valuable operative procedure.

scholarly journals Investigation of Turbulence Model Performance in Computational Fluid Dynamics Simulations of Horizontal Axis Wind Turbines

2020 ◽  
Author(s):  
Keaton Mullenix ◽  
D. Keith Walters ◽  
Arturo Villegas ◽  
F. Javier Diez
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Critical Role ◽  
The United States ◽  
Horizontal Axis ◽  
Small Scale ◽  
Horizontal Axis Wind Turbines

Abstract Wind turbines are critically important in the quest to decrease global dependence on non-renewable energy sources. With the space to add 5M wind turbines, the United States is at the forefront of this transition. Horizontal axis wind turbines (HAWTs) have been studied numerically and experimentally at length. The vast majority of computational fluid dynamics (CFD) studies of HAWTs documented in the open literature have been carried out using two-dimensional simulations. Currently, the available three-dimensional simulations do not provide a comprehensive investigation of the accuracy of different options for modeling of fluid turbulence. In this paper four sets of CFD simulations are carried out using four different turbulence models that are commonly used for engineering level CFD analysis: SST-k-ω, Transition k-kL-ω, Standard k-ε, and Monotonically Integrated Large Eddy Simulation (MILES). These models were compared with experimental performance and coefficient of power results for a small-scale industrial wind turbine with inverse tip speed ratios (λ−1) in the range 0.072–0.144. They were further investigated to highlight the similarities and differences for the prediction of coefficient of pressure and skin friction coefficient. The results showed that no singular model, of the four investigated, was able to consistently predict the power performance with a high degree of accuracy when compared to the experimental results. The models also exhibited both similarities and key differences for the other aspects of flow physics. The results presented in this study highlight the critical role that turbulence modeling plays in the overall accuracy of a CFD simulation, and indicate that end users should be well aware of the uncertainties that arise in CFD results for wind turbine analysis, even when other sources of numerical error have been carefully minimized.

Wind is an alternative source of energy

2019 ◽  
Vol 2 (1) ◽  
pp. 40-49
Author(s):  
J. S. Gribach ◽  
O. O. Egorychev ◽  
E. V. Kurguzova
Keyword(s):  
Carbon Dioxide ◽  
Renewable Energy ◽  
Wind Power ◽  
Wind Turbines ◽  
Carbon Dioxide Emissions ◽  
Alternative Energy ◽  
Mechanical Energy ◽  
Renewable Energy Sources ◽  
Economic Benefits ◽  
Energy Sources

Introduction: today, one of the most important problems of the world economy is a limited amount of traditional fuels, due to the consumption of which the needs of humanity for energy are being met. The chapter “Introduction” contains the definition of the term “alternative energy”, which is a set of ways to generate energy when using renewable energy sources. This chapter presents the need to search for renewable energy sources that will increase the ecological potential of the territories, as well as the energy and economic component. The prospects for the use of renewable energy sources have been highlighted, among which one of the most common alternative energy sources is wind. Methods: the chapter “Methods” describes the principles of operation of wind turbines. This chapter describes in detail the process of converting wind energy into mechanical energy. Also in the chapter “Methods” is a classification of existing installations along the axis of rotation with a description of the operation of each of them and highlighted four main ways to transfer wind power to the consumer. Results and discussions: the chapter “Results and Discussions” contains information on the economic benefits of using wind turbines in Russia, as well as a list of favorable regions for the creation of wind power stations. The structure of this chapter includes information on the environmental feasibility of the use of wind power plants, since wind generators compensate for carbon dioxide emissions. Conclusion: in the “Conclusion” presents conclusions that allow you to determine the positive aspects of the use of wind turbines, which include environmental friendliness, efficiency and affordability. It should be emphasized that the wind generator compensates for carbon dioxide emissions associated with its production, so that the use of this type of installation will create the most clean environment.

scholarly journals The influence of internationalisation of labour on the performance of small-scale rural-based agricultural firms: A South African perspective

2018 ◽  
Vol 18 (1) ◽  
Author(s):  
Patient Rambe
Keyword(s):  
South Africa ◽  
South African ◽  
Economic Benefits ◽  
Small Scale ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
North West ◽  
Foreign Labour ◽  
Managerial Implications ◽  
Northern Cape

Orientation: The main objective of this study is to determine the extent to which small-scale, rural-based agricultural firms in South Africa use foreign labour.Research purpose: South African business owners or managers’ perceived preference for labour from foreign nationals has heightened South African nationals’ concerns that these owners or managers are prejudicing local citizens under the guise of reducing overhead costs.Motivation for the study: There is a scarcity of studies on the influence of free movement of foreign labour on the performance of small-scale, rural-based agricultural firms in South Africa.Research design, approach and method: A cross-sectional survey research was conducted among 151 small-scale agricultural businesses’ (SSABs) owners or managers in Vryburg-Pokwani in North West and Northern Cape provinces of South Africa. Descriptive and inferential statistics were used to analyse the data. Furthermore, post hoc comparisons (Bonferroni) were conducted to establish the long-term performance expectations based on these firms’ utilisation of foreign labour.Main findings: The results showed that the majority (70.9%) of SSABs did not employ foreign labour. Moreover, despite the statistically significant differences in the performance of SSABs based on their usage of foreign labour, SSABs’ orientation towards internationalisation of labour increased with increased deployment of foreign labour.Practical and managerial implications: The study recommended the possibility of deploying highly skilled, value-adding and value-creating foreign labour, while rationalising the recruitment of semi-skilled and unskilled local labour.Contribution or value addition: The results are of significance to SSABs that need to consider the economic benefits of recruiting foreign labour even if that may increase their overhead costs.

scholarly journals Systematic Investigation of Integrating Small Wind Turbines into Power Supply for Hydrocarbon Production

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3243
Author(s):  
Zi Lin ◽  
Xiaolei Liu ◽  
Ziming Feng
Keyword(s):  
Wind Energy ◽  
Wind Power ◽  
Wind Turbines ◽  
Meteorological Data ◽  
Oil Production ◽  
Economic Feasibility ◽  
Offshore Wind ◽  
Levelized Cost Of Electricity ◽  
Small Wind Turbines ◽  
Power Curves

In this paper, the technical and economic feasibility of integrating SWTs (Small Wind Turbines) into remote oil production sites are investigated. Compared to large turbines in onshore and offshore wind farms, SWTs are more suitable for individual power generations. A comprehensive approach based on wind energy assessment, wind power prediction, and economic analysis is then recommended, to evaluate how, where, and when small wind production recovery is achievable in oilfields. Firstly, wind resource in oilfields is critically assessed based on recorded meteorological data. Then, the wind power potential is numerically tested using specified wind turbines with density-corrected power curves. Later, estimations of annual costs and energy-saving are carried out before and after the installation of SWT via the LCOE (Levelized Cost of Electricity) and the EROI (Energy Return on Investment). The proposed methodology was tested against the Daqing oilfield, which is the largest onshore oilfield in China. The results suggested that over 80% of the original annual costs in oil production could be saved through the integrations between wind energy and oil production.

scholarly journals The Potential of Variable Renewable Energy Sources in Mexico: A Temporally Evaluated and Geospatially Constrained Techno-Economical Assessment

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5779
Author(s):  
Edgar Ubaldo Peña Sánchez ◽  
Severin David Ryberg ◽  
Heidi Ursula Heinrichs ◽  
Detlef Stolten ◽  
Martin Robinius
Keyword(s):  
Renewable Energy ◽  
Open Field ◽  
Wind Turbines ◽  
Renewable Energy Sources ◽  
Offshore Wind ◽  
Energy Sources ◽  
Levelized Cost Of Electricity ◽  
Offshore Wind Turbines ◽  
Energy Technologies ◽  
Variable Renewable Energy Sources

Due to the increasing global importance of decarbonizing human activities, especially the production of electricity, the optimal deployment of renewable energy technologies will play a crucial role in future energy systems. To accomplish this, particular attention must be accorded to the geospatial and temporal distribution of variable renewable energy sources (VRES), such as wind and solar radiation, in order to match electricity supply and demand. This study presents a techno-economical assessment of four energy technologies in the hypothetical context of Mexico in 2050, namely: onshore and offshore wind turbines and open-field and rooftop photovoltaics. A land eligibility analysis incorporating physical, environmental, and sociopolitical eligibility constraints and individual turbine and photovoltaic park simulations, drawing on 39 years of climate data, is performed for individual sites across the country in an effort to determine the installable potential and the associated levelized costs of electricity. The results reveal that up to 54 PWh of renewable electricity can be produced at a levelized cost of electricity of less than 70 EUR·MWh−1. Around 91% (49 PWh) of this electricity would originate from 23 TW of open-field photovoltaic parks that could occupy up to 578,000 km2 of eligible land across the country. The remaining 9% (4.8 PWh) could be produced by 1.9 TW of onshore wind installations allocated to approximately 68,500 km2 of eligible land that is almost fully adjacent to three mountainous zones. The combination of rooftop photovoltaic and offshore wind turbines accounts for a very small share of less than 0.03% of the overall techno-economical potential.

Renewable Energy on Tribal Lands: A Feasibility Study for a Biomass-to-Energy Plant on the Cocopah Reservation in Arizona

2019 ◽  
Vol 3 (1) ◽  
pp. 1-12
Author(s):  
Lauren K. D’Souza ◽  
William L. Ascher ◽  
Tanja Srebotnjak
Keyword(s):  
Renewable Energy ◽  
Alternative Energy ◽  
Renewable Energy Sources ◽  
The United States ◽  
Biomass Energy ◽  
Policy Support ◽  
Small Scale ◽  
Energy Plant ◽  
Energy Projects ◽  
Alternative Investment

Native American reservations are among the most economically disadvantaged regions in the United States; lacking access to economic and educational opportunities that are exacerbated by “energy insecurity” due to insufficient connectivity to the electric grid and power outages. Local renewable energy sources such as wind, solar, and biomass offer energy alternatives but their implementation encounters barriers such as lack of financing, infrastructure, and expertise, as well as divergent attitudes among tribal leaders. Biomass, in particular, could be a source of stable base-load power that is abundant and scalable in many rural communities. This case study examines the feasibility of a biomass energy plant on the Cocopah reservation in southwestern Arizona. It considers feedstock availability, cost and energy content, technology options, nameplate capacity, discount and interest rates, construction, operation and maintenance (O&M) costs, and alternative investment options. This study finds that at current electricity prices and based on typical costs for fuel, O&M over 30 years, none of the tested scenarios is presently cost-effective on a net present value (NPV) basis when compared with an alternative investment yielding annual returns of 3% or higher. The technology most likely to be economically viable and suitable for remote, rural contexts—a combustion stoker—resulted in a levelized costs of energy (LCOE) ranging from US$0.056 to 0.147/kWh. The most favorable scenario is a combustion stoker with an estimated NPV of US$4,791,243. The NPV of the corresponding alternative investment is US$7,123,380. However, if the tribes were able to secure a zero-interest loan to finance the plant’s installation cost, the project would be on par with the alternative investment. Even if this were the case, the scenario still relies on some of the most optimistic assumptions for the biomass-to-power plant and excludes abatement costs for air emissions. The study thus concludes that at present small-scale, biomass-to-energy projects require a mix of favorable market and local conditions as well as appropriate policy support to make biomass energy projects a cost-competitive source of stable, alternative energy for remote rural tribal communities that can provide greater tribal sovereignty and economic opportunities.

Exploring the South African Government Communication on Land Expropriation without Compensation

2020 ◽  
Vol 72 (1-3) ◽  
Author(s):  
Lungisani Moyo
Keyword(s):  
South Africa ◽  
Food Security ◽  
South African ◽  
Small Scale ◽  
South African Government ◽  
Eastern Cape ◽  
The South ◽  
Land Expropriation ◽  
African Government ◽  
Government Communication

ABSTRACT This paper used qualitative methodology to explore the South African government communication and land expropriation without compensation and its effects on food security using Alice town located in the Eastern Cape Province South Africa as its case study. This was done to allow the participants to give their perceptions on the role of government communication on land expropriation without compensation and its effects on South African food security. In this paper, a total population of 30 comprising of 26 small scale farmers in rural Alice and 4 employees from the Department of Agriculture (Alice), Eastern Cape, South Africa were interviewed to get their perception and views on government communications and land expropriation without compensation and its effects on South African food security. The findings of this paper revealed that the agricultural sector plays a vital role in the South African economy hence there is a great need to speed up transformation in the sector.

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