Showing papers by "Kanzumba Kusakana published in 2019"

Optimal Peer-to-Peer energy sharing between prosumers using hydrokinetic, diesel generator and pumped hydro storage

Abstract: In this paper, an optimal Peer-to-Peer energy sharing model between two small prosumers is developed and simulated in the south African context. For this purpose, a case study of a commercial type prosumer sharing power with a residential prosumer, both on the same premise, is used to demonstrate the effectiveness of the model. The commercial prosumer owns a small hydrokinetic system operating in conjunction with a pumped hydro storage while the residential prosumer has a diesel generator. The developed model aims to minimize the resulting cost of energy linked to the diesel generator, while optimizing the power flow between the two prosumers. Using actual data, the developed model has been used to simulate and analyze the complex interaction between the different power sources, the energy storage and the demands within the proposed system sizing and operation constraints. The simulation results show that the power flows can be optimally managed, resulting in a substantial reduction in the residential prosumer's operation cost which can now rely not only on its diesel generator but also on the power shared by the hydrokinetic and pumped hydro system of the commercial prosumer.

Techno-economic feasibility analysis of a grid-interactive solar PV system for South African residential load

Abstract: The rapid depletion of fossil fuel resources and the need to reduce greenhouse gases (GHGs) emission level have resulted into worldwide concerns. Such concerns demand an urgent consideration of renewable energy sources as a means of addressing carbon emission challenges. Very limited research studies have been carried out to demonstrate/analyze the techno-economic benefits of battery storage coupled directly to a grid-connected photovoltaic (PV) generation system. However, none of the studies demonstrates the benefit of operating PV-battery based system with a feed-in-tariff (FiT) incentive, especially in South Africa. This paper contributes to the ongoing studies about grid-connected PV-battery based system. It draws attention to the optimal design and sizing by considering techno-economic factors such as net present cost and cost of energy under time-ofuse (TOU) and FiT incentive. The annual real-time load demand data from a typical residential consumer, has been used in this study. The data was acquired using Efergy monitoring system. HOMER (Hybrid Optimization of Multiple Energy Resources) Pro Version 3.6.1 software is employed to model the energy system. Based on the optimal sizing results, it was found that the annual average electricity production from PV is about 70% (6,514 kWh/year) of the total generation, while the remainder of the necessary power is purchased from the grid. Therefore, the major share of the power is obtained from the PV to meet the load requirement and to keep zero unmet energy by the system.

Energy Efficiency Improvements in a Microbrewery in South Africa

Abstract: The processes involved in brewing beer have been observed to be highly energy intensive. Breweries in particular may consume up to 8250 kWh per month. In addition, approximately 0.43 kWh is required to produce one liter of beer in large breweries, while energy usage in microbreweries are estimated to be significantly higher. A walkthrough energy audit revealed that a craft brewery located in Bloemfontein, South Africa, required approximately 0.65 kWh of electrical energy to produce one liter of beer. This equates to approximately 5.2% of the production costs involved, substantiating the need for energy management; this makes energy efficiency improvement an important way to reduce costs, especially in times of high energy price volatility. In South Africa, craft beer produced by these breweries became highly popular in recent years. The heating and cooling processes involved in the production of craft beer could be controlled based on the time-of-use (TOU) tariff to reduce the energy consumption. This may be achieved by shifting loads from peak demand to off-peak or standard time. Renewable energy source technologies can also be used to reduce the energy consumption; however, the renewable energy systems show a common disadvantage of not always meeting the energy demand during certain climate conditions. Therefore, in this paper, a methodology for reducing energy usage and associated costs is proposed to evaluate various energy management initiatives for prospective implementation.

Simulations and experimental validation of Pico conduit pressure hydropower systems with battery storage

Abstract: An increase in the world's population has led to an increased energy demand. Sustainable renewable energy sources must be broadly executed to fulfil the continuous need for energy. Amongst different renewable energy technologies, hydropower generation proved to be the most feasible solution. A portion of small hydropower can be acquired by recovering the energy inside water supply networks. This may lead to a sustainable electrification solution and reduced electricity bills for the water utility companies. Hence, the procedure of energy recovery using conduit hydro technology must be a part of the water cycle. Numerous nations have started with the improvement of this innovative conduit hydro technology. However, very little has been exploited. Hence, this study focuses on developing a simulation tool that can be used to analyse conduit hydropower generation system with a battery storage. Subsequently, this paper exhibits the modelling and performance analysis of a small conduit hydropower system in MATLAB/Simulink software. This will assist the conduit hydropower developers to quantify the available energy and evaluate the viability of the conduit hydropower projects. Furthermore, the performance of the modelled conduit hydropower system is compared to the performance of a prototype setup in a laboratory environment. Inlet water pressure was assessed to observe how the system reacts to the variation of the water pressure. This data was used to simulate the performance of the model in MATLAB/Simulink in comparison with the laboratory prototype. The results revealed that the developed model reacted viably under variable pressure. The conduit hydropower was just dynamic when the excess pressure was accessible, this is because of the pressure distinction between Pressure Reducing Valve (PRV) pre-set pressure and the system pressure. Hence, the excess pressure is used to drive the generator and the generated energy is then stored in the battery.

Economic performance of a grid-interactive system with storage under a dynamic electricity pricing environment

Abstract: This paper aims to evaluate the economic performance of a grid-connected system with storage under a dynamic electricity pricing environment with time-of-use (TOU) and feed-in electricity tariffs. The storage can assist in the demand side management as well as to reduce the electricity bill of the consumers. In this case, consumers would purchase electricity during off-peak pricing periods to charge the batteries, and during peak pricing periods, the energy stored would be used to supply the demand or sold back to the grid. Therefore, the two objectives are to minimize the cost of energy drawn from the utility, while maximizing the energy injected under the Time-of-Use and Feed-in-Tariff schemes. Thereafter, the performance of the developed model to maximize the proposed grid-interactive system’s economic profitability is analysed through a case study which is simulated using Matlab. Simulation results show that a potential of 52% energy cost saving can be achieved using the proposed system rather than supplying the load demand by the grid exclusively.

Energy Monitoring for Potential Cost Saving in a Typical South African Household

Abstract: Reducing energy demand in residential sector is an important problem worldwide. This study focuses on the awareness of residents to energy conservation and on the potential of reducing energy demand through energy-saving activities. The knowledge about demand variation in households is fairly limited in South Africa as well as the use of various tools used to analyze the demand. Due to the frequent increase of energy cost at a significant rate, many consumers are looking for ways to reduce the monthly electricity bill. The aim of the project is to identify possible areas where the consumer could reduce consumption in order to reduce the monthly bills. To achieve this, a real-time energy monitoring device “Efergy E2” was installed in the distribution board of a residential home. Among other benefits, the hourly load data analysis can provide the detailed characteristics of load demand, define the consumption patterns and can help to identify where the consumer could reduce the electricity bill. The analysis of results shows that a huge amount of electrical energy is used during peak billing periods of the day under the TOU tariff. With this information the consumer could make use of demand shifting to help reduce the bill.

Techno-economic analysis of a standalone solar PV with groundwater pumped-hydro-storage system

Abstract: South Africa is highly relying on the agricultural sector for market strengthening. Most farms are located in remote areas. This makes it difficult for farmers to receive quality water and reliable power supply. Supplying water through municipal pipelines is a reliable option. However, it comes with techno-economic challenges such as distance and the nature of the terrain. Therefore, pumping ground water has been a preferred option for farmers. This is due to the ease of water access when needed and can be pumped near the point of use. This paper determines the optimal size of the proposed standalone solar Photovoltaic (PV) with underground pumped-hydro storage (UPHS) system, supplying a typical farming load demand through open wells (boreholes). The hybrid optimization model for electric renewable (HOMER) software has been used during simulation. The optimal configuration results have proved that the proposed system can meet the farming load demand at an incurred cost of ZAR2.32 per kWh.

Hydropower Energy Recovery from Wastewater Treatment Plant: Case of Zeekoegat Plant

Abstract: Wastewater treatment plants (WWTPs) require a significant a significant amount of energy to operate. Currently, several opportunities for energy recovery and electricity generation purpose in wastewater treatment plants have been studied and implemented. This paper presents a case study of implementing a hydropower system at the Zeekoegat wastewater treatment plant. The WWTP is situated in the north-east of Tshwane, South Africa, and using such set up to generate power has not yet been implemented in the country. The WWTP’s electrical load demand, the water resources as well as the potential energy that can be recovered using the proposed hydropower plant has been evaluated to determine to projected cost savings over a proposed operation period of 20 years. The economic analysis shows that the breakeven point occurs after 6, 35 years at $ 327600.Fortheprojected20years,thepotentialcostsavedis $ 1 437 554, 98 which corresponds to 45, 63% of the total amount that would have been consumed if the grid is used as the sole supply.

Walk-through Energy Audit and Savings opportunities: Case of Water Heaters at CUT Residential Buildings

Abstract: In this work, a walk-through survey for the geysers and boilers used in the residences at the Central University of Technology has been conducted. The survey was conducted based on the rated power, storage tank sizes and period of operation in a day. The aim of the project is to review the energy efficiency and energy consumption of the geysers and boilers. From the survey, it shows that these water heating systems are operated 24 hours without any other control or energy management activities. Which means that power is supplied 24 hours a day and the thermostats automatically switch on to heat water whenever the water temperature decreases, even when there is no hot water demand. Also, seeing that load shifting can be a challenge mainly for the morning peak period due to the high hot water demand during that time because the majority of students’ classes starts in the mornings. The energy consumption during peak periods is charged more than during normal or off-peak periods. Energy management activities can be applied to water heating processes in order to reduce the energy consumption and can therefore reduce the institution’s energy costs. However, the hot water consumption and human behaviour profiles of the occupants are the most important precondition to a potential energy saving.

Peer-to-Peer Energy Sharing Model Between Grid-Connected Residential Wind and Commercial Photovoltaic Prosumers

Abstract: In this paper, a model to optimise the operation of two prosumers exchanging electricity under the Peer-to-Peer concept is presented. One prosumer is a residential type using a wind energy conversion system, while the second one is a commercial type using a photovoltaic system. The city of Durban, where both wind and solar resources are abundant, is identified to analyse the power flow between the prosumers. The created model intends to optimise the energy exchanged between the micro renewables-based energy generators while minimizing the amount of energy purchased from the grid operating with the Time of Use pricing structure. The simulation results have showed that the created model to optimally dispatch the power exchanged has reduced the prosumers’ combined daily cost of electricity from the grid by 84% while making best use of the on-site renewable energy productions and storage management.

Innovative Energy Management of an Integrated Space and Water Heating System: Case of a Residential Building at CUT

Abstract: The energy usage of space heating (SH) and water heating (WH) processes may account for approximately 60% and 24% of the total energy consumption in residential buildings, respectively. This paper proposes the optimal control of an integrated system for water and space heating at the Central University of Technology student residence. The system consists of solar PV modules, batteries, electrolyser, hydrogen storage vessel, fuel-cell, heat pump and domestic hot water storage. The main aim of this study is to propose a method to reduce the energy cost, by applying optimal control of the integrated system operating under the variable Time of Use tariff. The background on the problem statement, the literature review, aim, objective, methodology as well as expected results of the study will be discussed in the sections below.

Prospect of Solar-assisted Heat Pump Water Heating Systems for Student Residences

Abstract: Water heating is the major energy user in the residential sector. The hot water contribution in the residential sector of South Africa is up to 60% on an average monthly basis and accounts for more than 50% of the monthly electricity cost. Electric storage tank water waters are the main contributors to the high energy consumption in the residences and most of the heating process takes place during the peak times, when electricity is more expensive than off-peak and normal time. This and the growing population and living standards of the economy has led to the high demand of electricity and energy shortage in the country. Reducing the desired end users’ water temperature has been proposed as a solution to reduce the energy consumption this practice increases chances of diseases like legionella pneumophila. The water heating process could be incorporated with the time-of-use (TOU) tariff to reduce the energy consumption by load shifting from peak demand to off-peak or normal time. Renewable energy source technologies can also be used to reduce the energy consumption; however, the renewable energy systems show a common disadvantage in meeting the energy demand during certain climate conditions. And therefore, the hybrid energy systems can be implemented to promote energy conservation and energy efficiency of the renewable energy system. To further reduce the energy consumption, the TOU tariff can be used for optimal control and energy management of the hybrid system.

Experimental analysis of small conduit pressure hydropower systems

Abstract: The current study focused on developing a simulation tool that can be used for conduit hydropower generation. Hence, this paper presents the modelling and performance analysis of a small conduit hydropower system using MATLAB/Simulink software. This will assist the conduit hydropower developers to quantify the available energy and evaluate the viability of the conduit hydropower projects.Furthermore, the performance of the modelled conduit hydropower system is also compared to the performance of a prototype set up in a laboratory environment. The main findings revealed that the developed model responded effectively under variable pressure. The conduit hydropower was only active when the excess pressure was available, this is due to the pressure difference between pressure reducing valve (PRV) pre-set pressure and the system pressure. The performance can be studied using any generator including BPMDCG. Further research is required to address factors not covered by this work. This can include the evaluation of different turbine and generator technology, to validate the model as a universal conduit hydropower model, application of different configuration of the pipeline system and incorporating it to the simulation model and a thorough analysis of the physical losses in the pipeline, in order to accurately match the measured and simulated outputs.