Mohammed Abdulmajid, Professor and Researcher at Effat University, for teaching and providing guidance on the solar aspects of my thesis, Dr. Saeed Qaisar, professor and researcher at Effat University, for providing guidance on the optimization aspects of my thesis, Dr.
Introduction and Background
- Overview
- Problem Statement
- Research Question
- Research Aim and Objectives
- Significance of the Study and Contribution
- Outline of the Thesis
In this chapter, an in-depth review of the previous work related to HRESs will be given. In addition, there will be a mention of the improvements that could be made to this work for future research.
Literature Review
Overview of Previous HRESs
A battery backup system was also incorporated into the design of the HRES to increase reliability and cope with periods of peak demand. Furthermore, the NPC of HRES was calculated to be approximately $16,250 with a unit COE of $0.18/KWh. HOMER was used to determine the optimal system configuration that would provide minimized NPC and COE of $228,353 and $0.288/kWh, respectively, for the system.
PV/Wind Turbines/Diesel Generators formed the components of the HRES to be optimized using HOMER. Once again, HOMER was the optimization tool of choice to determine the ideal system design. After calculating several economic parameters, the project's NPC was found to be $1.01 million with COE being $0.106/KWh.
Analysis of Past Work and Identification of Present Gap
Research Methodology
Approach
Simulation & Optimization Software: HOMER Pro
Thus, by accounting for such variables, a more realistic representation of the system would be viable. Next, the total NPC of the proposed HRES (NPCtotal) could be easily determined through the summation of each component's NPC. The discrete costs of the previously mentioned economic parameters are collectively shown in figure 4.3 for all the components.
In this section, an analysis of the environmental impacts of the proposed HRES configuration will be examined. Consequently, this will help reflect the positive effects of HRES on the environment. Next, a summary of the amount of annual fuel consumed by the proposed HRES and the base case is shown below in Figure 4.5 and Figure 4.6 respectively.
At the same time, it is worth noting that the addition of the diesel generator helps offset the total capital costs of the proposed HRES. Once again, the results reveal that the optimized arrangement of the new HRES will contain all the energy components.
Resources Data and Evaluation
Load Profile
Thus, load sizing was logically designed by identifying the major electrical appliances that could potentially be found in a typical home and that consume the most power. After that, the amount of each device and its operating hours (for a 24-hour period) were reasonably assumed and their product was multiplied by the corresponding power of each device to calculate the daily load size for each component. Daily load for 1 house (kWh/day) Total daily load for 30 houses (kWh/day) Peak load (kW).
After calculating the daily energy consumption for each load in kWh, the total daily load for a single house would be determined and finally the result would be multiplied by a factor of thirty to take into account the total number of houses. 33 where TDL is used to denote the total daily load [kWh/day] and LF represents the load factor [dimensionless]. For refrigerators, the actual wattage is usually considered a third of the total watts, while air conditioners and washing machines can be divided by a standard factor varying between 3-5.
Proposed HRES Components and Parameters
The main properties of the diesel fuel used, represented by density, carbon content and sulfur content, are 820 kg/m3, 88% and 0.4%. Being a high concentration CPV, an expensive multi-junction solar cell is used instead of the traditional silicon based cells to absorb a wider range of wavelengths of the incoming solar radiation spectrum and in turn generate more output. A cooling system is also built in to minimize the unwanted effects of temperature on the output voltage.
Thus, the cost of the HCPV is much higher because it represents all of these components. In addition to entering the parameters of the five main system components, other general input parameters such as the inflation rates, discount rates and the life of the project. In addition, the load factor and random variability are also identified to allow for a more realistic representation and distribution of the load magnitude.
Technical Modeling
In HOMER, the product of surface solar transmittance, which corresponds to the fraction of the sun's radiation transmitted to a surface, and surface solar absorptivity, which indicates the amount of solar radiation absorbed by a surface, is recommended to be 0.9 inches. reference to the Duffie and Beckman model [92]. In addition, other factors also include the CPV efficiency, the area covered by the module and the performance ratio, which is a measure of the performance of the system at different temperatures, although it is not affected by radiation (the PR value is taken as 0.8 for CPV). First, HOMER identifies the wind speed at the desired center height selected by the user (in this case 30 m).
41 where Uhub represents the wind speed measured at the height of the wind turbine hub [m/s], Uanem indicates the wind speed measured at the height of the anemometer [m/s], Zhub refers to the height of the wind turbine hub [m], Zanem corresponds to the height of the anemometer [m], and α denotes the dimensionless exponent of the power law (usually taken as 1/7 or 0.143). Finally, after identifying the appropriate standard power output, the result would be multiplied by the air density ratio, the ratio of the actual air density to the standard air density that serves as a power correction factor, and the product would give the actual power output under operating conditions. 42 where Pwind, STP denotes the output power at standard pressure and temperature of the wind turbine [kW], ρ symbolizes the actual air density [kg/m3], and ρo symbolizes the air density at standard pressure and temperature [1.225 kg /m3].
Economic Modeling
43 As a result, the HOMER software operates on a linear model in estimating the SV of each component, which represents the decline in value of each HRES component over the life of the system, otherwise known as depreciation. Then, SVdiesel represents the repair value of diesel generator [$], SVPV symbolizes the repair value for PV panels [$], SVwind represents the repair value of wind turbines [$], SVconverter refers to the repair value of wind turbine converter [$], and SVbattery corresponds to the salvage value battery storage system. The purpose of the CRF is to determine the present value of all regular annual cash flow payments, known as annuities, assuming equal installments are paid.
In other words, the ratio is performed to determine the present value for each annuity that must be paid in a specified number of years to recover the cost of the HRES investment after taking into account a specific interest rate. The COE value of the proposed HRES could then be compared with the value of traditional power plants of a given country and based on this measure the performance of the system.
Results and Discussion
- HOMER Optimization Results
- Economic Analysis
- Technical Analysis
- Environmental Analysis
- PV-HRES vs CPV-HRES
A more in-depth economic discussion and analysis of the results is provided in this section. It is clear that the storage system, based on lead-acid batteries, contributes the largest part of the project cost, followed by the solar PV system, with an NPC of $138,493 and $116,854. The three main energy components of the hybrid system directly responsible for electricity production include the solar PV panels, the wind turbines and a diesel generator.
52 In the upcoming section, the weight of the environmental impact of the proposed hybrid system will be analyzed. It is therefore explicitly shown in figure 4.8 with further evidence from table 4.8 that the NPC for each individual component belonging to the CPV-HRES eclipses that of the PV-HRES, except for the inverter. This is due to the PV suffering from the higher temperature effects of the summer which slightly reduces their voltage output.
Conclusion and Recommendations
Conclusion
An environmental assessment of the amount of emissions generated by the proposed HRES was made after simulating a diesel generator system to meet the load requirements (used as a reference case). At the time of writing the thesis, the price of 1 kWh of electricity in KSA based on information from the Saudi Electricity Company was $0.048/kWh for residential use and $0.069/kWh for commercial use [108]. With a COE of $0.166/kWh for HRES, this suggests that KSA should eventually introduce grants and policies to help offset the costs of renewable energy production to encourage more investment and shift towards such projects.
On the other hand, a CPV-HRES (similar to the PV-HRES) was optimized after which an economic and technical analysis between the two systems was performed. Therefore, the PV-HRES is considered the most economical technology, despite the fact that the CPV-HRES produces a higher energy yield.
Recommendations
Technical and economic analysis of different configurations of stand-alone hybrid renewable energy systems – A case study. Techno-economic design and evaluation of hybrid energy systems for residential communities: Case study of Jubail industrial city. Economic Feasibility Analysis and Optimization of Hybrid Renewable Energy Systems for Rural Electrification in Peru.
Feasibility study and comparative analysis of hybrid renewable energy systems for off-grid rural electrification in a typical remote village in Nigeria. Techno-economic energy analysis of hybrid wind/solar system: case study for western coastal region of Saudi Arabia. Optimization and sensitivity analysis of stand-alone hybrid energy systems for rural electrification: a case study of Iraq.
