A Techno-Economic Comparison of a Stand-alone Hybrid System for a Household: A Case Study for the Royal Commission in Saudi Arabia

It's exciting today to use renewable off-grid sources for driving applications in the home sector (micro-grids). The current tendency is to use renewable energy sources to increase building sector energy efficiency and protect the environment. The economic element and the expense of building these grids is the biggest barrier to these applications. How to best choose the ratings and mix of certain renewable sources based on the location of the house is one of the crucial ways to lower the cost and boost the reliability of these grids. An efficient techno-economical design for a standalone hybrid system is presented in this research. A solar energy using photovoltaic (PV), wind energy, energy storage, and diesel generator are all parts of the system. This design is carried out by a thorough analysis of the techno-economical design of a standalone system to supply the required energy load for a typical residential building for the Saudi Arabian cities of Yanbu and Jubail. Yanbu, which is at latitude 24.0097 degrees north, and Jubail, which is at latitude 27.0726 degrees north, are the two cities' respective geographical positions. These two cities were chosen for the study of the impact of metrological influences on building performance based on total energy cost, load needs, and energy consumption of the differences in their geographic positions. To improve the performance of the suggested hybrid system, some restrictions were chosen, including Total Annual Cost (TAC) and Net Present Cost (NPC). Results show that the proposed stand-alone hybrid systems can be used to increase the economics and energy efficiency of existing buildings. For Yanbu and Jubail cities, respectively, the optimal integration of a diesel generator, PV array, wind turbine, and energy storage results in a minimum energy cost of roughly $0.483/kWh and $0.487/kWh.


INTRODUCTION
Clearing forests, putting trash in landfills, starting wars, and using fossil fuels as energy sources are just a few of the actions that humans take with the intention of advancing economic progress and improving human welfare.Climate change, harmful emmisions, deforestation, and desertification are all results of these activities.Additionally, they are harming the earth's environment, which is essential for the survival of all living things.To lessen these effects and safeguard the environment, many demanding activities must be taken [1].
The United States Environmental Protection Agency (EPA) claims that climate change is accelerating and that by 2100, global temperatures would have risen from -17.5 to -13 degrees Celsius [2].The ongoing generation of greenhouse gases is what is causing these changes.(GHG).The majority of greenhouse gas emissions come from the combustion of fossil fuels like oil, coal, and natural gas, which are used to provide heat, power, and energy for transportation.
Despite the significant rise in the consumption of renewable energy, the International Energy Outlook report projects that fossil fuels will continue to provide the majority of the world's energy needs [3], as illustrated in figure 1.Since fossil fuels will continue to be the main source of energy during this time, CO2 emissions are expected to drop by roughly 33%.These reductions are caused by robust energy saving initiatives, the switch from between fossil fuel resource, and the rapid expansion of renewable energy sources.However, because of the ongoing population and economic expansion, emissions will inevitably rise [4].Due to population expansion and diminishing energy resources, which are already scarce in some areas, the situation will become even more stressed.Water and energy are both used up in the generation of energy.Additionally, the majority of homes need a lot of heating and cooling.Additionally, energy generation uses a lot of water [5].Due to rising demand and the unsustainable rate of resource depletion, water, which is essential to the security of our energy supply, is becoming more limited in many areas.The world economy is in danger due to these pressures.
The majority of residential structures are composed of lowquality, very non-renewable materials, necessitating the use of superior insulators.Due to the extraordinarily high heat transfer rates [6][7][8][9], conventional homes require a substantial amount of energy in cold weather.Improving the thermal efficiency of ordinary dwellings can improve their utilization in a variety of climates while reducing energy production's costs and environmental impact.It is unsustainable and detrimental to natural life cycles to produce an excessive amount of energy from nonrenewable fossil fuels [10][11][12].Population growth and irresponsible energy production will eventually deplete natural resources, which could spark an economic crisis.To avert this result and generate safe, reliable, and sustainable energy generation requires novel ideas.These methods must utilize efficient, sustainable, and environmentally friendly energy sources.This will generate economic growth for a huge number of people in addition to ensuring energy supplies and preserving the environment.
Numerous designs for hybrid off-grid systems have been created with environmental and specific technological and financial considerations in mind.To do this, a hybrid off-grid system comprised of diesel generator, power electronics, wind energy turbines, photovoltaic (PV), wind energy turbines, and energy storage was constructed to meet the energy requirements of standard off-grid residential buildings.This technique was then updated to provide a feasibility study for many locations.For the development of an off-grid hybrid power system, techno-economic and environmental research was conducted using modern optimization techniques [13].Another feasibility study for off-grid microgrids in Saudi Arabia [14][15] was given in order to determine the optimal design for such renewable systems.Figure 2 depicts how the optmization methodology was used for simulation of a hybrid system at lowest energy cost using a battery as the storage system.The simulation of both cities used the same amount of energy load, which can be seen in figures 3 and 4, [16].It was intended that only renewable resources should be used to satisfy the load demand that was being utilized.However, a diesel generator was necessary to maintain the hybrid system's predicted energy expenditures within realistic limits.Based on the net present cost, the most economic and optimized system was selected.The results were analyzed to evaluate if renewable energy systems might be utilized in these cities while keeping low energy prices.Many papers have been published recently to explore the technical and economic aspects of autonomous hybrid systems for households.In Egypt, an optimal design of an off-grid hybrid power system along with some controllers was presented [17][18][19].These studies concluded that the of-grid hybrid renewable systems for rural areas are more effective.Other studies about the off-grid hybrid power systems in Saudi Arabia were presented [20][21][22][23][24][25].Amran et al., reviewed the current and future status of renewable energy potential in Saudi Arabia such as wind, solar, geothermal, hydro, and biomass [26].The paper covered only analyzing the collection of renewable resource data without considering the potential for power availability from renewable resources.The study by Tazay et al. investigated energy sustainability using off-grid and on-grid renewable resources for a specific city in Saudi Arabia [27].The study claimed that the high load consumption could not be covered by renewable resources because of the limited area of renewable resources and electric grid boundary.The paper also studied only one site by collecting meteorological data without considering other regions of Saudi Arabia.The paper in [28] compared metrological data and techno-economic assessment of different regions in Saudi Arabia.The study included only two renewable resources without considering other well-used resources such as diesel generators.Another study on techno-economic analysis of renewable resources at KSA using HOMER was covered in [29].The paper examined the feasibility analysis of residential load without considering other compared sites.More optimal and analytical studies need to be explored at different locations in KSA to evaluate the energy potential of renewable resources at KSA.
Mohamed Mosaad [30] presented a literature survey on PV systems.The study includes types, advantages, and shortages, generating level ratings, statistics, and the control units used in PV systems.Mohamed Alsumiri [31] Conducted a theoretical analysis of the effect of utilizing utility-interactive solar units in minimizing power consumption from the utility grid.The impacts of temperature and solar irradiance on the performance of the solar unit were also investigated.They showed that the used solar system of 3 kW generated about 160000kWh annually which minimizes the electricity consumption by 20%.Hazim Moria et.al [32] utilized HOMER software to analyse a solar wind hybrid system to find the optimum performance to meet the load requirements of a community in Yanbu city.They showed that the 200 kW PV system is the most economically feasible to meet the proposed demand and the minimum cost of energy for the proposed system is 0.617 $/kWh.This study describes an efficient techno-economical design of a hybrid system for a residential structure in Saudi Arabia.To gain a better understanding of the energy potential of renewable resources performance of the proposed hybrid system in KSA, the energy potential of renewable resources performance is researched under different weather climatic circumstances.In Saudi Arabia, a typical home structure for the cities of Yanbu and Jubail was researched.NASA then measures meteorological data for selected places between 2003 and 2018 [33].To undertake the analysis, a thorough examination of the techno-economical design of a stand-alone system that can provide the needed energy load is conducted.The hourly load consumption is initially obtained from the Saudi Electric Company (SEC) for a period of one year, and weather data for desirable regions is also acquired.The technical and economic analysis for each case study are then calculated and compared.

Metrological Data and Parameters
This feasibility study identified two places; the first being Yanbu city in the Western area.As indicated in Figure 5, Yanbu's climate is conducive to the use of renewable energy sources, with August's high peak temperature of 33.73°C (92.71°F) and January's lowest low temperature of 17.79°C (64.02°F).In addition, April is the wettest month with an average of 28.8 millimeters of precipitation, while June and July are the driest.
June has the longest days with 13.8 hours, while December has the shortest at 10.5 [34].The hybrid off-grid system model for both cities assumes a 6.5% discount rate, 2% inflation, no annual capacity gap, and a 25-year project lifetime.Eastern Jubail is the second place.Figure 6 shows that July has the highest average high temperature in Jubail at 36.1°C (96.9°F) and January the lowest at 17.1°C (62.8°F).April has the most rainfall at 47.9 mm, while October has the least.June has the longest days with 13.8 hours, while December has the shortest at 10.5 hours.Figures 7 and 8 show the solar radiation of both cities.The annual average solar radiation of Yanbu and Jubail is 5.9 and 5.6 kWh/m 2 /y, respectively.It can be seen from the collected data that Yanbu has higher solar radiation compared with Jubail city.Generally speaking, the average annual solar radiation is acceptable for both cities compared with the standard average solar radiation around the world.These data could reflect on designing the solar system as well as the impact on the total cost of the proposed system.
Table 1 shows some of the technical and economical parameters, the rest of the electrical, and statistics summary of the photovoltaic, wind turbine, batteries, converter, and diesel generator modules for both Yanbu and Jubail cities are shown in [Appendix A].The NASA Surface Meteorology and Solar Energy database contains data on solar radiation, temperature, and wind.Saudi Arabia is one of the top locations for solar applications in the world.It receives daily sun radiation averaging between 4 and 7.5 kWh/m2 [1].

BATTERY STORAGE MODULE
The 12-volt lead acid battery module has a nominal capacity of 1 kWh and a maximum capacity of 83.4 Ah.

CONVERTER MODULE
We decided to go with the converter that had a capacity of 1 kW and had an efficiency of around 95%.The cost of replacement using capital is $400, whereas the cost of operation and maintenance is roughly $10.The technical and statistical specifications of the converter module for the cities of Yanbu and Jubail are displayed in Table 2.

DIESEL GENERATOR MODULE
The diesel generator that was chosen was an ordinary unit with a set capacity of 25 kW.The price of diesel fuel per liter that was anticipated was $/L 0.02.[Appendix A] contains the diagnostic information that can be retrieved from the diesel generator.Because of the way the schedule is set up, the diesel generator will not be available between the hours of 8:00 AM and 4:00 PM.

OPTIMIZATION
The process of optimization determined that the wind turbine option should not be pursued.The Homer optimization technique resulted in the production of a hybrid system for the city of Yanbu.This system included a photovoltaic array with a capacity of 3.87 kW, a diesel generator with a capacity of 25 kW, a lead acid battery with a capacity of 10 kWh, and a converter with a capacity of 1.13 kW.This hybrid system has a cost of energy that is $0.483, an NPC that is $43,887, an operating cost that is $1,511, an initial cost that is $10,448, a fuel cost/year that is $306.79,an O&M cost/year that is $629.56, a renewable fraction that is 65%, and an unmet load that is 0.94kWh/year.The following data were discovered for Jubail: an annual cost of $0.487 for energy; an NPC of $44,228; an annual operating cost of $1,452; an annual beginning cost of $12,140; an annual fuel cost of $221,2; an annual O&M cost of $717.3; a renewable component of 70%; and an annual unmet load of 0.001% (0.007 kWh/yr).
According to the information presented in Table 3, the suggested systems have been selected for the purpose of conducting a techno-economic analysis since they are capable of meeting the load requirements for both cities.This system supplies the city of Jubail with electricity by utilizing photovoltaic cells, wind turbines, batteries, converters, and generators.As can be seen in Table 3, Yanbu's hybrid system did not include a module for a wind turbine yet was still able to fulfill all of the load requirements.As can be seen in Table 4, it offers values that are marginally superior than those offered by Yanbu, excluding the cost of fuel.Analyses of emissions and costs may be found in Table 5, which covers Yanbu and Jubail.

RESULTS AND DISCUSSION
The Yanbu system has a lower net present cost than the Jubail system, which has a net present cost of approximately $44,228.However, the cost of energy in Yanbu and Jubail is nearly identical, 0.483$/kWh and 0.487$/kWh, respectively.
Figure 9 depicts a cost breakdown of the hybrid system in Yanbu and Jubail, where the photovoltaic component outweighs the other system components in terms of initial cost.In the instance of Jubail, the lead acid battery is followed by the wind turbine.Moreover, the lead acid battery has the highest operating and replacement cost among the system's other components.

CONCLUSION AND FUTURE WORK
This article offered a stand-alone hybrid system model for the Saudi Arabian cities of Yanbu and Jubail, which demonstrated the impact of environmental factors on the economics and performance of both cities.Simulation and optimization determined that the optimal system architecture is PV/wind turbine/converter/battery/diesel generator, with a minimum cost of energy of $0.483/kWh for Yanbu and $0.487/kWh for Jubail.
TRNSYS software could be used for offering data for calibrating a more complex systems to combine the building envelope with power generating concept.Conventional homes gain and lose significant amounts of heat.Consequently, subsequent Homer model tests will include biomass plants and hydroelectric electricity.
A comprehensive analysis of the strategies used to optimize the system is one of the important steps that are still left to complete for this project.As a result, it would make the advantages of the hybrid system design in contrast to the conventional design very evident to the user.

Figure 1 :
Figure 1: Historical and forcast of energy consumptions.

Figure 2 :
Figure 2: Hybrid system components for selected locations.

Figure 3 :
Figure 3: Daily energy load for a residental house.

Figure 6 :
Figure 6: Jubail monthly averaged temperature.Figures 7 and 8 show the worldwide horizontal radiation and monthly averages for the cities of Yanbu and Jubail over a period of 22 years.

Table 2 :
Summary of Electrical Inverter for Yanbu and Jubail.

Table 3 :
Yanbu and Jubail economic results.

Table 4 :
Yanbu and Jubail production summary

Table 5 :
Yanbu and Jubail emissions and cost analysis

Table A .
4. Yanbu and Jubail Generic 1kWh Lead Acid Statistics

Table A .
6. Yanbu and Jubail Generic 25kW Fixed Capacity Genset Electrical Summary Table A.7. Yanbu and Jubail Generic 25kW Fixed Capacity Genset Statistics Table A.8. Yanbu and Jubail Diesel Consumption Statistics