Techno-economic Viability and Energy Conversion Analysis of RHES with Less Weight/Area

This article proposes a new strategy to find the optimal location, configuration and size of the Renewable (wind-photovoltaic-diesel-battery) Hybrid Energy Systems (RHES (off-grid)). This study has two steps: first, the proposaltoa strategybased on a weather change to find the optimal location in Iraq using Hybrid Optimization Model for Electric-Renewables (HOMER) software. Second, the study will examine the influence of the techno-economic viability from side less weight and area on the optimal configuration/size of the RHES, which gives the maximum output power. A period of one-year for meteorological data for both solar radiation and wind speed has used. Finally, simulation results indicated that the optimal location for this RHES is the AL Harithah location. The analysis has shown that RHES can supply 89% of the load demands by renewable-energy. It is also successful in reducing the area required for installation of the RHES about 28%.


Introduction
There is a difficulty with transporting fuel to remote and rural places, non-arrival of electric power to these areas, in addition to the annual increase in population ratios and increased pollution in the atmosphere.All of these factors led to the emergence of renewableenergy-sources.At present, many countries have directed research into alternative sources of conventional electric power, due to concerns about the global climatic change and fluctuating fuel prices, searching for reliable and green sources.In Iraq, the electricity generated is not enough to meet the load demands.By using Genetic algorithms and Matlab software, Reference [1] propose using hybrid renewable resources of power generation connected to the grid and also selecting the location size of Photo-Voltaic (PV) and Wind Turbine (WT) in threecities in Iraq [2].
The electrical loads in the Iraq power grid containa significant proportion of the residential load.In [3] proposed supplying part of the residential-load in the Mosul location using a hybrid system.References [4][5][6], proposed to determine high the renewable fraction and less the greenhouse gases emissions using economical and the environmental analysis of net-zero energy for tourist village.In Homer software, there are several indicators for the purpose of selecting the optimal design and size of the standalone such as NPC, COE, full consumption saving, capital cost, replacement cost, operation and maintenance (O&M) cost of Diesel generators (Dg), CO2-emission and pollutants and lifetime [7,8].These indicators are used to find the type and size of the hybrid system of renewable energy sources that give the best performance [9,10].It considered that Distributed Generation Technologies based on the renewable energy of essential technologies, called standalone hybrid renewable energy system [11][12][13], can be suitable options for remote and rural areas [14][15][16][17].
Several authors show the optimization of standalone hybrid renewable systems, analyse the application of WT, PV and Dg and reducing the NPC of the system [18][19][20][21].In addition to, reference [22] proposed creation of the best configuration of a plant based on renewable energies to operate the oil rigs, which sometimes located in remote areas or the sea and also when away from the electrical grid.References [23,24] presents a hybrid system from the perspective of the optimisation and management of the system.The problem of the weight of the equipment is fundamental in the transport process, where in some cases the transportation of the components and fuel from the manufacturing site to the work site is tricky.Also, the transport cost is expensive, due to the difficult and dangerous of the roads.The transport cost by trolley varies in each country, and it depends fundamentally on the kind of road and the fuel price.In addition to, the problem of the area isessential in decreasing area for installation of RHES equipment, which in turn will reduce the total cost and also the collision probability of the migratory birds with wind turbine fins.
However, these methods consist ofa drawback concerning the less weight and area using HOMER software.All the above mention methods have focused only on cost estimation, maximise human development index, use different battery technologies, NPC, COE, fuel cell and power management.These methods do not take into considerationless weight and area of the system, plus that negligence of the weight and area will cause an increase inthe cost of construction and generation of the energy.In Iraq, the abundant solar radiation and wind are not tapped into properly, because of the high cost and the lack of a variety of studies on this topic.This paper has two steps: First step: proposed of planning to choose the best location for the installation RHES (off-grid) in the remote areas based on a weather changes.The system consists of 400 houses with five capita per house.The average consumption per capitaof power about (1.639 kWh) [25] and the average consumption per household about (8 Kwh).For simulated, we took twelve locations in our country (Iraq) and divided into three regions.Second step: Study the techno-economic viability fromside less weight and area on the optimal configuration and size of the RHES (off-grid) using HOMER software.

Location and Meteorological Data
The meteorological data (global solar radiation, wind speed), were measured at twelve locations in Iraq for every month of the year 2016 [26].The locations in Iraq were divided into three regions and showed as follows: a.The northern region: Four locations and includes: Mosul, Chamchamal, Bayji and Erbil.b.The middle region: Four locations and includes: Baghdad, Abu Ghraib, Samarra and AL Suwayrah.c.The southern region: Four locations and includes: AL Basrah, AL Nasiriyah, AL Amarah and AL Harithah.The geographical coordinates of the Iraq data collection site were latitudes 33.3333° N, and longitudes 44.4333° E. Figure 1, shows the three geographical regions in Iraq [26,27].

Methodology & Proposed Hybrid Model
In this paper, the methodology used for simulation and modelling purposes is Electrical Renewable (HOMRE) software.The proposed hybrid model is a design using HOMRE and consists of WT, PV, Dg, battery and power-converter; Figure 2 shown this model implementation.HOMER is a design model that determines the optimal-configuration, control- 2333 strategy and feasibility-study of the hybrid system.HOMER needs the information data such as wind speed data, solar radiation data, load data, costs, economic and emission constraints [28,29], described as follows: Figure 2. Hybrid model (off-grid) in HOMER

Wind Speed Data
The primary resource for the hybrid model is the wind.The wind speed data presented graphically in Iraq in the northern region, middle region and the southern region in Figures 3, 4  and 5, respectively [25].We can note that the variation between the monthly averages of wind speed is essential; the abundant months are indeed those of May (5.556 m/s), July (5.278 m/s) and August (5.278m/s) for the northern region, June (14.806m/s), July (15.806m/s) and August (14 m/s) for the middle region and June (16.611m/s), July (15.5 m/s) and August (13.694m/s) for the southern region.On the other hand, for January, March, November and December for the northern region, the wind speed does not exceed 4 m/s.For better performance of a wind turbine, there must be a wind speed in the range of 4 to 8 (m/s).Can be considered unsuitable for conversion systems of wind speed (if the wind speed average is stable, there will be a guarantee for the generation of stable electrical power).

Solar Radiation Data
The second resource for the hybrid model is the sun.The solar radiation data are collected from [25] and shown in Figures 6, 7 and 8 for the northern, middle and southern region in Iraq, respectively.Average global solar radiation in Iraq is almost up to 8 (kW/m 2 ) because it locates within the equatorial zone.The figures above illustrate that solar radiation is more than 6 (kW/m 2 ) from May to August in all regions of Iraq, but the southern region has the highest rate of solar radiation.However, in June and July, various regions in Iraq show similar levels of radiation and hence constitute a vast potential for solar energy generation.

Diesel Generator
Diesel generators are used as backup power sources and are being developed to increase the reliability and stability of the electric power when the WT/PV hybrid system is not able to produce enough electrical power to meet the load demand.Therefore, Dg was used widely with the renewable hybrid energy system to increase the reliability and stability of the system [24].

Batteries and Inverter
Because of the climatic changes and the intermittent nature of the wind and the solar radiation, there is a need to use battery storage facilities to ensure steady power supply.Also, the inverter is used to convert the DC power produced by PV or wind to AC power (some units of wind power produce DC power, others produce AC power).In this study, Homer software is applied to simulate (WT, PV, Dg, Batteries and power-converter) hybrid system.Homer will calculate the different permutations of possible designs based-on inputs provided and simulate the system.The area of the WT and PV panel isan estimate in 1020 (m 2 ) and 22 (m 2 for 1kW), respectively.The input data are briefly described in Table 1 [11, 12, 14, and 24].

Mathematical Model
The RHES (off-grid) location problem has formulated as an objective minimisation problem.The matrix constrained has been used to formulate the planning problem.Mathematically, the first step in this paper, the multi-objective function and constraints can be formulated as follows: We can find the (α1, α2, α3) by using the matrix: where: The second step, the RHES (off-grid) planning problem has formulated as a multiobjective minimisation problem.The multi-objective function is minimising the cost and weight system, formulated as follows: The total system weight (W TOT ), we can formulate as follows: Moreover, the total system area for WT, PV (A(WT,PV)) formulated as follows: Where: W WT is the weight of the WTs.W PV is the weight of the PV panels, W Dg is the weight of the distributed generations, W Batt is the weight of the batteries.W conv Is the weight of the power-converters, W FUEL is the weight of the fuel, FL is numbers of the fuel litres, DOF is the density of the fuel (kg/cm 3 ), A WT is an area of the WT (m 2 ), and A PV is the area of PV (m 2 ).The NPC of a hybrid model is the present value of all the costs of installing and operating that component over the project lifetime.The costs include capital/costs, replacementcosts, O&M costs, fuel/costs and emissions.The revenues include salvage value and grid sales.HOMER calculates the NPC by summing up the total discounted cash flows in each year of the project lifetime using the following equation [17,28]: To calculate the total annualised cost (TAC) use the following equation: . , , 11 (10) where: CRF is the capital recovery-factor, shown in the equation below: The real discount-rate (i) is used to convert between one-time costs and annualised costs.HOMER uses the following equation to counting the real discount-rate: where: i' is nominal discount-rate, and fis expectant inflation-rate.
To calculate the COE, HOMER divides the annualised cost of producing electricity (the TAC minus the cost of serving the thermal load ( CH boiler served ) by the total electric load served ( E served ), using the following equation: The second term is equal to zero, at no thermal load on the system.The remaining value in a component of the power system at the end of the project lifetime called the salvagevalue (S), assumes linear depreciation of components.It also depends on the replacement-cost rather than the initial-capital cost [28,29].We can calculate the S using the following equation: Where Rrem is the remaining/life of the component at the end of the project lifetime, is shown as follows: Moreover, the replacement-cost duration ( R rep ), is shown as follows: .

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The operating-cost (Coper.) is the annualised value of all costs and revenues other than initial capital costs, the C oper value defined as follows: ., C TAC C oper ann cap  (17) Where: K is a number ofthe years, Crep is replacement cost ($), Rcomp is component life-time (yr), R proj is projected lifetime (yr), INT is a function that returns the integer amount of a real number, and , C ann cap is the total annualised capital cost ($/yr).

Optimal Location of RHES in Iraq
The proposed hybrid model in Figure 2 has been designed and simulated with the use of HOMER software.To find the optimal location for the installation RHES (off-grid), we took twelve locations in Iraq.A strategy has been proposed based ona weather-change to find the optimal-location.The planning load average of consumption per household about 8 (kWh), the average daily demand was 133.3 (kWh), and the average monthly consumption shown in Figures 9 and 10.The renewable fraction (fren) also studied in this paper.The fren is the fraction of the energy delivered to the load that originated from renewable-energy sources [28].Table 2 shows the results with the Minf1 to select the optimal location in Iraq.The results show that the optimal location to build a hybrid system in the northern region is the Bayji location, in the middle region it is the Abu Ghraib location, and in the southern region, it is the AL Harithah location.Also, it is clear that the optimal location to build RHES (off-grid) in Iraq is the AL Harithah location, which is regarded as an excellent location at Minf1 (0.1320), less COE and NPC with high penetration rate (86%).

Optimization Analysis of the AL Harithah Location
This section will examine the techno-economic viability of the optimal configuration and size of the RHES (off-grid) using HOMER software.This analysis aims to assess the technoeconomic viability of four cases arrangement for AL Harithah location (all cases shown in Figure 11), including all possible combinations of WT, PV, Dg, power converter and batteries to determine the best configuration and size for electrical output power in each case as follows: In this study, use two sensitivity factors in the system analysis with the adoption of the less weight and area to determine the optimal configuration and size of the RHES.The first factor, capital-cost multiplied by (0.6, 0.8, and 1).The second factor, replacement-cost multiplied by (0.6, 0.8, and 1).The optimal system designs obtained from the simulation of cases 1 to 4 for each considered community presented in Tables 3 and 4. It can be in these tables that to compare the configurations and size for weight minimisation, the resulting yearly for WTOT., COE, frenand Minf2 for each case has determined.The total yearly output power produced by each generation type (WT+PV+Dg) is also computed.Therefore, the analysis essence of economic, weight minimisation and less area is to find the most economically suitable cases for the AL Harithah location.From the viewpoint of the weight minimization analysis, Tables 3 and 4shown the minimum weight and Minf2 values for case 4 comparison with cases (1, 2, and 3).The case 4 (WT+PV+Dg) is the most savingdesign for the AL Harithah location.Also, we can see from Table 4 (cases 3 & 4) that renewable energy supplies the maximum part of the electrical load, while the case 3 configuration achieved 100% renewable energy but with increased weight and Minf2.
From the viewpoint of the techno-economic viability analysis, we used two sensitivity factors of the analysis with the adoption of the weight minimisation.The case 4 the optimal configuration case with capital cost multiplier by (0.8) and replacement cost multiplied by (1).Where Minf2 and weight are 0.26411 (p.u.) and 68.879 (ton) at capital and replacement Table 5 shows the total CO2-emissions for cases (1 and 4) are 131.895(ton/yr) and 87.934 (ton/yr), showing that case 4 results indicate a reasonable configuration.Regarding the less area of the system, we can see the renewable energy supplies the maximum part of the load demands, while the configuration of case 4 achieved 89% renewable energy and less cost of the fuel with less weight and area for RHES.

Conclusion
The analysis results revealed that the optimal location to build a hybrid system in the northern region is the Bayji location, in the middle region is the Abu Ghraib location and in the southern region is the AL Harithah location.Also, it is clear that the optimal location to build up RHES (off-grid) in Iraq is the AL Harithah location, which is regarded as an excellent location.Generally, it considered that the southern region is the optimal region in Iraq to create one or more hybrid systems because of the abundance of wind and solar radiation.
According to the analysis and selection of the most appropriate configuration and size for the RHES, we can see that the choice of case 4 (WT, PV, Dg) of Tables 3,4 are the optimum regarding less weight and area.Also at less weight for the system, we can see reduced COE about 3.52% by using techno-economic viability-analysis.The Table 5 confirms that the case 4 configuration is much better than the case 1 configuration with reduced the area required for installation of the RHES about 28% with 33.3% forCO2-emissions and 33.33% for fuel cost.
Finally, Reference [1,3] proposed selected the AL Basrah and Mosul locations as the best site for the RHES construction in Iraq.After comparing the results of this paper with Reference [1,3], it emerged that the AL Harithah location is better than the AL Basrah and Mosul locations.

Figure 1 .
Figure 1.The three geographical regions in Iraq

Figure 9 .
Figure 9. Daily load demand Figure 10.The average load of every month

Table 1 .
Input data of Homer software Techno-economic Viability and Energy Conversion Analysis of... (Mohammed Kdair Abd) 2335

Table 2 .
Results of the Minf1 for twelve locations in Iraq

Table 3 .
Optimized Results of the Proposed Configuration with Weight Minimisation (Case 1 & 2)

Table 4 .
Optimized Results of the Proposed Configuration with Weight Minimisation (Case 3 & 4)