Open access peer-reviewed chapter

# Economic Analysis of Stand-Alone Hybrid Wind/PV/Diesel Water Pumping System: A Case Study in Egypt

By Nagwa M. Khattab, Mervat A. Badr, Essam Tawfik El Shenawy, Hassan H. Sharawy and Marwa S. Shalaby

Submitted: October 20th 2018Reviewed: August 13th 2019Published: March 25th 2020

DOI: 10.5772/intechopen.89161

Downloaded: 12

## Abstract

The design and evaluation of a stand-alone hybrid renewable energy system for pumping underground water for small farm irrigation is presented. Given environmental conditions, system specifications and daily load demand data, the optimal size of main system components is obtained using a sizing algorithm. Different renewable energy systems are compared using yearly simulations, on hourly base via specialized commercial software simulation packages PVSYST and HOMER, to simulate the system performance and to reach the optimum configurations based on the objective criteria. The criteria used in economic optimization are the net present cost and the cost of energy, with the percent of the capacity shortage. The following systems can be compared: PV only, PV with horizontal axis wind turbine, PV with vertical axis wind turbine, and PV with horizontal axis wind turbine and diesel generator and diesel generator only. The simulation also was carried out for different load patterns for optimum operation. The study was illustrated for climatic conditions of an isolated area in El-Tour City, Sinai, Egypt. The installed 3.42 kW PV water pumping system for irrigation purposes in the same site was also described.

### Keywords

• water pumping
• stand-alone photovoltaic
• wind turbine
• hybrid system
• diesel generator

## 1. Introduction

Egyptian Government has embarked an ambitious plan to develop new villages in the desert far from Nile River and Delta by reclaiming and cultivating 5 million acres over 5 years. The main challenge facing the government efforts is the inability of the current energy sources to provide those communities with the main infrastructures from energy and water to fulfill agriculture requirements. This is because these communities are small, scattered and located in the desert far from the electricity grid.

Hence, the Egyptian Government strategies targeted providing agriculture water requirements (pumping and irrigation) for new rural areas by applying renewable energy systems. Clean, renewable energies such as solar and wind are considered fast solutions to provide such communities with the energy necessities. The adopted approach has been motivated mainly by Egypt’s location that is endowed with abundant solar energy, adequate average wind speed besides long sea shores and underground water.

Among the renewable energy options that are currently in wide use are solar photovoltaic (PV) and small wind turbines (WT) for water pumping and irrigation. Pumping water by mechanical wind mills in remote areas is an old technology [1, 2], and by renewable energy for the last few decades [3, 4]. Recently, many users of the water pumping have switched to solar energy via photovoltaic pumping for small systems, while for larger systems the diesel generations are still predominant for pumping water in Egypt [5]. Compared to PV systems and mechanical wind mills, small wind turbines are still in limited uses for water pumping systems in remote areas. Using hybrid photovoltaic/wind turbine (PV/WT) improves the water pumping reliability and increases the daily volume of the pumped water.

Different studies concerning the individual PV water pumping (PVWP) and wind turbine water pumping (WTWP) systems focused on the dynamic performance of these systems, in particular the match between water demand and water supply [6]. Benghanem et al. [7] compared the performances of different PVWP configurations for different hydraulic heads. Kelley et al. [8] studied the feasibility of PVWP systems for irrigation as a function of location, while Rehman and Sahin [9] investigated the technical and economic performances of several small WTs to provide water in Saudi Arabia.

The performances of PVWP and WTWP systems have also been compared. Kumar and Kandpal [10] assessed the potential of PVWP and WTWP systems for irrigation in India. Diaz-Mendez et al. [11] presented a simple methodology to compare PVWP and WTWP for irrigation of commercial greenhouses in Spain, Cuba and Pakistan. The study mainly focused on the economic comparison between PVWP and WTWP systems for irrigation for three specific locations with no indication to the match between water demand and water supply and the effect of water supply on the crop yield.

One of the most important limitation facing applications of renewable energies is that no individual source of solar or wind energies is capable of supplying both reliability and cost-effective due to the intermittent nature of them. Moreover, fluctuations in production and time-dependent are other challenges for renewable energy utilization. Flexible demand management [12, 13, 14], and smart energy management [15, 16], are useful, but they do not fully suffice in maintaining the balance between production and demand of electricity.

Hybrid PV/WT systems which optimize the contribution of solar and wind energy sources generation to provide continuous base requirements are the better solution of this problem. Using a hybrid solar/wind system helps to use solar energy in case of small wind speed and use wind energy in case of low solar radiation levels. Vick and Neal [17] analyzed the operation of solar PV and wind turbine as individual systems as well as a PV/WT hybrid system as off-grid system for pumping water. It was found that the hybrid system delivered more energy than only PV or wind by an amount of 28%. An additional buck/boost converter was also used as a controller to improve hybrid PV/WT water pumping system.

Research developments in the field of renewable energy-water pumping systems are reviewed by Gopal et al. [18]. They briefly reviewed hundreds of articles published in the water pumping systems and investigated five different system configurations with various types of energy; solar, wind, biomass, thermal and hybrid PV/WT. They concluded that using renewable energy (solar or wind or hybrid) highly reduces the dependence of conventional energy with good environmental impact. According to the meteorological data measured for the city of Xanthi, Greece and their systematic design approach for three different systems for water pumping which are; PV, WT and hybrid PV/WT, Skretas and Papadopoulos [19] concluded that the performance of hybrid system was better than that of solar or wind only.

Ma et al. [20] introduced a new solution of the problem concerning the energy storage in the renewable energy systems, especially in standalone systems. In that work, an important and most traditional storage technology was used, this is the pumped hydro storage (PHS) with a standalone renewable energy system (solar-wind). They developed a mathematical model for the hybrid solar-wind system and applied according to the operating parameters on a case study to feed the required energy to a remote area in Hong Kong and examined its technical feasibility. Time dependent simulation results showed that the inherent fluctuations nature of the renewable energy sources can be effectively compensated by applying the PHS technology. This can provide a reliable and clean energy source power supply. They concluded that 100% of the energy autonomy in remote and rural areas can be achieved by pumped hydro storage-based hybrid renewable energy.

Many researchers used two public models for optimizing the hybrid renewable energy systems [21, 22, 23]. The first model was hybrid optimization model of electric renewable (HOMER) and the second was hybrid solar-wind system optimization model (HSWSO) [24]. The second model mainly used when using a storage battery bank in the hybrid system. The optimization process of the hybrid systems concluded that using a storage tank for water storage is more cost effective than using a storage battery bank in hybrid solar-wind system, due to the higher maintenance and operation costs of the batteries and vice versa for the water storage.

Yahyaoui et al. [25] optimized the design of a hybrid solar-wind-pumped storage system in standalone mode for an isolated area. The initial design process of the system’s major components was presented, and optimized based on a techno-economic evaluation. The proposed design was evaluated using yearly simulations, on hourly base, performed by specialized commercial software, PVSYST.

A methodology for optimal sizing design and strategy control based on differential flatness approach was applied to the hybrid stand-alone PV/WT systems by Tégania et al. [26]. The aim was to find, according to life time of the system provided that the required load energy is completely supplied by the system, the optimal design of the system components that ensure minimum system costs. The problem formulation and the generic algorithm are used in optimization methodology to optimally configure the system, and the results are obtained using MATLAB/Simulink.

Therefore, the hybrid PV/WT system is usually installed to supply water in remote areas with considerably less costs and more reliable operation in case of inherent fluctuations of the renewable energy sources. The present study describes the main components of the installed stand-alone 3.42 kW PV water pumping system for irrigation purposes in El-Tour city, Sinai, Egypt. To investigate the feasibility of small, decentralized hybrid PV/WT system for water required for irrigation purposes, a theoretical comparison between different renewable energy systems for water pumping is carried out in the selected site based on using yearly simulations, on hourly base via specialized commercial software simulation packages PVSYST and HOMER, for optimum operation. The compared systems are: (i) PV only, (ii) PV with horizontal axis wind turbine (PV/HAWT), (iii) PV with vertical axis wind turbine (PV/VAWT), (iv) PV with horizontal axis wind turbine and diesel generator (PV/HAWT/D) and (v) diesel generator only. The criteria used in economic optimization are the net present cost, the cost of energy with the amount of unmet load or percent of energy shortage. The optimization process was carried out for different load patterns.

## 2. Installed PV/water pumping system

The installed small water pumping system is used to deliver water from a well for agriculture purposes in El-Tour city, Sinai, Egypt (latitude of 28.22° N and longitude of 33.61° E). The system consists of; the PV arrays, mechanical structure, pump controller and water pump.

Table 1 shows the site parameters; air temperature, wind speed and solar radiation levels, as average values. It is clear that the site has an annual average air temperature of 20.9°C with low values of wind speed reaches maximum value of 7 m/second which can be considered considerably low levels of wind speed. Figure 1 shows irradiation levels on a horizontal and an optimally tilted surface (30°) in El-Tour, Sinai [27]. It is seen that the location has high irradiation levels all over the year with an annual average of 6.86 kWh/m2/day on an optimally tilted surface. This average value can be considered one of the highest irradiation levels all over the world.

### 2.1 PV arrays

The PV system which is to drive the water pump motor, consists of 3.42 kW-PV power (18 PV modules) arranged in two parallel strings, each of them has nine modules connected in series. According to this arrangement, the PV system gives operating voltage about 216 V and 16 A at standard test conditions (STCs; 1000 w/m2 of irradiance, 25° of module temperature and 1.5 AM). Table 2 exhibits the characteristics of the used PV modules at STC.

Month (average values)Air temperature (°C)IR on optimally tilted surface (Wh/m2/day)Wind speed (m/second)
January11.856504.70
February12.765205.00
March16.277604.70
April21.071906.00
May24.772006.50
June26.873506.00
July28.273205.90
August28.174307.00
September26.472906.00
October22.870105.30
November18.161004.90
December13.455104.30
Annual20.968605.53

### Table 1.

Average air temperature, wind speed and solar radiation levels in El-Tour, Sinai.

ItemSpecifications
Module power190 W
Module cells48
Number of modules18
VOC29.76 V
ISC8.47 A
VMP24 V
IMP8.02 A

### Table 2.

Characteristics of the PV system.

### 2.2 Supporting structure

The supporting structure is used to fix the PV system facing south at tilt angle of 30° on the horizontal surface for optimum irradiation collection over the year. It is made of galvanized aluminum rods fitted via aluminum joints supported on eight concrete bases in order to ensure a stable and secure operation and to avoid vibrations or falling. This structure must withstand the environmental conditions of higher temperatures, humidity and wind speeds up to 15 m/second.

### 2.3 Pump controller

The pump controller is used to drive the pump electric motor via converting the input DC power from the PV arrays to the required AC power, voltages and currents suitable for the pump operation. The controller has many indicators to fully monitor the system operation. There are many protections features in the controller to safely start the pump at very low irradiation levels and protect it from vibrations and over load. Figure 2 shows the pump controller and the wiring diagram, while Table 3 illustrates the controller’s parameter specifications.

ParameterPower (kW)Input voltage (V)Optimum voltage (V)Motor current (A)Efficiency (%)Ambient temperature (°C)Enclosure classWeight (kg)
Specification4Max 375238Max 1598−30 to 50IP549

### Table 3.

Parameters of the pump controller.

### 2.4 Water pump

The water pump is solar-operated submersible pump with maximum flow rate of 7 m3/hour and maximum head of 140 m. The pump has maintenance-free brushless DC motor, has no electronics in the motor. The electrical parameters of the pump motor are given in Table 4, while Figure 3 illustrates the pump chart.

ParameterSpecification
Rated power3.5 kW
Efficiency92%
Motor speed900–3300 rpm
Enclosure classIP68
SubmersionMax 250 m
Weight of motor and pump18 kg

### Table 4.

Electrical parameters of the pump motor.

## 3. Optimization of hybrid PV/WT pumping system

To reach optimum system configurations, alternative configurations supplying the estimated daily load pattern are used to simulate the system performance. The optimum system fulfills the load requirements within the acceptable percentage of unmet load which is one of the decision variables. Optimality condition is based on the objective minimum cost which is defined by two criteria; the first is the minimum net present cost (NPC) and the second is the cost of energy (COE) generated from the system.

### 3.1 Hourly load curve estimation

The daily quantity of water required for irrigation is about 50 m3 in summer and 42 m3 in winter. Water is pumped for 7 hours on average. Thus, the hourly pumped quantity is 7 m3/hour for summer and 6 m3/hour for winter. The submersed pump is installed at a distance 41 m from ground level, assuming that the tank is at 2 m above the ground, and then the total elevating head is 43 m. Then the electrical power required for water pumping for summer is about 1.5 kW and for winter 1.3 kW. The estimated hourly electrical load is shown in Table 5.

Time (hour)WinterSummer
Q (M3/hour)kWQ (M3/hour)kW
1030.6530.65
1161.371.5
1281.7102.14
1381.7102.14
1481.7102.14
1561.371.5
1630.6530.65

### Table 5.

Hourly electric load of water pumping system.

For economic comparison purposes of the hybrid PV/WT pumping systems, five cases of the different investigated system configurations are simulated and analyzed using software packages PVSYST and HOMER. The proposed systems are as follows: (i) PV system, (ii) PV/HAWT), (iii) PV/VAWT, (iv) PV/VAWT/D and (v) diesel only system. The simulation is also carried out for different load patterns.

## 4. Results and discussion

### 4.1 Case 1: PV only

In this case, the system used the PV arrays only to drive the pump via a converter. Four batteries (12 V, 200 AH each) were included in the system simulation to control the energy shortage. The NPC and COE resulted from system simulation over 25 years are shown in Table 6.

### Table 6.

NPC and COE of PV system for water pumping.

From Table 6, the total NPC of the PV system is 22,523$and COE is 0.614$/kWh. The capacity shortage is about 8% of the total load, although four batteries are included in the system simulation. Figures 4 and 5 illustrate the cash flow and energy flow summaries of PV pumping system.

## 5. Conclusions

The present chapter illustrates the specifications of an installed PV water pumping system for agriculture purposes in El-Tour city, Sinai, Egypt. For economic comparison, the paper theoretically analyzed different renewable energy water pumping systems with different load patterns using commercial software. The systems using only PV power, PV/WT vertical and horizontal types with and without diesel generator. The systems contain storage batteries. The economic analysis was carried out based on the NPC and COE with system capacity shortage. The result of the analysis showed the following conclusions:

• The NPC and COE is lower in case of PV only and increased by using WT with PV system due to the lower wind speed rates in the specified location. The COE was 0.614$/kWh for PV only, 0.834$/kWh for PV/HAWT, 0.790$/kWh for PV/VAWT, 0.857$/kWh for PV/HAWT/diesel and 0.876\$/kWh for diesel generator only. The external cost of CO2 emissions is not taken into consideration which will raise the cost of energy generated from diesel alone system.

• The capacity shortage percent decreased with using diesel generator in the system, although the NPC increased. The capacity shortage was 8.3% for PV only, 3.9% for PV/HAWT, 3.1% for PV/VAWT, 0.4% for PV/HAWT/diesel and zero for diesel system only.

• Monthly average wind speeds on the location are much lower than the turbine rated wind speed which leads to non-optimal operation of the PV/WT. This leads to higher NPC and COE values. Also, high percentage of excess energy is noticed in cases of PV/WT system which causes the increase of COE.

• Increasing the load during the periods of excess energy decreases the COE. Thus, it is recommended to use abandoned energy in other optional loads.

## How to cite and reference

### Cite this chapter Copy to clipboard

Nagwa M. Khattab, Mervat A. Badr, Essam Tawfik El Shenawy, Hassan H. Sharawy and Marwa S. Shalaby (March 25th 2020). Economic Analysis of Stand-Alone Hybrid Wind/PV/Diesel Water Pumping System: A Case Study in Egypt, Modeling, Simulation and Optimization of Wind Farms and Hybrid Systems, Karam Y. Maalawi, IntechOpen, DOI: 10.5772/intechopen.89161. Available from:

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