1. Introduction

Energy is the primary basic requirement for all aspects of development and is at the core of all social, economic and environmental issues. The Kingdom of Saudi Arabia (KSA) is located in the Middle East, spread over about 2.15 million square kilometers and constitutes around 80 percent of the Arabian Peninsula. The country has a very harsh environment where the temperature varies from as high as 50°C in the mid-summer to as low as 0°C or even lower in winter [9]. The high temperature variation produces extreme variation in the electricity demand over the year, resulting mainly from the demand for air conditioning during the hot season and the need to have heaters running in the bitterly cold winters. The sudden surge in energy demand in the KSA has been due to urbanization, industrialization, population increase, higher standards of living, especially in urban areas, and cross-sectoral economic growth and development, as well as several other factors [9].

Renewable energy, particularly solar and wind energy, is an essential clean and green energy source worldwide. The knowledge of irradiation and wind speeds in a geographical location is very important for the development of the area in terms of energy generation and conservation. Current calculation systems are based on statistical models of measurements of ground stations, or using the data gathered by satellite-based external radiation calculations [23].

Increasing apprehension about rising energy prices, the need to preserve energy supplies across the globe, ecological sustainability and global climate changes have emphasized the need to consider renewable energy technologies as one of the most practical and workable options. The increasing use of conventional sources of energy is considered crucial not only for the economy of any country but also for the environment as it could be hazardous and lead to serious environmental issues.

Wind power technology, one of the most significant renewable energy resources is fast-growing, mature and cost-effective with the commercially attractive potential of generating electricity. The generation of electricity from wind power is competitive with fossil-fuel-plant power. According to statistics compiled by the Global Wind Energy Council, China and the U.S. lead the effort in terms of total installed wind power capacity. The total globally installed renewable power capacity in 2010 was 305 GW which is expected to grow by a four-fold increase to 1120 GW by the year 2030 [12].

Using GIS and data from 400 stations in the Middle-East, Eastern, Central and Southwestern parts of Iran, South Oman, nearly all of Iraq and Yemen, some Northern and Eastern parts of Egypt, South Jordan and Israel, and also a small region in the Southeast Turkey have been identified as predominantly suited for installation of wind power stations [26]. Site selection criteria for wind farms were developed based on compliance guidelines used both nationally and internationally [7]. Generally, the location of wind farms should be economically viable and should not have any significant impact on the local environment in terms of visual and noise intrusion, electromagnetic interference and possible wildlife collisions [15]. The average wind speed at a location is one of the most important criteria for determining the economic performance of a wind turbine. The remarkable advances in wind turbines have shown significant improvement in power output and efficiency [30]. The siting of a wind farm near residential areas can cause negative environmental impacts such as noise nuisance, visual intrusion (shadow flicker, light reflections, landscape impacts) or massing effects. Thus, considering noise and potential visual impacts, areas further away from urban areas are more potentially appropriate as wind farm sites. High density and tall vegetation cover in the vicinity decreases wind speed and increases turbulence intensity which may damage the turbines or increase development costs. Thus, fallow and bare land is generally considered the most suitable, agricultural land moderately suitable, thorn scrub forest and plantations less suitable, and forested land the least suitable. Due to accessibility and economic considerations, wind farm sites should be located in close to proximity to existing road networks to help minimize construction costs by easy delivery of materials and for maintenance purposes.

Saudi Arabia is considering exploration of wind energy resources to generate power for its future energy supply. This development is in line with the important strategy to expand energy resources and balance the mix of conventional and alternative energy resources. The country targets 9 GW wind power generation by 2040, which is expected to contribute nearly 6.3% of the total power capacity [25]. The development of wind power systems requires accurate and high-quality wind speed data for successful viability study in wind energy exploration projects. The King Abdullah City for Atomic and Renewable Energy (KACARE) established five wind monitoring stations at Riyadh City Site A, Riyadh City Site B, Hafar Al-Batin, Sharurah and Yanbu [25]. The average wind speed at the Hafar Al-Batin region on the east coast was 7.5–8 m/s, slightly higher than for other regions, whereas wind speed varied from 7 to 7.5 m/s in Yanbu on the west coast and Sharurah on the south coast. It was 5.5-6 m/s in Riyadh in the central region [25]. In August 2015 the average wind speed was higher in Yanbu and Riyadh but slightly on the lower side in Sharurah. Yanbu had a wind speed ranging between 9.5-10 m/s, while Sharurah on the south coast recorded 6.5-7 m/s. The wind speed in Hafar Al-Batin ranged from 7.5-8 m/s, while in Riyadh it was 5.5-6.5 m/s, the same as the wind speed in February 2015 [25]. It can be observed that the wind energy potential in the country is enough to enable even large capacity wind energy systems [16]. This promising energy potential can be utilized to complement fuel-based power generation.

Wind energy is currently the lowest cost renewable energy, widely available throughout the world. Hybridization of Concentrating Solar Power (CSP) with wind energy has not been explored to a great extent, predominantly because wind and CSP do not have wide synergy in terms of sharing infrastructure, unlike other thermal energy sources such as biomass and geothermal. Hence, CSP-wind integration has been referred to as a light hybrid [24]. However, solar energy naturally complements wind energy in generating power more uniformly as wind speed is lower during the day and summer compared to night and winter. The high-renewable hybrids such as CSP-wind, CSP-biomass, and CSP-geothermal have a minimum or zero negative impact on the surroundings. This category has been the least explored and hence presents a wonderful potential for research in the future. However, such plants would be restricted to selected locations due to the requirement of both renewable energy resources. While CSP-biomass hybrids are suitable for capacities less than 50 MW, CSP-wind, and CSP-geothermal hybrids can reach capacities greater than 100 MW [24].

Another recent trend in Saudi Arabia has been to exploit its attractive solar energy potential as an alternative source of energy. Solar panels placed in Najran city produced the highest energy across the Kingdom in three different configurations (fixed tilting angle, 1-axis tracker, and 2-axis tracker) which revealed that the 1-axis tracker configuration was the best choice for solar tracking in Saudi Arabia [26].

Renewable energy is established as an important source of energy for the future, not only for Saudi Arabia but for the entire world. Saudi Arabia has a copious potential for exploiting solar energy, which is renewable, clean, and freely available [3]. The average annual solar radiation falling on the Arabian Peninsula is about 2200 k Wh/m². Applications of solar energy in Saudi Arabia have been growing since 1960. Saudi Arabia is geographically well-located for capitalizing solar energy as the average daily solar radiation level reaches 6 kWh/ m² and it has about 80-90% clear sky days annually [435]. Annual solar radiation level reach over 2400 kWh/ m² [20]. In spite of such a rich potential and having initiated a sizeable solar village electrification project as early as 1981, the country is yet to significantly exploit solar energy. Under Vision 2030, solar energy is being planned to contribute the most to the 9.5 GW renewable sources target [14]. This paper focuses on the use of Multi-Criteria GIS (Geographical Information Systems) Modeling for locating optimum sites for solar and wind energy harvesting in the KSA. It also uses the capacity of GIS to display the results of the paper’s research. GIS provides the most effective way to handle and display such complex data [2].

2. Literature Review

2.1. Multi-Criteria GIS Model Evaluation

When working on a Multi-Criteria GIS Modeling project, well-defined variables and criteria that logically influence the modeling results are needed [13]. Since solar radiation is high throughout KSA, the influence of the other GIS variables is greater. The solar GIS model may be more useful than other models for identifying the most suitable areas. Ideal sites for solar and wind farms need to be verified by measuring the wind speed at different areas. Surveying local residents is important to ensure that there is no / minimum opposition. Field validation should also examine ecological variables such as sensitive habitats or migratory routes for birds or bats; though there is evidence that wind farms may not increase bird or bat death. Other multi-criteria variables should be examined to meet the demands of investors, utilities, governmental agencies and environmentalists [13]. Joint decision-making could be improved by prior combination of different criteria, to create a flexible problem-solving environment for planners, and to allow users to conduct a sensitivity analysis to understand the influence of each variable and the model’s efficiency.

We can create an integrated GIS system incorporating MC modelling that has been developed with the help of analysis of several physical and environmental spatial databases to locate the most favorable locations for solar energy projects [5]. Different criteria have been selected and analyzed to represent the most suitable conditions for investing in solar energy projects. The equity payback period can be largely reduced while increasing the electricity rate, because saving more money on the annual cost of electricity will compensate for the cost of the solar PV system. Therefore, installing PV systems is greatly recommended in the countries that have high electricity rates [26]. When modelling such solar farms, it is necessary to properly analyze the number of sun hours, the range of temperature fluctuations and irradiance in order to maximize power generation capacities [13].

When establishing wind farms, it is necessary to avoid mountain summits, steep slopes, woodlands or dense populations. Ideal sites are close to roads and any existing power grid system. Multi-Criteria Analysis of a vector data model (discrete point, line, and polygon representations) often involves Boolean operators such as AND or OR [13]. An AND operator can result in inflexible solutions about whether a variable meets the criterion or not. An OR operator is very liberal as the results will be included even when a single variable meets the criterion. MCA in a continuous grid-based representation model (the raster data model) allows more trade-off among variables. GIS data model selection can lead to different optimal solutions. Hence, it is ideal to use a combination of data models to develop the best model.

The following variables influence wind speed and solar power generation, namely land cover, population density, federal lands, access to highways for maintenance and repair and availability of transmission lines. Three classes of land cover were created according to their suitability for development. Ideal locations contained short vegetation, such as steppe, shrubs, grasses, agriculture or barren lands, which would not impede wind or solar power generation. Areas that were not as appropriate contained sparse, but taller vegetation or wetlands, which would be difficult to develop due to their ecological importance. Non-ideal land cover contained pine, sub-alpine and aspen forest or other inaccessible, unstable areas such as dunes, bedrock, ice, cliffs, canyons, alpine tundra, developed areas and mines [13]. Federal lands such as National Parks, National Monuments etc., have to be excluded given that funded renewable energy projects may be difficult to implement in such areas.

A number of processing procedures have been performed in order to apply the multicriteria approach within a GIS environment [6]. Basically, Multi-Criteria Analysis aims to optimize spatial locations to meet a number of limiting factors. Hence, the input datasets consist of several geospatial databases. The acquired input data contains a Digital Elevation Model (DEM) for Jeddah and Makkah, the annual average of solar radiation map, and several topographic and remote sensing images. The first step in the data processing stage includes data manipulation, such as slope extraction from the available DEM, digitization of required datasets including the road and electricity distribution networks, and unification of geodetic datums for all raster and vector data types. It is necessary to evaluate and select the best location for utility-scale solar PV projects using Geographical Information Systems (GIS) and Multi-Criteria Decision-Making (MCDM) techniques [21].

2.2. Photovoltaic (PV) Technology

Solar photovoltaic (PV) technology is based on PV cells that permit direct conversion of solar energy to electricity. PV is an established technology from both a technical and an economic point of view [8]. PV is one of the fastest growing industries globally growing at an annual rate of 35-40%. It is being globally used to supply power to remote communities such as remote oil fields and gas-oil separation plants, cathodic pipeline protection, highway telephones and billboards, telecommunication towers, remote off-grid houses and resorts, community and irrigation water supplies, exterior home lighting, municipal park lighting etc. [10], There are diverse applications of solar PV systems: integrated systems, solar home systems, desalination plants and remote area pumps. Railing or bannister shadows, rooftop constructions such as rooms, air conditioning units, commercial shadows (taller apartments overshadowing neighboring houses), terrace covers (in villa type houses), satellite dishes and water tanks should be considered along with cultural aspects to find the final real utilizable area for PV installation [14].

PV technology can be classified into various categories such as PV based on crystalline silicon materials, including monocrystalline, polycrystalline, and gallium arsenide cells, thin-film solar cells based on cadmium telluride (CdTe), amorphous silicon, cadmium sulphide (CdS), or copper indium gallium selenide/ copper indium selenide materials, organic and polymer cells, hybrid solar cells, dye-sensitized solar cells, PV based on nanotechnology and so on [11]. These technologies differ in terms of efficiency and cost per PV module, but crystalline silicon materials are taking the lead in the market, with monocrystalline materials accounting for about 80% of the total PV market [30]. The efficiency of PV technology has improved considerably in the recent years.

A number of factors such as higher ambient temperatures, dust cover and humidity, as well as decreased solar irradiance reduce the efficiency of a PV module. It is therefore necessary to consider the performance ratio (PR) of PV systems, which is calculated as the difference between nominal efficiency and efficiency practically achievable [31]. The PR of modern PV systems is around 80-90%. PV technologies are implemented in two types, grid-connected and off-grid systems [29]. Grid-connected systems can be large-scale and in a distributed form and are much economic compared to off-grid systems. Off-grid systems may supply energy to a single consumer, or a number of consumers through a midi-grid with no connection to major electricity grid lines. Such off-grid systems provide the prospect of supplying power in remote areas while avoiding expensive investments in distribution and transmission systems [29].

The power produced by the PV panels is not only dependent upon its efficiency and input annual irradiation per surface area but also other factors like dust, shadow, cloud and malfunction [14]. Hence, the annual power generation of any region can be calculated using the formula in (1).

(1)

where:

Wg is the annual electric generation of the geographic location in Watts,

A is the area of module surface in square meters,

IR is the irradiation of the geographic location in W/m²,

E is the PV panel efficiency in percentage,

PR is performance ratio in percentage (the KSA ideal value = 0.75),

and L is the total loss in percentage.

The total loss is the sum of losses due to connection errors, the age of the structure, shading and weak radiation, temperature fluctuations, soiling or improper maintenance, inverter related issues, and any connectivity mismatches [14].

A thorough review of the present and future directions of solar energy studies in terms of different aspects, such as solar desalination, solar cooling, and PVs reveals many interesting findings [10]. Saudi Arabia has a considerably high level of solar energy potential that can be a part of the total energy network in the country and has a massive potential for exploiting solar energy. Saudi Arabia can hence be a leading producer and exporter of solar energy in the form of electricity, provided major penetration of solar-energy conversion is achieved. Saudi Arabia was among the first countries to invest in renewable energy research through major joint worldwide cooperation programs, where the Saudi government provided half of the funds needed, the other half of the funds being provided by some developed countries, such as the United States and Germany [10]. The availability of mountains in Saudi Arabia and islands in Bahrain is good for installation and generation of renewal energy sources. There exists a very high potential for the application of solar energy in Global System for Mobile Communications (GSM), desalination, road lighting in addition to cooling systems [10]. These systems can enhance the quality of life in these regions, through the delivery of modern social services. Renewable and energy-efficient technologies can meet a substantial portion of the energy needs of Saudi Arabia. Renewable energy, particularly solar energy, is an abundant resource in the country and holds huge economic promise. In the process of shifting new investment to these energy forms, numerous public advantages will be created, including enhanced environmental excellence, increased energy protection, and local financial development benefits [32].

Even though the Arab States of the Gulf region are leading in the global production of oil and natural gas, they need to take an active part in the development of technologies for exploiting and developing Renewable Energy Sources (RES) [10]. The use and development of solar and wind technologies could make a significant contribution to improving environmental protection and to guaranteeing continuing oil supplies in conditions of stability and security in the Gulf region. The use of renewable energies for desalination appears to be a sensible and technically established option for the emerging energy and water problems. In spite of worldwide research, the actual penetration of RES-powered desalination installations is very low [10]. More feasibility studies have to be conducted for hybrid systems. In this regard, the market penetration of these systems should be encouraged and facilitated by demonstrating the cost-effective and environmentally friendly solution to be provided.

The utilization of PV modules for grid-connected and as well as hybrid systems have been studied by the researchers at universities and the institutes in Saudi Arabia, with 3895 kW of PV installed capacity by the end of the year 2008. Solar radiation data are a fundamental input to solar energy applications, such as PV, solar-thermal systems and passive solar design, they should be reliable and readily available for simulation, design, and optimization and performance assessment of various solar technologies at any location. In this regard, for estimating the solar radiation in various cities of Saudi Arabia, different correlations have been developed by many investigators [10].

The installed capacity of a PV plant is 2 MW with 9,300 panels which occupies almost 11,600 m² of roof space can save 1,700 tons of carbon emissions and produces about 3,281 MWh of energy per year [22].

This research paper covers the suitability criteria for wind power plant installation in Jeddah based on seven data layers: wind speed, water, vegetation, proximity to urban built-up areas, Digital Elevation Model (DEM), proximity to transmission lines and proximity to roads. Practical uses of solar and wind energy in Saudi Arabia include lighting, cooling, water desalination, cooking, water heating, providing road and tunnel lighting, crop/fruit drying, operating irrigation pumps and meteorological stations, as well as traffic lights, road instruction signals etc., [10].

3. Analysis

Applications of solar energy in Saudi Arabia have been growing since the 1960s when the French established the first photovoltaic (PV) beacon at the small airport of Madinah Al-Munnawara [10]. Research activities were initiated with small-scale university projects during 1969, while systematized major research and development (R&D) works for the development of solar energy technologies were initiated by the King Abdulaziz City for Science and Technology (KACST) in the late 1970s. The Energy Research Institute (ERI) at KACST has conducted major research and development work in this field. Considering the importance of the need for exact measurements of solar radiation, the Saudi Atlas Project was initiated in 1994, with a joint project between the ERI and the National Research Energy Laboratory (NREL) in the U.S. Twelve locations in the following cities throughout the country were carefully selected: Riyadh, Sharurah, Gassim, Al-Jouf, Madinah, Jeddah, Al-Ahsa, Wadi Al Dawasir, Abha, Tabuk, Qaisumah, and Gizan [1]. All these stations are connected to a central unit for data collection and all the devices are calibrated on a regular basis, so they can extract reliable and accurate data. This has led to the capture of accurate surface solar radiation flux measurements to validate satellite-derived surface and atmospheric solar radiation flux measurements, related to the NASA Mission to Planet Earth component of the Earth Science Enterprise Earth Observing System (EOS) project to evaluate long-term climate trends based on measurements from EOS Terra Platforms [19]. KACARE has proven to be a center for renewable research and for co-coordinating national and international energy policy. It contributes to achieving sustainable development in Saudi Arabia through exploiting the science, research and industry of atomic and renewable energy for peaceful purposes [10].

The following maps and figures highlight the regions in Jeddah and Makkah of KSA suitable for implementing solar panels and wind farming with the help of digital elevation model.

3.1. Digital Elevation

Figures 1 and 2 illustrate the Digital Elevation Model (DEM) of Jeddah and Makkah cities. The DEM is extracted from the Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (ASTER GDEM) product. ASTER GDEM was developed by The Ministry of Economy, Trade, and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA). The first version of the ASTER GDEM, released in June 2009, used stereoscopic images collected by the ASTER instrument onboard Terra. ASTER GDEM coverage spans from 83° North to 83° South latitudes, encompassing 99% of Earth's landmass. From these figures, it is clear that Jeddah has relatively low elevation (373 m maximum) and smooth terrain while Makkah has higher elevation (933 m) and more diverse terrain.

Figure 1. Digital Elevation Model of Jeddah

Figure 2. Digital Elevation Model of Makkah

3.2. Landcover

Table 1. Jeddah Landcover Percentage

Freely available Landsat 8 images covering Row 169, Column 045 of World Reference System (WRS) for Makkah and Row 170, column 045 for Jeddah, dated December 2017, were downloaded from the NASA Earth Explorer portal. Landsat 8 Operational Land Imager (OLI) product consists of 11 layers, 15 m resolution for Panchromatic, 30 m for visible and Near Infrared (NIR) and 60 m for thermal infrared bands. After acquisition of the image, all the layers were stacked to make a Red Green Blue (RGB) color composite.

Later, subsets were extracted from entire scenes for the classification into four classes: Barren Land, Built-up, Vegetation and Water by using the supervised classification technique in Erdas Imagine 2014 software. Figures 3 and 4 show these for Jeddah and Makkah.

Figure 3. Jeddah Landcover

Figure 4. Makkah Landcover

The percentage of the area for each class is shown in the graphs: 65% for Barren land, the highest, to 1% for Water, the lowest, for Jeddah and 74% Barren land and less than 1% Water for Makkah. These classes will be subsequently used for Multi-Criteria Analysis to find out the wind power potential from remote areas within city boundary.

Table 2. Makkah Landcover percentage

3.3. Solar Radiation and Population Density

The solar radiation observed by Jeddah and Makah city are demonstrated in Figures 5 and 6, ranging from 25945 kJm-2day-1 (kilo Joule per meter squared per day) to 24585 kJm-2d-1 for Jeddah and ranging 25550 kJm-2day-1 to 24662 kJm-2day-1 for Makkah - and hence higher for Jeddah. The city or built up area receives the lowest radiation while barren land areas on the northern side receives the highest radiation.

Figure 5. Comparison of Solar Radiation and Population Density in Jeddah

Figure 6. Comparison of Solar Radiation and Population Density of Makkah

However, scope of the present study is to install Solar Photovoltaic (PV) panels over the rooftops with in study area. Though radiation there is are not the highest it will help to save on transmission costs as it is good to have rooftop PV panels installed in the areas occupied by people.

3.4. Wind Speed

Figures 7 and 8 depict wind speed in meter per second for Jeddah and Makkah respectively. It is clear that Jeddah, being a coastal city, has a high wind speed, i.e. 3.6 m/s and hence has more potential for wind energy production. This hypothesis can be verified by looking at Figure 7’s legend where red denotes the highest speed and all the coastal areas are in red.

Figure 7. Jeddah City Wind Speed

Figure 8. Makkah City Wind Speed

If we compare Makkah and Jeddah with respect to the wind energy potential, Jeddah’s is greater. Wind energy potential data of 30 seconds has been downloaded from Version 2 in GeoTiff format, clipped and processed in ArcMap 10.2 software.

3.5. Solar Radiation

Figures 9 and 10 contain maps showing the solar energy potential within the cities of Jeddah and Makkah respectively. The solar energy potential of each city has been calculated by using the ArcMap 10.2 Area Solar Radiation Tool that enables mapping and analysis of the effect of the sun over a geographic area for a specific period of time. In this case, the tool has been used to calculate solar energy potential for the year of 2018 against each city. The diagrams show how much energy could be produced through solar panel rooftop implementation. This leads to a calculation of solar potential but does not aim to provide suitability analysis. The solar potential depends on the heights of roofs and solar radiation.

Figure 9. Jeddah Solar Energy Potential

Figure 10. Makkah Solar Energy Potential

3.6. Data Layers

Figure 11 presents all the data layers for Jeddah, Land use classes, main transmission lines and road networks that are used in Multi-Criteria Analysis to find out wind energy potential and suitability.

Figure 11. Jeddah Data Layers

3.7. Jeddah Wind Farm Site Suitability

Figure 12 presents the final output of Multi-Criteria Analysis for the location of site suitability for wind energy turbines installation in Jeddah. The criteria adopted against each data layer are summarized in Table 3. Some areas were restricted from analysis such as those covered by Water and Vegetation. Similarly, the areas within 500 m of Built-up areas, or within 200 m of transmission lines were also restricted. Moreover, areas of potential Built-up development and transmission lines were not suitable either. It is worth mentioning that wind energy turbines can only be run and installed in a location where the wind speed is equal to or greater than 3 m/s. Unfortunately, the wind speed in Makkah is not high enough, so there is no place in Makkah suitable for installing wind energy turbines.

Table 3. Suitability Criteria for Wind Energy Plants installation in Jeddah

Figure 12. Jeddah Wind Farm Site Suitability Map

Hence, careful and thorough data-based analysis and research reveal that Jeddah is suitable for both PV solar power generation and wind power generation, while Makkah is suited for solar installations only as the wind speeds in Makkah are too low.

4. Discussion

The location of the KSA is well-suited for generation of power through renewable energy sources, considering the availability of a vast area of uninhabited land and the extreme temperatures that enable generation of PV solar energy. Consequently, it has enormous potential for exploiting both solar and wind energy, with a tremendous potential for generating over 50% of its power requirements by exploiting renewable sources of energy.

It is necessary to come up with a simple and efficient model that can be easily adapted to numerous geographical areas, taking into consideration the fact that the currently installed PV solar units have large expansion opportunities in many geographical areas [23].

The Multi-Criteria GIS model used in this study has proven very useful for identifying the most appropriate sites for solar and wind farms elsewhere in the KSA - in addition to the ones it has already located in specifically Makkah and Jeddah.

Several technical and economic criteria have to be taken into account in relation to any proposed target area. Technical criteria include those such as its levels of solar radiation, the nature of the slopes of its terrain, and the distance of the proposed installed power unit from the electrical distribution network. Economic criteria are important for making optimum use of resources to make the unit cost-effective. They include the distance of the proposed installation from roads, the availability of coastlines in the area and the distance of the unit from them, the proximity of cities to the area and the population of those cities, and the availability and accessibility of airports in nearby areas. Additionally, there is the need to consider the distance of protected areas from the installation site.

The Area Solar Radiation Tool, which can be used for calculating the insolation across the entire landscape, reveals that installation of renewable energy units in the cities of Jeddah, Makkah, Riyadh, Makkah Al-Mukarramah, and the Eastern region can produce more than 60% of the total estimated power generation for the KSA, but to achieve this, there is a need for appropriate policies and incentives in place to promote the take-up of PV in residential buildings.

If major penetration of solar-energy conversion was achieved, Jeddah and Makkah can potentially be leading producers and exporters of solar energy in the form of electricity, as they have an immense natural potential for solar power generation.

The Multi-Criteria GIS model can also be used to decide which other geographical areas are best-suited for the production of PV solar energy or wind energy units in the KSA. By this means, studies have revealed that the cities of Dhulum and Arar are potential sites for off-grid, remote wind power generation units, and have also proved the feasibility of using grid-connected wind power generation units to partially power the two coastal cities of Yanbu and Dhahran [9].

Additionally, it has been observed that Saudi Arabia has an edge over many other locations in that it has a vast unpopulated, deserted land area with a long coastline free from any man-made obstacles and thus it presents a huge potential in exploring opportunities in wind power generation.

It is necessary to ensure that a single statistical measure is not used as the basis for deciding on the geographical locations best-suited for installation of solar or wind energy installation units. It is necessary to consider multiple criteria that consider the costs involved and the need to avoid any issues in the future. Such thorough research will enable avoidance of unprecedented hassles during or after installation [31].

By this means (Multi-Criteria rather than Single-Criterion) it has been found that most of the areas in the KSA are promising for solar energy harvesting with variable suitability index.

This is exactly what was done in our study to reveal that Jeddah has higher potential over Makkah for wind power generation as it is a coastal city with high wind energy potential; that in actual fact, Makkah is unbefitting for wind power generation given its the low wind speeds; and that both Jeddah and Makkah are highly suited for installation of PV solar panels for economic and environment-friendly power generation.

Janke also used GIS overlay techniques to examine the relationship between land cover classes and solar and wind potential data [13]. High elevation sites have the strongest winds since these are exposed surfaces near mountain or ridge summits, whereas Federal lands have low wind speed. Wind potential scores for National Parks and Monuments corresponds to a National Renewable Energy Laboratory (NREL) ranking of moderate to poor. Inter-mountain basins and Indian Reservations have the greatest potential for solar development based on NREL solar data [13]. Overall, mean NREL solar scores are high for all land cover categories, indicating that there is slight variation in insolation received over much of the state [17].

The multi-criteria GIS wind model suggests that wind farms should be located in the more densely populated parts of the country, providing a renewable energy source for areas that can directly utilize the generated power thereby reducing the cost of transmission. The PV panels can be designed optimally to provide a plant with a 12 kW of total capacity. Analysis of this sort of installation using RETScreen software [26,27] indicates that the equity payback period is 14.1 years. The median cost of electricity from the electric grid was set at 8 cents/kWh based on the electricity tariffs in the KSA with a reduced equity payback period of around 8 years. Thus, the increase in the electricity prices has a noteworthy and optimistic effect of reducing the project payback period. The electricity tariffs have a significant effect on the equity payback period, which decreases by 40% when the rate is doubled. Furthermore, the reduction of greenhouse gas emissions is around 70 t CO2 [25]. The trend in Saudi Arabia has seen great progress in exploiting its attractive solar energy and wind energy potential as an alternative source of energy. Solar panels placed in Najran city produced the highest energy across the Kingdom in three different configurations.

Analysis of yet another scenario with partial power switching was carried out for the sake of comparison. In this situation, the power demand was observed to be met by a combination of solar PV (contributing 27%) and grid electricity (contributing 73%). The equity payback period is significantly increased to 21.71 years, while the reduction in greenhouse gas emissions is a minimum of 23 tCO2 [25] These results make it obvious that installation of solar photovoltaic systems in the countries that have high electricity rates, considering the greenhouse gas emission reduction for the sake of protecting the environment and also in terms of economic feasibility and viability is recommended.

The maps produced by this current study would be very helpful for the identification and installation of renewable energy units in the cities of Jeddah and Makkah.

5. Conclusions

The global green movement and various international policies designed for the sake of a greener environment have continuously emphasized the need to focus on cheaper renewable environmentally-friendly sources of energy. Wind energy and solar PV power seem to be such obvious green choices for renewable energy for developing countries considering that they are very environment-friendly. Production of power from wind resources and the sun would assist in meeting the energy demands locally, considering that electric power supply in remote rural areas is capricious and mostly insufficient. They can be exploited locally in a decentralized approach in rural areas for applications such as pumping water systems for crops and cultivated areas. Either wind-driven electricity generation or solar PV electricity generation can be utilized as a stand-alone system and also to supplement the regional grid supply during peak hours.

This study offers a methodology and provides for an intelligent decision-making process to those interested in establishing PV solar and wind farms in the study area. This study provides a great scope for future research and expansion works in the renewable energy resources sector. Saudi Arabia has an immense natural potential for solar power generation and economic enticement to develop renewable energy to meet the domestic demand for electricity. The swift development of solar energy technology has made it the most promising substitute for conventional energy systems in the recent years. The research concludes that KSA has a lot of potential for using solar and wind energy. Using the Multi-Criteria GIS model, one could identify the sites suitable for both solar and wind farms. The KSA could prove to be a significant producer of solar energy to generate power and electricity once proper penetration in solar-energy conversion can be attained. Wind energy potential is higher in Jeddah than Makkah because the former is a coastal city with high wind speed.

In relation to Makkah and Jeddah, the research concludes that Makkah is more suitable for solar energy generation while Jeddah is suitable for both wind and solar power installation.