Reducing the Highway Networks Energy Bills using Renewable Energy System

Jordan has significant renewable energy potential due to its remarkable geographical location and climate conditions. This potential elevates engaging several innovative renewable alternatives in energy development, which may efficiently minimize the excessive import of traditional energy sources. The objective of this research is to study the potential of utilizing clean and affordable solar energy along roadways such as Jordan’s Desert Highway-15 to be in line with the United Nations Sustainable Development Goals (UN-SDG’s) by installing selected solar panels that possess adequate friction and the ability to allow solar radiation to reach the solar cells, in addition to allowing the load to be bypassed around the cells. The shoulder of the highway, with a length of 315 km and a width of 3.0 meters, has been exploited in order to supply the neighboring areas with energy for those roads, particularly those paved roads, which are poorly lit at night. Furthermore, this study provides direction and guidance concerning the structural performance of non-traditional pavement materials, which are a form of subgrade or pavement reinforcement. The performance of a prototype board on a variety of structural bases has also been evaluated. Overall, this paper found that it is possible to design a solar road panel to withstand traffic loading and that the concrete structural base allows for a significant improvement of the analyzed prototype design, especially in countries with limited energy sources and dependent on imports such as Jordan.


Introduction
The energy sector is one of the most important sectors that plays an important role in economic prosperity and social development, improving the quality of life for citizens.Energy consumption is growing at a rate of approximately 3.1% in Jordan [1], which imports today 91% of its needs to generate the necessary energy.Reliance on fossil fuels from oilexporting countries affects the wheel of the economy and makes it dependent on other countries and hostage to the fluctuation of oil prices.Consequently, these factors affected the movement of oil transportation, such as the embargo that occurred at the time of the Corona epidemic, paralyzed most sectors, and played an important role in oil prices.According to these data, the importance of this research has become essential and urgent, which makes alternative energy a priority for Jordan through the implementation of environmentally friendly renewable energy technologies with reasonable prices [2].
Based on the general analyses that were performed by the researchers, this research work sheds light on the feasibility of renewable energy-related equipment in road construction.Jordan has invested nearly $1.7 billion over the last five years, with a relatively low return on investment compared to other middle-income countries.Figure 1 shows a flow chart of the research methodology.

Literature Review
Renewable energy is becoming increasingly popular to reduce energy bills and manage the ever-increasing demand for electricity.In particular, it is being used to help power highway networks across the country.With the use of solar panels and other renewable energy sources, we can create an artificial control system to better manage our energy consumption.By optimizing the integration of renewable energy sources into the electric grid, we can achieve a more sustainable energy infrastructure and reduce our dependence on non-renewable sources.The use of solar energy has been growing rapidly due to its reliability, sustainability, and renewability.Photovoltaic pavement and solar roads are some of the latest inventions that aim to revolutionize the use of solar energy.These technologies offer the possibility of harvesting solar energy on the go, for example, while driving or walking.Utilizing these technologies can significantly reduce our dependence on fossil fuels and decrease our carbon footprint.The solar cell is the main electrical element of the photovoltaic coating.It is based on the photoelectric effect, first proposed by Becquerel in 1839 [5][6][7].
A solar cell consists of a P-type and N-type semiconductor, while a P-N junction is formed at their boundary [8,9].When a solar cell is exposed to sunlight, electrons receive energy from photons and move towards the N-type region, making it negatively charged.Accordingly, the holes will move towards the P-type region, making the P-type region positively charged.Thus, the electromotive force is generated on different sides of the P-N junction.When connected to external loads, direct current will be observed.The ideal electrical characteristics of silicon solar cells can be described by a five-parameter model based on the equation of a single diode [10].The direct current is then converted to alternating current through the inverter.Part of the electricity is intended for the operation of the photovoltaic coating module itself, and the remaining part will be stored in a roadside battery pack or transported to the grid [11].Solar energy plays a vital role in the energy system around the world.At the same time, since most roads are exposed to sunlight, the collection of solar energy has a high degree of consistency with the road network system, the form of use of which can be divided into three categories: solar thermal systems [12][13][14], thermoelectric systems [15], and photovoltaic systems [16].
An asphalt solar collector converts solar energy into heat energy through a working fluid in an underground pipeline.However, such a huge pipeline network system makes it difficult to build or maintain.When replacing pipes with drainage asphalt, porous layers can also be considered as a type of solar collector.However the low structural strength and poor permeability of asphalt are its main disadvantages.In addition, the need for auxiliary heat storage units will dramatically increase the cost of the entire solar thermal system.Based on the See Beck effect, a thermoelectric generator can generate electricity when there is a temperature difference between two thermoelectric materials.The thermoelectric system, mainly limited by its low energy conversion efficiency, is also strongly influenced by the local temperature gradient of the layer.In contrast, the photovoltaic system is technically mature with relatively high efficiency and low cost at present, accounting for approximately 3.4% of China's electricity generation in 2020 [17].Therefore, it is an ideal form of solar energy harvesting technology combined with roads.Some researchers have put forward a project that combines a photovoltaic system with a noise barrier [18] or arch [19] along the highway.Despite the ease of installation or dismantling, the system output largely depends on the area of the barrier or arch itself.To solve this problem, the concept of photovoltaic (PV) pavement appears [20,21].Modified photovoltaic modules are considered a single part of the road structure, equipped with the integral functions of generating electricity and ensuring the movement of vehicles.The main advantage of this technology is the absence of additional occupied land.It can be foreseen that the development of photovoltaic coatings will bring huge benefits in the economic and environmental fields.According to previous studies, large-scale asphalt pavement is considered a significant factor in the urban heat island effect, but photovoltaic pavement can effectively mitigate this phenomenon [22].In combination with various energy storage technologies [23], such as pumped storage [24], batteries [25], and super capacitors [26], its overall performance can be further improved.At the same time, various new photovoltaic road technologies, such as snow-melting wireless charging and unmanned technologies [27], are expected to be integrated in the future to achieve a more sustainable and intelligent transportation system.
Roadways are a massive spatial resource that can be fully utilized by photovoltaic (PV) pavement, which combines established solar power generation technology with conventional pavement features.Despite the work completed by multiple organizations towards the development of this concept, questions exist about the viability of these panels as a structural pavement surface [28].The development of solar collector pavement technology has made significant strides, and this trend's various technologies are grouped according to how they might be used in urban settings.The characteristics of each application and the current obstacles that might prevent the solar pavement approach are listed [29].
Table 1 shows the results of more than 450 articles that were analyzed as part of the previous research studies.Keywords in the below table were used to collect and search for information.Publications related to the research topic on the use of renewable energy sources near the road were selected from each group.When searching for topics on renewable energy sources in the databases, there were a very large number of retrievable results.However, a literature search related to Jordan, especially linking renewable energy systems to the development of highways, has changed the values (decreased) [30], which indicates the importance of research in this field.

Key Word
All Road Highway Street Noise Barrier

Solar Energy
Solar electromagnetic radiation is defined as high-energy radiation.Studies showed that when it passes through the nucleus from the sun, it reaches the outer limit of the atmosphere.For an estimated energy flow of about 173 pW [31], it is estimated to be 30,000 times the power of all man-made devices [1].Moreover, about 23% of this radiation reaches the Earth's surface, forcing the oceans to evaporate.In addition to the wind blowing or with the episode of photosynthesis, there is a possibility for solar radiation energy to stay in its unchanging form; moreover, in the form of wind, water, and biomass energy, it is expected that its use, direct or indirect, would produce heat and electricity [32].

Expected Lifetime of Solar Panel System
Manufacturers of photovoltaic cells generally issue warranties on performance in terms of the power output, which they will continue to deliver when in service.In most cases, these warranties guarantee good performance for a period of twenty to twenty-five years [33].This period may be conservative, as some of the earliest solar electric panels, made about 35 years ago, are still producing energy today.The few examples of current performance warranties are as follows: (a) Siemens solar modules are designed to withstand the toughest environmental conditions and are characterized by their long service life.Siemens solar modules are covered by a 25-year limited warranty on power output, "your guarantee of trouble-free solar power generation", (b) Kyocera offers a 25-year warranty, and their quality assurance system ensures that their multi-crystal modules exceed the US government specifications for tests involving thermal cycling, thermal shock, thermal/freezing and high humidity cycling, electrical insulation, hail impact, various mechanical and wind loads, salt mist, light and water exposure, and field exposure, (c) All products manufactured by BP Solar are individually tested and labeled.A 20-year performance warranty guarantees that the solar module will continue to deliver a minimum of 80% of its rated power, with all modules rated at 40w and above.Several modules with higher power output have a 25-year performance warranty; (d) All Astro Power modules carry a 20-year limited warranty and are designed and manufactured to meet all relevant international safety and performance certifications; and (e) Evergreen Solar and Uni-Solar also offer a 20-year limited power warranty on most photovoltaic modules.Uni-solar rigid panels are framed in anodized aluminum, which is highly resistant to corrosion.It should be noted that the performance warranties given above are only a few selected examples, and there are many other manufacturers, some of which may offer a longer warranty.For the purpose of whole-life costing, the assumption of serviceability over 25 years is not unreasonable.After 25 years, the modules may well continue to function, although some reduced efficiency should be assumed [2,34].

Jordan Road Network
Jordan is known to be a passageway country for various merchandise and services to different countries, such as the Palestinian territories and Iraq [35].This permits Jordan to maintain a well-developed transportation infrastructure internationally.According to the World Economic Forum's Index of Economic Competitiveness, Jordan was classified as one of the highest-ranking countries in developing countries and as having the 35th best infrastructure in the world.Moreover, it ranks way higher than some developed countries like Italy, Ireland, and Greece, as well as it was only two places behind the United Kingdom.The Ministry of Public Works and Housing manages the road network in Jordan, as well as the establishment and maintenance of road networks (main, secondary, rural, and agricultural) outside the organization's boundaries (external roads).Meanwhile, Greater Amman municipalities administer areas within planning boundaries (for internal roads) [3,36].
Roads in Jordan are classified into main roads with a width of not less than 40 meters that link cities, large residential communities, and border crossings.Secondary roads are characterized by having a campus width of not less than 30 meters, being a link between towns and villages, and connecting with main roads.Rural roads, on the other hand, are those with a campus width of not less than 20 meters that link villages and agricultural areas and connect to main or secondary roads, as shown in Figure 2 (Jordan road map).The road network has developed greatly in terms of design, construction, and maintenance.In the 1950s, the total lengths of the paved network were 895 km for main, secondary, and rural roads, and at the end of 2009, it became about 7,999 km in length [17], with the main roads reaching a length of 3,281 km, secondary roads with a length of 2,190 km, rural roads with a length of 2,491 km, and Route 15, or Desert Road, a line connecting southern and northern Jordan at a distance of 315 km.It starts from Aqaba in the south, crosses Ma'an Governorate, and extends into the Jordanian desert to the east of all the southern cities and villages until it meets Route 35 towards Amman, as shown in Figures 3 and 4. The Dead Sea Road, or the Royal Road, is a highway linking southern and northern Jordan at a distance of 380 km.It starts from Aqaba in the south, crosses Wadi Araba, and aligns with the Dead Sea and the Jordan Valley until it reaches the western outskirts of Irbid in the far north of the country.The history of this road goes back to ancient times.It was first built in the time of the Romans after they occupied the region, and it was part of the "Hadrian's Road", which was launched on the historic royal road, one of the oldest trade routes in the world [37].This express line was established as part of a comprehensive Jordanian plan over 25 years to connect all parts of the country together and create ring roads around major cities such as Amman, Irbid, and Salt.The value of the project upon completion is expected to reach approximately $1.8 billion [38].The Amman Development Corridor, or Route 45, also called Route 100, is a four-lane highway that forms part of a future circumferential road that runs around the Jordanian capital, Amman.It was established in 2017, east of the city, with the aim of linking it with major cities, easing traffic congestion within the capital and its suburbs, and reviving the surrounding poor areas and villages.This road is considered a vital artery for transportation in Jordan and one of the main roads in Amman, as it was implemented according to international standards.The corridor connects the desert road near Queen Alia International Airport with the Azraq Expressway (Route 40) towards the Iraqi border and ends with the free zone in Zarqa with a length of 41 km and side services with a length of 50 km.This distance is the currently implemented part of several parts within a project called the Ring Road, which extends around the capital with a total length of 116 km and was implemented in three bids and financed by three financing bodies, where its construction cost amounted to 160 million dollars.After all, utilizing technology alone cannot convey business outcomes without assuring that the adopted procedure is proactively managed to guarantee that the organization gets the results it expects [38,39].The development of highways in Jordan is growing, which demands a necessity for clean and inexpensive energy sources.Table 2 shows the road network in the Kingdom per governorate [24].

Pavement Design
The desert road in Jordan is designed using flexible pavements (high-type pavement), which have wearing surfaces that adequately support the expected traffic load without visible distress due to fatigue and, at the same time, are not susceptible to weather conditions, in Jordan most of the pavements are made of asphalt concrete pavements which consist of aggregates, mineral fillers, some additives and bitumen.Asphalt concrete pavements can withstand substantial loads and environmental conditions for a reasonable time and various forms of admixtures have been used to prolong the serviceability life of pavements by alleviating temperature and environmental effect [40][41][42].These pavements consist of a bituminous surface underlay, a layer of granular material, and a layer of a suitable mixture of coarse and fine materials [43], as shown in Figures 5 and 6.

Solar Road Panel Design and Construction
Literature shows that the main structural design requirement is the need for the solar road panels to have the capacity and ability to tolerate the cyclic loading from vehicles [44].In the field, these panels would be installed on a structured base, on compacted granular materials, or on a paved asphalt or concrete structure, as shown in Figure 7.These together provide greater support to the panel and should be considered important during material selection.

Figure 7. Components of solar roads
In addition, another major structural requirement for this panel is to have the surface capacity or ability to provide adequate friction for vehicles to safely travel through it.However, it is considered the most important challenge because the surface needs to be transparent enough to allow solar radiation to reach the solar cells rooted within the structural layers (Figure 8), in addition to other sorts of texturing that could damage or impair light transmission in the case of an improperly designed situation [45].Literature shows that a solar road panel component design (Figure 9) needs to allow the load to be bypassed around the cells according to the updated and current standards of high-efficiency solar cell composition that are made from brittle silicon wafers.This can be accommodated by cantilevering the transparent layer over the solar cell compartments.Nonetheless, to avoid any deflection and extra load on the solar cells, it is necessary that the transparent layer be as strong as possible [15].

Figure 9. The components of a solar road panel [1]
Having a weatherproof ability of the panel is another condition that needs to be considered during the design period.This condition is important to have for both structural and electrical reasons because the penetration of water and contaminants would destroy the physical or structural integrity of the composite panel as well as damage the implanted electronics.Generally, the electrical design requirements mostly focus on the exposure of the photovoltaic cells to solar radiation as well as the physical robustness of the electrical circuit formed between the individual cells.One of the major concerns for photovoltaic panels is shading since cells that are not exposed to radiation will operate properly as part of the electrical circuit; consequently, rapid panel performance degradation will result.Moreover, the fact that the design requires the solar cells to be recessed from the transparent layer means that special, tremendous care is needed in order to prevent the internal shading of the solar cells by avoiding the ledges of the structural layers.Additionally, the removal of the collected debris on the surface through street sweeping, rubber removal, or other processes is needed, especially if the overall radiation reaching the solar cells begins to show a certain effect [46][47][48].

Photovoltaic Cell Selection
The monocrystalline silicon photovoltaic cell is presented in various sizes to satisfy the required needs.The best size for power generation applications that can be produced efficiently is 150 mm 2 of the solar cell.However, this 150 mm 2 is considered a large area for the suspension of the transparent material; therefore, the use of a successive size down of high-efficiency solar cells is preferable, namely the 125 mm 2 solar cell.This provides more surface area than the panel to generate electricity, while at the same time leaving enough space to transfer the load around the cell [49].The 125 mm 2 cells have been shown to more appropriately fit the need than the 150 mm 2 cells, as described in this section.Figure 10 shows the project's solar cell dimensions, all in millimeters.

Cell Interconnection
The best way to bond between the solar module's cells is to solder (fuse) a tin-lead strip to the rails above each cell and below the adjacent cell.This works superbly in conventional unit manufacturing because of the low load on the joint, where the cells are adjacent to each other, and with merely slight cell separation.However, these conditions are not obtainable in a solar road panel design.It is important to ensure a strong connection between the carrier cell tape and the electrical conductor; a welded tape is necessary; however, the tape is extended as a small tab of the solar cell, and an electrical wire is bonded or fused between the welded tabs of the inline adjacent cells [39].It is preferable to use a 22-gauge wire for this application for the reason of the expected electrical load in the unit.This cabling or wiring is made according to the layout shown in Figure 11.

Transparent Layer Design
Consequently, under these previously mentioned conditions, the uppermost load condition would get the load evenly distributed from any passing tire, assuming a pressure of 470 kPa.This information has been applicable to the established strain correlations, using the low-bending theory as shown in Table 3. Figures 12 and 13 show solar roadway prototype panels.Literature shows that the occurrence of a phenomenon known as 'heat islands' leads to an increase in the urban temperature besides the energy demand for cooling, as well as aggravating and deteriorating the comfort and environmental situations in the urban environment.More specifically, solar irradiation during the summer can heat up asphalt pavements up to 343 K because of their heat-absorbing properties.The alleviation of the latter thermal energy from asphalt thermal collector pavements seems to be probable.The routine use of these asphalts and pavements facilitates lessening the surface temperature of the urban skin by around 284 K and, consequently, reducing the sensible heat released to the atmosphere as well as decreasing the environmental effects [50,51].
As mentioned beforehand, the materials and design of construction produce an effective system.The analysis aimed to evaluate how feasible it is to use solar pavements as an enduring long-term energy producer to provide electrical energy through the introduction of an innovative energy generator pavement design.The study projected a system that includes several layers of solar cells in addition to an electrical system on the asphalt layer, which meets both the electrical energy requirements and the safety requirements of the road.The general broad design includes a transparent and permeable absorbent surface allowing sunlight to pass through, in addition to the solar cells with their connections and a base to transfer the load to asphalt, as shown in Figures 14 and 15 [37][38].The main goal of this design was to perform a structural analysis, build a finite element model that duplicates the structural results, and subsequently apply the model to various subgrade, pavement, and structural-base models to determine the optimal characteristics of a solar road panel for use in different settings such as roads, parking lots, and similar infrastructure [52][53][54][55].This would refine the specific glass thickness requirements, solar cell spacing, interconnection routing, and other design parameters as discussed in this report and, moreover, determine the service life of a solar road panel.

Conclusions
This research work reviewed important considerations during different applications of solar collector pavement technology.Thermal and electrical collector technology is employed to cover the thermal and/or electrical needs of the urban environment.Even though the potential claims that it is adequately promising, the large-scale pilots for the past 5 years are quite few.It looks like further research should be conducted with the aim of studying new ways of increasing the efficiency of the systems through different approaches such as new designs, novel implementation, and advanced material science.By securing not only efficiency but also the economic viability and robustness of the system, solar pavement technology can become conventionally mainstream in the future.From this research, the following conclusions can be drawn:  The combination of the rigidity and the transparent layer materials of the solar cells is very important in order to minimize the strains that the solar cells are subjected to.
 Roads cover around 0.5% of the earth's surface.It is noteworthy that using this technology on public roads, residential streets, driveways, and parking lots will provide us with clean and inexpensive alternative energy.
 Using the solar roads would make it feasible to light roads and surrounding areas with barely minimum cost.
 Using solar panels or solar photovoltaic cells provides a facility for heating the roads, particularly in cold regions, in order to melt the ice and snow.
 Solar panels could be used for traffic safety purposes in terms of alerting drivers by operating alarm devices that warn drivers of any dangers they might encounter on the road.
 The use of renewable energy resources plays an important role in the future carbon-free energy supply for various applications such as heating, electricity, transportation, and safety.

Figure 1 .
Figure 1.Flow chart of the research methodology

Figure 8 .
Figure 8. Exploded view of a conceptual solar road panel [45]

Table 2 . Roads network in the Kingdom per governorate during the period (2018) Agricultural roads (Km) Village roads (Km) Secondary roads (Km) Main roads (Km) Agricultural roads (Km) Village roads (Km) Secondary Roads (Km) Main roads (Km) City Provinces
Total road lengths (km)