Global warming has risen as a primary global concern. It has stimulated interest in the development of the renewable energy (RE) system. Studies demonstrated that the regions of Gulf Corporation Council (GCC) such as Bahrain, Kuwait, Oman, Qatar, Kingdom Saudi Arabia (KSA), and United Arab Emirates (UAE) face several changes in the form of uncertain weather conditions. Given the strategic location of the Gulf States and its enormous oil and natural resource, it is characterized to hold potential for using renewable energies such as solar, wind, and geothermal energy for meeting the power production needs. Previous studies suggested that energy consumptions such as crude oil and fossil fuels are the major sources of providing economic benefits to the states. The high oil price, deterioration of the financial markets, and incident of Arab Spring has shifted the working at a national and international level, making it important in using RE resources to generate excessive energy. The primary focus was to explore the scope of energy efficiency (EE) and the use of solar, wind and geothermal energy resources given their proliferation potential for the GCC region. The review assessed the energy and electricity consumption trends in the region. Also, it discussed the problems related to the effects of dust accumulation on devices. Moreover, it also highlighted the use of various computer interfaces that demonstrate the feasibility to use various RE technologies. Further, it draws conclusions and recommendations based on the issues. Abbreviation: A/CAir Conditioning AGHE Air-Ground Heat Exchanger CF capacity factor CPVC oncentrated Photovoltaic CSP Concentrated Solar power DHI Diffuse Horizontal Irradiance DNI Direct Normal Irradiance DEWA Dubai Electricity and Water Authority EE energy efficiency EER energy efficiency ratio GHI Global Horizontal Irradiance GHE Ground Heat Exchanger GSHPs Ground Source Heat Pump system GCC Gulf Corporation Council ISCC Integrated Solar Combined Cycle IRENA International Renewable Energy Agency KAUST King Abdullah University of Science and Technology KSA Kingdom Saudi Arabia MPPT Maximum power point tracking NPV net present value OECD Organization for Economic Co-operation and Development PV photovoltaic PV/T photovoltaic/therma lR Erenewable energy RC RANKEN cycle SWH solar water heater SWOT strength, weakness, opportunity, and threat TOU Time-of use TPES Total primary energy supply UAE United Arab Emirates VAV Variable Air Volume VGSHPs Vertical Ground Source Heat Pump system

Benefiting from renewable energy (RE) sources is an economic and environmental necessity, given that the use of traditional energy sources is one of the most important factors affecting the economy and the environment. This paper aims to provide a review of hybrid renewable energy systems (HRESs) in terms of principles, types, sources, hybridization methods, cost of unit energy produced, and applications. The works were reviewed for HRESs with and without energy storage. The results can be summarized as follows: It is noted from the studies that Greenius, SAM, HOMER, and TRNSYS were often used in simulating, designing, evaluating, and optimizing these systems. There is often a difference in the economic and environmental indicators between different projects due to the type, fraction, price of energy and components, and efficiency of RE sources. All the studies showed that there are environmental benefits from hybrid systems, not only compared with conventional energy systems but also with RE systems with a single source. All of the related studies showed that hybridization between biomass and concentrated solar energy (biomass-CSP) presents a promising option for producing thermal energy and electricity, and this option also provides a solution for environmental problems related to waste biomass, such as municipal solid waste and wastewater and many industrial wastes, and provides high-quality fertilizers for agriculture. In addition, the multi-use of HRESs increases the economic and environmental benefits, which makes these systems more sustainable. There are various options available for hybridizing RE sources, particularly in the context of energy source integration. The selection of the appropriate options depends on several factors: system type, size of the system, type of energy needed, availability and prices of RE sources, technical knowledge, and experience in operation and maintenance. Several parameters play a crucial role in evaluating HRESs: system makeup and capacity, the fractions of RE in the overall energy produced, efficiency, investment, and energy costs, technical knowledge requirements, and environmental effects.

Using phase change materials (PCMs) in energy storage systems provides various advantages such as energy storage at a nearly constant temperature and higher energy density. In this study, we aimed to conduct a numerical simulation for augmenting a PCM’s melting performance within multiple tubes, including branched fins. The suspension contained Al₂O₃/n-octadecane paraffin, and four cases were considered based on a number of heated fins. A numerical algorithm based on the finite element method (FEM) was applied to solve the dimensionless governing system. The average liquid fraction was computed over the considered flow area. The key parameters are the time parameter ($100 \le t\le 600 \mathrm{s})$ and the nanoparticles’ volume fraction ($0\%\le \phi \le 8\%)$. The major outcomes revealed that the flow structures, the irreversibility of the system, and the melting process can be controlled by increasing/decreasing number of the heated fins. Additionally, case four, in which eight heated fins were considered, produced the largest average liquid fraction values.

Amid escalating energy demands and growing environmental concerns, educational institutions are transforming into crucibles for enduring innovation. This comprehensive review summarizes the complex relationship between Energy Efficiency and Renewable Energy Systems (EERES) within the sphere of educational institutions. By instituting Energy Efficiency initiatives, organizations can curtail energy consumption, resulting in substantial cost savings and a diminished carbon footprint. Moreover, the integration of renewable energy technologies empowers the localized generation of electricity, ensuring a reliable and sustainable energy source. Noteworthy in this study is the novel linkage of energy usage indicators to the comfort levels experienced in university settings during both summer and winter. An exhaustive examination of consumption indicators, rooted in the diverse activities on college campuses, further enriches the investigation. Beyond technical intricacies, this study scrutinizes the economic viability, environmental advantages, and educational significance of these integrated systems. Embracing EERES not only aligns with the commitment of educational institutions to environmental stewardship but also establishes a paradigm for broader communities. These institutions aspire to exemplify sustainable practices, influencing larger societal behavior positively. Various factors, including the institution’s type, energy source, facility nature, building construction, internal activities, weather conditions, and user behavior, wield substantial influence over energy utilization. This study offers a nuanced exploration, shedding light not only on the technical dimensions but also on the broader economic, environmental, and educational implications of adopting EERES.

Lately, with the growth in energy consumption worldwide to support global efforts to improve the climate, developing nations have to take significant measures. Kingdom of Saudi Arabia (KSA) implemented meaningful policy actions towards promoting energy efficiency (EE) in several sectors, especially in the building sector, to be more sustainable. In this paper, various EE measures and solar energy prospects are investigated for the residential sector, in two locations in the middle region of the KSA. An energy performance analysis of pre-existing residential buildings with an overall design is performed using simulation programs. However, installing EE measures in the building envelope is important to achieve an efficient sector regarding its energy consumption. The findings showed that applying EE measures for the building envelope, walls, roof, and windows should be considered first that makes the energy conservation possible. In Riyadh, EE measures are responsible for reducing energy consumption by 27% for walls, 14% for roof, and 6% for window, and by 29%, 13%, and 6% for walls, roof, and windows, respectively, for Qassim. However, the most impactful EE solution was selecting a heating, ventilation, and air conditioning (HVAC) system with a high energy efficiency rate (EER), which can minimize the energy consumption by 33% and 32% for Riyadh and Qassim, respectively. The study's feasibility showed that the number of years needed to offset the initial investment for a proposed roof PV system exceeds the project's life, if the energy produced is exported to the grid at the official export tariff of 0.019 $/kWh. However, the simple payback time was 13.42 years if the energy produced is exported to the grid at a rate of 0.048 $/kWh, reflecting the project's economic feasibility.

The Kingdom of Saudi Arabia (KSA) is considered one of the countries with the highest consumption of electric energy per capita. Moreover, during the period of 2007–2017, the consumption rate increased from 6.9 MWh to 9.6 MWh. On the other hand, the share of residential electricity consumption in the KSA constitutes the biggest portion of the total electric consumption, which was about 48% in 2017. The objectives of this work were to analyze the exergy and assess the economic and environmental impacts of energy consumption in the residential sector of the Qassim region to determine potential areas for energy rationalization. The consumption patterns of 100 surveyed dwellings were analyzed to establish energy consumption indicators and conduct exergy analysis. The performances of different consuming domestic items were also examined, and energy efficiency measures are proposed. The average yearly consumption per dwelling was determined, and the total energy and exergy efficiencies are 145% and 11.38%, respectively. The average shares of lighting, domestic appliances, water heaters, and air conditioning from the total yearly energy consumption were determined.