This review examines the vast opportunities and key challenges in renewable waste management across the Gulf region, with a particular emphasis on Saudi Arabia. As global demand for sustainable energy intensifies, driven by technological advancements and environmental concerns, the Gulf Cooperation Council nations, notably Saudi Arabia, are beginning to acknowledge the urgency of transitioning from fossil fuel reliance to renewable waste management. This review identifies the abundant renewable resources in the region and highlights progress in policy development while emphasizing the need for comprehensive frameworks and financial incentives to drive further investment and innovation. Waste-to-energy (WTE) technologies offer a promising avenue for reducing environmental degradation and bolstering energy security. With Saudi Arabia targeting the development of 3 Gigawatts of WTE capacity by 2030 as part of national sustainability initiatives, barriers such as regulatory complexities, financial constraints, and public misconceptions persist. Ultimately, this review concludes that advancing renewable waste management in the Gulf, particularly through stronger policies, stakeholders’ collaboration, investment in WTE and an enhancement in public awareness and education, is critical for achieving sustainability goals. By harnessing these opportunities, the region can take decisive steps toward achieving sustainability, positioning Saudi Arabia as a leader in the global fight against climate change and resource depletion.

Water is one of humanity’s most fundamental needs. The demand for freshwater rises in tandem with population expansion. Only 0.01 percent of freshwater is available as surface water in lakes, wetlands, and rivers. As a result, the only choice is to extract water from the oceans. Desalination is an effective option for this. This study focused on the multi-objective design optimization, fabrication, and thermal evaluation of an integrated desalination system combining a solar still with a flat plate collector (SS-FPC). The study investigated the trade-off between two competing objectives: maximizing the efficiency of the SS-FPC system while minimizing its total cost. A numerical code is written in MATLAB to simulate the influence of changing design parameters (DPs) on the SS-FPC performances. The optimal SS-FPC design, offering low costs and a high thermal efficiency, was identified using the multi-objective colonial competitive algorithm (MOCCA). This design was subsequently fabricated and experimentally evaluated under the climatic conditions of Unaizah in Al Qassim, Saudi Arabia. The optimal numerical results were compared with both the literature values and experimental measurements. The comparison revealed strong agreement with the experimental data, with a maximum relative error of 4%. Moreover, the obtained results indicate that the optimized SS-FPC design is capable of achieving a 31% increase in efficiency and a 49% reduction in total cost relative to those reported in the literature.

This paper introduces a novel approach for designing a Fractional Order Proportional-Integral-Derivative (FOPID) controller for the Hydraulic Turbine Regulating System (HTRS), aiming to overcome the challenge of tuning its five complex parameters ($K_p,K_i,K_d$, λ and μ). The design is formulated as a multi-objective optimization problem, minimized using the Multi-Objective Imperialist Competitive Algorithm (MOICA). The goal is to minimize two key transient performance metrics: the Integral of Squared Error (ISE) and the Integral of the Time Multiplied Squared Error (ITSE). MOICA efficiently generates a Pareto-front of non-dominated solutions, providing control system designers with diverse trade-off options. The resulting optimal FOPID controller demonstrated superior robustness when evaluated against simulated variations in key HTRS parameters (mg, eg and Tw). Comparative simulations against an optimally tuned integer-order PID and established literature methods (FOPID-GA, FOPID-MOPSO and FOPID-MOHHO) confirm the enhanced dynamic response and stable operation of the MOICA-based FOPID. The MOICA-tuned FOPID demonstrated superior performance for Setpoint Tracking, achieving up to a 26% faster settling speed (ITSE) and an 8% higher accuracy (ISE). Furthermore, for Disturbance Rejection, it showed enhanced robustness, leading to up to a 23% quicker recovery speed (ITSE) and an 18.9% greater error suppression (ISE).

In Saudi Arabia, hot water for domestic uses consumes a great portion of home electricity. Thus, solar collectors can be considered as an important alternative to reduce the amount of consumed electricity. Therefore, in recent researches, a great attention was given to develop flat plate collector (FPC) with optimal performance. In this paper, a multi-objective modified imperialist competitive algorithm (MOMICA) was employed for optimizing the performance of a FPC. The optimization results showed a capability to reach higher FPC efficiency with a relatively small collector area and hence lower price. It has also been proved that the change of the insulator depth from 0.02 to 0.05 m has a strong influence on the system’s efficiency.

In this paper, an analytical mechatronic dynamic design model of a full rail vehicle system is developed. Based on the rail vehicle motion, its degree of freedom can be reduced to only 38. This reduction is necessary for the model simplicity. The developed model is validated with experimental result and compared with other one from literature. The real characteristics of the actuators are discussed, and its controller is designed. A mechatronic model that expresses the controlled tracking error as function of the vehicle dynamics and the actuator characteristics is developed. This model is used by the linear quadratic regulator approach to identify the mechatronic rail vehicle proportional–integral–derivative controller’s gains. The mechatronic rail vehicle comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a rail irregularities caused by a lateral and two vertical track irregularities. The simulations of vibration analysis are obtained in time and frequency domains and compared with railway vehicle status. The robustness of the designed mechatronic rail vehicle is verified by simulations, carried out for the cases of car body mass variations. The results show the effectiveness of the proposed mechatronic rail vehicle design which improves significantly the transportation of passengers.