### Objectives  
The design of a pumped hydroelectric energy storage (PHES) system to utilize rainwater runoff at multi-level carparks (MLCPs) in Singapore targets several critical objectives related to environmental sustainability and infrastructure efficiency [4]. Firstly, it seeks to enhance environmental sustainability by providing the dual benefits of energy production and water management. Secondly, the design aims to improve the resilience and efficiency of the energy infrastructure by offering a reliable energy storage solution. By leveraging the gravitational potential energy of stored water, the PHES system can serve as a dynamic and responsive energy reservoir, contributing to grid stability during peak demand periods [5]. This innovative approach aspires to create an intelligent and sustainable energy solution that efficiently harnesses rainwater runoff while addressing the intermittent challenges associated with renewable energy sources. Ultimately, this contributes to a more resilient and environmentally conscious urban infrastructure in Singapore [2]. The primary objective of this research is to evaluate the efficiency and feasibility of different hydroelectric turbines for maintaining overnight operations in a multi-level carpark (MLCP) in Singapore. Key factors influencing this project include the duration of operation and the system's ability to provide adequate lighting. The optimal turbine must maximize the number of light bulbs powered and extend the duration of continuous operation. By meticulously evaluating these variables, the research aims to determine the hydroelectric turbine configuration that  
Figure 1: UNSDG 17 goals.  
best meets the operational requirements for overnight use in an MLCP [1]. The initiative aims to establish a sustainable and eco-friendly energy solution by capturing and utilizing rainwater, abundant in Singapore's tropical climate. Integrating PHES technology with multi-level carparks (MLCPs) optimizes rainwater runoff as a renewable energy source, aligning with Singapore's commitment to green and innovative urban development. This approach reduces reliance on conventional energy sources and promotes environmentally friendly practices in urban infrastructure [1; 4]. Additionally, the project enhances energy resilience and grid stability by converting rainwater runoff into a stored energy resource through the PHES system, addressing the intermittent nature of renewable energy sources. The efficient release of stored energy during peak demand periods ensures a reliable and responsive energy supply [5]. Furthermore, the initiative creates a sustainable and adaptive energy infrastructure tailored to Singapore's MLCPs, promoting energy efficiency, environmental sustainability, and long-term resilience, while adapting to evolving energy demands in urban areas [2]. Firstly, the system aims to contribute to Singapore's sustainable energy goals by utilizing the abundant and often-underutilized resource of rainwater runoff [1]. By integrating PHES technology with MLCPs, the project seeks to maximize the capture and utilization of rainwater, converting it into a reliable and renewable energy source. In practical terms, the system described in this study has been designed to store and manage energy in such a way that its output is not limited to just one MLCP. Specifically, the system can generate enough power, using the stored water and Turgo turbine setup, to supply energy for up to three separate MLCPs, assuming each has similar energy demands as the MLCP used in this study (i.e., powering 289 light bulbs for a certain duration). This means that if the system was scaled or replicated across three different MLCPs, it would still be able to meet their energy requirements under the same conditions, demonstrating its robustness and potential scalability. Essentially, the system's storage capacity and energy output are sufficient to serve multiple buildings, making it a more versatile and efficient solution in urban energy management.