## 5 Methodology  
**Fluid Mechanics**: The analysis begins with a comprehensive examination of the water flow dynamics within the micro-pumped hydroelectric energy storage (PHES) system. This includes a detailed assessment of flow rates, velocity profiles, and pressure distributions throughout the system. The system's design incorporates a Turgo turbine, which operates at a flow rate of 0.03 m\({}^{3}\)/s. The turbine's performance is analyzed to understand how it effectively converts the kinetic energy of flowing water into electrical energy, achieving an efficiency of 85%. This involves calculating the turbine's power output and assessing how variations in flow conditions might affect its performance. The hydraulic design must also address the water distribution and storage mechanisms, ensuring that the system's configuration optimally utilizes the height of the multi-level carpark to maximize the potential energy of the stored water. **Thermodynamics (Energy Equation):** A thorough energy balance is crucial for evaluating the system's efficiency. We must calculate the total potential energy stored in the 1655.5 m\({}^{3}\) of water, considering gravitational potential energy based on the height of the carpark. This energy is then analyzed in terms of its conversion into electrical power by the Turgo turbine. The energy equation should include the efficiency losses during energy conversion and assess the system's ability to deliver a consistent power output over a 12 h period. This ensures that the stored energy can be reliably discharged to power 289 light bulbs for the intended duration. **Physical Properties:** The analysis of water properties, such as density (approximately 1000 kg/m\({}^{3}\)), viscosity, and specific heat capacity, is essential for accurate fluid mechanics and thermodynamic calculations. These properties influence how water behaves under different conditions and impact the overall efficiency of the energy storage system. Additionally, the physical characteristics of the materials used in constructing the PHES system must be examined to ensure they can support the water load without compromising structural integrity. The system must adhere to the design constraint of a floor load capacity of 5 kN/m\({}^{2}\), ensuring safety and durability. Figure 11: Proposed water tank design. By addressing these aspects above, our proposal provides a robust theoretical foundation for understanding the operational efficiency and feasibility of integrating micro-pumped hydroelectric energy storage in multi-level carparks, aligning with environmental sustainability goals. Singapore is regarded to have a high annual rainfall, with an average annual rainfall of 3012 mm, which is higher than the global average. With this advantage, a micro-hydroelectric generator is ideal, and the abundance of rainfall can be used as a renewable source of energy. Singapore's highly urbanized environment affects the natural water cycle and rainwater runoff patterns. Various infrastructures, such as multi-level carparks, alter the natural flow of rainwater, making it easier to capture and harvest this runoff for renewable energy. Being known as a small country, Singapore aims to maximize the usage of land spaces and high-rise buildings to the fullest; thus, Singapore has an abundance of multi-level carparks, being the uniqueness of Singapore and making use of Singapore's advantage of the high amount of multi-level carparks. Most of Singapore's multi-level carparks have rooftops, and they are always underutilized; therefore, by installing a micro-hydroelectric generator, it maximizes the usage of the multi-level carparks, providing a more sustainable energy source. The average monthly rainfall for each month (Figure 12) can be used to determine the average rainfall monthly. Average rainfall per month is calculated to be 253.43 mm. We did not consider Fixed Pitch Propeller and Crossflow turbines in our study due to several key factors mentioned below. 1. **Suitability for the Application.