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Energy plays a very important role more or less in every aspect of human life as well as economic activities. It is one of the sectors that play a pivotal role in the development of every county as it helps in easing or reducing poverty through job creation and manufacturing and supports infrastructural development. Renewable energy resources particularly hydropower remain one of the main sources of energy in recent times to overcome energy demand globally and reduce CO2 emissions and other Greenhouse gases from energy generation. The energy produced from sources such as coal, geothermal, burning of fossil fuels, and thermal have a negative impact on the environment as they release pollutants that affect aquatic life and other parts of the environment. Generating energy from hydroelectric power using a pump operating in reverse as turbine serves as the best and cheapest way to operate. This is due to its numerous advantages such as cheater installment and operation and low environmental hazards. This study examines the role of Pump as turbine for energy generation in reducing emission generation. Considering pump as turbine performance at different flow conditions for selection to be used for small hydro energy generation. Both numerical and experimental studies have been conducted and the results are discussed in this study. A literature survey has also been conducted to analyze data on global emission generation from energy generation. This study offers valuable information which supports the reduction of CO2 emissions and other Greenhouse gases from power generation through the provision of appropriate methods for the generation

Abstract Hydropower has been the leading renewable source and cheapest ways to generate electrical energy in the world. In recent years, there has been a major upsurge in the hydropower development because of the use of pump as turbine (PAT). However, the operational reliability of a PAT is greatly affected by the unsteady flow fields; therefore, it is important to examine the unsteady flow behavior which can be used as a reference to reduce the noise, vibration, and cavitation performance for centrifugal pumps working as turbines. Thus, the objective of this study was to evaluate the unsteady flow fields by analyzing the distribution of the pressure pulsations using both numerical and experimental measurements in a PAT operating in pump mode. Firstly, the three‐dimensional (3D) unsteady flow equations were solved using SST k‐ω turbulence model during the numerical calculations. Secondly, the numerical results of the hydraulic pump performance were validated by the experimental measurements for numerical accuracy. Lastly, pressure transducers are positioned at certain monitoring points to measure the pressure in the PAT investigated. The numerical and experimental results show that the main frequency of the pressure pulsation is equal to the blade frequency, and as it deviates from the design operating condition, the magnitude of pressure pulsation intensifies. Furthermore, the impeller eye marked the lowest pressure coefficients especially at the design condition and makes it highly susceptible to cavitation. High pressure coefficients were obviously seen at the pressure side on the blade surface closer to the trailing edge at all studied operating conditions. Meanwhile, the rotor‐stator interaction generated the highest pressure pulsation distribution at the volute tongue. Thus, modification of the volute tongue is an optimal approach of reducing the pressure pulsation intensity in the volute and pump as a whole.