Technical feasibility study of a Grid connected pumped storage hydropower plant on Lake Kivu

Abstract

Electrical energy and the other forms of energy in general play an important role in the global economy and the significant portion of global energy demand is met by burning fossil fuels which are non-renewable and with limited lifespan. To gradually decouple the economic development from non-renewable energy sources and to address climate change issues, exploring more renewable energy alternatives is widely encouraged. Rwanda has the plan of increasing the generation of electric power from renewable energy through solar power plants. One of the difficulties the electrical industry is facing currently is the production and efficiency utilization of energy. Energy management means production of energy and efficiency utilization of energy and finally storing the energy for future use. Due to environmental issues, the entire world is encouraged to develop different renewable energy technologies in electrical power generation to save the planet. On Rwanda national electric grid, different renewable energy generations are connected where solar energy generation (intermittent) is among them. The energy on Rwanda national electric grid can be managed well by bringing in an efficiency, reliable and environmentally friendly storage system. A very well-known worldwide energy storage technology is chemical battery. Chemical batteries are technically suited to be used with small scale distributed renewables and the main problem of that technology is the short life which is equivalent to 3 to 5 years when daily used. However, due to the intermittency of solar energy, short life span of chemical batteries and its environmental issues, pumped hydroelectric energy storage technology has been found advantageous to Rwandan electric network. During this thesis work, the study and analysis of power generation and load demand on the Rwandan network have been done to know the availability of renewable energy which needs to be stored during light loads and released during peak loads hours. As per the study, there are 204 MWh which can be stored on daily basis. After concluding that Rwandan electric network has renewable energies to be stored during light loads, the survey around Lake Kivu on Rwandan side to find out the candidate places suited for pumped hydroelectric energy storage have been carried out where one site among five candidate sites has been selected as the best-suited place. Then, 36 MW pumped hydropower plant has been designed and its operational economic feasibility study has been also done. Simulation with MATLAB/Simulink has been carried. The study results show that currently having the storage system will remove completely 27.6% of diesel power generation on Rwandan electric network. Moreover, the studies confirmed better operability of the system with a round trip efficiency of 81%.