Assessment of Reservoir Based Hydropower System, a Case Study: Dwangwa River, Malawi

Unreliable power in Malawi mainly results from fluctuating water levels in most run-of-river hydropower plants. These power outages worsen during the dry season making it difficult to accommodate the existing demand of electricity. The best solution to ensure reliability of the hydropower system is to incorporate reservoir storage. This study aimed at designing a reservoir based hydropower system to ensure reliability and maximum generation of power at a low cost. The system was designed to export all the energy to national grid for distribution. The monthly average design flow was 29.129 m3/s. Reservoir storage capacity of 536.998 Mm3 was estimated using mass flow curve in MS-Excel while potential head of 100 m was deduced using Google Earth. RETScreen software was used to calculate hydropower potential and determine financial viability of the project. The results showed that the hydropower potential was 22.70 MW and the initial capital cost was $79,434,044 with payback period of 4.8 years. This paper’s levelised cost of energy (LCoE) was 0.099 $/kWh which relatively smaller than grid cost of 0.155 $/kWh. Therefore, this paper presents part of the solution for the persistent power outages and also overcomes the serious power problems during dry season in Malawi.