Run-of-river hydropower plant
The Nachtigal hydropower project is a 420MW greenfield hydroelectric power plant being developed in Nachtigal, Cameroon.
The project is developed by Nachtigal Hydro Power Company (NHPC), which is jointly owned by Electricité de France (EDF, 40%), International Finance Corporation (IFC, 30%) and the Republic of Cameroon (30%).
NHPC will develop the project under a build-operate-transfer (BOT) model for a period of 35 years, following which the ownership will be transferred to the government of Cameroon.
The total investment for the hydropower project is €1.2bn ($1.4bn). IFC, the State of Cameroon, and EDF signed the final agreements for the construction of the project in November 2018.
The construction is expected to commence by the end of 2018, while operations are expected to begin in 2023. The project is expected to boost Cameroon’s power generation capacity by 30% and reduce annual generation costs by $100m.
The proposed plant is planned to be built on the Sanaga River near the Nachtigal Falls, which is 65km north-east of Yaoundé in Cameroon. Sanaga is the largest river in Cameroon, covering roughly one-third of the country by its basin.
The location is also in close proximity to the existing Mbakaou dam and the under-construction Lom Pangar dam, which will be used to contain the flow of the Sanaga River.
The Nachtigal hydropower project includes construction of a 2km-long roller compacted concrete (RCC) dam with a height of 14m. The reservoir of the dam will have a capacity of 27.8 million metres cubed and a surface of 4.21m² at normal operating level. A 3km headrace-lined canal will transfer the water from the dam to the powerhouse at a maximum rate of 980m³/s.
The powerhouse of the plant will be 142m-long, 47m-wide, and 36m-high. It will be equipped with seven 60MW turbines and water intake facilities to generate power. An 800m-long tailrace channel will return the water from the powerhouse into the Sanaga River.
The project will also include a 4.5MW secondary power plant downstream of the dam to produce electricity from the environmental flow.
The construction of the Nachtigal hydropower project has been divided into four lots – civil works, installation of electro-mechanical equipment, construction of transmission lines, and construction of housing for staff.
The civil works include dam construction, downstream works, penstocks, and hydromechanical equipment of downstream additions.
An estimated 1.8 million metres cubed of soil and rock will be extracted for the construction of the concrete dam and channel, while approximately 290ha will be cleared of vegetation for the laterite quarry and the basecamp. The soil and rock recovered from excavation will be utilised in different forms during construction.
A 225kV substation and a 50.3km-long double-circuit transmission line will be constructed to transfer the power generated to the Nyom 2 substation, which will connect to Southern Interconnected Grid (SIG), which is the national grid. The SIG is managed by Energy of Cameroon (ENEO).
The transmission line will be constructed by NHPC and handed over to GoC, upon commissioning. It will be operated and governed by National Electricity Transport Company (SONATREL).
IFC is investing €60m ($70m) in equity and providing a loan of up to €110m ($127m) for the project. IFC is arranging another €806m ($935m) for the project from a group of 11 commercial banks and institutions.
The International Bank for Reconstruction and Development (IBRD) and MIGA are providing €257m ($300m) and €192m ($223m) respectively for the project.
The civil works contract has been awarded to a consortium of NGE Contracting, Société Générale des Travaux du Maroc (SGTM), and NV Besix. Tractebel and ISL have been appointed as consultants for the civil works, while NV Besix will design and build the dam.
GE Hydro France and Elecnor have been awarded the contract for the electromechanical works of the project, while Bouygues Energies and Services will build the transmission lines.
Artelia carried out the environmental impact assessment for the Nachitgal hydropower project, while Nodalis rendered technical, economic, and financial services related to the project to the Government of Cameroon.
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