Kenya Electricity Transmission Company (KETRACO) has today energized the 400/220kV Mariakani Substation.
This development means reliable, stable and adequate electricity for homes, businesses, hotel industries and small scale and large scale manufacturing industries across the Coastal region ending years of power instability and reducing dependence on costly diesel generators.
The Mariakani substation is a critical power gateway linking the Coast to Nairobi national transmission grid. By reinforcing this link at 400kV, KETRACO is unlocking stable electricity supply that will support industrial growth, attract investment and improve everyday life for millions of Kenyans.
The energized Mariakani substation forms part of the Nairobi-Mombasa Transmission Line, designed to carry more than 1000MW electricity between the two regions and ease pressure on the Coast’s power network.
The 400/220kV Mariakani Substation is a strategic component in reinforcing Kenya’s national power transmission grid, which underpins the strength of the regional interconnected power system. Strengthening the grid is essential to fully realize the operational benefits of the 500kV Ethiopia - Kenya and 400kV Kenya - Tanzania Interconnectors.
The substation will additionally play a key role in Kenya’s push toward 100 per cent clean energy by 2030, allowing more geothermal power from Olkaria, wind power from Lake Turkana Wind Plant and hydro power from Ethiopia to reach the Coast region.
“With this development, the Coast will significantly reduce its reliance on expensive and polluting diesel power, especially during peak evening hours. Cleaner, reliable and stable energy will now flow more efficiently, lowering costs and stabilizing supply,” said KETRACO Acting Managing Director Eng. Kipkemoi Kibias.
Financing for the Mariakani Substation was provided through a partnership between the Government of Kenya and the African Development Bank (AfDB) at a total cost of KES 3B. China CAMC Eng. Co. Ltd were the implementing Contractor for the project and supervised by KETRACO engineers. This collaboration underscores strong confidence in Kenya’s energy future.
Beyond the substation, AfDB is also the lead financier of the transmission lines linking Mariakani to Nairobi and Rabai. These include the 400kV double-circuit transmission line from Isinya to Mariakani and the 220kV double-circuit line from Mariakani to Rabai.
400/220kV Mariakani Substation completes the second phase of Mombasa-Nairobi Transmission Line Project.
The first phase included the double circuit transmission lines from 220kV Rabai Substation to 220kV Embakasi Substation near the Internal Container Deport (ICD) in Nairobi. The double circuit transmission line was designed for 220kV between Rabai Substation to Mariakani Substation and 400kV from the Mariakani Substation to 220kV Athi River Substation through the 400kV Isinya Substation, then 220kV between Athi River Substation to 220kV Embakasi substation through a 6.7km, 220kV Underground Cable through the Nairobi National Park. The total length of the transmission line from 220kV Rabai Substation to 220kV Embakasi Substation is 492km. The transmission line has been operating at 220kV voltage level since 2017. The total cost of the first phase of this project was KES 17B being jointly financed by the African Development Bank, the European Investment Bank, and the French Development Agency, and the Government of Kenya.
Phase II of the project was to construct the two Substations of 400/220kV Mariakani and 400/220kV Isinya with the goal of upgrading the transmission line capacity between the two substations by raising the voltage from 220kV to 400kV.
400kV Isinya Substation was completed in the year 2022 and with the 400kV Mariakani Substation being energized, the cycle of the entire 400kV Mombasa-Nairobi Transmission Line comes to an end with the benefits of increased transmission line capacity to the coastal region of over 1000MW of clean electrical energy from hydros, geothermal and wind, reduced technical power losses thus reducing the cost of power, reinforcement of the coastal power grid thereby improving the system reliability and stability. Phase II of this project costed KES 7B.
Beyond boosting power supply, the project improves power quality, reliability and grid stability, ensuring the Coast region is fully integrated into Kenya’s modern, clean and resilient electricity network.