MOMBASA, Kenya — The Kenya Electricity Transmission Company (KETRACO) has energised the 400/220kV Mariakani Substation, a milestone expected to deliver stable, reliable, and adequate electricity to homes, businesses, and industries across the Coastal region, while significantly reducing dependence on costly diesel generators.
The commissioning of the Mariakani substation marks a major boost for the Coast’s power network, which has for years struggled with instability, outages, and high costs, particularly during peak demand hours.
The facility serves as a critical power gateway linking the Coast to the national transmission grid centred in Nairobi.
By reinforcing this link at 400kV, KETRACO says the project will unlock a stable electricity supply capable of supporting industrial growth, attracting investment, and improving the quality of life for millions of residents in the region.
“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 stabilising supply,” said KETRACO Acting Managing Director Eng. Kipkemoi Kibias.
The Mariakani substation forms part of the Nairobi–Mombasa Transmission Line, a strategic project designed to carry more than 1,000 megawatts of electricity between the two regions. Once fully operational, the line is expected to ease pressure on the Coast’s power network and enhance grid reliability.
KETRACO said the substation is a key component in strengthening Kenya’s national transmission grid, which also underpins the regional interconnected power system.
Officials noted that a stronger grid is essential to fully realise the benefits of the 500kV Ethiopia–Kenya interconnector and the 400kV Kenya–Tanzania interconnector, both of which are designed to enhance cross-border power trade and stability.
The project is also central to Kenya’s push towards 100pc clean energy by 2030. By expanding transmission capacity, the Mariakani substation will allow more geothermal power from Olkaria, wind energy from the Lake Turkana Wind Power project and hydroelectric power imported from Ethiopia to reach the Coast.
“With this development, we are not only improving reliability but also supporting the country’s clean energy transition by enabling more renewable power to flow to the Coast,” Eng. Kibias said.
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 Sh3 billion. The project was implemented by China CAMC Engineering Co. Ltd under the supervision of KETRACO engineers.
Beyond the substation itself, AfDB is also the lead financier of the transmission lines linking Mariakani to Nairobi and Rabai, including the 400kV double-circuit line from Isinya to Mariakani and the 220kV double-circuit line from Mariakani to Rabai.
The energisation of the Mariakani facility completes the second phase of the Mombasa–Nairobi Transmission Line Project. Phase I involved the construction of double-circuit transmission lines from the 220kV Rabai Substation at the Coast to the 220kV Embakasi Substation near Nairobi’s Inland Container Depot.
The 492-kilometre line has been operating at 220kV since 2017.
Phase I cost Sh17 billion and was jointly financed by the African Development Bank, the European Investment Bank, the French Development Agency and the Government of Kenya.
Phase II focused on constructing the 400/220kV Mariakani and 400/220kV Isinya substations to upgrade the transmission capacity between the two points from 220kV to 400kV, at a cost of Sh7 billion. The Isinya substation was completed in 2022.
With the Mariakani substation now energised, KETRACO says the full 400kV Mombasa–Nairobi transmission corridor is complete, delivering increased transmission capacity of over 1,000MW to the Coast, reducing technical power losses and lowering the cost of electricity.
Beyond boosting supply, the project is expected to improve power quality, reliability and grid stability, fully integrating the Coast region into Kenya’s modern, clean and resilient electricity network and supporting long-term economic growth.
