mburu jeff 
President William Ruto has inspected the KETRACO 400kV/ 220kV Mariakani Substation in Kilifi County highlighting its significance as part of the Mombasa-Nairobi Transmission Line, which enhances electricity transmission from Mariakani to Isinya near Nairobi.
The project aims to enhance transmission capacity between Mombasa and Nairobi, strengthening power supply, improving system reliability, and supporting industrial growth while expanding electricity access in the coastal region.
The initiative includes a 400/220kV substation equipped with four 200 MVA transformers at Isinya Substation and a 220/66kV 90MVA transformer at the existing Nairobi North Substation, financed by the World Bank (WB).
The System reinforcement Project is linked to the broader 220kV Nairobi Metropolitan Ring.
The project also facilitates the activation of the 400 kV Mombasa-Nairobi Transmission line, alongside the proposed 220/400 kV Mariakani Substation.
This substation is financed through a supplementary loan under the Ethiopia-Kenya Electricity Highway project by the African Development Bank (AfDB), aimed at enhancing system reliability in the coastal region.
According to KETRACO Managing Director Dr. Eng. John Mativo, the energization of the 400 kV Mariakani-Isinya Transmission Line will significantly reduce dependence on costly diesel-powered generation in the coastal region.
The double-circuit line will efficiently transfer power between the Mombasa and Nairobi load centers, minimizing power losses and improving efficiency.
Moreover, the project will enhance the quality and reliability of power supply in the Coast region and provide stable electricity to the Special Economic Zone in DongoKundu.
Additionally, the importation of power from Ethiopia, combined with electricity from the Olkaria geothermal complex, is expected to lower the reliance on local generation in the Coast region, impacting bus voltages at key locations.
The 400 kV link’s charging capacity will address this challenge, ensuring the safe operation of the HVDC link.
Project financing
The Mariakani Substation is financed through a partnership between the Government of Kenya and the African Development Bank(AfDB), with a total project cost of Kshs.3.9 Billion.
Where of this amount, the AfDB contributed USD 29,030,400.94, while the government of Kenya provided Kshs. 143,534,873.02.
The 400 kV transmission line from Rabai to Nairobi via Mariakani was completed in 2017 and currently operates at a 220kV voltage level.
The 400 kV Mariakani-Isinya link will be completed in June 2025, marking a significant milestone in Kenya’s energy Infrastructure development.
