Kenya has taken a decisive step towards strengthening its energy infrastructure with the energization of the 400/220kV Mariakani substation. The project is expected to transform the power supply to homes, communities and industry across the coastal region.
Commissioned by the Kenya Electricity Transmission Company (KETRACO), the substation now forms a vital link in the national electricity grid, connecting the electricity generated with the coast hundreds of kilometers away. This is one of Kenya’s most significant power grid upgrades in recent years and is the culmination of nearly a decade of engineering work designed to stabilize supply between Nairobi and Mombasa.
The Mariakani facility is located on the larger Mombasa-Nairobi Transmission Corridor, a network designed to transmit more than 1,000 megawatts of electricity between Kenya’s two largest population and economic centres.
Coastal regions have repeatedly faced instability over the years, particularly during peak demand hours when demand exceeds locally available electricity. The region’s power grid relies heavily on diesel power plants to fill the gaps, locking consumers into high electricity rates and exposing businesses to occasional power outages. This energization is expected to allow the region to draw far more power from geothermal, wind and hydropower resources generated inland and imported from the region, reducing its dependence on fossil fuel-based backups.
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KETRACO’s Acting Managing Director Kipkemoi Kibias said the substation is a critical enhancement to Kenya’s electricity transmission backbone supporting Kenya’s growing energy economy. He said the facility would introduce reliability that has been missing for years in coastal areas and allow the region to benefit from lower-cost electricity flowing through the grid.
By reducing the need for fuel-based electricity during peak periods, the substation is expected to reduce grid operating costs, stabilize voltage levels, and provide predictable supply to industrial parks, hotels, and small businesses that previously factored power outages into their operating models.
The substation is strategically positioned within Kenya’s broader integration into regional electricity markets. The facility is located at a junction benefiting from both 500kV Ethiopian and Kenyan interconnectors. Recently completed to bring hydropower to the south, a 400kV Kenya-Tanzania interconnector connecting East Africa’s power systems has also been completed. Together, these lines will open up the potential for greater cross-border power interchange, supporting Kenya’s ambition to achieve a fully clean energy power mix by 2030.
Olkaria geothermal fields, wind power from Turkana, and hydropower imported from Ethiopia can now successfully reach coastal demand centers without being bottlenecked by old, low-voltage transmission infrastructure.
The funding for Mariakani represents a partnership between national and continental institutions. The KES 3 billion investment is co-financed by the Government of Kenya and the African Development Bank (AfDB) and reflects the latter’s increasing involvement in power infrastructure across the continent. Construction and equipment installation were carried out by China CAMC Engineering Co., Ltd., and KETRACO supervised the supervision, technical guidance and domestic integration.
AfDB’s support extends beyond the substation footprint. The bank also financed high-voltage lines linking Mariakani to both Nairobi and Rabai as part of a major power transmission upgrade program.
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The energization of Mariakani completes the second phase of the Mombasa-Nairobi transmission line project. Phase II saw the installation of 400/220kV substations in Isinya and Mariakani and the upgrading of long-distance transmission lines to accommodate higher capacity.
The initial phase of the project, commissioned in 2017 at a cost of Ksh17 billion, saw the construction of a 492-kilometre double ring from Rabai to Embakasi, underwritten by a coalition including the AfDB, the European Investment Bank, the French Development Agency and the Government of Kenya. The second phase, costing 7 billion Kenyan shillings, will provide the voltage boost needed to move significantly more electricity and reduce energy losses that occur over long distance transmissions.
Now that energization is being implemented, the expectations for the region are real and immediate. Companies operating in Mombasa and surrounding counties are expected to benefit from stable supply, allowing factories to expand shifts without the cost of backup generators.
Hotels and resorts along the coast are used to budgeting for interruptions, giving them more predictable energy inputs and supporting the tourism economy. Local businesses, from seafood processors to grain millers, are poised to access electricity more reliably and at lower effective costs. Households in densely populated areas, where voltage sags are common, are expected to experience fewer fluctuations.
This project goes beyond economics and strengthens Kenya’s global position as a leader in clean grid development. The country, where more than 90 percent of its electricity is generated from renewable sources, is building the transmission backbone needed to absorb more capacity as new geothermal and wind farms come online.
The Mariakani commissioning shows that investing in power generation is equivalent to investing in grid stability, ensuring clean electrons reach the homes and businesses that need them most.
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