Mariakani substation under construction in the coastal County of Kilifi will enable increased supply to the Coast of cheap geothermal power from Olkaria fields in the Rift Valley alongside hydropower from neighbouring Ethiopia.
Sitting on 200 acres of land, the 400/220kV substation is set to be the biggest step-down facility at the Coast. It will have the capacity to allow supply of more levels of geothermal power to the coastal economy, according to Kenya Electricity Transmission Company (KETRACO). Construction is set for completion in October 2020 and will also see the Coastal region start receiving hydropower imports through the Rabai-Mariakani-Isinya-Suswa line linked to Wolayta/Sodo substation in Ethiopia.
“Mariakani substation will offer reliable and stable power supply to the proposed Dongo Kundu Special Economic Zone area through the 220kV Dongo Kundu – Mariakani transmission line,” said FCPA Fernandes Barasa, MD. Step-down substations, such as the Mariakani facility, reduce the voltage of incoming electricity from power plants to lower levels suited for homes and businesses.
At the site of power plants, there’s always a nearby step-up substation that raises the voltage of the generated electricity to be transmitted over long distances through high voltage power lines. Power transportation via high voltage lines reduces transmission losses. On the other end, at the load/demand centres, a step-down substation plays the reverse role and feeds the stepped-down electricity to lower voltage distribution lines (below 132kV) connected to homes and businesses.
KETRACO is the agency behind construction and operation of high voltage transmission lines (132kV and above), with those below falling in distributor Kenya Power’s domain.
The rapid development registered in the electricity sector in the last six years revealed the need for additional system reinforcement through extension of the 400 kV network for the safe operation of the Ethiopia-Kenya Interconnector and to absorb the initial 400 MW as per the Power Purchase Agreement (PPA). Supply of more geothermal and hydropower to the Coast is expected to steeply cut reliance on expensive diesel generated electricity in the region. The expected overall impact is lower bills for consumers across the country since power tariffs on the national grid are harmonised regardless of location and energy source.
The Mariakani substation contract was awarded to Chinese firm CAMCE and is co-financed by the African Development Bank and the Kenyan government at a total cost of Sh2.96 billion.
Kenya and Ethiopia are constructing a 1047km 500kV direct current (DC) bi-pole transmission line which will allow hydropower imports from Ethiopia in line with a State-to-State agreement entered in January 2012.