After adding a 280-MW geothermal power complex to its grid last year, Kenya is producing most of its power from geothermal sources, says the state-owned Kenya Electricity Generating Co. (KenGen).
This February, the East African country formally inaugurated the last phase of the Olkaria geothermal power complex, which comprised the 140-MW Olkaria IV plant and the additions of Olkaria I Units 4 and 5 (Figure 6), each with a capacity of 70 MW. The phase accounts for about 20% of Kenya’s total generating capacity.
|6. Geothermal saves the day. Drought-stricken Kenya recently commissioned a 280-MW phase of the Olkaria geothermal power project, which involved adding a 140-MW plant at Olkaria IV and two 70-MW units at Olkaria I, shown here. Courtesy: Toshiba Corp.
Kenya, which typically depends on hydropower for its electricity needs, has been stricken by a two-year-long drought. Since adding the much-needed 280 MW of capacity to the national grid when last year’s phase was commissioned, total geothermal capacity has grown to 1.6 GW, surpassing hydro as the country’s main source of power and mitigating power shortages at a time when rains have failed.
According to KenGen, geothermal currently accounts for 51% of the national generation mix (it averaged 41% over the period spanning September 2014 to February 2015), followed by hydro at 36%—due to poor inflow of water to generating facilities. Thermal sources and those powered by diesel and heavy fuel oil accounted for 21%. The new projects have also resulted in a 65% drop in the generating company’s fuel costs, KenGen reported.
Geothermal exploration at Olkaria, a region that lies in the Naivasha sub-basin of the Rift Valley and is characterized by hot springs and fumaroles, began in 1955. But despite a total potential of about 10 GW, only 800 MW has so far been developed in Kenya. Most is owned by KenGen, with the remainder owned by Ormat International subsidiary Orpower4.
The Olkaria geothermal field has been divided into seven portions for ease of development and management. Olkaria I hosts a KenGen power plant with three 15-MW turbogenerators that were commissioned between 1981 and 1985. That field was last year expanded by 140 MW with the addition of the two new 70-MW units. KenGen says the increase of steam in the field was due to drilling wells of 3,000 meters (m), deeper than earlier wells that were drilled to between 900 m and 2,200 m.
Olkaria II hosts a 2003-commissioned 70-MW power plant and a 2010-commissioned 35-MW unit (for a total installed capacity of 105 MW). Olkaria III hosts a 110-MW power plant owned by Orpower4, operating on Organic Rankine Cycle binary plant turbines. At Olkaria IV, where a potential of more than 350 MW has been shown as a result of drilling over the last decade, another 140-MW power plant was completed and commissioned in 2014.
Japanese firms Toyota Tsusho Corp. and Hyundai Engineering Co. jointly received the order for the construction of the 280-MW Olkaria phase in November 2011. The companies teamed up with Toshiba Corp., which delivered the steam turbine generators.
Kenyan officials note that public corporations and independent power producers are expected to continue developing the region’s geothermal power resources in the future, though Toyota Tsusho is poised to play a major role.
In August 2012, the company became the first private firm to sign a comprehensive memorandum of understanding with Kenya to support the country’s VISION 2030, a policy roadmap that foresees a wide range of energy and development projects—and calls for a boost in generating capacity from 2.24 GW in 2014 to 17.5 GW in 2030. Targets will require adding 1.6 GW from geothermal resources by 2017. Tenders under consideration will include single units for Olkaria I and V projects, along with the geothermal units for Olkaria VI.
—Sonal Patel, associate editor