Kenya

Olkaria II - a 70 MW power plant

Energy Sector

The base load power generation in Kenya is provided through hydro and geothermal energy. 35% of Kenya’s current electricity system capacity comes from geothermal energy. However, geothermal energy, because it is environmentally clean and with a very high availability factor (Olkaria over 98%) is the preferred base load power source compared to hydro-power which is affected by drought.

Little more than 20% of the total population in Kenya has access to electricity. This has resulted in an extremely high level of repressed demand and a vast potential for load-growth nationwide. The development of geothermal energy in Kenya is guided by fiscal and legal regimes that provide incentives to promote its development. There are advanced plans of the Kenyan government to increase electricity generation by developing 1500 MW by 2019.

Geothermal potential

Kenya is the only country in Africa to exploit geothermal energy for electricity power in a significant manner. Geothermal investigations in the Rift Valley began in 1956, and the first geothermal unit of 15 MW capacity was commissioned in June 1981 at Olkaria. Currently the Olkaria I-IV geothermal capacity is about 585 MW.

Besides Olkaria there are 12 other additional prospective areas. Initial investigations indicate that Kenya’s Rift Valley has a potential of more than 3000 MW exploitable for the generation of electricity using conventional methods. The high potential areas include: Suswa, Longonot, Eburru, Menengai, Silali, Korosi, Paka and Emuruangogolak volcanic complexes in addition to Olkaria geothermal field. KenGen has carried out detailed surface exploration work at Eburru, Suswa, Longonot and Olkaria. In 2009 GDC was founded and adopted the exploration work.

Project

One of the major tasks of geothermal resource assessment includes evaluation of the numerous geothermal prospects within the Kenya rift. Detailed surface investigations using various geoscientific methods are carried out before a field is committed for exploration drilling. Menengai geothermal area is one of the priority prospects in the current prospects ranking. Detailed surface investigations were carried out by KenGen starting early 2004 aiming at recommending locations for exploratory drilling.

In 2005 a co-operation between the Ministry of Energy, KenGen and GEOTHERM Project undertaken by BGR of Germany concerning the exploration of Menengai prospect was commenced. Since “standard” geological, geochemical and geophysical exploration methods had almost been completed the partners agreed a thermal mapping mission in the Menengai area which scarcely applied airborne exploration method to date. 8 thermally anomalous areas or “hot spots” had already been identified by KenGen. These areas could be confirmed and used as references to search for additional “hot spot features” on the thermal images. Finally, 77 new areas could be detected.

The digitally processed photographs have been linked with temperatures from fumaroles steam discharge sampling, soil gas sampling and with several hundred temperature measurements in shallow boreholes (1m deep). All in all the method has proven to be a valuable additional exploration tool particularly in relatively unknown prospect areas with limited vegetation.

In the course of the co-operation project a on the job training in GIS was provided for 5 scientists of KenGen staff. This 6 week GIS education was held by a BGR instructor.

Early 2011 GDC and BGR signed another cooperation agreement for accomplishment of a “High-Resolution Thermal Infrared Remote Sensing for Geothermal Site Characterization at Silali, Northern Kenya Rift”. The aerial survey was conducted in Jan./ Feb. 2012 yielding very promising results.

Since 2013, BGR and the GDC collaborate on the project “InSAR, structural analyses and dating of Paka volcanic products, Northern Kenya Rift”.

Main objective of the project is the detection of surface movements related to Paka volcano´s activities. Former and recent activity with regard to eruptive history of the volcanic sequences and a structural analysis of the study area is carried out. The objectives are achieved by performing an InSAR baseline study for the years 2006 to 2010 using ENVISAT data, an InSAR study for the period between March and October 2013 using TerraSAR-X data, an age-dating of different lava flows using the ⁴⁰Ar/³⁹Ar-method and the generation of a high-resolution digital terrain model (DTM) using Pléiades data.

InSAR (Interferometric Synthetic Aperture Radar) is a very useful method to detect small surface movements. The present InSAR study using Envisat data covers an area of about 100 km x 100 km. An uplift on the eastern flank of Paka volcano that tends to behave non-linear can be stated during the investigation period. Between 2006 until February 2008, an uplift of ~ 20 cm is detected. After that, the movement stops and the area turns into stability.

The InSAR study using TerraSAR-X data covers an area of about 30 km x 50 km. By analysing the TerraSAR-X data, a non-linear surface movement can be stated on the eastern flank of Paka volcano. The existing dataset shows a subsidence of ~ 20 mm between March and July 2013. This is followed by a short phase of stability and turns into uplift again at the end of the investigation period.

For the ⁴⁰Ar/³⁹Ar age dating, a total of 32 different lava flows and pyroclastic deposits were sampled. The dating yields ages between ~ 0.6 Ma to 0.012 Ma with three phases of pronounced volcanic activity: (1) between 0.428 and 0.372 Ma, (2) between 0.160 and 0.126 Ma, and (3) between 0.039 and 0.012 Ma.

Furthermore, a high-resolution digital terrain model for an area of ~ 420 km² covering all Paka related lava flows was generated using Pleiades satellite data. The DTM has a horizontal resolution of 4 meters and is an ideal base for structural analyses. Such a DTM can also be used as a base for infrastructural planning of roads, water pipelines or supporting buildings.

Detail of surface movement map of TerraSAR-X data showing the subsidence area on the eastern flank of Paka volcano. Time series plot of five representative points show a slight subsidence of ~ 20 mm at the beginning and the turn into uplift at the end of the investigation period.

Recent Development:

BGR is continuously evaluating a monitoring system of seismological stations that should be able to register movements in the area of Baringo-Silali. This accompanying service is required for the construction of geothermal plants and infrastructure. Measurements should be continued after the construction. In addition, staff from Djiboutis's Geothermal Unit ODDEG has been tranferred to Menengai drilling field in order to get practical skills.

Cooperating Partners:

Geothermal Development Company GDC