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Wamalwa H.M.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2011

Given the strength of commodity prices in recent years, concerns over energy security and widening adoption of carbon emission pricing, renewables are well positioned to play growing role in global energy mix. Geothermal energy is on the face of it. By harnessing the heat of the earth, geothermal power plants tap into a virtually inexhaustible and continuous source of energy, using a small footprint facility to provide baseload electricity that is virtually CO2 and waste free. Geothermal projects today center on the exploitation of hydrothermal resources- reservoirs of naturally occurring water. This could change with Enhanced Geothermal System (EGS), a new form of geothermal exploitation being tested in areas that are not hydrothermal. This paper discusses the prospect of Enhanced (or Engineered) Geothermal System as a means to the baseload power generation. It also focuses on the technology behind creating engineered reservoirs; it reviews the environmental impacts as well as possible mitigation measures.


Njue L.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2012

Plate boundaries are part of the earth's tectonic system. Divergent plate boundaries are zones where lithospheric plates move apart as a result of tensional forces causing melting as a result of pressure decrease. Typically, they are characterized by tensional stresses that naturally produce long rift zones, normal faults, and basaltic volcanism. A comparison is made of cuttings from geothermal wells located within a continental divergent margin in Kenya and samples from an oceanic divergent margin Iceland. The stratigraphy of Menengai well MW-02 is mainly composed of trachytic rocks whilst samples from Hellisheidi HE-27 based on binocular observations aided by petrographic thin sections and XRD analysis are primarily basaltic. The comparison of cuttings from Menengai and Hellisheidi show dissimilarity in geology mainly as a result of the type of divergent boundary.


Kiruja J.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2012

The growth of industries is dependent on the availability and affordability of energy. However, conventional energy sources such as fossil fuels are getting depleted and their price is increasing rapidly due to market forces and world politics. It is therefore necessary to consider alternative sources of energy and geothermal energy is a potential option. Geothermal energy can be utilized for both electricity generation and direct uses such as heating and cooling. The dairy industry in Kenya can benefit immensely from the vast geothermal energy in the country since both dairy farming and the geothermal resources are located in the same region i.e. the Rift Valley region. Furthermore, dairy processing involves both heating and cooling operations, whose energy requirements are within a range for the geothermal resource in Kenya to cater. This paper discusses some of the dairy processing operations which can utilize geothermal energy and the appropriate technology which can be applied for each operation. The energy demand and the cost of each operation are also discussed.


Chepkochei L.C.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2012

Kenya is endowed with geothermal resources mainly located in the Rift Valley. Menengai Geothermal Field is one of these fields with its re-charge source being Wanjohi area in Aberdares region. From the hydro-geologic controls, it is evident that there are three distinct geologic formations that physically translate into the different water yield levels i.e. highest to the east and lowest to the west. Perhaps this is because the east is characterized by a regional groundwater aquifer likely to be recharged from a larger area with high rainfall or through deep and expansive faults such as those found at the edges of the Rift Valley. A methodology of Object-Oriented Image Classification method of remote sensing is a useful and promising method of classifying objects from high resolution satellite images. The method segments the image pixel into objects and utilizes the texture and contexture information of the object rather than only using spectral information relied upon by traditional methods. This paper, using high resolution multispectral satellite imagery from WorldView-2, sought to explore ways to identify and extract accurate trees of varying crown sizes. IMAGINE Objective tools from ERDAS IMAGINE software were used to define individual trees model parameters by employing different feature detection and extraction techniques. These enable geospatial data layers to be created and maintained through the use of remotely sensed imagery. The results show that IMAGINE Objective provides a high accuracy function for tree extraction especially when one is dealing with cluster of individual tree crowns. By using cue parameters like color, tone, orientation, texture, etc. the spectral differences between tree and others features were able to be detected. Based on training samples, the trees were quantitatively extracted by means of probability of Bayesian Network on Single Feature Probability (SFP) function. In conclusion, Object-oriented analysis proves a successful method of identifying and extracting individual trees of varying crown sizes. A high accuracy is achieved compared to other pixel-based classification techniques.


Mutonga M.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2012

Silali is the largest and trachytic caldera volcano in the axis of the northern Kenya Rift Valley. This paper describes the results from examination of existing data and detailed geological exploration by the geology team of GDC. The study involved geological mapping of the rock formations, structural mapping and geothermal manifestations well as hydrogeological and volcanological studies of the volcano and sampling of rocks for thin section cutting and petrographic analysis. Fieldwork was carried out in the month of May and July 2010. Basalt is one of the most common types of lava in Silali, manifested mainly as flank fissure basalts and flood basalts. Basalts are aphiric or porphritic and vesicular. The Silali Trachytes are both silica-oversaturated and silica under saturated. In the post caldera group increasing differentiation is thought to have resulted in progressive silica under-saturation. The Blackhill Trachytes are among the youngest lavas are critically under-saturated with respect to silica. The latest activity from a satellite vent on the northern slopes of Silali is basaltic in composition and was erupted about 200-300 years BP. The presence of a still active heat source to sustain a geothermal system(s) indicates that there is a geothermal resource in the area that can be commercially exploited.


Kimani H.M.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2012

The practice of manual reservoir data collection is much debated and criticized because it is time consuming and expensive. Automation and real time data transmission from the Menengai Geothermal field will create a strong economic value for Geothermal Development Company. This paper will present the result of an integrated system that utilizes fiber optic technology and radio systems to provide real time reservoir data, to reservoir engineers and technicians in the comfort of their office both in Nakuru and Nairobi offices. It will allow reservoir engineers to carry out any reservoir design within a short period depending on the output of the wells.


Malimo S.J.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2013

Production of fluids from high-temperature (>200°C) geothermal reservoirs by deep drilling has provided extensive information on the origin and chemistry of these fluids, the associated hydrothermal alteration and various hydrological characteristics of such systems. Geothermal geochemistry is used to identify the origin of geothermal fluids and to quantify the processes that govern their compositions and the associated chemical and mineralogical transformations of the rocks with which the fluids interact. Six (6) geothermal wells from the Menengai Geothermal Field in Kenya have been used in this study to infer the reservoir fluids with respect to species composition. Steam fraction, is estimated to range from 0.1-0.5 of the total well discharge, with the fluids feeding the aquifer having a near neutral pH. Correlation of aqueous silica species with increasing temperature gives a linear pattern indicative of silica as a temperature indicator. Fluid gas concentrations show an increase with increasing aquifer temperature with the one phase wells having the highest aquifer concentration of CO2, H2S and H2. The CO2 concentrations show a systematic correlation with respect to selected aquifer temperature, indicating that activity of dissolved CO 2 in the deep fluid is controlled by local equilibrium between geothermal solution and secondary minerals but this correlation can be disturbed by excessive CO2 input due to magmatic intrusions in the roots of the geothermal system.


Mwakirani R.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2013

Magnetotelluric (MT) method is prefered for sub-surface exploration of geothermal areas. The MT method is effective for delineating geothermal reservoirs that are characterized by high resistivity contrast between the reservoir and the overlaying cap rock (clay caps), The transient electromagnetics (TEM) was used to resolve the static shift problem in MT due to its good resolution near the surface. In this study, we investigate the geothermal potential over the Suswa geothermal prospect through correlation of electromagnetic and gravity survey results. The two data sets show quiet a good correlation and thus helps us confirm there exists a geothermal system at Suswa. A look at the resistivity maps reveal a low-resistivity anomaly at depth which is probably the deeper conductor acting as a heat source on the northern and the southern part of the prospect. This is confirmed by a high-density body seen on the gravity survey at similar locations of the prospect.


Mutonga M.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2013

Paka is a complex multi vent low basalt-trachyte volcano dominated by a young central caldera at the summit, which is 1.5 km in diameter. It is situated 25 km north of Lake Baringo and 15 km east of Nginyang' Village. The volcanic complex is dotted with a number of smaller satellite volcanic centers, which are linked to the main volcano by linear zones of basalt and trachyte cones and eruptive fissures. The main heat source(s) for the Paka geothermal system are the trachyte-basalt intrusive or intrusion complexes underneath the volcano. These bodies are long-lived and are fed by up-welling from time to time of fresh magma from depth. Altered grounds, fumaroles and well-crystallized sulphur deposits along faults within the caldera and the Eastern crater indicate that the faults are deep-seated and are magmatic in provenance. At a local scale, the NNE-SSW and N-S trending faults and fractures are essential in enhancing permeability in the prospect area. The subsurface rocks of Paka prospect wherein the geothermal reservoir is expected to be situated are made up of mainly faulted Miocene lavas. The combination of local and regional structures has enabled fracturing in the reservoir rocks to allow for movement and retention of geothermal fluids. The cap rock for the system is expected to be the Plio-Pleistocene lavas and their associated pyroclastics.


Chebet S.K.,Geothermal Development Company
Transactions - Geothermal Resources Council | Year: 2013

Kenya is endowed with vast geothermal potential along the Kenya Rift valley that transects the country from north to south. Exploration reveals that geothermal potential exceeds 10,000 MW and is capable of meeting nearly all of Kenya's electricity needs over the next 20 years. The government has embarked on an ambitious plan to develop at least 5,000 MWe from geothermal power by the year 2030 and therefore to harness this resource, surface exploration surveys have to be carried out in all the prospects in Kenya. Suswa caldera volcano is one of the promising geothermal prospects in the Southern Kenya rift in which Geothermal Development Company (GDC) has been carrying out surface exploration surveys to determine the potential of the prospect. This paper discusses the Socio- Economic aspects on the communities surrounding the prospect that might arise as a result of developing geothermal energy in the Suswa caldera and strategies adopted by Geothermal Development Company to achieve mutual co-existence with the host community who are mainly the Maasai. This will ensure that the local community enjoys a wider range of socio-economic benefits associated with geothermal energy development. The paper can serve as a working reference for other project developers who harness geothermal power within local communities.

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