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close this bookCERES No. 074 (FAO Ceres, 1980, 50 p.)
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View the documentTanzania to weigh impact on environment

First move made to tap geothermal source of energy project in Kenya

Kenya is about to become the first country to harness on a big scale the geothermal energy accessible through a vast fault in the earth's crust across Africa from Mozambique to Ethiopia and on to Turkey. The project heralds considerable agricultural development in the region.

The World Bank has completed an agreement with the Kenyan Government for the joint financing, with help from third parties, of two geothermal electricity generation plants near Nairobi. They are to have a total capacity of 45 MW. Sources close to the World Bank describe the project, which is to cost about $41.2 million initially to meet a tenth of the nation's rapidly increasing energy requirements, as merely a modest beginning.

For the specialists whose surveys have led to the Kenya project regard the whole of the 6 500-km Rift Valley as a potential source of relatively cheap and abundant geothermal energy. Indeed, the United Nations Development Programme (UNDP) - which played an important role in securing the Kenya agreement - has already helped Ethiopia to locate more than 600 geothermal "hot spots." Predictably, most of them lie in the valley.

Kenya is undergoing rapid industrialization which calls for growing energy consumption despite all the ambitious national oil conservation policies. At present Kenya's oil imports cost $350.2 million a year and, in the absence of the ample and reliable domestic sources of industrial energy, the steady, steep increase of world oil prices could strangle the young economy at a particularly vulnerable stage of its development.

Unlike oil, geothermal energy is renewable because it feeds from the immense heat beneath the crust of the earth. In the few years since the oil crisis of 1974, more than 50 countries have made serious attempts at the exploitation of geothermal energy. It is being utilized in many places, including the United States, Iceland and Japan.

In Kenya, the construction of the Olkaria geothermal project near Lake Naivasha about 80 km from Nairobi follows more than two decades of intermittent survey and exploration. The development programme is based on a survey carried out by a combined team of Swedish and Icelandic consultants. UNDP has invested about $2.06 million in financing various surveys, feasibility studies and actual drilling work. The UN geologists and geochemists eventually withdrew from the work to make way for Kenyan specialists. The overall responsibility for the scheme rests with the East African Power and Lighting Company of Nairobi.

The projected plant is to feed from an immense geothermal reservoir identified 700 m beneath the earth's surface. The feasibility report recommended a stage-by-stage expansion of the programme both at Olkaria and at two other known geothermal regions. Apart from electricity generation, the Olkaria energy yield would be put to work for many purposes, including the dehydration of vegetables in driers probably similar to those used in Iceland.

A small dehydration thermal plant is already at work in the Naivasha area, near the geothermal field, where up to three excellent crops of vegetables can be grown a year. Geothermal steam is also applied in Kenya for the drying of pyrethrum, the plant base of a non-persistent, natural pesticide manufactured by a thriving East African industry.

One of the drawbacks of geothermal energy is the accompanying problem of chemical waste disposal. Arsenic, salt, boron and many other mineral compounds are frequently included among the geothermal effluents brought to the surface; they can be harmful to animal and plant life and can contaminate the water if discharged untreated. An ecologically sound method of large-scale geothermal waste disposal is therefore essential for any such project.

The authors of the feasibility study considered that local effluent disposal by infiltration in ponds and topographic depressions would cause no significant harm to the environment. One available alternative method is the re-injection of geothermal effluents into the earth; but a lot more research work is required.

Kenya's industrial planners are thus expected to compromise. First, they are to build a water-treatment plant together with the geothermal power stations. Later, they will launch an ambitious scientific research programme aimed at the development of a reliable and cost efficient waste re-injection technology.

The benefits of such a programme would be reaped first by Kenya in the course of its own long-term geothermal development, which may eventually turn the country into a net exporter of energy. It may also benefit many other countries-in East Africa and elsewhere- in their quest for cheap industrial energy from the volcanic depths of the earth.