On a mission in Kenya

11 September 2009

Two small hydro specialists from the Hangzhou Regional Center for Small Hydropower in China were invited on a consultation mission to Kenya to help select and design projects for development in the country. Here, Pan Daqing and Lin Xuxin share their experiences of the trip with IWP&DC

In the summer of 2008, the Hangzhou Regional Center for Small Hydropower was invited by Kenya’s Power Technology Solutions Co to send two representatives to visit the country and consult on hydro developments. The specialists were asked to help select dam and powerhouse sites, determine heads and installed capacity, assist with general layout and determine the type and size of potential civil works. Three sites of particular interest were Gikiri, Chinga and Ihuririo in the Othaya Division of the Nyeri District.

After visiting the three sites for reconnaissance, followed by a further trip to the Gikiri and Chinga sites to assist local surveyors, and the collection and analysis of hydrological data, the specialists concluded that Gikiri and Chinga were the most suitable sites for development.

Chinga project

Chinga reservoir was established in 2007 to supply fresh water for local farmers. The catchment area above the dam site is 38km2 and the elevation in the reservoir area is 1920m. Based on the local hydrological data provided, the multi-year mean precipitation is as high as 1400mm.

Previously, local technicians had estimated 12m head at the site. However, following a couple of site visits and further research by the Chinese specialists, a 22.5m head was determined. The specialists helped select the most appropriate location for a new powerhouse and designed the layout of the necessary penstock. It was decided that one 400kW Francis turbine should be installed at the project, offering annual mean power generation of 1.4MkWh. The reservoir would provide daily regulation function for the hydro power station.

It was also concluded that no large-scale excavation or dam construction would be necessary, thus reducing investment costs and environmental impact. Only a small weir at the spillway would be needed, together with a diversion canal, forebay, penstock, powerhouse and substation. The intake of the diversion canal and the sluice gate should be situated on the left bank. The total length of the diversion canal would need to be around 150m and the penstock should be 55m long with the slope 25°. Transportation would not be a problem at the site, as the highway is just at the side of the reservoir.

With the design of the new project, the original function of fresh water supply and fishery would remain unaffected.

Gikiri project

The proposed Gikiri project site is located at the lower reach of the Chinga site. The catchment area here is around 100km2 and the annual mean flow at the dam site is 2.5m3/sec. The rated head at the site was determined at 20.5m and multiyear mean power generation at 2.8MkWh, utilizing two 400kW Francis units.

At the Gikiri site, local technicians had estimated the discharge as 15m3/sec. Following site investigations and analysis however, the rated design flow was determined at around 5m3/sec.

Access to electricity

With the increasingly high price of oil, it is even more necessary to tap the abundant hydro power resources available in the country in order to benefit rural farmers. The development of new schemes would likely by welcomed by the rural communities. For example, during the consultation mission, numerous farmers and other locals came out to watch the Chinese specialists working with Kenyan engineers, even helping to make site access easier by chopping tree branches and crops. When asked why they were helping, the reply was simple: ‘Because there will soon be electricity which is a very good thing’.

At present, rural electrification in the country is still quite low – only around 10% – with many potential hydro sites unutilized. However, the Kenyan government has said that it expects small hydro stations to play a very significant role in the provision of clean and affordable energy in the future. In order to facilitate the development of small hydro resources, in its Session Paper on Energy No. 4 (2004) the government came up with a number of policies and strategies, including:

• Continuous collection of hydrological data from all of the country’s drainage basins with a view to determining small hydro potential.

• Package and disseminate information on small hydro to create investor and consumer awareness on its economic potential. This will include establishment of community based pilot projects.

• Remove existing legal and regulatory barriers (amendment of Electric Power Act, 1997) to allow vertically integrated mini-grid systems for rural electrification using small hydro even in areas where licenses have been issued to public electricity supplier.

• Formulate and enforce standards and codes of practice.

• Promote development of local capacity for manufacture, installation, maintenance and operation of small hydro technologies.

• Fiscal incentives to financial institutions to support small schemes.

Construction starts

In early January 2009, the authors were delighted to be informed that the developer of Gikiri and Chinga small hydro stations had received loans for the project, and that construction had begun on both sites. The two projects are expected to be commissioned at the end of this year.

Pan Daqing, Chief of Foreign Affairs & Training, and Lin Xuxin, Deputy Chief Engineer, Hangzhou Regional Center for Small Hydropower. Email: [email protected] or visit www.hrcshp.org

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