Author: John Steele, Robert Greyling, Egbert Scherman
Conference: Hydro 2018
Date: October 15-17, 2018
Throughout the world, there has been an increasing trend toward development of low impact small to medium sized hydropower schemes by Independent Power Producers (IPP’s) and Private Developers.
The inflow of private investments into the dams and hydropower market, which has traditionally been the domain of public financing, is having a positive impact on this market. Compared to the risk-adverse public sector, the private developers approach to the project life-cycle is quite different. Private Developers are often more willing to absorb risk to ensure that the project progresses on schedule and within budget during construction and that the hydropower plant gets commissioned on the committed date, so that the investors begin to realize the committed returns.
Joint risk-based decision making has afforded the developer, engineer and contractor an opportunity to approach these projects from a different perspective. Under the correct conditions, and with the correct implementing team, it is possible to deliver small hydropower plants (HPP’s) that are purpose-built, low impact and cost effective.
In this paper, the authors present the design and construction of Azambi Hydropower Project, the third HPP developed by the Kibali Gold Mine, located in the remote north-east province of Democratic Republic of Congo, Africa. The mines concession is not serviced by an electricity utility provider but is favourably enveloped by large untapped rivers.
Azambi HPP is configured as a run-of-river hydropower station, whose output is used to offset thermal power supply by supplementing the base load power generation during the mine operations. There is no Power Purchase Agreement (PPA) and the bankability is directly related to the capital cost of the hydropower plant itself and its peak spinning reserve, offset against the running of thermal power supply which is fueled by expensive imported diesel fuel. The term of the scheme is the Life of Mine (LoM) and the economic model does not consider future value. The hydropower station will ultimately become a legacy asset to the local communities once the mine has reached its end of life.
Central Africa, being notorious for instability is generally bereft of infrastructure, equipment suppliers or experienced hydropower contractors, particularly where small hydropower development may be attractive. To remain competitive, engineering design must be tailored to the available topographical and geotechnical site conditions, local construction materials sourced within the immediate vicinity of the site, and constructed with basic plant and equipment and generally semi- or unskilled manpower. Where specialist materials or equipment are required, importation from developed areas becomes the only alternative, at significant cost.
By describing the design basis adopted for Azambi HPP, the important constraints encountered and specific challenges overcome during the engineering and construction implementation, the reader will be introduced to the
importance of formulating design on basic engineering and construction principles, reinforced with innovation and lateral thinking to mitigate risk and to allow an integrated implementation approach between the key parties.
Such an approach makes it possible to promote run-of-river hydropower development within uncertain conditions
and unreliable communications, in a cost effective, fit for purpose and successful application.
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