Aging equipment, missing documentation and a plant geometry dating back more than six decades: The revitalization of Donkéa Hydropower Plant in Guinea required more than simply replacing old components. Global Hydro combined reverse engineering, advanced hydraulic development and comprehensive Water-to-Wire expertise with close cooperation between its headquarters in Austria and its subsidiary in India. The result: A modernized plant that makes use of existing infrastructure while increasing installed capacity from 15.3 MW to 16.8 MW.
Located around 130 kilometers northeast of Conakry, Donkéa Hydropower Plant has been contributing to the regional electricity supply for decades. Over the years, however, the condition of its electromechanical equipment had deteriorated significantly. One unit was operating only at partial load, while the second turbine had already been out of operation for an extended period.
In 2023, Global Hydro was awarded the contract for the comprehensive electromechanical revitalization of the plant. Rather than replacing the entire facility, the objective was to make targeted use of the existing infrastructure and integrate modern technology into the existing powerhouse.
This approach turned Donkéa into a project that demonstrates what revitalization can achieve when detailed knowledge of existing assets is combined with modern engineering.
For operators of aging hydropower plants, declining reliability or outdated equipment does not necessarily mean that an entirely new plant is required.
Donkéa was a particularly demanding case and had proven difficult to modernize for decades. When Global Hydro took on the project, the task was therefore not only to replace aging equipment, but to develop a technically viable solution for a plant that had proven difficult to modernize for decades.
Against this background, revitalization offered an opportunity to retain suitable parts of the plant while fundamentally renewing its electromechanical equipment. Where existing structures are suitable for continued use, this approach can reduce resource consumption, shorten project implementation and lower investment costs compared with a complete rebuild. At Donkéa, these considerations were important factors in the decision to modernize the existing plant.
The extent of the modernization was nevertheless substantial. Around 95 percent of the equipment in the powerhouse was renewed, including turbines, generators, auxiliary systems, aggregates, cables and control panels. Mainly the existing draft tubes and structural elements of the powerhouse remained in place. The task therefore went far beyond replacing aging equipment. It was to integrate an almost completely new electromechanical system precisely into infrastructure constructed in the 1960s.
This is where Global Hydro's expertise in revitalization and reverse engineering became essential.
A key complexity at Donkéa was the limited availability of reliable original documentation. At the beginning of the project, even essential dimensions such as the runner diameter were not known. Although historical drawings were eventually located, the exact interface dimensions could only be determined after dismantling the existing units.
For aging hydropower plants, this is not an unusual situation. Drawings may be incomplete, modifications made over decades may not have been documented, and the actual geometry on site may differ from the information available on paper. Reverse Engineering provides the basis for working with these uncertainties.
At Donkéa, Global Hydro carried out detailed 3D surveys of the existing equipment and powerhouse. The resulting data allowed the engineering teams to digitally reconstruct the relevant geometries and develop the new equipment around the actual conditions of the plant.
Knowing the existing geometry was only the first step. The new turbine technology then had to be engineered specifically around it.
At Donkéa, the dimensions of the existing penstock required the development of a DN1700 intermediate size for the main inlet valve. Restricted space, high flow velocities and the fixed positions of the inlet and draft tube axes placed additional constraints on the design. The customer also required the runner to be removable downwards, which had to be incorporated into the turbine concept.
For the two Francis units, Global Hydro used an internally developed reference runner supported by extensive prototype measurements and CFD analyses. The hydraulic design was then further developed specifically for Donkéa.
Using CFD simulations, the interaction between the new runner, wicket gate and existing draft tube was optimized to achieve the best possible hydraulic performance within the given geometry. The runners were developed and manufactured at Global Hydro's headquarters in Austria before being shipped to West Africa.
The engineering and manufacturing expertise of Global Hydro’s headquarters in Austria was combined with the project execution and on-site expertise of its subsidiary in India. While the Austrian teams were responsible for key areas including hydraulic development, turbine engineering and runner manufacturing, the Indian subsidiary played a central role in the activities on site and project implementation in Guinea. Regular technical coordination, online meetings and joint site visits connected both teams throughout the project.
This close exchange was essential throughout the project. Precise information collected at the existing plant had to flow directly into engineering and design decisions. At the same time, solutions developed by the engineering teams had to take the actual conditions on site into account.
Donkéa demonstrates the advantage of Global Hydro's international setup: Regional project capabilities and centralized hydropower expertise work together as one team, bringing the right expertise to each stage of the project.
The modernization extended far beyond the turbine itself. Global Hydro's Water-to-Wire scope included the turbine-generator units, control and protection systems, turbine governors, main inlet valves, transformers, switchgear, SCADA integration and the associated mechanical and electrical auxiliary systems. The dismantling of the existing equipment, installation and commissioning were also part of the project scope.
Taking responsibility for the complete electromechanical package allows the individual systems to be considered as one integrated solution, from initial engineering through manufacturing and installation to commissioning and subsequent operation.
Global Hydro's involvement does not end with commissioning. Following completion of the revitalization, a five-year Operation & Maintenance (O&M) contract provides continued support for the operator. This lifecycle approach can be further complemented by Global Hydro's Digital Solutions. Real-time plant monitoring, data analysis and predictive maintenance provide operators with additional tools to identify potential issues at an early stage, optimize plant performance and reduce unplanned downtime. Solutions such as HydroxConnect and HydroxOptimize combine plant data with Global Hydro's hydropower expertise to support reliable and efficient operation throughout the plant lifecycle.
In this way, revitalization becomes more than a one-time modernization project. It provides the foundation for managing and continuously optimizing the plant over the years that follow.
The total installed capacity increased from 15.3 MW to 16.8 MW, corresponding to an increase of approximately 10 percent. Modern turbine technology as well as new control and protection systems also provide the basis for higher availability, reduced maintenance requirements and reliable long-term operation.
For Donkéa, this means more than increased output. The plant supplies electricity to factories as well as smaller villages and communities in the Kindia region, making reliable long-term operation particularly important.
Older plants often come with incomplete documentation, unknown or modified geometries, worn electromechanical equipment and increasing maintenance requirements. At the same time, a complete rebuild can require substantial investment, resources and project time.
Global Hydro combines detailed plant assessment, high-precision 3D scanning, Reverse Engineering, hydraulic development and CFD optimization with comprehensive Water-to-Wire expertise. Instead of applying a standard solution, new equipment is engineered around the actual conditions of the existing plant.
With Austrian engineering and manufacturing capabilities, international project teams, Digital Solutions and long-term service expertise, Global Hydro can support the complete process from initial assessment and modernization through to operation and maintenance.
Revitalization allows operators to preserve valuable infrastructure while integrating modern hydropower technology. Depending on the individual plant, this can reduce the resources, investment and implementation time required compared with a complete rebuild while increasing output, reliability and availability.
Donkéa demonstrates the potential: Extensive modernization and advanced engineering increased the plant's performance while preserving suitable parts of the existing infrastructure. The result is a modernized hydropower plant designed for reliable and efficient operation for years to come.
Every hydropower plant comes with its own technical conditions and requirements. Whether aging equipment, incomplete documentation or the need for higher performance, Global Hydro develops tailored revitalization solutions based on decades of hydropower expertise.
Let’s discuss how we can bring new potential to your hydropower plant. Contact our experts.
Thierry Burckhart
Director Revitalization
+1 (970) 710 1285
thierry.burckhart@global-hydro.eu Contact
