Hydropower modernisation and rehabilitation are essential tasks within ageing hydropower plants, essential for ensuring continued efficiency, sustainability, and resilience in our evolving energy landscape. As these plants age, the integration of cutting-edge technologies and updated engineering solutions becomes imperative to optimise energy output, enhance safety measures, and minimise environmental impact. Through meticulous modernisation, we unlock the potential for increased energy generation, improved operational flexibility, and seamless integration with emerging renewable energy systems. Moreover, rehabilitation efforts address wear and tear, prolonging the lifespan of critical components and safeguarding against potential hazards. By investing in these transformative initiatives, we not only uphold the reliability of our energy infrastructure but also uphold our commitment to a cleaner and more robust energy future for generations to come.

Across the world, an array of rehabilitation projects are currently in progress, tackling a range of challenges that impact hydropower initiatives.  

Overcoming corrosion

In the US, when engineers at Hoover Dam determined that the original cast iron lantern rings built into some of its turbines needed to be replaced, they were looking for a solution to help them overcome the corrosion issues they experienced with the cast iron.

The maintenance team also faced another challenge. The Colorado River serves as a water source for the Hoover Dam hydropower station, and the water in this area is commonly referred to as “hard water” due to its high mineral content, specifically high levels of calcium and magnesium ions. Aluminium lantern rings that were first tried as a replacement, were corroded by chemical reactions with the minerals in the water. 

Having used Vesconite Hilube bearing material in other applications, such as guides on their pressure relief valves, the engineers were familiar with the no-swell, non-corrosive properties of the material and also with Vesconite Bearings’ capability to create large-diameter parts such as these 44-inch diameter lantern rings (Ø1,100mm). Vesconite Hilube also had the added advantage that it is not chemically attacked by the “hard water”. 

Two lantern rings were supplied, one of which was divided into two segments and another of which was divided into three segments. Like the lantern rings Vesconite Bearings makes for pumps, the large-diameter hydroelectric power plant lantern rings were easily machined and included the necessary flush holes that would cool the shaft on which they were located.

“Our experienced staff in the machine shop can machine these large-diameter parts with the necessary accuracy,” notes Monique Potgieter, the application engineer who assisted the Hoover Dam team with the design and supply of the lantern rings. “Even though not all lantern rings are designed to run in close proximity to the shaft, it is important to know that our materials can be used with small clearances. This will result in better shaft support and stability, all the while you’ll have no worries of contact between the shaft and the lantern ring,” she says.

“Vesconite’s low-friction materials are non-galling, and occasional contact with the shaft will not result in damage,” Potgieter adds.

The two lantern rings were supplied in early 2022,  and are the largest lantern rings Vesconite has produced to date.

New generators

KONČAR – Generators and Motors has two significant contracts for substantial ventures in Germany and Austria, with the initial phase of these projects valued at over €10 million. Austrian electricity provider Verbund chose KONČAR’s proposal for the comprehensive revitalisation of two hydropower plants situated on the German-Austrian border following a competitive tender process initiated in October 2022.

In the Egglfing–Obernberg project, KONČAR – Generators and Motors is manufacturing six entirely new generators for the German-side power plant. Meanwhile, as part of the Braunau – Simbach undertaking, the company is undertaking the revitalisation of four generators, alongside crafting new stators and rotor poles for the Austrian segment in the coming years.

The equipment for both projects will be simultaneously manufactured and delivered in the upcoming years. The on-site delivery of the first generator components is planned for Q1 2024, with manufacturing of the remaining generators planned in the period up to 2030, valued over several tens of millions of euros.

The Egglfing-Obernberg Hydropower Plant is located on the German side of the Austrian–German border on the River Inn. The remaining scope of work encompasses the manufacturing of six completely new generators, the dismantling of old generators, the installation of new generators at the existing power plant and their commissioning. The project includes upgrading the power output of the 200-tonne generators from 16 MVA to 20 MVA. The Braunau-Simbach Hydropower Plant, also on the River Inn, is located on the Austrian side of the German–German–Austrian border. The remaining scope of work consists of the revitalisation of four generators, including new stators and rotor poles, the dismantling of old generators, with installation and commissioning of new generators. Within the project, the generators weighing more than 300 tonnes, will also undergo upgrade in power output from 32 MVA to 35 MVA.

KONČAR has previously secured a tender with the same customer, for the delivery of three new generators for the Ering – Frauenstein Hydropower Plant, which is in the final phase, and on-site operations are due to commence on the last generator.

Control system

In October 2022, Rittmeyer was granted the contract to embark on a comprehensive control system renewal initiative at the Ryburg-Schwörstadt hydropower plant in Switzerland. This extensive undertaking is slated to span a duration of five years, culminating in its completion by 2027.

With a capacity of 120MW (four 30MW Kaplan turbines), the Ryburg-Schwörstadt hydropower plant is the most powerful hydropower plant on the High Rhine and is located about 20km upstream from Basel. The entire control technology is being renewed. Among other systems, it includes a complex automatic water management system with the main task of ensuring a constant water level at all times. It also controls the power redistribution between the two Swiss and two German machine groups. The system includes complex weir controls for the four weir fields as well as an emergency controller.

The modernisation process and automation of the four machine groups will be executed in a phased approach, intertwined with the ongoing operation of the remaining three machine groups. The inherent challenge in this endeavour lies in deftly managing the substantial water flow of the Rhine River. In the event of a trip of one or more machine groups, the water of the tripped machine groups must be redirected to the weirs in the shortest possible time. This requires highly available and very fast-acting systems to avoid excessive level increases in front of the power plant. Rittmeyer’s expertise, particularly in the renewal of safety-critical processes within expansive river power plants, played an instrumental role in clinching the contract. As part of this initiative, the encompassing control system responsible for redundant electricity production dedicated to the power plant’s internal use will be revamped. Furthermore, the station control technology governing a total of eight switchgear panels will undergo a comprehensive overhaul, integrating into the new overarching control framework.

Employing the advanced RITOP control system equipped with remote alarming, complemented by the RITAS alarm server and the efficient RIFLEX process stations, the Ryburg-Schwörstadt hydropower plant is poised to embrace a state-of-the-art solution from Rittmeyer, meticulously aligned with the most current safety benchmarks. After the renovation, the run-of-river power plant will again be state of the art and can be operated reliably and safely for another 15 to 20 years.

In addition to the entire Rittmeyer AG project team, Beat Karrer, CEO of Kraftwerk Ryburg-Schwörstadt AG, is also looking forward to the extensive project: “We have come to know Rittmeyer as an efficient, solution-oriented, and pleasant partner who brings the necessary expert knowledge and has the right solutions and products for this sophisticated modernisation. I look forward to working together on the renewal of our hydropower plant’s control system.”

Turbine modernisation

Andritz has secured a contract from Engie Brasil Energia for the comprehensive modernisation of the 424MW Jaguara hydropower plant in Rifaina, State of Sao Paulo. The plant is a pivotal component of Engie’s hydro generation portfolio and has been in uninterrupted operation since its inception in 1971.

The project, slated for completion by the close of 2028, is set to encompass an extensive overhaul of the plant’s core components. Andritz’s scope of work entails the modernisation of all four 106MW Francis turbine generator units. The renovation will also encompass the refurbishment of governors, the excitation system, the automation system, as well as all associated auxiliary systems. The contract will be executed by Andritz Hydro Brazil.

The contract increases the partnership between Engie and Andritz and is the biggest contract Andritz Hydro Brazil has ever signed for a single hydropower plant modernisation project.


GE Vernova’s hydropower business has been chosen by Hafslund Eco to provide new Rotorpoles for the 3x 280MW / 300 MVA water-cooled generators used by the Aurland 1 hydropower plant in Norway.

Scheduled to take place between the summer of 2025 and 2027, the service activities will be carried out in GE Vernova’s Norway Services Workshop located in Lier. By combining the generator service with the forthcoming refurbishment program of the hydropower plant, Hafslund Eco aims to optimise downtime and streamline the overall operational efficiency of the facility.

“We are happy to be working with GE on this project,” said Tormod Kleppa (Director of Projects), Hafslund ECO. “The Servicing of our Aurland 1 is an important project for us and we are glad to count on GE to deliver the new Rotorpoles while the refurbishment program is undergoing.”

The Aurland 1 hydropower plant, constructed between 1969 and 1989, represents Hafslund Eco’s largest power plant and ranks as the third-largest hydropower facility in Norway with 840MW capacity.

Norway heavily relies on hydropower, which accounts for over 90% of its total power generation. The country’s unique geography, characterised by high mountain plateaus, abundant natural lakes, steep valleys, and fjords, offers immense potential for hydropower development. Hydropower has been a cornerstone of Norway’s industrialisation since the late 19th century and continues to serve as the backbone of its power system.

Pascal Radue, Hydro Power President & CEO of GE Vernova, expressed his enthusiasm for the project and the broader role of hydropower in Norway’s energy transition, stating: “Norway has been an inspiring example of how hydropower can contribute to the energy transition by delivering a large amount of renewable energy in the very long term. Today, the average age of the fleet is about 50 years, opening up for refurbishment needs, that will help extend the lifetime but also increase even more the efficiency of hydropower plants, without any need to re-build a dam. We are thrilled to partner with Hafslund ECO on this service project.”

Work on dams

As part of an extensive modernisation initiative for the Vioreau dam in France, the Loire-Atlantique departmental council recently revealed that it has granted the contract for lot 2 (which involves waterproofing the foundation and implementing drainage solutions) to Soletanche Bachy.

Situated in the town of Joué-sur-Erdre, the Vioreau dam serves a primary purpose of supplying water to the Nantes-Brest canal. It plays a crucial role in storing water throughout the winter season, facilitating the replenishment of low water levels during periods of navigation.

Originally constructed in 1834, this gravity dam stands at a height of 13.7 meters and spans a length of 131.6 meters. It forms a reservoir with a capacity of approximately 7.5 million cubic meters.

 Commencement of Lot 2 activities will be undertaken subsequent to a partial reduction in the reservoir’s water volume. The tasks associated with the upstream segment of the dam encompass:

  • Establishing a grouting curtain that extends to a depth of 20 meters within the bedrock beneath the structure. This procedure will employ the GIN method to enhance subsoil impermeability where it interfaces with the ground/structure and bolster the mechanical properties of fractured zones.
  • Installing a secant jet-grouting column cutoff wall, which will reach depths of around 6 meters within the central area where an alluvial zone has been identified.

In relation to the downstream portion of the dam:

  • Implementing a drainage network utilising oriented drains that will be directly drilled into the masonry using the Hi’Drill technique. These drains will encompass varying azimuths to optimise effectiveness.

Throughout the tendering process, project designers from the Eurofrance design office facilitated the creation of 3D blueprints depicting different work stages. This enabled a comprehensive assessment of machinery movements and interactions.

The technical department meticulously examined the injection methodology, drawing insights from recent experiences in rock injection projects.

Commencement of injection and jet-grouting began in mid-April 2023 and is expected to be complete at the end of 2023.

In August, on India’s 77th Independence Day celebrations, it was announced that a JV of SMEC-Stucky has secured a role as the Engineering & Management Consultant for Phase II & III of the country’s Dams Rehabilitation and Improvement Project (DRIP).

Commissioned by India’s Central Water Commission (CWC), this project signifies a significant step forward in enhancing the safety and operational efficacy of designated dams throughout the nation. With joint financial support from both the World Bank and the Asian Infrastructure Investment Bank (AIIB), the implementation of DRIP Phase II and III will span across 19 states and involve three central agencies, notably including the CWC.

Focusing on bolstering institutions, the team’s efforts will be dedicated to providing comprehensive management consulting aimed at integrating enduring operational and asset maintenance capabilities throughout the system. The project’s duration spans a decade.

The project’s scope encompasses four components:

  • Revitalisation and enhancement of designated dams and their related components.
  • Strengthening of institutional frameworks for dam safety.
  • Incidental revenue generation to ensure the sustainable operation and maintenance of dams.
  • Effective project management.

Anticipated outcomes from the project encompass heightened safety standards, augmented water availability, and a diminished threat of floods, thereby fortifying communities against the repercussions of climate change.

“This project is aligned with SMEC’s mission to create the infrastructure that stands the test of time, safeguards precious resources, and propels India’s development agenda to new heights,” said Mallikarjunagouda Patil, Director of SMEC, India. “As we celebrate India’s 77th Independence Day, we are honoured to have been chosen for this prestigious project that aligns perfectly with our vision of building a sustainable future. Our Joint Venture is excited to contribute our expertise and technical acumen to rehabilitate these vital dams, ensuring their long-term viability and the safety of surrounding communities.”

Smt. Debashree Mukherjee, Special Secretary, Central Water Commission, New Delhi, added: “This partnership comes at a crucial juncture as we work together to ensure the safety and functionality of our nation’s dams. We look forward to witnessing the positive impact of this endeavour on the communities and the environment.”

Back online

At the end of July, it was announced that the Lesotho Highlands Development Authority (LHDA) had successfully restored and brought back Unit 1 at the Muela Power Station into operation. The unit experienced an unexpected breakdown on 18th June 2022 and has now been fully repaired and operational since the 13th of July 2023.

The LHDA’s internal team of skilled engineers and technicians played a pivotal role in managing the replacement of hydropower machinery and equipment. The thorough dismantling and reassembly of the turbine and generator were carried out with precision and expertise, ultimately leading to the successful restoration of Unit 1.

The restoration of Unit 1 not only brings relief to LHDA but also aligns with the Lesotho government’s efforts to provide accessible energy to its citizens and reduce reliance on electricity imports. With the full generation capacity of hydropower now restored, the ‘Muela Power Station is expected to play a crucial role in providing clean, affordable, and sustainable energy to the people of Lesotho, thereby bolstering economic growth and enhancing the overall quality of life.

“Indeed, we are delighted to make this announcement, after a year of around-the-clock work by our dedicated teams.” said Mr. Tente Tente, LHDA Chief Executive. “This achievement represents a significant step forward in our efforts to provide accessible and reliable energy for Lesotho. We extend our gratitude to the dedicated team whose hard work and expertise made this accomplishment possible. An invaluable experience has been gained, and there are lots of lessons learned to be shared with the hydropower fraternity “.

The LHDA expressed its heartfelt appreciation to all stakeholders, including international, regional, and local partners, as well as the government of Lesotho, for their unwavering support throughout the refurbishment process. Their collaboration played a vital role in ensuring the success of this ambitious project.

The Lesotho Highlands Water Project (LHWP) is a multi-phased, multi-billion Maloti/Rand project between the governments of the Kingdom of Lesotho and the Republic of South Africa. It includes water transfer and hydropower generation components, with the goal of enhancing water usage from the Senqu (Orange) River and its tributaries, both for South Africa and to generate hydroelectric power in Lesotho.

Phase I of the project included the construction of the Katse Dam, transfer and delivery tunnels, ‘Muela Hydropower Plant, and the Mohale Dam. Phase II comprises a dam at Polihali and a gravity tunnel connecting the Polihali reservoir with the Katse reservoir. The hydropower component of Phase II, the Oxbow Hydropower Scheme, is currently in the procurement phase for scheme design.

The Lesotho Highlands Development Authority (LHDA) serves as the implementing and management authority for the Lesotho Highlands Water Project on behalf of the government of Lesotho.

This article first appeared in International Water Power magazine.