Meet Thierry Verhulst, Tractebel hydropower plant rehabilitation expert in France

The hydropower plant rehabilitation market is growing, a trend that is expected to continue worldwide in the coming years. As assets age, investment in the rehabilitation of an existing plant is generally less costly than construction of a new plant, with significantly lower environmental and social impact.

 

Q: Tell us something about yourself that most people don’t know

Not only do I spend long hours on the computer at work, but also at home. For the last ten years, I’ve undertaken the project to digitize all my media’s old physical supports: it’s a long-term job. I’m scanning all my photos (more than 20,000 scanned so far), converting VHS tapes to DVD files (more than 120 DVDs created), converting vinyl records and audio tapes into high-quality audio files (over 12,000 audio files created at date). The job is not only to convert everything to digital, but also to correct the defects in images, video and audio.

 

Explain your job as expert in the rehabilitation of hydropower plants

My job has multiple aspects in relation to rehabilitating hydropower plants. The first step is to gather knowledge and familiarize yourself with the plant to be rehabilitated. Then, detailed site inspections and discussions with operating and maintenance staff are mandatory. Extensive experience in power plant design and a lot of plant inspections are necessary to be able to understand quickly and efficiently the issues that will be faced in the rehabilitation. 

The plant’s documents and drawings also need to be analyzed. Combined with the site inspection results, it allows us to establish the diagnostics of all the plant’s equipment and systems. The diagnostics, or condition assessment, is the second step.

Based on that, the different possible scenarios of rehabilitation are studied, including the evaluation of costs. Apart from the technical aspects, costing is also a tough and sensitive part of my job. It’s more difficult to evaluate the cost of rehabilitation works than the construction of a new plant, as some equipment is replaced, some is partially rehabilitated (keeping part of the existing components) and some is simply cleaned and repaired, for example. And there are specific activities to be considered such as hazardous materials removal, dismantling and erection activities in a plant in operation.
 

Q: What are some of the challenges you encounter in these kinds of projects? What was the biggest challenge you faced and how did you resolve it?

The main challenges in hydro rehabilitation are:

• Rehabilitating or installing new equipment in an existing structure: you have to fit it into the existing structure while minimizing civil modifications.
• Performing the site works in a plant that continues to be partially operational during rehabilitation. The sequences of the rehabilitation work have to be studied in detail to allow continuity of operation, minimizing complete shutdowns of the plant and limiting the risks as much as possible.
• Finding the best compromise of improvement of the plant performance (efficiency, availability, reliability, etc.) versus profitability.
• Defining the solutions for rehabilitation of underwater parts (such as on the upstream side of the dam) when it’s not possible to dewater or lower the water level of the reservoir.
• Removal and treatment of hazardous materials found in old plants like asbestos, lead and oils.
• These are equipment issues, but great challenges are also encountered in the rehabilitation of the civil structures such as the dam, spillway, water intake, headrace tunnel and powerhouse building.
   

 

Q: What are the most innovative solutions that you and your team have applied to hydropower rehabilitation projects?

I can’t exactly say that we implement technically innovative solutions on rehabilitations, but we face a lot of difficulties specific to each plant that need to be solved in the course of the project, like the challenges listed above. This is required to ensure modernization and improvement of the performance of the hydro power plant.

However, there is one innovative solution that I can mention: 
Original drawings of the plant are not always available, or if else they’re not up to date. So for more efficient site surveys, we are foreseen to use accurate 3D laser scanning to rapidly obtain a reliable 3D model of civil and equipment arrangements on which our studies can be based.

Q: What is the most satisfying part of a project and why? 

The most exciting part is the site visit when you discover the old plant. You get to witness firsthand the solutions designed 40, 60, or even 100 years ago. You learn a lot from the past, and it’s always impressive to see equipment continuing to operate after a half-century or more. 

Also, visiting plants from the former Soviet Union is very interesting because the Russian engineers have developed a unique way of technical thinking. It’s always surprising to discover the innovative and different technical solutions they’ve implemented in their plants. 

Finally, discussions with the operating and maintenance staff are also very interesting. They provide a lot of information on the history of the plant, and on the special events the plant has faced.

 

Q: Consider the following statement
As engineers, we have a crucial role to play. Achieving UN Sustainable Development targets depends on integrated engineering solutions that ensure access to sustainable, affordable and reliable energy, water and smart infrastructures.

How does your role in rehabilitation of hydropower plants contribute to UN SDG targets or climate change?

Hydropower plants provide green and sustainable energy. Our role is to develop plants that are more environmentally friendly. In the case of plant rehabilitation, the original design is not always sufficiently safeguarding the environment. Some plants generate pollution by leaking oil into the river, for example, so this and any other environmental issues will be addressed during rehabilitation. 

Rehabilitation is a great opportunity to create a greener and safer plant. We aim for improved efficiency (less water consumption for the same power production), lower internal electrical consumption to operate the plant’s auxiliary systems, and to combine the hydro power plant with other green energies such as solar and wind.

Our concern is also to make the plant more resilient to climate change. This last point is related to the economic sustainability of the plant and to the reliability of power production despite climate change. This aspect is now always studied in the frame of a rehabilitation project, to define improvements and potential implementation of additional equipment to ensure the long-term, safe operation of the plant.

Rehabilitation is also the opportunity to improve the management of water resources, to provide clean water for irrigation and potable water. So it’s always a rewarding experience to contribute to the modernization of a hydropower plant and extend its service life. That’s our way of contributing to take care of people and the planet.