Hydropower is the world’s largest source of renewable energy, accounting for roughly 16% of the global power supply, with capacity expected to grow. One major challenge facing hydropower is reservoir sedimentation, which reduces storage volume, energy output, and discharge capacity, while increasing wear and tear on equipment and stress on the dam.
Several sedimentation management methods exist, including desander basins, which minimise turbine wear by reducing water velocity and allowing sediment particles to settle. However, discharging the accumulated sediment below the dam can lead to power losses due to high water consumption for flushing. Additionally, dam operators often struggle to fully control sediment discharge during flushing, posing environmental challenges.
The SediCon Desander Dredge is a gravity-powered hydrosuction system designed to remove sediment from desanders or other small structures. Highly effective, it can significantly extend the life cycle of hydropower plants.
The SediCon Desander Dredge uses the water head difference between the desander and the discharge pipe outlet to remove water and sediment. Its patented suction head ensures high removal capacity with low water consumption. The dredge can be fully automated with a winch system or a travelling crane.
Utilising an efficient jetting and unrestricted flow system, the SediCon Desander Dredge handles a wide range of sediments, from cohesive clay and organic material to sand and stones.
The SediCon Desander Dredge is easy to operate with low investment and operating costs. Maintenance costs are minimal due to the few moving parts.
Powered by gravity, the hydrosuction system is virtually emission-free. Users have complete control over when and where sediments are discharged, maintaining a natural sediment balance in the downstream river.
The SediCon Desander Dredge can be quickly adapted for new or existing desanders and can be installed and operated without disrupting normal desander operations. Power production can continue while the dredge operates, as the water level and quality remain unaffected.
Autonomous vessel
Neoenergia fosters innovation, bringing benefits to the energy sector. The company has developed an autonomous vessel designed to measure suspended solid discharges in hydroelectric power plant reservoirs. The necessity for these data is growing due to erosion and sediment transport issues in rivers. This innovation will enhance the accuracy and reliability of sediment sample collection, which is currently performed manually worldwide. This initiative is part of the Research and Development (R&D) Program, regulated by the National Electric Energy Agency (Aneel).
The vessel complements studies using data from another autonomous vehicle dedicated to measuring liquid discharge. These surveys are conducted by the Federal University of Juiz de Fora (UFJF) in collaboration with the Institute of Systems and Computer Engineering, Technology and Science (INESC TEC) and the University of Porto in Portugal.
Existing measurement methods depend on each river’s characteristics – current speed, sediment concentration, and course size. The new equipment is adaptable to different rivers and was developed to collect integrated or occasional sediment samples across the section. It can collect equal volumes of water vertically, ensuring more accurate samples.
“Our project is leading to the development of state-of-the-art technologies, benefiting the entire segment of hydro power generation with the possibility of more accurate analyses. This vessel is revolutionising the way solid and liquid discharges are measured, which is essential to determine reservoir conditions,” says Neoenergia’s Hydraulic Engineering and Operations Superintendent, José Paulo Werberich.
This equipment is particularly relevant in the current context of the water crisis. In addition to providing increased reliability in results for low flows, its automation ensures safe data recording regardless of the river’s flow. All data is stored in the on-board computer and can be transferred to the company’s computer system, optimising performance analysis, filing, and consultation of historical data.
The vessel has already arrived in Brazil and was taken to the Itapebi hydro power plant (BA), where it will undergo field measurements on a quarterly basis, as mandated by a joint resolution from Aneel and the National Water and Basic Sanitation Agency (ANA). After testing, the vessel can be utilised at other company hydro generation sites: Baguari (MG), Baixo Iguaçu (PR), Belo Monte (PA), Corumbá (GO), Dardanelos (MT), and Teles Pires (MT/PA).
The boat’s route is determined by geo-referencing to collect samples at specific points in the reservoirs. At these locations, a sampler attached to the autonomous vehicle is deployed into the water, reaching depths of up to 20 meters. This design ensures the sampler remains aligned with the same vertical line of the river’s cross section relative to the vessel, enhancing the reliability of the data collected.
The captured material can then be analysed automatically using a microscope developed as part of the same R&D project. This granulometric analysis, which examines the size of suspended particles, allows for the assessment of reservoir conditions, such as silting.
The R&D project that resulted in the development of the vessel and the microscope began in 2017. Besides this equipment, other technologies were created, including a boat designed to measure flow and water quality. Additionally, the project facilitated the nationalisation of a geo-referencing technology at a cost ten times lower than the market price.
Monitoring
The LISST-SL2, developed by Sequoia Scientific, Inc., has been deployed for monitoring purposes within a critical hydropower facility. This advanced equipment is designed to measure various parameters, including depth, velocity, temperature, sediment concentration, and size distribution.
Hidroeléctrica CELEC, a state-owned holding company involved in the entire spectrum of electric power activities—from generation to distribution, commercialisation, and international trade—oversees a diverse portfolio of energy projects. Notable among these is the 1500MW Coca Codo Sinclair hydroelectric plant, a flagship project located in the Napo and Sucumbios provinces, which stands as the country’s largest energy initiative.
Facilitating the acquisition process, Caracterización De Partículas Ostos & Ostos Limitada, acting as Sequoia’s regional distributor, coordinated the procurement and delivery of the LISST-SL2 equipment to CELEC.
The LISST-SL2 stands as Sequoia’s foremost multi-parameter instrument for monitoring river sediment. It provides real-time Point-Integrated, Depth-Integrated, or time-series data, effectively replacing outdated samplers.
Designed with a streamlined, low-drag body, it measures depth, velocity, temperature, sediment concentration, size distribution, and other auxiliary parameters using laser diffraction technology.
The system features an active intake pump control that ensures intake velocity matches the river’s velocity (iso-kinetic), enhancing accuracy and reliability in data collection.
The LISST-SL2 features significant advancements over its predecessor, the original LISST-SL, including:
- A simplified user interface for enhanced usability.
- Utilisation of laser diffraction technology with redesigned optics to cover an expanded grain size range of 1-500 microns (compared to 2-386 microns for the LISST-SL).
- Isokinetic capability with advanced pump control.
- Integration of a 2-wire special communication protocol compatible with USGS B-reel standards.
- The Topside Box (TCB) containing batteries and facilitating data transfer via Bluetooth to a laptop.
- Real-time display of current speed, temperature, concentration, grain size distribution, depth, and mean sediment grain size.
- New software providing point-integrated and depth-integrated sediment data.
- Bluetooth connectivity enabling operation in diverse weather conditions.
- Ability to switch between different units (ft, ft/s, m, m/s) for depth and velocity measurements.
- Real-time data processing supporting time-series or vertical profile formats.
- Simplified storage and maintenance post-use.
Key distinguishing features of the LISST-SL2 include its role solely as a sensor, requiring connection via a USGS B-Reel to a Topside Control Box (TCB). The TCB, equipped with a rechargeable battery and electronics, supplies power to the LISST-SL2 and receives raw scattering data. These data are transmitted via Bluetooth to a nearby Windows laptop or tablet, where real-time processing occurs. The software processes raw data to display optical transmission, velocity, depth, temperature, particle size distribution, and total concentration. Operators can select between time-series or vertical profile views, with post-processing software generating point-integrated or depth-integrated concentrations. This capability offers detailed insights into sediment flux across 36 distinct size classes.
All data, both raw and processed, are presented in user-friendly formats, enhancing accessibility and usability for scientific analysis and environmental monitoring applications.
This article first appeared in International Water Power magazine.
