There’s no two ways about it: developing and operating sustainable hydropower requires dealing with the accumulation of sediments in reservoirs. Facing its customers’ dissatisfaction with traditional methods of removing silt, sand, and fine gravel from the bottom of their reservoirs, global equipment manufacturer Voith has partnered with specialist firms to develop Sediment Care Program, a combination of technical and contractual tools designed to replicate as closely as possible the natural flow of sediments in the river while guaranteeing equipment performance to power plant owners.
Sediments are part of the natural flow of a river. Over time, sedimentation can reduce the amount of water stored in hydropower reservoirs and make energy production depend entirely on seasonal flow. In practice, storage hydropower plants can become akin to run-of-river plants and lose the benefit of flexibility.
Most hydropower dams are designed to sustain a loss in storage over the course of their lifetime: the dead storage portion of the Three Gorges reservoir in China is designed to be filled with sediment in about 120 to 150 years (1). But for most hydropower plants with storage, the problem of sedimentation comes sooner rather than later. Clearing the bed of the reservoir by scooping out mud and accumulated sediments can be expensive, particularly if it requires emptying the reservoir and halting power production. Finding a place to deposit the material collected safely is another expensive endeavour. Another alternative, flushing sediments in large quantities every now and then, causes distress for the environment and is now heavily restricted or forbidden in certain parts of the world.
An option remains: replicating the natural river flow by passing small amounts of sediments through the turbine in a continuous way. But it is problematic, or rather was problematic until recently: who would be reckless enough to damage their expensive equipment in this way? The answer: someone who can benefit from cutting-edge turbine design that minimizes erosion and who is insured against serious damage to their equipment.
Voith’s Sediment Care Program does all that. The programme begins with the sizing and design of the equipment on the basis of a comprehensive sediment and hydrology analysis. The manufacturer delivers the sediment transfer floating vessel and monitoring system, operated on a pay-for-use model. This enables the production of information for environmental authorities. The manufacturer also provides what it calls “full coverage of turbine erosion” at no extra cost, for the duration of the contract. This includes turbine maintenance, turbine repair, coating of turbine and turbine parts, yearly inspection and modernisation, among other services.
The vessel uses the ConSendTrans method to transfer sediment continuously through the turbines without water losses, which is an automated and fully controlled process. Its operation can be adapted to the ecological and weather/discharge conditions of the plant. The system is GPS-controlled and monitored in real-time via the user interface.
Taken in isolation, these services and products are not new. The incremental innovation in Voith’s Sediment Care Program resides in the combination of all under a single programme that makes business sense for hydropower operators, who can be reassured by the manufacturer’s long-standing expertise in turbine modelling, manufacturing and monitoring.
(1) Wang, Z., and C. Hu, “Strategies for Managing Reservoir Sedimentation,” International Journal of Sediment Research, Volume 24, 2009, pages 369-384.
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Head of Global Business Development, After Market Business
Emad is working with Voith Hydro in Germany as Head of Global Business Development and product owner of “Sediment Care Program”. He is in contact with hydro operators, environmental authorities and universities around the world to find the best and most sustainable solution for hydro power plant owners and operators. He has successfully develop different products and services for Voith hydro in the last years.