The Ashlu Creek run-of-river hydroelectric project’s more than 200 meters of head and specific physical characteristics made Francis turbines the most efficient choice. However, unlike Pelton turbines, which are commonly used in British Columbia, Francis turbines make ramping very difficult outside of normal operating conditions.
Ramping is defined as the rate of change in water flows in a stream. It occurs due to changes in the demand for water flow passing through the turbines, as a result of turbine start-up or shut-down. While it is relatively easy to adjust water flows during normal operation of the turbines, the need to suddenly or rapidly change water flows through the turbines (for example, due to equipment failure or loss of connection with the network) creates risks for the river’s ecosystem, as well as for the safety of recreational kayakers who may be using the river. Ramping regulations to address these risks have existed in British Columbia since the mid-1990s, and have become increasingly stringent since the mid-2000s.
To address the new and more stringent ecological and environmental requirements associated with ramping, Ashlu’s development team needed to find a new technological solution. The request for proposals issued to turbine suppliers specified the ramping criteria, without specifying a particular technology; thus, the door was opened to a new and innovative solution. As it turns out, Innergex found what it deemed to be the most technically appropriate and the most reliable solution in the proposal submitted by ANDRITZ HYDRO, which addressed ramping issues with an inventive energy dissipation system.
The energy dissipation system basically allows water to flow through the hydro plant while bypassing the turbines (when there is a need to shut them down quickly, for example), and therefore allows for a controlled and progressive change of water flows in the stream. To develop this new system, ANDRITZ HYDRO approached and jointly worked with D2FC energy valves SAS, a French valve manufacturer specializing in hydropower applications and renowned for its ability to develop reliable, high-performance, and innovative products. D2FC chose to adapt a technology on which the patent had expired that already existed in the United States for hydroelectric facilities with lower head, but that had never been adapted to facilities with higher head.
Innergex found in ANDRITZ HYDRO’s proposal a solution to address its ramping requirements at Ashlu Creek and became the first hydro developer to install this new technology in Canada. In turn, its development team successfully completed the critical task of integrating the new technology into the plant’s operating system.
For its part, ANDRITZ HYDRO had the opportunity to actually test and implement this new technology at Ashlu Creek. According to Pierre Duflon, Manager Compact Hydro at ANDRITZ HYDRO Canada Inc., “Innergex is unique in both its in-house concentration of technical expertise in run-of-river hydro that exists nowhere else and its willingness to seek and implement innovative solutions – to ‘think outside the box’.” He adds that “we probably could not have sold this first system to anyone else.” Rising environmental awareness is leading to increasingly stringent ramping regulations in many parts of the world, and ANDRITZ HYDRO has since successfully introduced this system to several small hydro developers in other countries.