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Keeping the Weeds Out - An Intake Case Study

July 14, 2022
Booth #313, Exhibit Floor
Knowledge Hub - Learning from Case Studies
Hydrogeneration is the dominant source of energy in New Zealand, providing approximately 70% of total electricity. The Hornwort, a submersed, free-floating perennial which can reach nearly 20 feet of height above water, has invaded New Zealand's waters. The plant quickly proved to be an issue for Genesis Energy at the Tokaanu Power Station, a 240 MW hydroelectric power station. The Hornwort has a tendency to break from its roots, creating potential for blockage which directly impacts the country's electrical grid. The Engineering team, led by Ian Meredith (now retired) for Genesis Energy researched options for screening solutions to prevent the problematic aquatic plant from hampering power generation. Duperon® Self-Cleaning Trashrack was chosen as a proactive measure against the plant. The multiple rakes cross the entirety of the screen resulting in continuous cleaning of the intake.  The first “weed-up” of the season proved the choice to be successful: large mats of Hornwort were driven into the screen, rapidly creating a head differential of 400mm (15.75 in). “Without any doubt, this situation would previously have led to a dropped load and generation constraint,” relays Ian Meredith of Genesis Energy. “Within two minutes of starting the SCTs, the head differential dropped to zero.”  This presentation will cover the challenges of intake debris management, types of solutions available, and specifically address the problem of aquatic vegetation and the solution implemented at the Genesis Energy Tokaanu Hydroelectric station.    

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