12 Years Algae-Free: EnviroSonic Delivers Long-Term Results and Cost Savings

Location
The Stratford Power Station, owned and operated by Contact Energy, is a 577 MW facility located east of Stratford in Taranaki, New Zealand. It includes a 377 MW combined cycle unit, along with two open cycle gas turbines used for peaking power.

Challenge
In 2012 the powerstation experienced recurring algal blooms in its raw water reservoir, particularly during summer. The blooms were driven by nutrient-rich conditions, warm temperatures, low water flow, and continuous seeding from the Pātea River. This resulted in consent breaches, organic fouling, increased chemical use, and aesthetically unpleasant water. Some algal species also posed serious risks to human health. As part of a whole-system approach, the stormwater pond and cooling towers were also included in the solution.

Solution
At first installation, EnviroSonic ES300 ultrasound units were installed across the site in the main water reservoir, cooling tower and stormwater ponds. Further installations of Envirosonic have been installed in their Pre-treated water storage tank, and in other areas.

Results

• Savings in chemical applications required since the time of installation

• Improved water clarity within days of installation

• Improved condenser performance

• Improvement in cooling tower efficiency

• Zero algal blooms and levels remain consistently low, even in high nutrient and warm conditions.