High Temperature Resistant (HTR) geomembranes
After 7 years PE-HTR geomembranes are still successfully in operation at Ngatamariki Power Station near Lake Taupo, New Zealand. Artificial lagoons are used for hot water up to 100 °C.
Introduction
Lake Taupo with a length of 40 km and a depth of 400 m is located in the middle of the northern island of New Zealand. Near the lake there are wells, which bring hot water (up to 130 °C) to the surface from a depth of 1500-3000 m. This water is pumped to a nearby power station and used to generate electricity.
Regularly there is excessive water, and with a temperature of up to 100 °C it flows into the artificial lagoons. Due to the high temperature, it cannot be released into a river or a lake because all animal being would die. Thus, it is kept in the lagoons until it cools down to ambient temperature.
Multi layer sealing system
Normal HD-PE is not suitable for this application due to the high temperature of the water. Consequently, a high temperature resistant PE (PE-HTR) was selected for this demanding application and installed in 2012 by AGRU New Zealand. A multi-layer sealing system is used:
- PE-HTR geomembranes (1.5 mm)
- Swell-able geotextile
- HD-PE geomembranes (1.5 mm)
- Geotextile (protection)
- Earthwork
A success story
Several hot water basins were lined using AGRU PE-HTR geomembranes. End of 2019, Mr. Christian Kahr (Head of Business Unit Lining, AGRU) visited the project. “After more than 7 years in service, the PE-HTR geomembranes are still in a good shape and working as designed,” he reports.
