One of the most comprehensive, data-intensive and successful geothermal projects in Australia is located at Hale School in the Western Australian suburb of Wembley Downs.
Hale School, founded in 1858, is the oldest private boys' school in Western Australia (WA). The school boasts an impressive amount of world-class sporting facilities that attract elite sporting teams while touring in Australia. Some of these teams include the English Cricket team, the Springboks, the English Rugby team and the Argentinian Pumas.
In 2012, the school added to its sporting facility's repertoire and started construction of two outdoor heated swimming pools. One a 25m (1.2m deep) learners pool, the other an Olympic sized 50m (2m deep) water polo pool. The intent was to run the two outdoor heated pools 24/7/365, which meant that they needed to find a way to mitigate their energy costs.
A direct-use geothermal system was installed at the school to enable warm groundwater to be pumped from the deep Yarragadee aquifer through two separate heat exchangers. The geothermal heat is then used to warm both pools and the heat-depleted groundwater is returned to the aquifer, making it a zero net loss system.
The Yarragadee aquifer in the Perth Basin is the oldest and largest sedimentary aquifer supplying groundwater to the Perth Water Supply Scheme. Its groundwater resource is available all year long with temperatures, in the upper part of the aquifer, ranging between 35°C and 55°C, making it ideal for direct-use geothermal heating.
Geothermal energy is the perfect alternative to conventional off-the-shelf gas or electrical heating systems. It's a cost effective, environmentally friendly and sustainable heating solution. The system at Hale School has now been running successfully since 2014.
The most comprehensive monitoring records to date
The geothermal system installed at Hale School includes two deep Yarragadee bores located about 100m east of the swimming pools. A production bore was constructed to a depth of 974m and was fitted with a submersible pump; it now produces between 14 and 33 L/s of groundwater at up to 47.5°C. An injection bore was constructed about 20m away from the production bore, to a depth of 477m to allow for reinjection of the heat-depleted water.
The entire geothermal system has been designed to maintain the temperatures in the pools at 26.5°C (water polo pool) and 28.0°C (learners pool). It runs mainly during winter and on windy days when pool heating requirements are the greatest. Heating requirements are lowest in summer with solar radiation assisting in keeping the pool temperatures up during the day. Occasionally, on hot summer days, the system does not run at all.
The geothermal system is licenced under the Department of Water and Environmental Regulation, allowing for the use and reinjection of groundwater from the Yarragadee aquifer. To ensure the system is working without negative impacts to the aquifer, a comprehensive monitoring program has been put in place and is reviewed by Rockwater hydrogeologists on a yearly basis. This includes the monitoring of groundwater pumping and injecting water levels, groundwater temperatures and quality.
The monitoring records from Hale School have been the most comprehensive to date, compared to other geothermal systems around Perth, with data recorded up to every 15 min.
This provides a clear understanding of the geothermal system and the aquifer responses and greatly assists with the interpretation and the reporting process.
Rockwater uses ORCAview and EnteliWeb, as the front-end, to observe the operating groundwater levels on a regular basis. The data is backed up using an SQL database and Delta continues to assist every year with the ongoing system monitoring.
Delta's geothermal expertise
Due to the harsh environment and the high temperatures found in the aquifer, Delta uses industrial grade Programmable Logic Controllers (PLCs) to maintain and monitor the system.
Every geothermal project is unique and has to have a customised solution developed. The flexibility of the Delta products, its BMS and employees has allowed Delta Building Automation (DBA) to continue using their expertise to interface with other Supervisory Control and Data Acquisition (SCADA) projects, like Hale.
At the moment DBA is involved with several other geothermal installations in WA—mechanical and geothermal heating at Scarborough Beach and a geothermal installation at Aegis Montgomery House.
DBA regularly contributes its expertise, through the University of Western Australia, to Landcorp's ongoing research into geothermal optimisation in housing.
The Delta offering is robust and further proof of the wealth of experience and quality product for which they're known.
“[Hale’s] monitoring records have been the most comprehensive to date, with data recorded every 15 minutes. Using ORCAview and enteliWEB, Delta assists us with the ongoing system monitoring.”
Hanna Stokes, Project Hydrogeologist, Rockwater
