The Oasis Leisure Centre in Kalgoorlie Boulder, WA, is now heated by one of the largest closed loop geothermal systems in the State. The system is unique in a couple of respects. Even though the facility is in a hot climate, with summer temperatures as high as 46°C (115°F) and deep earth temperatures at 23.5°C (74.3°F), the building requires more heating than cooling. There are two reasons for this:
evaporation from the pools requires make up water to be added and the evaporation cools the water, and the adjacent gymnasium uses an evaporative cooling system is very effective and efficient in the hot, dry climate.
The second unique feature about the GCHP system is that a vertical borehole GHX is integrated with a horizontal slinky GHX that is built above it. This approach was taken for a number of reasons:
We can take advantage of the different temperature profiles. When the system is heating, the pump on the warmest GHX module can be activated. When cooling, the pump on the coolest GHX module is selected. More importantly, energy can be transferred from the warmer GHX to the cooler. By managing the operation of the different GHX modules it's possible to manage the GHX temperature to optimize the system performance.
The operation of the GHX modules is controlled using a control package developed by Greensleeves Energy Solutions. The software uses the proprietary software that allows the input of the building hourly energy model and hourly GHX temperature predictions and uses them to control the operation of the GHX pumps...selecting the appropriate module to target the predicted GHX temperature. The benefits include:
This project was constructed by Direct Energy Australia with design assistance from GEOptimize Inc. and Geo-Xergy Systems Inc. This project was presented at the IGSHPA Conference in Las Vegas in October, and can be seen on their website.
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.