Aquatic Centre Retrofit of Hybrid Vertical and Horizontal Ground Heat Exchanger

Abstract

Rising gas prices (accelerated by upcoming international price-parity - Liquefied Natural Gas plants) are motivating uptake of direct geothermal systems in Australia. Aquatic centres use a substantial amount of energy for heating (typically gas) and are thus motivated to consider more energy-efficient options. One of the first aquatic centres to implement closed-loop direct geothermal is the Goldfields Oasis Recreation Centre (GORC) in Kalgoorlie, Western Australia. Ground Heat Exchanger (GHX) configurations are typically either vertical or horizontal however for GORC an innovative solution with both vertical or a horizontal GHX was implemented. The horizontal GHX operates differently from a vertical GHX because of the impact of the atmosphere on the piping that is buried only 1-2m from the surface. Heat rejected into the horizontal piping dissipates more quickly to the atmosphere during colder weather and, in summer, solar energy warms the earth around the shallow piping while the impact on the earth around a vertical borehole at depth cannot be measured. With both vertical and horizontal GHXs, it is possible to take advantage of both the storage & dissipation properties. With innovative controls and the pending addition of cooling capabilities, these advantages can be enhanced for optimal management of the overall GHX and energy efficiency. During the first month operation savings on gas usage was 618 GJ worth approximately $21,000.