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Jane Nees BOP Regional Councillor www.janenees.co.nz |
All around us we have evidence of our geological past.
Mauao, the iconic mount at the entrance to Tauranga Harbour, is the remnant of a large lava dome, formed by upwelling and outpouring of rhyolite lava about 4.3 million years ago.
A leftover of this activity is the Tauranga Geothermal System, which is a large low-temperature geothermal system (between 30°C and 70°C) that extends over 60km from Waihi Beach to Paengaroa. It shares the same aquifer as the cold groundwater resource.
The Bay of Plenty Regional Council is completing further scientific research in order to better understand the attributes of this geothermal system and how sustainable the use of geothermal bore water is. There is potential that parts of the Tauranga Geothermal System are sensitive to permanent cooling if it is overused. For example, if too much geothermal water is taken, then cool water may replace the warm, cooling the heat left in the rocks and potentially taking many years to regenerate.
There are currently more than 100 water bores that are used to take geothermal water from the groundwater system. The heat energy in this warm water is then used for a range of purposes such as heating commercial and municipal hot pools, frost protection on orchards, and heating of private buildings and pools. Many of these bores have been in continuous use for over 30 years.
To help with scientific modelling work on the extent of the Tauranga Geothermal System, in terms of its depth and geographic scale, geothermal bores and groundwater takes are being monitored and tested. The scientific data gathered will be used in modelling to see if there is further capacity in the system and how it can best be allocated.
Once we better understand the science, we will be working with key stakeholders and the community to develop new policies and rules to help ensure the long-term sustainability of the geothermal system.
If you have views on this or any other issue, you can email me at neesj@xtra.co.nz or ring me on 07 579 5150.