Geothermal fluid contains lots of heat energy and this has many useful benefits for society;
- The energy is what creates the spectacular geothermal surface features like the geysers;
- Hot mineral pools;
- Providing direct heat for domestic and commercial use (through radiators and small scale heat exchangers); and
- As a power source to create electricity.
Geothermal energy is considered a renewable energy - meaning with appropriate management the geothermal system will continue being able to provide geothermal energy indefinitely. However, geothermal energy is also considered a finite energy - there is only a certain amount available for everybody (cumulative use), and if we take too much the system can be severely damaged.
One of the best ways to use geothermal energy is to undertake cascading energy use - this means you use the same geothermal fluid multiple times before disposal, a couple of examples are below.
Fresh geothermal fluid is used in a power station --> spent fluid is then used to heat a hotel --> spent fluid is then used to heat an aquatic centre --> spent fluid is then used to heat up a fish farm --> spent fluid is discharged.
Fresh geothermal fluid is used to heat a town supply water --> spent fluid is then used to heat a house --> spent fluid is used to heat a swimming pool --> spent fluid is used to irrigate/frost protect crops.
Note: The ability to cascade energy uses can be limited by the temperatures required for successful reinjection.
There are many unique plants and organisms which have adapted to living in and around geothermal surface features. Geothermal surface features provide microclimates (they make the immediately surrounding area different than the wider environment) which allows plants and animals to develop and interact in ways that are found no-where else. In the Waikato/Bay of Plenty geothermal areas we have plant associations that are found no-where else in the world. All these species are uniquely important to our genetic biodiversity. Diverse life forms and their genetic material provides many unique opportunities for the future. An example of this is the use of bacteria that thrive at extreme temperatures being used in industrial processes. Who knows what geothermal ecosystems might provide us with next.
A number of geothermal vegetation surveys have been undertaken by the Bay of Plenty Regional Council, contact an Environmental Scientist on 0800 884 880 to obtain access to these documents.
Effects of Land Use
Geothermal surface features as well as being dynamic are also surprisingly fragile, and so land use around surface features is managed by the Bay of Plenty Regional Council. As well as the potential damage to the surface features, any work near surface features will also need to consider issues like health (some natural gases can be harmful at high levels), and site stability, as mentioned earlier geothermal sites are notoriously dynamic and can shift and change very quickly.
If you wish to undertake works near a surface feature you are likely to require a Resource Consent.
If you're planning on undertaking work within the Rotorua geothermal field, give our friendly Consents Team a call to see if there are any recorded geothermal sites that might be affected.
Other Geothermal Fields
The Taupo Volcanic Zone crosses through the Bay of Plenty and gives us our many geothermal fields which all have a wide variety of values. The identified fields are;
- Whakaari/White Island
- Moutohora/ Whale Island
- Rotoma/Puhi Puhi
Using fluid or energy from any other geothermal field will be considered under the Regional Policy Statement and the Regional Water and Land Plan. Provisions of the Regional Air Plan, the Regional Coastal Environment Plan and the Regional Plan for the Tarawera River Catchment may also apply.Please contact our Consents Team if you would like to discuss this further.
Geothermal Surface Features in the Bay of Plenty
Geothermal surface features provide a tangible example of the amazing processes occurring underneath our feet. Surface features include geysers, mud pools, or hot ground. We are very fortunate in the Bay of Plenty that we have so many surface features, and so many types of surface features - they are an increasingly rare occurrence all over the world. Because surface features are so rare, it is important we enjoy them and protect them for the future.
Bay of Plenty Regional Council recently prepared Guidelines for Mapping and Monitoring Surface Features(464 KB, pdf) with the assistance of geothermal surface feature experts throughout New Zealand.
This sets out a methodology we hope will become the standardised way of mapping and monitoring for surface features throughout New Zealand.
Download a field sheet Geothermal Feature Survey Form (27.8KB, pdf) from the mapping and monitoring guidelines.
If you would like the electronic database, please contact us on the details below.
Great Geothermal Surface Features to Visit:
Bore - Any structure, well or hole in the ground, which is drilled or constructed. This includes bores that access underground resources (such as groundwater, geothermal water or geothermal heat) and those not accessing underground resources (such as monitoring or geotechnical bores).
Downhole Heat Exchanger - A device installed down a bore to remove heat from a geothermal field without removing geothermal fluid. Generally uses freshwater circulate through a heat exchanger at depth.
Freshwater - All water, excluding coastal water, that is under 30 degrees Celsius.
Geothermal energy - Energy derived or derivable from and produced within the earth by natural heat phenomenon; and includes all geothermal water (Resource Management Act 1991).
Geothermal field - An discrete area where geothermal energy is known to be found, and includes all areas that are hydrologically linked.
Geothermal fluid - Combined geothermal water and steam, undifferentiated proportions of either state, or a system that utilised both steam and water.
Geothermal surface feature - Includes, but is not limited to; mud pools, sinters, hot springs, hot pools, rogue bores, fumeroles, tomos, geysers, geothermally influenced freshwater systems, steam vents and areas of hot ground. Surface features may or may not be of natural origin, and includes extinct or intermittent features.
Geothermal water - Water heated within the earth by natural phenomenon to a temperature of 30 degrees Celsius or more; and includes all steam, water, and water vapour, and every mixture of all or any of them that has been heated by natural phenomenon.
Reinjection - Geothermal fluid being pumped back into the ground to the same aquifer from which it was sourced.
Downhole heat exchanger - A single bore system which results in no geothermal fluid being abstracted from the bore.