Innovating Energy

Experimental geochemistry lab unlocks new knowledge for supercritical geothermal

Energy Futures

The GNS Science experimental geochemistry lab at our Wairakei campus was already one of the best in the business, but it is now unique in the world.

The recent acquisition of new experimental reactor equipment has extended the lab’s capabilities, so that we can now replicate the high pressures and temperatures found in geothermal reservoirs up to 7km below the surface.

The facility now has four high temperature and pressure reactors, designed to study chemical reactions between water-based fluids and rocks at depth. The new equipment can operate at temperatures up to 700ºC and 300 atmospheres to simulate extreme conditions found in the deepest geothermal environments in the world. Three hundred atmospheres is 300 times the pressure you would feel at sea level.

The new equipment is already contributing significantly to supercritical research.

Supercritical geothermal is uncharted territory. The reservoirs are more than 5km deep, and the fluid temperatures are above 400ºC – with the potential to produce many times more energy than conventional geothermal wells.

With increasing demand for low-emissions electricity, harnessing the potential of supercritical geothermal could play a key role in a carbon neutral future. While several countries are working towards this goal, no-one has yet managed to successfully harness these super deep resources.

At supercritical temperatures and pressures, fluid becomes a different beast and behaves more like a gas. It transfers energy much more efficiently than conventional fluids in lower temperature geothermal systems, but extreme pressures and corrosiveness encountered in these deeper environments can overwhelm conventional well and power station technologies.

Lead Scientist in the Experimental Geochemistry Laboratory, Dr Bruce Mountain, says the specialist equipment unlocks new knowledge about the chemical and physical reactions that occur in geothermal reservoirs.

Image caption: Dr Bruce Mountain in the Experimental Geochemistry Laboratory. Credit: Jeff Brass, GNS Science.

“Understanding the complex chemical processes occurring at supercritical conditions is crucial to their successful and sustainable development. Our lab can reproduce these conditions and provide critical data to contribute to their understanding”.

Image caption (left): A look inside the Experimental Geochemistry Laboratory. Credit: Jeff Brass, GNS Science.

Image caption (top): A look inside the Experimental Geochemistry Laboratory. Credit: Jeff Brass, GNS Science.

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