Thursday, August 9, 2018

New Zealand: Commercial Extraction of Silica from Geothermal Brine to Start This Month

Silica extraction starts at Ohaaki (New Zealand Herald)

Geo40's commercial demonstration plant at Ohaaki.
In a world-leading sustainable energy partnership, Geo40 in co-operation with Contact Energy and the Ngati Tahu Tribal Lands Trust, is this month set to start commercially extracting silica from geothermal fluid.

Once extracted using Geo40's technology, the silica will be sold to manufacturers for use in everyday consumer goods, such as paint, providing an environmentally-sound source of silica that would otherwise require amounts of carbon-intensive energy to make.

The potential volume of high grade silica that will be sourced from Ohaaki is up to 10,500 tonnes a year, most of which will be exported overseas.

"Geothermal energy is a proven source of renewable energy and this partnership builds on geothermal's already impressive environmental credentials," said James Kilty, chief generation officer at Contact Energy.

For Contact, the operational benefits are significant. Silica builds up in the geothermal pipes over time, and removing the silica significantly reduces equipment maintenance costs and increases the overall life-span of the plant. Removing silica also allows the plant to extract more heat from the geothermal fluid, making it more efficient to run.

The deal provides financial and social benefits to Ngati Tahu Tribal Lands Trust. The partnership will provide an ongoing revenue stream to the trust, and the processed fluid will restore clarity to the Ohaki Ngawha, a sacred natural hot spring.

A detailed description of the silica extraction process can be found in an upcoming article in the GRC Bulletin. Transforming Silica into Silicate – Pilot Scale Removal of Problematic Silica from Geothermal Brine by Thomas Borrmann, Michael Schweig and James H. Johnston of the School of Chemical and Physical Sciences, Victoria University of Wellington, will be available in the next Bulletin to be published next week.