Silica extraction starts at Ohaaki

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.

This will be the trust's first commercial venture of this nature, with the proceeds going towards restoring the Ohaki community.

"Our initial aim has been to support the Ohaki Marae Reservation Trust to improve the clarity of fluid supplied to the Ngawha, marae protection from the Waikato River and re-establish the road from the marae to the Ohaki Bridge, thereby connecting the whanau that live along the Te Toke Rd," said Aroha Campbell, a spokeswoman for the trust.

"We have strengthened our relationship with Contact Energy as an enabler to form new relationships, and we have already seen the benefit of whanau being employed by Geo40. We will see positive changes to our landscape over time while being fully in control of that destiny."

The benefit for Geo40 is the ability to access a source of silica that does not require the same level of heat processing as silica sourced through traditional means.

"Ohaaki's geothermal fluid enables us access to a valuable mineral without harming the environment," said Geo40 chief executive John Lea. "The beauty of our technology is that nature — the geothermal reservoir — has already done most of the work for us, by dissolving the naturally occurring silica. Our process extracts the silica and turns it into silica products that will be exported around the world."

Plans are already progressing on expanding the partnership, with the parties investigating the possibility of processing up to 10 times as much fluid per day.