Business Central February 2021

24 | Geo40’s $3.5m fixed installation Ohaaki demonstration plant has been in operation for the last three years, with global sales of silica. Geo40 REGIONAL DEVELOPMENT P roducing 500 tonnes of high quality sale- able colloidal silica a year, Geo40 Ltd’s $3.5 million fixed installation Ohaaki demonstration plant has been in operation for the last three years, with global sales of silica. “When we first started we went out selling colloidal silica with the objective of displacing silica already out there that was made almost entirely from melting quartz sand in a blast furnace at 1600 degrees and then chemically extracting it,” says John Worth, Geo40’s CEO. Geo40 has spent the last three years prov- ing to customers that if you get colloidal silica out of geothermal fluid rather than melting it from quartz sand you can produce the same product if not better and through more envi- ronmentally friendly means. “We still sell to those markets and will con- tinue to do so. But our attention has shifted to using colloidal silica to displace things that are unsustainable. “We’re producing a liquid that contains silica particles and our process can control the size of those particles anywhere from 4-nano- metres—4 billionths of a metre in diametre— up to 14-nanometres.” The markets John refers to include the man- ufacture of paint where colloidal silica is used to reduce the amount of titanium dioxide required in white paint. Cement is the single largest consumer of carbon in the world with 8% of the world’s carbon going into its manufacture. “If you add a very small amount of colloidal silica to concrete you can reduce the cement content by 10%,” explains John. “Soil surfaces in civil projects are often sprayed with polymers to seal the surface so that you don’t end up with sediment run off in the rivers and waterways. “But the polymers are plastic and when they wash off they break down to a micro plastic. “We can do the same thing with a mix of colloidal silica and salt and therefore displace the polymers with something that is natural.” But the recovery of colloidal silica from the geothermal fluid is where it starts to get really interesting for geothermal energy companies like Contact and Mercury. “If you take the silica out, there is a lot more heat in the geothermal fluid that can be utilised. Instead of having to keep the fluid at 140 – 200 degrees you can take more heat out of the fluid and re-inject at 60 – 70 degrees. “ John notes that is what led the company to sign a collaboration agreement with global low-temperature generation specialist Clime- on of Sweden in late 2019. “That’s a significant opportunity for the pow- er sector because they could build another little power station after the Geo40 plant that generates more electricity or, the energy could be sold as process heat used in industry. “This opportunity is very compelling, but in our early days we all missed the big one. The CO2 emissions out of geothermal power stations can be very high. “If you can get the silica out of the fluid and reduce the temperature you re-inject at, you can grab most of those C02 emissions and re-dissolve them into the fluid and re-inject them back into the aquifer. That’s a game changer, and a little company in Taupo holds the keys to that.” Richard Loader Pioneering technology may slash emissions