Business Central February 2021

22 | Geo40 REGIONAL DEVELOPMENT Silica extraction a real game changer Richard Loader The first of Geo40’s two commercial scale silica extractions plants is in the closing stages of commissioning. T aupo-based Geo40 Limited’s mandate is easy — you cannot have a sustainable future without sustainable minerals. You cannot have green transport without green lithium. You cannot have touch screens and 5G networks without caesium, and the key to low carbon concrete is colloidal silica. And that, says Geo40’s CEO John Worth, is why the pioneering company was established — to take on the challenge of recovering key future minerals from geothermal fluids used in the production of electricity, while also being kind to the environment. Referred to as strategic minerals by most governments, high value minerals such as lithium, caesium and antimony are critical for a prosperous future but are in short or restricted supply. John says until Geo40’s groundbreaking work no-one on the planet had been able to successfully recover colloidal silica from geo- thermal fluid at scale. “The company realised that before it could chase lithium and other minerals it needed to get the silica out. That was a tough journey and largely what Geo40 has focused on to date.” With a pedigree steeped in mining and resources, Geo40 has well-defined DNA in terms of scaling up its innovative processes and technology. Over a 10-year journey the company’s tech- nology has evolved from lab bench, test tubes and beakers, to vessels the size of buckets sitting on a shipping pallet, to progressively bigger version of the same thing, constantly refining processes and fleshing out new chal- lenges to overcome. John says three epiphanies became appar- ent early in Geo40’s journey. The first was that the concentration of stra- tegic minerals varies hugely across the North Island, let alone across the world, while colloi- dal silica is ubiquitous across most locations where there is high temperature geothermal fluid. In central North Island there might be lithium at 10 parts per million, while silica is present at typically 800 parts per million. The second epiphany was that a lot of the strategic minerals hide behind silica. So be- cause silica is present in such high concentra- tions in order to recover lithium, for example, you have to extract the silica first. The third epiphany was that silica is a major problem for geothermal energy companies as it blocks up geothermal reinjection pipes and wells and limits how much heat can be extracted from geothermal fluid for conver- sion to electricity. “A lot of electricity is wasted because of the silica and Geo40 realized that if it wanted access to the geothermal fluid and access to the high value minerals it was going to have to deal with the silica first.” In simple terms, John explains that geo- thermal fluid comes out of the ground and up a well at 350 degrees Celsius then travels through a power station that converts much of that heat to electricity. The geothermal fluid is re-injected back into the aquifer through another reinjection well. The design of the power station and how much electricity can be generated from the fluid depends on how much silica is present in the geothermal fluid. While energy companies would like to ex- tract more heat to generate more power they currently can’t. The geothermal station has to keep the fluid at about 140 degrees — some- times up to 200 degrees — or the silica will immediately block the pipes. “The reinjection wells are worth $10 - $12 million each and typically last for 4 – 5 years before they’re absolutely blocked with silica, instead of the 20 years that they should last. “The wells can be replaced or re-cored or you can acid dose the reinjection fluid and continually pour concentrated sulfuric acid into the reinjection fluid, which ends up in the aquifer. “The pipes might last 12 months before having to be cut into sections with a gas torch and the silica blasted out. So that’s what most geothermal energy operators around the world are doing. It’s expensive and environ- mentally questionable, pouring huge quanti- ties of sulfuric acid back into the ground.” Geo40 realised that if it could solve the silica problem it would provide compelling motivation for the global geothermal energy community to offer access to their geothermal fluids for silica extraction. “That has proven to be true,” says John. “We’ve now had 44 global geothermal oper- ators visit our demonstration plant in Ohaaki and express genuine interest in what we’re doing.” A development agreement with Contact Energy and the Ngati Tahu Tribal Lands Trust provided for the demonstration plant, which has been successfully operating for the last three years, as well as two large-scale com- mercial plants. The size of two rugby fields and located at the northern end of Contact Energy’s Ohaa- ki geothermal power station on Ngati Tahu Tribal Lands Trust land, the first of the two commercial scale silica extractions plants is in the closing stages of commissioning and is expected to ‘go-live’ this month. “The agreement with Ngati Tahu Tribal Lands Trust and Contact Energy gives Geo40 access to the geothermal fluid and Contact gets the benefit of silica not blocking the pipes and wells. “The plant effectively means Contact’s wells and pipes should last 20 years, and is pre- Getting it right - page 24 dicted to eliminate their problems with silica scaling.” A $15 million debt/equity contribution by New Zealand’s Provincial Growth Fund (PGF) was a major milestone in getting development of Geo40’s $20 million silica extraction plant over the line and attracting additional funding from key local and overseas investors. Overseas investment came from Swedish partner-company Baseload Capital, itself 22% owned by Breakthrough Energy Ventures, the climate-change investment fund of Bill Gates, Jeff Bezos, Jack Ma and other billionaire anthropologist. John presented the Geo40 story to Break- through Energy Ventures in early 2019, and he says the company is hugely proud they have invested. Processing about 6 million litres of geother- mal fluid a day, the extraction plant is expect- ed to produce 5–8000 tonnes of high quality colloidal silica a year, with saleable product available early 2021. “This extraction plant is the first time we’ve treated fluid going back down reinjection wells, so the plant will provide definitive proof that we can make those wells last. And Contact Energy, quite rightly, want to see that in action.” A second plant of a similar scale at the southern end is yet to commence construc- tion. 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