Turning greenhouse gas into stone: First carbon-negative power plant opens

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This was published 6 years ago

Turning greenhouse gas into stone: First carbon-negative power plant opens

By Cole Latimer
Updated

While Australia rejects a clean energy target, Iceland is aiming to go beyond zero, creating a carbon-negative power industry.

On October 11, one of the world's largest geothermal power plants, located in Iceland, began capturing carbon dioxide and removing it completely from the atmosphere by turning captured carbon emissions into stone.

The operation, a joint venture between Climeworks and Reykjavik Energy, is an evolution of the world's first commercial carbon capture facility - the Direct Air Capture plant which opened in Switzerland in June this year and is also run by Climeworks.

Iceland's Hellisheidi geothermal power plant draws carbon dioxide into the plant where it is chemically bound to a filter. Once this filter is saturated with CO2, it is heated to boiling point using heat from the geothermal plant itself before the CO2 is released from the filter and collected as a concentrated gas, releasing the now carbon dioxide-free air back into the atmosphere.

The Hellisheidi geothermal facility is the world's first carbon-negative power plant.

The Hellisheidi geothermal facility is the world's first carbon-negative power plant.Credit: Arni Saeberg

The plant dissolves this gas in water before piping it more than 700 metres underground, where it reacts with basaltic rock, forming a solid mineral or stone, such as calcite.

This method imitates natural processes, and shortens the petrification timeframe from centuries to less than two years.

The air collectors' capacities range in size from 135 kilograms per day to 4.9 tonnes per day, with each filter able to last for approximately several thousand gas collection cycles.

While it is still at the pilot level, and only able to capture 50 tonnes of CO2 annually, it is the first plant to go beyond simply storing carbon dioxide.

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The process works by petrifying concentrated carbon dioxide gas by pumping it into basaltic rock formations.

The process works by petrifying concentrated carbon dioxide gas by pumping it into basaltic rock formations.

Initial estimates put capture and calcification prices at around US$100 per tonne of carbon, with aims to halve this figure once the project is scaled up. Australian carbon emissions were priced at around $24 per tonne prior to being scrapped.

"The potential of scaling-up our technology in combination with CO2 storage is enormous," Climeworks founder Christoph Gebald said.

The process petrifies carbon dioxide in two years, as opposed to centuries at natural rates.

The process petrifies carbon dioxide in two years, as opposed to centuries at natural rates.Credit: Sandra O Snaebjornsdottir

"Not only here in Iceland but also in numerous other regions which have similar rock formations," Mr Gebald said.

Climeworks will use the technology to sell carbon credits for businesses with non-avoidable emissions.

The partnership aims to capture one per cent of all global emissions by 2025.

In Australia, Chevron's Gorgon LNG operation in Western Australia is forecast to become the world's largest carbon capture and storage project, aiming to sequester up to four million tonnes per annum of carbon dioxide once operational.

In Victoria's Latrobe Valley, the CarbonNet project aims to capture carbon dioxide from electricity generation in a similar fashion to the Icelandic project, however, it has no plans to turn captured emissions to stone.

Speaking to an expert in Australian geology, he said application of the technology to turn captured CO2 into stone in Australia is fairly unlikely due to differing geological strata.

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"Iceland's a fairly young country, compared to Australia, and has formations that are thousands of years old compared to billions, like in Australia," he said.

"It might be possible, but as our rocks are so much older here it'd have to use different technology and modify for the type of rocks. It would depend on the chemical reactions, but it wouldn't be analogous."

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