The Swiss company Climeworks in October said it had begun another round of testing for a direct air capture (DAC) facility at a 300-MW geothermal power plant in Hellisheidi, Iceland. Climeworks, which is running the trial with Iceland utility Reykjavik Energy, is part of a research project to demonstrate that DAC of carbon dioxide (CO2) can be combined with permanent geological storage, as proof that DAC is a highly scalable carbon removal technology.
Climeworks said the Hellisheidi facility is the world’s first “negative emissions” plant, meaning it takes in more carbon than it emits.
Climeworks has developed a DAC module, installed at the site (Figure 1) and designed to be heated with low-grade heat from the geothermal plant, which captures gas in a Climeworks-designed filtration system. In the trial, researchers have injected CO2 at an industrial scale. The captured CO2 is bound to water, and then sent more than 700 meters underground, where it reacts with basaltic bedrock to form solid minerals (Figure 2). The company said the gas would remain stored for at least 1 million years.
The trial is part of the CarbFix2 project led by Reykjavik Energy and financed by the European Union’s Horizon 2020 research program. It began in August and is financed into 2021. The Hellisheidi plant first began using carbon capture technology in 2007, when a group of scientists, engineers, technicians, and business leaders began work on the first CarbFix project led by Reykjavik Energy.
CarbFix researchers last year released a study documenting how CO2 injected into the ground turned into carbonate minerals in less than two years, a process previously thought to require hundreds of years, enhancing the viability of the Climeworks’ project. “Our results show that between 95 and 98 percent of the injected CO2 was mineralized over the period of less than two years, which is amazingly fast,” the study’s lead author, Dr. Juerg Matter, said.
The CarbFix2 pilot program can remove an estimated 50 metric tons of CO2 from the air each year, eliminating more CO2 than it produces. Climeworks’ engineers want the testing to show that similar projects could be used globally, though cost is among the issues—Climeworks estimates it costs $600 to extract one ton of CO2 from the air.
The capacity of the plant is expected to be 900 metric tons annually by year-end 2017, which the company notes is equivalent to the annual emissions of about 45 people in the U.S. Climeworks’ founder and CEO Christoph Gebald said, “The potential of scaling-up our technology in combination with CO2 storage is enormous.”
The company’s goal is to cut costs to $100 per metric ton by 2025, and capture 1% of global manmade carbon emissions each year. The company has not released details on how to move forward, but investors in the technology include the European Space Agency and Microsoft co-founder Bill Gates, one of the world’s richest people.
Iceland’s geology helps the technology work. In some carbon capture projects, CO2 is injected into sedimentary rock, which does not react with gas. Iceland features volcanic rock, known as basalt. CO2 reacts quickly with basalt to form carbonate rocks, eliminating the need for management of an underground gas reservoir.
Other companies involved in DAC technology include Global Thermostat in the U.S., Carbon Engineering in Canada, and Skytree in the Netherlands. Skytree is a spinoff of the European Space Agency, originally set up to develop ways to filter CO2 breathed by astronauts in spacecraft.
—Darrell Proctor is a senior associate editor for POWER (@POWERmagazine).