Direct Air Capture Companies: Similarities & Differences

Every year, 9,000 tonnes of carbon dioxide (CO2) are sucked directly out of the air by machines. In fact, 15 direct air capture (DAC) plants worldwide remove this greenhouse gas from our atmosphere.1 Operating them are several innovative direct air capture companies, namely Climeworks, Carbon Engineering and Global Thermostat.

Each DAC company uses its own technology and facilities. There are both similarities and differences in the approaches they take. However, in all cases, it remains expensive to capture and remove CO2 directly from the air. Unfortunately, the process continues to require large amounts of energy.2 Like other carbon capture and storage solutions, it is still in development and cannot be relied upon to solve climate change.

What is direct air capture?

Direct air capture, as its name suggests, involves removing CO2 from the atmosphere. It is a type of carbon capture and storage (CCS) technology. However, most CCS technologies capture CO2 emissions from power plants or industrial facilities. They prevent the CO2 that is produced by burning fossil fuels from escaping into the air. This may occur pre, post or during combustion.3 

Instead of stopping CO2 emissions from entering the air, DAC reduces the concentration of CO2 already in the atmosphere. This is a potential solution to climate change. CO2 is a greenhouse gas and the principal long-term contributor to the rise in our planet’s average temperature. It traps heat in the atmosphere, which leads to global warming.4 But to truly combat climate change, we must stop adding greenhouse gases to the atmosphere and remove those that we have already contributed. 

What are the three main direct air capture companies?

Worldwide, there are three direct air capture companies with pilot plants processing significant quantities of CO2.5 Collectively, they capture more than 9,000 tonnes of CO2 per year.6 However, climate change models recommend removing 10 gigatonnes of CO2 each year by 2050.7 The sector requires an enormous scale-up to meet these ambitious targets.

Carbon Engineering

Carbon Engineering is a Canadian DAC company. Founded over a decade ago by Harvard Professor David Keith, Carbon Engineering began capturing CO2 from the air in 2015. In fact, it is currently constructing the world’s largest DAC plant in Texas.8 

The facility will capture over 900,000 tonnes of CO2 per year once complete. Geologic formations will sequester some of the CO2. Therefore, it will be permanently kept from the Earth’s atmosphere.9 This is a useful negative emissions or climate mitigation approach. 

But, some of Carbon Engineering’s captured CO2 will also be used for oil production.10 Enhanced oil recovery uses a lot of CO2 and permanently stores the majority of it underground.11 Nevertheless, the oil it produces will inevitably release lots of CO2 through combustion. As a result, Carbon Engineering’s approach is not entirely carbon negative.

Climeworks

Climeworks is a Swiss company founded in 2009. It is one of the most successful direct air capture companies worldwide. In 2017, it was commissioning the first commercial-scale DAC capture plant in the world.12 Now, it has built 14 DAC facilities in total.13 Moreover, since 2020, Climeworks has been constructing a massive new DAC plant in Iceland. 

The Orca plant will capture over 3,600 tonnes of CO2 per year.14 The project is a collaboration between Climeworks, Carbfix (a carbon storage company), and ON Power (an Icelandic geothermal energy provider). Orca will use power and heat from ON Power’s geothermal energy source. Climeworks’ technology will capture CO2 from the air. Carbfix will store the CO2 underground using natural underground mineralisation.15

Microsoft billionaire Bill Gates is just one of Climeworks’ high-profile investors. In an interview, he said that he had bought out their capacity and received a volume discount. Normally, Climeworks sells units of CO2 captured to companies looking to offset their emissions at USD $1,089 per tonne. With Gates’ discount, it still cost him USD $544 per tonne.16 This may not be much for one of the richest men on the planet, but it is still an expensive climate mitigation approach.

Global Thermostat

New York-based company Global Thermostat claims to have the world’s cheapest carbon capture technology.17 Founded in 2010, it has raised USD $70 million from investors. This includes USD $15 million from oil giant Exxon Mobil.18 Like many fossil fuel companies, Exxon Mobil is keen to invest in solutions that permit the continued use of coal, oil and natural gas – including DAC.

By 2019, Global Thermostat had built two pilot DAC facilities. Both can capture about 3,000 to 4,000 tonnes of CO2 from the air.19 However, two of Global Thermostat’s DAC plants are not currently operating. One prototype in Huntsville was shut down in 2019. Another being built in Tulsa is at least a year behind schedule.20

How are direct air capture companies evolving their technology to become more efficient?

Direct air capture is relatively new. As the International Energy Agency (IEA) mentions on their website, “the technology has yet to be demonstrated at large scale”. Direct air capture companies are still trying to improve their efficiency.21 

This makes the future costs of DAC uncertain. At present, prices suggest that future costs range from USD $100 per tonne to USD $1,000 per tonne.22 DAC companies continue to evolve their processes and techniques to become more efficient and, therefore, cheaper. But it takes time for technology to mature. It could be many years before DAC is capturing the 10 gigatonnes per year target.

Carbon Engineering

The Canadian DAC leader, Carbon Engineering, is adapting its technology in its new Texas plant. It is employing the use of a bank of large fans to draw air into a larger structure. As the air is pulled into this contactor, it passes through a plastic mesh. The mesh is coated with a potassium hydroxide solution. It binds with the CO2 in the air, thereby capturing it.23  

Chemical processes then concentrate and compress the CO2 into small white pellets. Heating these to 900°C releases the CO2 as a gas. The company aims to capture over 2,450 tonnes of CO2 daily in this way. This is a significant improvement on its pilot plant in British Columbia. That site currently captures 0.9 tonnes of CO2 each day. But Carbon Engineering plans to enlarge this and their other operations too.24

Climeworks

Instead of improving its technology to scale, Climeworks is using a modular approach. Its CO2 collectors can be stacked to build larger facilities. Similar to Carbon Engineering, Climeworks’ technology uses fans to pull in the air. However, it uses a split filter material to catch the CO2. Heating this to between 80 and 100°C releases the concentrated CO2.25 

Climeworks is also using renewable energy or energy-from-waste to power its DAC machines. 90 per cent of the CO2 that its machines capture is permanently stored underground.26 It aims to keep its emissions as low as possible to maximise the environmental benefit of its technology.

Global Thermostat

Global Thermostat uses a combination of amine-based chemical sorbents bonded with ceramic honeycomb structures to catch CO2. These carbon sponges can soak up CO2 directly from the air or smokestacks. This makes its technology applicable to both carbon capture and storage facilities attached to power plants or industrial complexes, as well as stand-alone DAC plants.27

Once the CO2 has been captured, it can be stripped off and collected with steam at about 85 to 100°C. Global Thermostat sources its steam from residual or process heat to help reduce costs. As a result, it captures 98 per cent pure CO2. Since its technology can be built anywhere, it reduces transportation costs and emissions.28

Direct air capture companies and global warming

Direct air capture companies are developing their technologies to try and make it as cheap and efficient as possible to remove CO2 from the atmosphere. But few remain, with just one large-scale operation. Their technology is still expensive, costing between USD $250 to $600 per tonne of CO2.29 

The high costs are partly due to the low concentration of CO2 in the atmosphere. There is more CO2 in the atmosphere today than at any time in the past 800,00 years.30 But this still only amounts to 0.04 per cent.31 Therefore, it is difficult to isolate the CO2 and capture it. 

As investment in DAC increases, more companies will enter the space. Interest is already growing. For example, Elon Musk has offered USD $100 million to anyone capable of designing new DAC technology.32 Whilst publicity and funding can give the sector a boost, ultimately, it will take time for DAC to scale up and maximise efficiency. Unfortunately, it cannot compete with the amount of CO2 we continue to emit. Only by stopping the production, refining and combustion of fossil fuels can we hope to limit global warming.

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