In January 2021, eight shipping container-sized boxes were assembled in Hellisheiði, Iceland, next to the third-largest geothermal power station in the world. The facility, called Orca, is intended to suck approximately 4,000 tons of carbon dioxide directly from the air each year. Developed by the Swiss engineering firm Climeworks, Orca is the largest example of direct air capture to date — a technology intended to extract carbon dioxide directly out of the air. 

You can think about the carbon dioxide in Earth’s atmosphere like a bucket. Today, that bucket is almost full: We have about 9% of the volume left to fill if we want to stay below 1.5 degrees Celsius of warming by 2050 (1.5 degrees is the target to avoid catastrophic climate disruption). To keep that bucket from overflowing, we’ll certainly have to cut back on global emissions.

Orca Facility in Iceland

However, all of the pathways that keep us at or below 1.5 degrees C, as outlined by the Intergovernmental Panel on Climate Change, also include development of direct air capture technologies like the giant fans set to start spinning in Iceland. Direct air capture can’t keep us below that threshold on its own, but it can help poke a hole in our proverbial carbon bucket to drain out some of our past emissions. 

What is Direct Air Carbon Capture (DAC) ?

Direct Air Capture is a technological method that uses chemical reactions to capture carbon dioxide (CO2) from the atmosphere. When air moves through these chemicals, they selectively react with and remove CO2, allowing the other components of air to pass through. These chemicals can take the form of either liquid solvents or solid sorbents, which make up the two types of DAC systems in use today.

The two major components of a liquid solvent direct air capture process are the air contactor and the regeneration facility. In this process, an aqueous potassium hydroxide solution (KOH) reacts with the CO2 from the air to form water and potassium carbonate (K2CO3).

How does DAC Direct Air Capture work?

Once carbon dioxide is captured from the atmosphere, heat is typically applied to release it from the solvent or sorbent. Doing so regenerates the solvent or sorbent for another capture cycle. Other systems in development use electrochemical processes, which could reduce energy needs and costs.

The captured CO2 can then be injected deep underground for sequestration (storage) in certain geologic formations or used in various products and applications. The carbon use in products, or the net quantity of carbon that is durably stored, depends on the product. Use in products like concrete or plastic can provide long-term sequestration (decades or even centuries), whereas using carbon dioxide in products like beverages or synthetic fuel would quickly re-release carbon into the atmosphere.

In some cases — jet fuel for example — synthetic fuel produced with CO2 could still be a more favourable substitute for more emissions-intensive fossil fuel. However, to maximize climate benefit, most captured CO2 would need to go to vast and permanent underground sequestration rather than useful but more limited utilization routes.

Why is DAC necessary?

As the effects of climate change are increasingly felt through more severe storms, wildfires and flooding, the need to reduce greenhouse gas (GHG) emissions — such as by switching to electric vehicles, deploying solar panels and reducing deforestation — is critical. At the same time, the latest climate science indicates that such efforts will not be enough to keep temperature rise below 1.5 degrees C (2.7 degrees F), which would prevent the worst impacts of climate change.

While efforts to reduce GHG emissions should always take priority, meeting climate goals will also require carbon dioxide removal (CDR) — systems that remove carbon directly from the air — likely at the billion-tonne scale by mid-century.

Carbon removal is needed not only to balance out residual emissions that cannot be or are not eliminated by 2050 but also to reduce the high concentration of carbon dioxide in the air, which is triggering increasingly devastating climate change impacts. The United States, as the largest cumulative historical emitter of CO2, has a responsibility to be a leader in pulling it back out of the atmosphere. The precise amount needed will depend on how fast the world reduces emissions.

Carbon removal can take numerous forms — including natural solutions like growing trees and increasing the ability of soil to sequester carbon and technological solutions that accelerate or mimic natural carbon removal processes or directly pull CO2 from the air.

Direct air capture (DAC) is one type of technological carbon removal that shows promise today and will likely be part of a larger carbon removal portfolio. Compared to other types of carbon removal it uses relatively little space and can also be installed flexibly, so would avoid competition with other land uses and could be built on marginal land or near geological storage sites to minimize the need for CO2 pipelines.

What is the cost of DAC?

Despite the benefits and flexibility, direct air capture is more costly per tonne of CO2 removed compared to many mitigation approaches and natural climate solutions as it is energy-intensive to separate carbon dioxide from ambient air. The range of costs for DAC varies between $250 and $600 per tonne of CO2 today depending on the technology choice, low-carbon energy source, and the scale of their deployment; for comparison, most reforestation costs less than $50/tonne of CO2.

However, depending on the rate of deployment, which could accelerate through supportive policies and market development, costs for DAC could fall to around $150-$200 per tonne over the next 5-10 years. Going further than this, the Department of Energy launched its Carbon Negative Shot initiative in late 2021, which aims to reduce the cost of carbon removal technologies and approaches that could reach a gigaton scale of $100/tCO2 over the next decade.

What are some technological advancements in DAC?

Let’s take a look at some companies trying to make advancement in this field.

Heirloom Carbon Technologies INC.

A California-based startup has found a way to use limestone — a cheap and widely available material — to remove carbon dioxide directly from the air, potentially overcoming a major hurdle in scaling up the technology needed to avoid catastrophic global warming. 

Heirloom Carbon Technologies Inc. raised $53 million from investors including Breakthrough Energy Ventures, a clean-technology fund led by Bill Gates, and the Microsoft Climate Innovation Fund. 

Company’s Website -:

See O2 Energy

See O2 Energy is a Canadian startup working to efficiently convert carbon dioxide and water into marketable and clean value-added products using reversible fuel cell technology. The startup is developing reversible solid oxide fuel cells to enable the electrochemical conversion of water to hydrogen and carbon dioxide to carbon monoxide. This results in the production of syngas, a mixture of carbon monoxide and hydrogen. This solution makes it possible to effectively capture and use carbon to produce fuels, power, heat, and oxygen.

Company’s Website -:

Mirreco – Carbon Emissions Into Industrial Hemp

From paper, textiles, biodegradable plastics, construction, food, and fuel, industrial hemp provides several applications. As one of the fastest-growing biomasses, hemp currently delivers exciting value for industrial carbon capture. Hemp is also suitable for mitigating against potentially harmful substances, such as dioxins, which are carcinogenic and contribute to deforestation, cosmetics, and plastics accumulation, most of which require fossil fuels and do not easily degrade.

Australian startup MIRRECO™ combines non-synthetic advanced polymers and hemp to create hemp CAST®, Carbon Asset Storage Technology, products. By blending hemp with proprietary polymers, the technology completes a carbon-storing polymer chain for producing high-performance construction products.

Currently undergoing testing and certification, MIRRECO™ aims to launch its patented technology, CAST®, to help organizations offset their carbon emissions.

Company’s Website -:


DAC also provides atmospheric clean-up, which is a public good rather than a product people need to purchase, so opportunities for direct revenue are more limited. Captured CO2 can be sold for use in products from concrete aggregate to carbon fibre, markets that don’t typically provide enough revenue to offset the cost of capture. The largest market for CO2 today is enhanced oil recovery (EOR), which is controversial given its connection to fossil fuel production.

Climate models make it increasingly clear that carbon dioxide removal will likely need to happen on a multi-billion-tonne scale by mid-century along with deep emissions reductions. And the slower we are to reduce emissions, the more we may need to rely on carbon removal — including DAC — to meet national and global climate goals.

Achieving large-scale carbon removal will require a portfolio of different approaches, which will reduce cost and the risk of anyone’s approach failing to provide expected removal. Investing in DAC now will help reduce future costs, which can prove critical as carbon dioxide removal becomes even more necessary.

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