Science and Technology (What Is It)
What is Direct Air Capture?
Direct Air Capture (DAC) is a type of technology that removes carbon dioxide from the air. Sometimes referred to as a Negative Emissions Technology (NET), direct air capture (DAC) systems extract CO2 directly from the ambient atmosphere. The CO2 can be permanently stored in deep geological formations (thereby achieving negative emissions or carbon removal), utilized for long-lived durable products such as building materials, used in food and beverage processing, or combined with hydrogen to produce synthetic fuels.1
How Does DAC Work?
While often thought of as a single type of technology, there are a number of engineered methods for DAC systems. These approaches can use heat, moisture, pressure or electricity to separate CO2 from the air on a range of different scales – from large scale stand-alone industrial facilities to building integrated applications. Currently, two prevailing approaches are (1) chemical liquid solvent DAC and (2) chemical solid sorbent DAC. Although differences exist, these technologies operate under the same premise: selective removal of CO2 from ambient air (∼415 ppm) by contact with a basic solution (chemical liquid solvents) or a basic modified surface (chemical solid sorbents).
The CO2, now fixed in a carbonate or carbamate bond is released from the capture media through application of heat, producing high purity CO2 and regenerated solvent, or sorbent, capable of many cycles of CO2 removal. Regardless of technology, the average energy requirement is approximately 80% thermal and 20% electrical. This technology was first developed and demonstrated decades ago for air quality regulation in submarines and spacecraft at small scales. At larger scales, DAC technologies can be a critical tool to addressing climate change by safely and permanently removing excess CO2, the main greenhouse gas responsible for climate change in the Earth’s atmosphere.2
How is The Technology Deployed?
Several companies have begun deploying various types of DAC technology and significant R&D efforts are underway to continue improving effectiveness. Additional approaches being explored for capturing CO2 from air include passive systems, membrane systems, electrochemical systems, refrigeration systems, and more. DAC is an active area of scientific and engineering research, and new methods are rapidly emerging.
What Can We Do With The Captured CO2?
The two primary uses for captured CO2 are underground sequestration and utilization for goods or industrial processes.
CO2 sequestration removes the CO2 from the atmosphere permanently, but relies on government or sponsor funding as it does not generate an otherwise usable product. Two common forms of geological sequestration are mineralization in underground rock formations and storage in saline reservoirs. CO2 utilization is already core to many industrial processes and the number of applications for air-sourced CO2 is growing rapidly.
What is The Current Global Market Size for Commercial CO2?
The merchant market for CO2 today is roughly 180 million tons per year.3 Innovators are developing ways that air-sourced CO2 can be used as an additive by beverage companies, upcycled into chemicals and advanced materials like carbon nanotubes, and injected into concrete to make it stronger.4 Other entrepreneurial efforts are also creating economical ways of transforming CO2 into advanced fuels that can power cars, ships, or even aircraft and rockets. The total available market for carbontech products has been estimated at over $1 trillion.5
DAC’s Role in Addressing Climate Change (Why Do We Need It)
Why is DAC Important?
DAC deployment is necessary to prevent catastrophic changes to the climate. Given that carbon dioxide remains for thousands of years in the atmosphere, we need to permanently remove billions of tons of carbon dioxide within the next decade. Stopping emissions is necessary, but no longer enough. Specifically, in order to limit temperature increase to 1.5°C we must drastically reduce CO2 emissions by 2050 and we need DAC, along with a portfolio of other carbon removal approaches, to balance out residual emissions from hard-to-abate sectors, such as aviation, maritime shipping, and certain industrial processes as well as to remove legacy emissions to bring down the CO2 concentration in the air to safer levels.
The recent United Nations Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report found that the effects of climate change were ‘widespread, rapid, and intensifying.’ These impacts, seen in flooding, drought, heat waves, wildfires, shifting rainfall patterns, and melting ice caps, among others, are due to the anthropogenic emissions of CO2 and other greenhouse gasses (GHGs) in the atmosphere.
Direct Air Capture enables the direct removal of CO2 from the atmosphere. The latest climate science makes it clear that hundreds of billions of tons of waste CO2 will likely need to be permanently removed from the atmosphere this century to avoid catastrophic climate change. In addition to reducing, or mitigating emissions through steps such as switching to cleaner sources of power, installing energy efficiency measures, and decarbonizing most sectors of the economy, it has become clear that society will need to pursue carbon dioxide removal strategies as well. Direct air capture, among others, can serve as a central component of that approach.
How Much Carbon Removal Do We Need Over Time?
Estimates from the IPCC suggest that 100 – 1,000 billion metric tons (Gigatons or Gt) of carbon dioxide removal will be needed over the 21st century for the world to limit global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above pre-industrial levels (identified as a critical target threshold under the 2015 Paris Agreement). Extensive analysis has found that scenarios achieving 1.5°C included carbon removal deployment by 2050 ranging from 1.3 to 29 gigatons of CO2 removal per year, with most falling between 5 and 15 gigatons. This massive level of carbon dioxide removal is in addition to the very aggressive measures we need to take to reduce humanity’s ongoing carbon dioxide emissions through the widespread adoption of renewable energy and many other emissions reduction measures.
What is the Current Capacity of Existing DAC Technology?
According to the IEA, currently 19 direct air capture (DAC) plants are operating worldwide, capturing more than 10,000 tons of CO2/year (approx. 2,000 passenger vehicles). Current technologies have been limited by high costs (several hundred dollars per ton of CO2 removed) and substantial energy requirements (more than 7 gigajoules, or GJ, of energy per ton of CO2).6
Is Carbon Removal a Substitute for Reducing Emissions?
Given the amount of CO2 in the atmosphere today, reducing emissions and removing carbon dioxide from the air are necessary and complementary strategies which are both needed to avert the worst impacts of climate change.
What Other Carbon Removal Solutions Exist Besides DAC?
Direct Air Capture is just one of several carbon removal methods being developed. Other potential solutions range from technological approaches like Bioenergy Carbon Capture and Storage (BECCS) to biological and nature-based approaches like reforestation, soil carbon sequestration, and engineered wood, as well as geological approaches like enhanced weathering and seawater carbon sequestration, among others.7
But Trees Can Remove CO2 From The Air, Why Do We Need DAC?
Removing the massive amount of CO2 from the atmosphere that is required to address climate change in the coming decades will require a broad portfolio of such solutions, optimized for varying circumstances around the world. A portfolio of options additionally reduces risk of any one option failing to produce expected removals, as well as decreases cost overall.
Research is ongoing but multiple independent studies have clearly identified that Direct Air Capture has several unique advantages suggesting it will need to play a significant role in addressing climate change. Current estimates suggest DAC could remove over 10 gigatons of carbon dioxide per year by 2050.8 Relying entirely on nature-based solutions will not suffice due to geospatial and biophysical limitations, e.g, there isn’t enough available land and many biosequestration methods result in less permanent removal, such as when CO2 is released as a result of wildfires and other climate induced changes.
What Are DAC’s Advantages?
The primary advantages of Direct Air Capture as a means of carbon removal are its siting flexibility, large degree of scalability, high land and water use efficiency, precise measurability of CO2 removed, and the duration/permanence of storage.
- Location Flexibility: DAC can be sited in many different types of locations that don’t compete with other valuable uses, such as agriculture. Additionally, it can be located near sources of clean energy or waste heat to reduce costs and impacts on the energy system.
- Highly Scalable: It can be scaled up to very large capacities, but also embedded as smaller distributed applications.
- Land Efficient: It is highly efficient at removing CO2, and therefore has a smaller land footprint relative to many other CDR solutions.
- Highly Measurable: CO2 captured by DAC can be precisely measured in real time.
- Multiple Sequestration/End Use Options: Captured CO2 can be paired with diverse forms of storage that are secure and permanent.9
How is Direct Air Capture (DAC) Different from Point Source Carbon Capture and Storage (CCS)?
Carbon Capture and Storage (CCS) involves capturing CO2 at emissions sources such as cement plants or power plant smokestacks, preventing its release into the atmosphere by directly capturing it. By contrast, Direct Air Capture involves the removal of CO2 that has already been emitted directly from ambient air.
CCS is a method of emissions reductions while DAC is a method of permanent carbon removal.10
What Economic Opportunities Does DAC Create?
At full scale deployment, DAC is expected to generate between 600,000 to 1.35 million high-wage jobs by 2050 in the United States alone. Breaking this estimate down, a typical 1 megaton capacity DAC plant can generate roughly 3,500 jobs across the DAC supply chain. The sectors that would benefit most from these new jobs include construction, engineering and equipment manufacturing that could see a minimum of 300,000 new jobs. Whereas, the cement and steel employment could increase by 50%; operation and maintenance as well as chemical and natural gas workers would see major new job growth opportunities.11
What Is The Potential Equity Impact Of DAC?
If mobilized in a thoughtful, careful, and equitable manner, DAC deployment can be a powerful force for advancing environmental, social, and economic equity.
On the most fundamental level, DAC, along with other NETs, can serve to a way for industrialized nations, the ones who have emitted the vast majority of current and historical CO2, to make the investments and lead the effort to scale up carbon removal technologies such as DAC to help remove the excess carbon dioxide they have put into the atmosphere over centuries.
As noted in “What Economic Opportunities Does DAC Create,” DAC mobilization will create hundreds of thousands, if not millions, of high paying jobs in the coming decades. The skill-sets that will be required for successful operation of DAC facilities will also overlap significantly with those held by workers in industries likely to be disrupted by the clean energy transition. Utilizing these workers’ talent and knowledge for DAC is a way to mitigate that disruption and enable a just transition to a more sustainable economy.
Why Is Scaling DAC Today Important?
It is critical to begin scaling DAC technology as soon as possible due to the urgency created by climate change. Both sophisticated scientific models and real world extreme weather events clearly show accelerating impacts of climate change which demand societal action.
Direct Air Capture will take time to scale up and reduce costs through deployment experience and learning. As such, society needs to begin deploying DAC as soon as possible to accelerate the process of cost reduction and technological and process improvements. Leading climate models require several gigatons of technological carbon dioxide removal by mid-century so scaling now is critical to meeting those goals.
Investing now will lower costs in the future, when even more DAC is required. The best time to begin deploying DAC at an industrial scale would have been decades ago. The second best time to do so is today.12
Does DAC Encourage Continued Reliance on Fossil Energy?
Some are concerned that DAC and other NETs will serve as a convenient excuse to continue burning fossil fuels, commonly referred to as the “moral hazard” problem. However, the fact is that BOTH emissions reductions via rapid decarbonization and shift to cleaner sources of power AND excess carbon dioxide removal are needed at massive scale to meet international climate goals. To hit these targets, global society does not have the luxury of treating it as an either/or situation, rather it requires a both/and inclusive approach to reducing current carbon emissions and removing legacy CO2 emissions to return atmospheric CO2 to safe levels.
Is Direct Air Capture Too Expensive To Be a Practical Solution?
Scientists agree that, to reach the scale of negative emissions required in order to keep 1.5C alive, we will need to deploy a portfolio of carbon removal approaches.
Direct Air Capture has potential to pull gigatons of CO2 directly from the atmosphere every year, in a permanent and measurable way, whilst requiring little land area compared to other approaches such as reforestation. However, today’s leading DAC technologies are too expensive to deploy at scale.
The range of costs for DAC varies depending on the technology, with an estimated average of around $600 per tonne of CO2. For context, most reforestation costs less than $50/tonne. Depending on market development, it is estimated costs for DAC could fall to around $150 per tonne over the next 5-10 years, or even lower in some scenarios.
Fundamentally, DAC is expensive because it is a nascent technology. There are only a handful of companies developing this approach – as of 2021, 19 DAC plants were in operation globally, many of which are very small pilot or demonstration scale projects. Most emerging technologies, such as solar panels, computer hard drives, or recently offshore wind farms, start with very high costs, which substantially decline as they scale and innovate.
The Third Derivative and RMI report highlights the innovation and step-change technologies that will drive significant cost reductions as DAC scales up. Third Derivative DAC Report highlights important opportunities for cost reductions around capital expenditure, costs of materials such as the solvents that pull the CO2 from the air, and innovative ways to generate the energy required by the plants, such as electrochemistry.
Overall, according to this report, the best scenario sees the cost of DAC reduced by an order of magnitude to close to $50 per ton of CO2 removed.
This is the defining decade for technology development. Investing in DAC now can make the costs lower in the future. In 2050 and beyond, humanity may find itself in a position where it needs immediate carbon removal at gigaton scale. At $50 per ton, the world could achieve 10 gigatons of annual CO2 removal at a cost below $500 billion per year. While this is still a large sum, we believe that humankind will increasingly realize the value of solutions to the climate crisis.
Who is Developing DAC Technology?
Check out our DAC Directory to see some of the leading innovators in the field!
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