top of page
  • Donald J. Pagel

Global Warming: Will DAC Technology Save the World?

Updated: Jun 17, 2022

Direct air capture (DAC) of carbon dioxide is a promising but controversial technology that could help keep global warming within the target range set at the Paris Agreement in 2015. In this article it is argued that direct air capture is much more promising than controversial, and that the field offers many opportunities for enterprising technology companies.

What is Direct Air Capture?

DAC is a technology for removing carbon dioxide (CO2) directly from the atmosphere. It’s important because it can help nations meet accepted global warming benchmarks. Specifically, the 2015 Paris Agreement established a goal of keeping the global mean temperature rise to considerably below 2°C above pre-industrial levels (i.e., the period of 1850-1900). This goal was accepted to mean a temperature rise of no more than around 1.5°C and most modeling of global warming impacts uses scenarios based on a 1.5°C temperature rise as the baseline reference point.

To achieve this goal, global greenhouse gas emissions (i.e., CO2 plus other greenhouse gasses) need to be cut in half by about 2030, and CO2 emissions need to be reduced to net zero levels by about 2050. Net zero CO2 emissions means that as much CO2 is being removed from the atmosphere as is being put in, and the removal can be accomplished by any method that permanently removes CO2 from the atmosphere.

Unfortunately, many estimates show that nations are not reducing greenhouse gas emissions at the rates necessary to meet these benchmarks and keep global warming at the 1.5 ˚C level. For example, at the COP26 conference held in Glasgow in late 2021, countries made pledges about the steps they would take to limit global warming. Several independent organizations used these pledges to model the probable temperature rise that would result. The modeling showed that the most likely temperature rise range for this century was between 1.8 and 2.7°C (more information here). This type of temperature rise would have serious to catastrophic consequences for the Earth’s ecosystems depending on which end of the range turned out to be correct.

Since nations don’t appear to be cutting greenhouse gas emissions quickly enough to limit global warming to somewhere near the 1.5 ˚C goal, it seems likely that we will have to start removing billions of tons (gigatons) of CO2 from the atmosphere by around 2050 (more information here and here). DAC is a way of doing this if some technological problems can be worked out. Currently, there are numerous approaches to DAC methodology. Below, the approaches that two companies are taking are described, but there are probably at least another dozen approaches under investigation.

The Canadian company Carbon Engineering Ltd. uses an archetypal approach to DAC. In this approach, large fans pull in air from the atmosphere and force it to flow over a liquid chemical solution that acts as a capture agent. The capture agent reacts with the CO2 in the air to produce a solid material that precipitates out of solution. The solid material is then heated to release pure CO2 gas which is collected and stored. The rest of the reaction product from heating the solid material is recycled back into the original liquid chemical solution as regenerated capture agent.

In the Carbon Engineering system, the capture agent is probably potassium hydroxide (KOH) and the solid material is potassium carbonate (K2CO3). However, in other systems, other chemicals can be used, as can variations of this technique. For example, the liquid chemical solution can be replaced with a filter, analogous to what would be used in a central air-conditioning system but containing a solid adsorbent material that adsorbs the CO2. Heating the filter releases the adsorbed CO2, which is then collected, and the filter is ready for reuse.

The Swiss company Climeworks uses this type of technology with the CO2 adsorbent material in the filter possibly being comprised of activated carbon impregnated with an alkali carbonate salt such as K2CO3 (Climeworks' published patent application Pub. No. US 2021/0187480, published June 24, 2021, describes this chemistry).

Currently, the main problems with the archetypal approach to DAC are cost and scalability. The energy required to run the intake fans and to heat the capture material drives up the cost. Using inexpensive renewable energy for these steps is preferable, but cost is one of the problems that must be resolved before DAC is economically feasible at the gigaton level. Scalability is another problem as current DAC pilot plants only remove about one million tons of CO2 per year. That’s a long way from the required gigaton level. However, technology tends to scale quickly once it gains momentum, and these problems present businesses with the opportunity to make inventions that improve the DAC technology.

Another issue is that the pure CO2 that is collected must be permanently stored in a manner that prevents it from being released back into the atmosphere. One approach is to inject the CO2 into underground rock formations that react with the CO2 and hold it in place, ideally forever. Other approaches are to reuse the CO2 to produce new fuels or other products, but CO2 storage and/or sequestration is another area that presents opportunities to inventive businesses.

The controversy surrounding DAC is that it either will never be economically feasible or that it might work so well that it discourages the development of renewable energy technology, such as solar and wind energy. For example, petroleum companies might use the availability of DAC technology to justify the continued use of hydrocarbon fuels instead of developing energy sources that don’t produce greenhouse gasses. However these scenarios play out, the need for DAC technology seems to be so important that its development can’t be delayed just because oil companies might try to game it, or because development will be challenging.


Funding for research and development of DAC technology is available from both private and government sources. For example, the U.S. Department of Energy (DOE) continues to support DAC research through its Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs. In May of 2022, DOE announced grants of $53 million to fund 259 small business climate change projects, some of which involve DAC technology. This SBIR funding round is described here.

Another recent funding event by the DOE is a $14 million grant to support five pilot projects (known as front-end engineering design (FEED) studies) that will help determine the feasibility of DAC technology (DOE announcement here). Specifically, the five pilot projects involve building DAC plants that use low-cost and/or greenhouse gas-free energy sources to power the DAC process. Two of the projects use Climate Engineering and Climeworks DAC technology. The five pilot projects will also dispose of the recovered CO2 using methods like permanent geologic storage, or conversion of the CO2 into concrete or value-added chemicals.

In the private sector, philanthropic organizations, as well as venture capitalists, private equity companies, corporations, and individuals are providing funding to companies involved in DAC research and development. In the philanthropic arena, the Musk Foundation is sponsoring a $100 million X-Prize competition for carbon (as CO2) removal from the atmosphere. Recently, fifteen teams in the competition were awarded $1 million each for reaching certain milestones. The competition has now been reset and will remain open until 2025 when another $80 million will be awarded to the winners (details here).

In the venture capital (VC) arena, investments in DAC companies are being made by firms such as First Round Capital, Starlight Ventures, and Thomvest (more information here). Overall, this level of public and private investment in DAC technology, along with the importance of carbon removal technology over the next several decades, indicates that there are many opportunities for companies interested in working in this field.


The international community has done a reasonable job of studying global warming and laying out plans for limiting its worse effects. The Paris Agreement of 2015 and the various UN reports such as the COP and IPCC reports are evidence of this work. However, execution of the plans has been underwhelming, and present projections show that not enough is being done to keep global temperatures from rising more than the 1.5°C set out in the Paris Agreement. DAC technology provides two ways to help meet the 1.5°C goal: 1. It provides a way to meet the 2050 carbon neutrality goal; and 2. It provides a way to compensate for temperature overshoots that will likely occur if nations don’t start meeting their greenhouse gas reduction promises immediately. For these reasons, the development of DAC technology must proceed with high priority right now. If DAC technology turns out to not be feasible, we need to learn this as soon as possible so that something else can be developed to take its place.

37 views0 comments


bottom of page