Carbon capture

Regionally, the DAC patent landscape has some key differences from the overall carbon capture trends (Figure 2B). The United States and China are now the two leading countries for DAC-related patent filings, followed by Europe. The US continues to be a major source of DAC innovation, leveraging its robust R&D infrastructure and policy support (e.g. enhanced 45Q credits for DAC in the Inflation Reduction Act) to spur development.

China’s emergence is especially notable – even with Chinese domestic-only filings excluded in our analysis (a methodological step reflecting China’s extraordinary large volume of patents filed only in-country), China ranks as a top DAC innovator worldwide. This suggests Chinese companies and institutions are not only developing significant DAC technologies, but also seeking international patent protection for them, implying an intention to commercialise these solutions globally.

Europe remains a key player as well, contributing a substantial share of DAC patents, in line with its strong climate tech initiatives. In contrast, South Korea – which is a leading region in carbon capture patents overall – has a relatively small footprint in DAC patenting. This indicates that South Korean efforts in carbon capture are currently focused on other methods (such as point-source capture or bio-based solutions) rather than direct air capture.

In summary, the DAC field is expanding rapidly and internationally, with the US and China at the forefront and a growing cadre of global innovators driving the technology forward.

Carbon capture innovations span a variety of approaches for separating CO₂ (and other greenhouse gases) from emissions or the ambient air. The choice of capture technique generally falls into two broad categories based on the type of sorbent used: absorption (using liquid solvents that chemically absorb CO₂) or adsorption (using solid materials that bind CO₂ on their surface). In addition, alternative methods (such as bio-based capture) and new hybrid or novel systems are being explored. Below we review patent trends in these categories, highlighting how different technologies are contributing to the overall landscape of carbon capture innovation.

Absorption is one of the most established methods for CO₂ capture, traditionally employing liquid chemical solvents to scrub CO₂ from gas streams. A classic example is amine scrubbing, where aqueous amine solutions (like MEA) chemically react with CO₂ to form stable compounds (carbamates/bicarbonates), thereby removing CO₂ from the gas.

This technique has been used for decades in industrial settings and remains a baseline for comparison. In recent years, there has been a revival of interest in improving absorbent-based systems. Since around 2020, patent filings for absorbent technologies have notably risen, with 2023 marking the highest number of filings in the past two decades (Figure 3). However, the data suggests that this surge may be beginning to plateau, hinting that absorbent innovation – while still active – is reaching maturation.

The United States and Europe lead in developing absorption-based carbon capture solutions. In 2023, the U.S. accounted for roughly thirty eight percent of all CO₂ absorbent-related patent filings among the five major regions, closely mirroring its overall share in carbon capture patents. Europe ranked second with about twenty seven percent of absorbent filings, driven by significant contributions from chemical industry leaders (for instance, Air Liquide and BASF are noted as key European filers in this space).

These patent activities largely focus on incremental improvements and optimisations of the well-established solvent absorption process. While amine-based systems can achieve high CO₂ capture efficiencies, they face persistent challenges: the regeneration of solvents is energy-intensive (often requiring substantial heat to release captured CO₂), the chemicals can degrade over time (losing effectiveness and creating waste), and the solvents can be corrosive to equipment.

Recognising these issues, recent innovations have introduced new solutions such as advanced amine formulations, ionic liquids, and biphasic solvent systems. These aim to reduce energy consumption, enhance solvent stability, and mitigate corrosion. For example, some patents propose phase-changing absorbents that can be regenerated at lower energy cost, or novel additives that inhibit solvent degradation.

Altogether, the ongoing work in absorption technologies highlights a commitment to overcoming the traditional drawbacks of solvent-based CO₂ capture, in order to improve its practicality and scalability for large-scale deployment

Adsorption-based carbon capture uses solid sorbent materials to bind CO₂ onto their surfaces. In an adsorption process, CO₂ (the adsorbate) adheres to the surface of a solid adsorbent. This can occur via physisorption – where CO₂ molecules are held by weak Van der Waals forces – or via chemisorption, which involves the formation of stronger chemical bonds on the sorbent surface. The adsorption approach has gained tremendous traction in recent years due to a proliferation of new solid materials with high affinity for CO₂.

The field of adsorbents is highly diverse, including porous solids like zeolites, metal–organic frameworks (MOFs), porous organic polymers (POPs), activated carbons, and others. Each material class offers different advantages (e.g. selectivity, capacity, regeneration energy) and thus opens multiple avenues of innovation. Correspondingly, patent filings in adsorbent-based capture now far exceed those in absorbent-based capture.

In 2023, there were roughly 2.5 times more new patent applications related to CO₂ adsorbents than to liquid absorbents. This gap has widened in recent years as research interest heavily favours solid sorbents. Figure 4 illustrates how adsorbent-related patent activity has skyrocketed over the last five years, sharply outpacing the growth in absorbent patents. Unlike the modest tapering seen in absorbents, adsorbent patenting shows no sign of slowing down – indicating that innovation in adsorbent technologies remains a dynamic and rapidly expanding frontier.

Beyond the conventional chemical absorption and adsorption methods, researchers are actively exploring alternative carbon capture techniques that leverage biological processes or novel physical/chemical systems.

One such avenue is bio-trapping, a bio-based approach to carbon capture. Bio-trapping entails using living organisms – such as specific strains of microorganisms, algae, or even engineered plants – to capture and convert CO₂ from the atmosphere or flue gases. These biological systems naturally uptake CO₂ through processes like photosynthesis or microbial metabolism, transforming CO₂ into biomass or other stable forms.

Currently, bio-based capture represents a relatively small portion of patent activity (on the order of one patent for bio-trapping for every 10 patents on adsorbents). However, interest in this area is growing as the technology matures and concerns about sustainability and energy input of traditional methods drive pursuit of low-energy alternatives (Figure 5).

Notably, South Korea appears to be a leader in this niche: in 2023, nearly half of the new patent filings related to bio-trapping among the major regions came from South Korea. This aligns with South Korea’s strategic interest in carbon capture.

In addition to biologically driven solutions, a broad range of emerging carbon capture technologies is under development. These include membrane-based separation systems (which use selective permeable membranes to filter CO₂), electrochemical capture methods (which capture CO₂ via electrochemical reactions or pH swings), and new types of chemical absorbents that go beyond traditional amines. For example, some researchers are investigating carbonate looping or ionic liquid sorbents as alternatives to amine solvents, aiming to overcome issues of amine degradation and volatility.

A notable case is the work of Carbon Engineering, a company that has pioneered a liquid solvent DAC process using a strong potassium hydroxide (KOH) solution. In Carbon Engineering’s system, air is bubbled through KOH, which reacts with CO₂ to form potassium carbonate; this is then converted to solid calcium carbonate (limestone) in a secondary step, and finally the CO₂ is released in pure form by heating the calcium carbonate.

This innovative process has attracted significant industry attention. In 2023, Occidental Petroleum (Oxy) announced a USD 1.1 bn acquisition of Carbon Engineering, underscoring the confidence in this technology’s potential. Oxy is now in the process of deploying Carbon Engineering’s DAC technology at a large-scale facility in Texas, which is designed to capture about 500,000 metric tons of CO₂ per year once operational, making it one of the world’s largest DAC plants.

These kinds of developments highlight how alternative and hybrid approaches are expanding the carbon capture patent landscape. Innovators are essentially casting a wide net to discover methods that could complement or surpass the current dominant technologies, potentially offering improvements in energy efficiency, cost, or applicability to different sources of emissions

Innovations targeting N₂O and F-gases, while fewer in number, are also on the rise as industries seek ways to limit these potent emissions (for instance, new catalysts to break down N₂O in industrial off-gas, or treatment of HFCs from refrigeration equipment).

Overall, the patent trend for non-CO₂ greenhouse gas capture is upward, indicating that this niche, too, is becoming an important part of the climate technology portfolio. It is worth noting that in 2023, Europe accounted for the largest share of patent filings related to capturing non-CO₂ gases. European researchers and companies have been at the forefront in this area, likely driven by strict EU regulations and targets for a broad range of greenhouse gases (for example, the EU has policies aiming to curb methane emissions and F-gas uses). As efforts to mitigate climate change broaden beyond CO₂ alone, we can expect continued growth in innovation for capturing these other gases, ensuring that carbon capture and storage techniques evolve to address the full spectrum of greenhouse contributors.