Are Climate Geoengineering Technologies Being Patented? An Overview

Abstract

Efforts to address anthropogenic climate change have been focused sensibly on mitigation and adaptation. However, given the difficulties in the implementation of a rapid global mitigation process, increasing attention is being given to geoengineering as a way to countervail some of the climate change impacts. This development has increased the private investment in geoengineering research in the last few years, leading to patent filing. The article examines the recent evolution of patents in the emerging field of geoengineering technologies. Despite the secrecy surrounding the field of geoengineering, especially solar radiation management at the state level, patent databases provide transparency, offering technical details, market insights, and information about the key players. Patents, published 18 months after filing, reveal valuable data about geoengineering technologies, the targeted markets, and involved stakeholders. The databases of the International Patent Classification (IPC) and Cooperative Patent Classification (CPC) are used. The focus of the present analysis is on patents in the sub-domains of carbon dioxide removal and solar radiation management and on those held by the large oil producer corporations. The results highlight the patents filed in the controversial area of SRM. The growing economic significance of geoengineering requires the protection of innovations through patents coupled with the implementation of a global governance system based on climate justice and ethical responsibility.

1. Introduction

1.1. Introduction and Objectives

Anthropogenic emissions of greenhouse gases (GHGs), in particular carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (NO₂), have significantly increased their atmospheric concentration since the industrial revolution, causing a progressive global climate change that is provoking widespread harmful impacts across the world [1,2]. About half of global CO₂ emissions during the period 1850–2020 were emitted since 1990 [3], which presents a mounting mitigation challenge. The Paris Agreement became legally binding in 2016 with the overarching objective of holding “the increase in the global average temperature to well below 2 °C above pre-industrial levels” and of pursuing efforts “to limit the temperature increase to 1.5 °C above pre-industrial levels”. However, since then, global energy-related CO₂ emissions have increased annually, except for the COVID-19-related drop, reaching in 2024 an all-time maximum of 37.8 Gt CO₂, with an increase of 0.8% relative to 2023 [4]. This rise contributed to record atmospheric CO₂ concentrations of 422.5 ppm in 2024, around 3 ppm higher than 2023. According to the World Meteorological Organization, based on six global temperature datasets, the ten-year average 2014–2023 of the global mean surface temperature (GMST) was 1.20 ± 0.12 °C above the pre-industrial levels [5]. The chances of staying below 1.5 °C or even 2 °C are fast decreasing, which implies that the global mitigation efforts have to be strongly enhanced.

Our focus here is on climate geoengineering, which has been frequently proposed and increasingly researched as an alternative broad set of interventions in the climate system with the aim of countervailing some of the harmful effects of anthropogenic climate change. There are fundamentally two types of climate geoengineering, or climate intervention actions, with the objective of countervailing climate change. One is GHG removal (GHGR) from the atmosphere, in particular, using negative emission technologies (NETs). Since CO₂ is the most important GHG in the atmosphere, with anthropogenic emissions accounting for approximately 64% of the warming effect on the climate, the main objective is to remove it directly from the atmosphere using natural sinks or chemical engineering processes. This specific type of intervention is called carbon dioxide removal (CDR) and there is a large variety of NETs based on chemical engineering processes that have been developed, tested, and used [6,7]. In particular carbon capture, use, and sequestration (CCUS) geoengineering is now considered as an indispensable tool to reach the Paris Agreement temperature goals [8,9]. Recent research has evaluated the possibility of methane removal from the atmosphere (MR), but this technology is still in an early development phase [10,11]. The other form of geoengineering is solar radiation management (SRM), and its most promising form is Earth’s albedo modification (EAM) [6]. It consists of purposely modifying the radiative energy balance in the atmosphere to reduce the excessively positive radiative forcing caused by the anthropogenic emissions of GHGs in order to lower the GMST [12,13,14].

The criteria to classify a given climate intervention as geoengineering involves questions of scale and intent. Geoengineering aims to countervail anthropogenic climate change at the planetary scale. Some CDR methods fall under the category of geoengineering if they satisfy those criteria, while this is not the case for other CDR methods that are usually classified as mitigation, with the distinction being based upon the magnitude, scale, and impact of the particular CDR activity [7,12,15,16]. CO₂ capture and sequestration (CCS) can be applied to a bioenergy facility. This technology is called bioenergy with carbon dioxide capture and storage (BECCS) and is recognized by the IPCC as a CDR technology and, depending on its magnitude, scale, and impact, can be considered as a form of geoengineering. The direct air capture of CO₂ coupled with CCS, called DACCS, is also recognized by the IPCC as a CDR technology. The CCS technology applied to fossil fuel-energy-related sources, from industrial-related sources, such as in a steel plant or cement-producing facilities is not recognized as a potential geoengineering intervention by the IPCC. All interventions based on CCS may have a magnitude, scale, and impact that would justify the classification of geoengineering. The mitigation of climate change is defined as a human intervention to reduce emissions or enhance the sinks of greenhouse gases [6].

The present analysis is focused on methods that “use or affect the climate system (e.g., atmosphere, land or ocean) globally or regionally and/or could have substantive unintended effects that cross national boundaries”, considered by the IPCC [17] as the definition of climate geoengineering. There is a partial conceptual overlap between geoengineering and climate change mitigation.

The role of the oil and gas industry in the transition to net zero emissions is a strong determinant for the degree of severity of future anthropogenic climate change impacts. According to the IEA [4], oil and gas companies account for about 1% of total renewable energy investment globally. More than 60% of this investment comes from four companies, out of thousands of other oil and gas companies around the world today. The situation is different as regards CCS. CCS geoengineering has been mostly used by the fossil fuel industry. The main CCS application that has been employed for decades is to remove CO₂ from raw natural gas. CO₂ removal has to be performed to avoid problems such as pipeline corrosion, compression cost, and reduction in heating value. The removal of CO₂ and H₂S, which also contributes to the corrosion of the pipelines and to the production of harmful SO₂, is called natural gas sweetening. The CO₂ resulting from natural gas sweetening is captured and stored underground instead of being released into the atmosphere.

The other most common use of captured CO₂ that is considered economically viable is the enhanced oil recovery (EOR) technology. Here, CO₂ is injected directly into an oil reservoir to facilitate oil extraction through multiple mechanisms: oil swelling, viscosity reduction, and oil displacement. Until recently, the source of the CO₂ used in EOR came from naturally occurring underground deposits. In recent years, the oil industry has begun to utilize CO₂ that has been captured as a by-product of fossil fuel combustion, gasification, or other industrial processes. However, the reduction in CO₂ emissions through these processes is very small compared with the CO₂ emissions that result from burning the extracted oil or natural gas. Norway’s Sleipner and Snøhvit gas fields in the North Sea produce raw natural gas with about 9% of CO₂. They constitute an important early example of CCS deployment. To prevent the emission of the excess CO₂ into the atmosphere, the CCS infrastructure for these fields has been operating since 1996 and 2008, respectively. The CO₂ captured in the extracted gas mixture is compressed and reinjected several hundred meters below the sea floor. The two Norwegian gas facilities have already sequestered about 22 Mt (million tons) of CO₂ in offshore storage. However, a recent report stated that both projects faced problems that could have caused CO₂ leakage [18]. The combustion of the natural gas produced at Norway’s Sleipner and Snøhvit fields emits an estimated 25 times more CO₂ when burned than the CO₂ captured by processing the extracted raw natural gas [19].

To comply with the Paris agreement, there needs to be a substantial reduction in fossil fuel production and use at the global scale. In this scenario, CCUS technologies should be used to reduce emissions in hard-to-abate sectors, particularly heavy industries like cement, steel, or chemicals, to deliver CO₂ to be used together with green hydrogen in the production of synthetic fuels and to minimize the use of the remaining unabated fossil fuels [20]. CCUS is also an enabler of least-cost low-carbon hydrogen production, which can support the decarbonization of parts of the energy system, such as industry, trucks, and ships. Recently, oil and gas companies have started to invest in the direct air capture of CO₂ (DAC), a technology that can lead to applications with net-zero or negative CO₂ emissions in the process lifecycle. One example is provided by Occidental Petroleum that acquired in 2023 [21] all the equity of Carbon Engineering Ltd., specialized in DAC technologies and founded in 2009 by David Keith, one of the most knowledgeable and outspoken defenders of SRM geoengineering [22].

The current involvement of the big oil and gas companies in SRM geoengineering is more difficult to decipher. The direct involvement by big oil and gas companies in specific SRM projects is not always transparent, but it is clear that there is indirect involvement through funding and connections to organizations that promote SRM geoengineering.

Some of the methods, processes, and technologies involved in mitigation, adaptation, and geoengineering are registered as patents with the global patent system, overseen by the World Intellectual Property Organization (WIPO). The process of registration incentivizes innovation by granting exclusive rights to inventors and increases the openness in the research and development of geoengineering technologies. The social control over geoengineering through access to information about new technologies is vital in deciding how to proceed with geoengineering research, field experiments, and eventual deployment [23].

The present paper has three main objectives. The first is to identify the current trends in registered geoengineering filed patents using the International Patent Classification (IPC) and the European Cooperation Patent Classification (CPC), with a focus on CDR and SRM technologies. The second objective is to analyze the recent patents filed by the major oil and gas companies in CDR and SRM geoengineering technologies. These companies play a critical role in addressing the climate change challenge, and they have filed a significant number of patents on geoengineering. The third objective is to propose a classification of the major geoengineering current technologies that could update the IPC system.

By examining the current state of CDR and SRM geoengineering patents in WIPO, one can better understand the technological landscape and identify the key players and innovations driving the progress in geoengineering research [24]. It also provides an overview of the organizations active in these technological fields, which are likely to become major players in these markets. Observing the patent application filing strategy of a certain organization provides information on its evolution from using traditional technologies with unabated GHG emissions to a situation where they use technologies that reduce strongly, or lead to net-zero or negative, CO₂ emissions. Searching for patent applications in the field of geoengineering is presently hindered by the lack of a specific international class adapted to the current classification of different forms of geoengineering technology. In addition, geoengineering includes a large number of technologies and potentially a large number of patent applications. This article does not aim to exhaustively identify geoengineering patents, but to demonstrate that the patent approach provides information on the present dynamics and future objectives of the stakeholders involved in the field of climate geoengineering.

1.2. Classification of Geoengineering Interventions and Technologies

The IPCC (2012) Meeting Report on Geoengineering provided the first in-depth analysis of various geoengineering technologies, categorizing them primarily into two groups, CDR and SRM. Other forms of geoengineering include infrared radiation management and glacial geoengineering to slow the sea level rise [25]. Geoengineering technologies have been extensively discussed as regards their potential effectiveness, side effects, risks, uncertainties, governance issues, and ethical implications of their deployment [12,13,14,26]. Stratospheric aerosol injection (SAI) is a prominent form of SRM geoengineering that consists of launching sulfate aerosols into the stratosphere to reflect a small part of the incoming solar radiation [27,28,29,30]. The other prominent form of SRM geoengineering that is currently receiving increasing attention is marine cloud brightening (MCB) [31,32].

Since about 2009, research on SRM geoengineering has been confined to very few academic institutions but now projects are being developed or planned in various countries such as the US [33], Canada [34], the UK [35], Australia [36], and the EU [37] group of countries, with an estimated total investment of several tens of millions of US dollars per year. A few other countries are likely to be developing geoengineering field experiments, but the information is not publicly available. The US Government appears determined to be the leader in SRM geoengineering. In 2022, a USD 200 million five-year research program on climate interventions was established. This program is likely to initiate SAI field experiments. More recently, the US Congress approved a research plan and an initial research governance framework related to SRM [33], and the UK, through its Advanced Research and Invention Agency (ARIA), committed USD 75 million to small-scale field SRM experiments [38].

A MCB field experiment involving the University of Washington, US, was performed in 2024, involving a device that sprayed sea salt particles into the air from the deck of the USS Hornet, a decommissioned aircraft carrier docked in Alameda, California. The funding for the experiment comes from philanthropists, venture capitalists, and organizations, such as SilverLining and the Quadrature Climate Foundation created by Quadrature Capital, which has stakes worth more than USD 170m in fossil fuel companies, according to filings with US regulators [39].

This technology may be used in the future to brighten clouds, so they can reflect more of the incoming solar radiation reaching the Earth, thereby reducing the GMST. However, there is a high degree of uncertainty that the full global implementation of SRM geoengineering would follow because of various factors, including the need for a global governance framework and the cautionary recommendations of the UNEP [40], scientists, and NGOs. Table 1 lists and describes succinctly the main current climate interventions and technologies, which, depending on questions of scale and intent, are considered to be climate geoengineering. The objective is not to evaluate the history of the conceptual work, feasibility, cost analysis, side effects, and risks associated with each intervention or technology but just to enumerate and describe them briefly. This listing may serve as a framework to update the IPC current classification for filing patents in geoengineering. The taxonomy of the geoengineering technologies is organized into seven groups according to the physical medium where they are based. For the ground-based CO₂ removal, the classification of the IPCC [41] is used. For the other groups, the terminology of the IPCC and of recent geoengineering research articles and reports is used. Table 2 includes interventions based on the CCS technology, in particular CCUS, excluding BECCS and DACCS, in accordance with the current IPCC taxonomy [41].

Table 1. Geoengineering technologies categorized into six groups.

(1) Ground-based CO2 Removal (GCDR)	Carbon dioxide removal (CDR) involves anthropogenic activities removing CO2 from the atmosphere and durably storing it in geological, terrestrial, or ocean reservoirs, or in products (IPCC, 2021a). GCDR refers to ground-based CO2 removal from the atmosphere. Afforestation, Reforestation, and Improved Forest Management (ARIFM) Afforestation (foresting areas previously with no tree cover) could convert large territories into biological sinks of CO2. Reforestation (reforesting deforested areas) is a restoration and conservation that is widely considered the most reliable means to sequester CO2 and has the added value of contributing potentially to biodiversity conservation [42,43]. Improved Forest Management is a broad array of forest management practices aimed at increasing or maintaining forest carbon stocks. Soil carbon sequestration (SCS). Increases in the carbon content are particularly significant in soils that were degraded by using intensive agricultural systems [44]. Regenerative agriculture contributes to increasing the carbon content of soils [45]. Peatland and wetland restoration Peatlands and wetlands store a large amount of carbon compared with other types of vegetation. Their restoration is critical for preventing and mitigating the effects of climate change, preserving biodiversity, minimizing flood risk, and ensuring a high water quality. Biochar is a carbon capture material with a wide variety of applications. It is a porous carbonaceous solid material produced by the thermal decomposition of biomass from plant or animal waste under oxygen-free or limited-oxygen conditions [46]. Direct Air CO2 Capture and Storage (DACCS). DACCS is potentially a negative emissions technology where CO2 is removed from the atmosphere. It involves two steps. In the first step, CO2 is directly captured from the atmosphere using chemical or physical processes [47,48]. It is more expensive and energy demanding than the point source capture of CO2, which is named CO2 capture and sequestration (CCS), and is referred to below in the table, under (4), the reason being that the concentration of CO2 in the atmosphere, currently about 420 ppmv or 0.042%, is much lower than industrial and energy-related point sources. In the second step of DACCS, the CO2 captured directly from the atmosphere is conditioned, compressed, and transported to a storage location for long-term isolation from the atmosphere. Bioenergy with CO2 capture and storage (BECCS). BECCS involves three steps. The first is to convert biomass, such as fast-growing perennial grasses, short-rotation coppicing or forest biomass, into thermal energy, electricity, or liquid or gas fuels. The combustion of biomass emits CO2 into the atmosphere. The second step is to capture the point source CO2 emissions generated in the energy conversion process. The third step is to condition, compress, and transport the CO2 to a storage location for long-term isolation from the atmosphere. BECCS is the only CDR technology that generates energy, which can be of many types, e.g., high-temperature heat, electricity, or fuels. The large-scale deployment of BECCS, which is the characteristic of a geoengineering intervention, could have potentially adverse impacts on agriculture and food production [49,50,51]. Enhanced weathering (EW). EW, sometimes also called accelerated mineralization, is a technology that accelerates the continental weathering reactions to increase the delivery of atmospheric carbon in the form of the bicarbonate ion, HCO3-, to the oceans. Most EW studies focus on reactions in silicate rocks (such as basalt) and minerals (such as olivine, Mg2SiO4, or wollastonite, CaSiO3) and carbonate minerals (such as calcite, CaCO3). EW can be achieved by pulverizing and distributing large amounts of crushed silicate minerals on the land surface, in particular olivine [52,53,54].
(2) Ocean-based Carbon Dioxide Removal (OCDR).	The objective of OCDR is to reduce the amount of CO2 in the atmosphere by enhancing the downward air–sea flux of CO2 from the atmosphere to the ocean surface through biotic and abiotic processes. Biotic OCDR. There are four main biotic methods. - Recovery of ocean and coastal ecosystems (ROCE). ROCE is a nature-based approach of restoration and rehabilitation of marine ecosystems that include seagrass meadows, reef corals, fishes, and other animals [26]. - Seaweed cultivation (SWC). SWC is large-scale seaweed afforestation [55]. - Ocean iron fertilization (OIF) Consists of increasing the availability of iron for ocean photosynthetic processes to enhance the biological carbon pump [56,57,58]. - Artificial upwelling (AU). Consists of pumping up nutrient-rich ocean deep water through ocean pipes with the objective of absorbing CO2 by stimulating the growth of phytoplankton [59,60]. Abiotic OCDR. There are two main abiotic methods. - Ocean alkalinity enhancement (OAE). Consists of dissolving silicate or carbonate rock in the ocean to form calcium, magnesium, or sodium ions. These ions, by bonding with CO2, increase the concentration of bicarbonate ions and other dissolved inorganic carbon species, thereby promoting atmospheric CO2 influx into the ocean [61]. - Electrochemical approaches (ECAs). ECAs use chemical reactions that are produced by electric currents. They exploit the pH-dependent solubility of CO2 via the passage of an electric current through seawater, which, by inducing electrolysis, changes its pH and forms an acidic and a basic solution. The acidic solution can be used to degas CO2 from seawater for use elsewhere or storage, while the basic solution can be used to enhance ocean alkalinity, which can then absorb CO2 from the atmosphere and stabilize it in the ocean as bicarbonate and carbonate ions [62,63,64,65].
(3) Methane Removal (MR)	The main technologies for methane removal from the atmosphere are thermal-catalytic oxidation, photocatalytic oxidation, biological uptake by methanotrophic bacteria or their bio-engineered methane-oxidizing enzymes, and methane uptake on zeolites or porous polymers and iron salt aerosols [10,11,66,67]. This last technology consists of lifting aerosol particles containing iron into the atmosphere to enhance the amount of chorine radicals, which constitute a CH4 sink.
(4) Solar Radiation Management (SRM)	SRM is a form of the Earth’s albedo modification (EAM), which consists of purposely modifying the Earth’s radiative energy balance in the atmosphere by reflecting an additional small fraction of incoming solar radiation in the atmosphere or on the Earth’s surface [7,12,13,14]. The other form of SRM geoengineering is space-based solar geoengineering (SRG) consisting of placing mirrors, shades, or reflecting particles in the outer space between the Sun and the Earth to reflect a small fraction of the solar radiation reaching planet Earth. There are four main forms of EAM, which are based in the stratosphere (SAI), troposphere (MCB), on land (GAM), and in the ocean (OAM). Stratospheric aerosol injection (SAI). SAI consists of launching sulfate aerosols into the stratosphere to increase the reflectivity of the incoming solar radiation and therefore increase the Earth’s albedo [27,28,29,30]. Marine cloud brightening (MCB). MCB is a technology with the objective of increasing the reflectivity of marine stratocumulus clouds and possibly their lifetime to reflect more sunlight back into space and therefore increase the Earth’s albedo [31,32]. Ground-based albedo modification (GAM) is a set of solar geoengineering technologies that aims to reflect more sunlight back to space, thereby enhancing the Earth’s albedo by modifying land or land-based structures. The proposals include covering large desert or ice areas with reflective materials, and whitening mountaintops and roofs with various materials [68,69]. Ocean-based albedo modification (OAM). OAM is a type of surface albedo modification that aims to increase the albedo of the ocean surface by using various means, including using a stable and nondispersive foam comprising tiny and highly reflective microbubbles or reflective materials on the seawater’s surface [70,71]. Space-based solar geoengineering (SSG). SSG seeks to diffract, deflect, or block a small fraction of the incoming solar radiation back into space and thereby diminish how much radiation ultimately reaches the Earth using outer-space-based devices. It is equivalent to transforming the “solar constant” to a controlled solar variable [72,73].
(5) Infrared Radiation Management (IRM)	Instead of reducing the amount of incoming solar radiation that is absorbed by the Earth’s system, as SRM intends to achieve, IRM aims to act on the longwave radiation of the Earth’s budget to increase the amount of longwave or infrared radiation emitted to outer space by the Earth’s system. Cirrus cloud thinning (CCT). CCT is a form of IRM geoengineering that aims to increase the atmosphere’s transparency to outgoing infrared radiation by reducing the lifetime of high-altitude cirrus clouds that are made of ice crystals that absorb infrared radiation. The proposed technology is to modify the properties of these ice crystal clouds so that they absorb less outgoing infrared radiation [74,75]. CCT is often categorized as an SRM technology, although this is not strictly correct since instead of reducing the amount of short-wave radiation that enters the Earth’s system, it allows more infrared radiation emitted by the Earth to escape into outer space.
(6) Glacial Geoengineering (GG)	GG is a set of interventions in the ice streams, glaciers, and coastal seawater in Antarctica and Greenland that seek to slow the disintegration of ice sheets caused by increasing GMST so as to slow the sea-level rise. The three main approaches that have been proposed are ocean-heat transport interventions, basal-hydrology interventions, and seawater pumping interventions [25,76,77].

Table 2. CO₂ capture and storage (CCS), including utilization (CCUS), but excluding BECCS and DACSS.

Carbon capture and storage (CCS). A process in which CO2 is captured in the atmosphere from a stream of gases with a relatively high CO2 concentration, usually at the large point sources of emissions from fossil-fuel-energy-related sources, from industrial-related sources, such as in a steel plant, cement producing facilities, or from biomass-based plants [78,79]. The process of capture is named point source capture. The captured CO2 is conditioned, compressed, and transported to an underground location where it is stored, usually in oil and gas reservoirs, deep saline formations, and un-minable coal beds where it is sequestered via long-term isolation from the atmosphere. Investment in CCS has been mostly driven by the oil and natural gas industries. The main CCS application globally is gas processing of the extracted raw gas from gas fields and enhanced oil recovery (EOR) technology [7,18,19,80]. Carbon capture, utilization, and storage (CCUS) The captured CO2 is used as a feedstock to convert it into value-added products such as synthetic fuels, chemicals, and building materials [81]. Deploying CCUS is important for the cement industry since two-thirds of the direct emissions come from the chemical production process through the calcination of limestone into cement clinker during the burning process in the cement kiln. CCS, CCUS, BECCS, and DACCS are all Carbon Burial technologies, because they all involve CO2 storage.

1.3. Significance of Patents in Technological Development

Intellectual Property Rights (IPRs) provide certain exclusive rights to the inventors of that property, which, in the domain of technology, play a pivotal role in promoting research and development. Patents are one of several types of IPRs. The existing IPR system, organized at the global level by WIPO, encompasses legal protections and rights granted to individuals and organizations for their intellectual creations, such as inventions, designs, and trademarks. This system incentivizes innovation and creativity by granting exclusive rights to innovators and creators, allowing them to benefit financially from their innovations and creations. Patents provide inventors with incentives to invest in research and development. However, the patent system also faces criticism for potentially stifling competition, hindering access to some technologies, and fostering patent wars among companies. Efforts to reform and improve the patent system continue, with the aim of balancing the interests of inventors, businesses, and society [24].

The patent system promotes scientific and technological development by encouraging inventors to disclose their inventions, rather than trying to protect them through secrecy. Patents grant a time-limited monopoly over the exploitation of an invention, typically 20 years, in exchange for full disclosure of the technical details of the invention. This mechanism contributes to preventing the unnecessary reinvention of the same property and allows everyone to be aware of the work of third parties, which may be beneficial for their own work [24].

A company can promote its research and development efforts through its patents [82] since the temporary monopoly generally contributes to increasing its return on investment. Alternatively, or complementarily, a company can also sell licenses of its patents, allowing other entities to exploit its inventions, while obtaining a fair reward in return. These principles of financing through patents have, for example, been heavily used by pharmaceutical companies and have notably enabled the very heavy financing of technological investments for the development of COVID vaccines in record time [24].

Analyzing the patent applications within a specific field provides valuable insights into the stakeholders involved, their strategies and strengths, and their relative positions. This analysis ultimately facilitates the measurement of both market and technological advancements. While patent observation offers valuable insights, it cannot provide a comprehensive view of scientific progress. However, statistics indicate that approximately 80% of scientific knowledge is present in patent application publications [83].

Monitoring patent publications provides valuable insights into a specific sector, enabling the identification of new research opportunities and information about competitors’ research and protection strategies. It also helps assess the feasibility of patenting inventions. These publications are often complemented by research outputs from organizations, such as publicly funded research institutions that do not rely on patent filings. Some entities operate under “utility models” where patents are not crucial [84]. Often referred to as “petty patents” or “innovation patents”, the utility model provides a form of intellectual property protection that is distinct from standard patents, offering a faster, more cost-effective means of protecting incremental innovations or technical improvements. Utility models are particularly well suited for businesses in sectors where rapid innovation is essential, but the inventions may not meet the inventive step required for traditional patents. Unlike patents, utility models typically have a shorter protection period (usually 7 to 10 years) and may involve a less rigorous examination. This makes them especially valuable for industries with shorter product life cycles, such as electronics, mechanical engineering, and consumer goods. In some jurisdictions, utility models can be registered quickly, allowing companies to gain market exclusivity while keeping their R&D costs lower.

Utility models offer a strategic tool for protecting smaller, incremental innovations without the lengthy processes associated with full patents. They are also used in combination with patent portfolios to cover the different aspects of a product or technology, thus creating layered protection. However, they are not available in all countries, and the scope of protection may vary significantly depending on the local legislation.

While patents protect inventions and provide exclusive rights to new technological solutions, there are other forms of IP that may be more suitable or effective depending on the nature of the business or innovation, including utility model, trade secrets, trademarks, etc. [24].

1.4. Understanding Patents and the Challenges of Patent Classification in Geoengineering

As mentioned above, a patent is a legal right granted by a government authority to an inventor or an entity, giving them exclusive rights to make, use, or sell an invention for a limited period, usually 20 years from the filing date. In exchange for this exclusivity, the inventor must publicly disclose the details of the invention in the patent document. Patents serve multiple functions: they incentivize innovation by offering a temporary monopoly, promote knowledge sharing by making technical details publicly available, and facilitate technology transfer by allowing licensing agreements [85,86].

To be granted a patent, an invention must generally meet three main criteria [87,88]:

• Novelty—The invention must be new, not previously disclosed to the public;
• Inventive Step (Non-Obviousness)—The invention must not be an obvious improvement to an expert in the field;
• Industrial Applicability—The invention must be capable of being used in an industry or have a practical application.

Patents are categorized and classified under an internationally recognized system known as the International Patent Classification (IPC), which helps in organizing and retrieving patent documents based on technical fields [89]. Other complementary classification exists. Particularly, the Cooperation Patent Classification (CPC) is a particular version of the IPC, adding further subclasses.

Patent law exists to balance innovation incentives with the public access to new technologies. By granting exclusive rights to inventors for a limited time, it encourages investment in research and development while ensuring that knowledge eventually becomes part of the public domain. However, patent law has historically struggled to keep pace with rapidly evolving scientific fields, sometimes leading to misclassification and regulatory gaps.

A classic example of this misalignment occurred in the field of biotechnology. In the 1970s and 1980s, genetic engineering and biotechnological inventions were emerging, but patent laws and classifications were initially not designed to accommodate these advancements [90]. The landmark case of Diamond versus Chakrabarty in 1980 in the U.S. Supreme Court, which ruled that a genetically modified bacterium could be patented, demonstrated the need for legal adaptation to scientific progress [91]. Over time, patent classification systems were updated to better reflect the innovations in genetic engineering and synthetic biology.

Similarly, software patents faced significant legal uncertainty in the 1980s and 1990s. Initially, software was considered a mathematical algorithm and not eligible for patent protection. However, as the software industry expanded, legal frameworks evolved, leading to the patenting of lots of software.

One of the key factors in improving the alignment between patent classifications and scientific definitions is the accumulation of a large number of patents in a given technological domain. As more patents are filed in an emerging field, patterns begin to emerge, providing a clearer understanding of how these technologies should be categorized. Over time, patent offices and classification systems adapt to these developments by refining the existing categories or introducing new ones that better reflect the technological landscape [87].

For instance, in the early days of Artificial Intelligence (AI), patents were often classified under general computing or automation categories, failing to capture the unique aspects of machine learning and neural networks. As the number of AI-related patents grew, specialized classifications were introduced to accommodate these advancements, improving the accuracy of patent searches and legal assessments [87].

Similarly, the evolution of patent classifications in biotechnology and pharmaceuticals demonstrates how sustained patent activity can drive refinements in legal frameworks. The initial resistance to gene patents gave way to a more structured classification system as the volume of biotechnology patents increased, compelling patent offices to create distinct subclasses for genetic engineering techniques [90].

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Nanotechnology: In the early 2000s, nanotechnology patents were scattered across multiple classifications, as there was no dedicated category for nanoscale inventions. Early patents were classified under chemistry, materials science, or electronics, making it difficult to track nanotechnology innovation. It was only after significant patenting activity that the IPC introduced specific classifications for nanotech [92].

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Renewable Energy Technologies: Wind and solar energy patents initially faced classification issues because patent systems were historically structured around fossil-fuel-based energy. As the number of renewable energy patents grew, patent offices introduced more precise subcategories, such as photovoltaics, wind turbine technologies, and energy storage [88].

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Blockchain and Cryptography: The emergence of blockchain technology presented classification challenges, as it straddled multiple fields, including finance, data security, and distributed computing. Initially, blockchain-related patents were categorized under general cryptographic methods or secure transactions. As the volume of filings increased, dedicated classifications for blockchain applications in finance and supply chain management were introduced [87].

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Three-dimensional Printing (additive manufacturing): Early 3D printing patents were classified under traditional manufacturing or industrial machinery. As the technology advanced and applications diversified (e.g., bioprinting, aerospace, and construction), classification systems adapted by creating specific categories for additive manufacturing [87].

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Telecommunications and 5G: Patent law initially struggled to adapt to the rapid evolution of telecommunications, particularly with the transition to 5G. Earlier telecommunications patents did not adequately distinguish between different generations of mobile networks. With increasing patent activity in 5G-related technologies, patent offices refined their classifications to better distinguish the innovations in spectrum allocation, low-latency communication, and IoT connectivity [93].

These cases demonstrate that patent classification systems tend to evolve reactively rather than proactively. It is only when a large volume of patents accumulates in a given technological area that legal frameworks adapt to better reflect scientific advancements. This pattern suggests that geoengineering patents, if they continue to grow in number, may eventually drive refinements in classification systems. However, since patent classification is primarily a legal tool rather than a technical one, these adaptations often lag behind scientific progress.

The classification of patents related to geoengineering presents a unique challenge due to the divergence between legal and scientific terminologies. Patent classification systems, such as the IPC, are structured based on the existing technological domains but do not necessarily align with emerging or interdisciplinary fields like geoengineering [94].

Geoengineering encompasses various scientific disciplines, including atmospheric sciences, climate modeling, material sciences, and mechanical engineering, which means that relevant patents may be dispersed across multiple IPC sections rather than being grouped under a single, dedicated classification [93]. Some patents relevant to geoengineering may be found under categories related to aerosol dispersion, carbon sequestration, solar radiation management (SRM), or even general climate adaptation technologies, rather than a distinct “geoengineering” category. This dispersion complicates the retrieval and systematic analysis of geoengineering-related patents [95].

Moreover, since geoengineering is a relatively novel and evolving field, its definitions and terminologies are still debated within the scientific community [14]. This lack of standardization further exacerbates the difficulty of mapping existing patents to specific geoengineering technologies. Some inventions may be classified under broader environmental management, weather modification, or renewable energy technologies, making it challenging to assess the extent of patenting in this field.

Finally, in the case of geoengineering, the relatively small number of patents compared to more established fields contributes to the classification challenges. As the field expands and more inventions are patented, a clearer structure may emerge within patent classification systems, improving searchability and regulatory oversight [96]. However, since the primary objective of patent classification remains legal rather than technical, these refinements are often reactive rather than proactive, requiring sustained engagement from both the scientific and legal communities to ensure alignment [97].

The misalignment between the scientific categorization of geoengineering technologies and their classification within patent databases has several implications:

-

Incomplete Patent Searches: researchers and policymakers may struggle to obtain a comprehensive view of patented geoengineering technologies due to classification inconsistencies [97].

-

Legal and governance gaps: the absence of a dedicated patent category for geoengineering might hinder the development of legal frameworks tailored to emerging climate intervention technologies [96].

Transparency and ethical concerns: given the global implications of geoengineering, there is a pressing need for improved transparency in patent filings, including clearer classification criteria that reflect scientific advancements [87]. To fully understand the role of patents in geoengineering, it is essential to recognize the limitations imposed by the current patent classification system. While some geoengineering technologies are indeed being patented, the difficulty in systematically identifying them highlights the need for a more refined and standardized classification approach. As history has shown, the accumulation of a significant number of patents in a given field often leads to adjustments in classification systems, but these changes are typically driven by legal rather than scientific priorities. This challenge underscores the complexity of legal and scientific interactions in the governance of emerging climate technologies and emphasizes the importance of developing regulatory frameworks that align with evolving scientific knowledge.

In summary, patent classification is a legal tool designed to enable patent professionals to optimally perform legal work, such as prior art searches and freedom-to-operate studies. Furthermore, a single patent application often corresponds to several scientific fields, since the aim is to address a technical problem, which can be achieved by combining several scientific fields. For this reason, the classification is designed with a specific logic, which does not necessarily correspond to the scientific definitions used by scientists in their specialized fields of research.

A patent professional will be able to identify the criteria in patent databases that best identify the patents being sought. Most of the time, this requires using several potentially relevant international classes, cross-referencing them, and adding keywords to more precisely target certain solutions. For example, for carbon capture applications, there are numerous solutions, which are classified into different classes, depending on the field concerned. For example, such solutions are found in land transportation, exhaust gas treatment, air transportation, metal manufacturing industries, etc., and in classes specifically related to climate change. Solutions for removing carbon molecules are classified into chemistry classes related to gas treatment. However, there is no class corresponding to the CDR and CCS definitions.

For this reason, a patent search is a feasible exercise, and one that provides many insights, as the article seeks to demonstrate, but it requires considerable time and resources. It often involves finding a needle in a haystack, since it requires navigating the extremely large volumes of published patent applications. In this context, it is unthinkable to simply identify all geoengineering patents, at least given the current state of patent classification. For this reason, this article is limited to a few examples, with the aim of raising readers’ awareness of the often unexploited possibilities offered by patent databases to obtain a relevant perspective on secret fields such as geoengineering.

1.5. Search Tools for Patents

The IPC system, managed by WIPO, categorizes patents and utility models to streamline search and examination processes. The IPC helps patent offices and researchers find relevant patents, supports international patent harmonization, and facilitates the sharing of technological information across borders. Overall, the IPC system aims to create a standardized and systematic approach to patent classification. Classification is indispensable for the retrieval of patent documents in the search for “prior art”. Such retrieval is needed by patent-issuing authorities, potential inventors, research and development units, and others concerned with the application or development of technology.

The IPC provides the foundational classification system used globally for organizing patents according to different technology areas. It has its origin in the European Classification of Patents for Invention that was introduced in 1968. In 1971, following the Strasbourg Agreement, the system was officially recognized as the IPC, with the first edition published on 24 March 1971. The IPC divides technology into eight sections, with approximately 80,000 subdivisions, classes, subclasses, and groups, organized hierarchically, and uses a combination of letters and numbers to classify patent documents. Sections are denoted by letters (A to H), and further subdivisions use numbers and additional letters. Its key features include:

-

Sections: eight main sections, each representing a broad technological area, e.g., “A” for Human Necessities, “B” for Performing Operations, etc.;

-

Classes: where each section is divided into classes, each representing a more specific field within the section;

-

Subclasses: classes are further divided into subclasses, providing even finer categorization;

-

Groups: subclasses are split into groups, detailing the specific aspects of technology.

The IPC is periodically revised to accommodate technological advances and improve the classification accuracy. Revisions involve adding new classifications, revising the existing ones, and deleting the outdated categories [87].

The European Patent Office (EPO) has used the Cooperative Patent Classification (CPC) since 2013. The CPC is jointly managed by the EPO and the United States Patent and Trademark Office (USPTO), though the USPTO also uses its own classification system, the United States Patent Classification (USPC). The CPC builds upon the IPC by adding more detail and specificity to the classification of patents, including more than 250,000 subdivisions, compared to about 70,000 in the IPC, enabling the more precise classification of patents, particularly in specialized or emerging technological fields.

Within the CPC, class Y is dedicated to emerging technological developments and is defined as “general tagging of new technological developments; general tagging of cross-sectional technologies spanning over several sections of the IPC; technical subjects covered by former USPC cross-reference art collections (XRACs) and digests”. Specifically, the Y02 class focuses on technologies and applications for mitigation or adaptation to climate change, as detailed further in Table 3 below.

Table 3. Cooperative Patent Classification (CPC) system: details of class Y02 “technologies or applications for mitigation against climate change”. Source: [89].

Ref.	Subclass Names
Y02A	Technologies for adaptation to climate change
Y02B	Climate change mitigation technologies related to buildings, e.g., housing, house appliances or related end-user applications
Y02C	Capture, storage, sequestration, or disposal of GHGs
	▪ Y02C20/00: Capture or disposal of greenhouse gases ▪ Y02C20/40: Capture and disposal of CO2
Y02D	Climate change mitigation technologies in Information and Communication Technologies (ICTs), i.e., ICT aiming at the reduction of their own energy use
Y02E	Reduction of GHG emissions, related to energy generation, transmission, or distribution
Y02P	Climate change mitigation technologies in the production or processing of goods
Y02T	Climate change mitigation technologies related to transportation
Y02W	Climate change mitigation technologies related to wastewater treatment or waste management

The creation of the Y02 class was prompted by the challenge of identifying climate change-related technologies within the vast EPO databases, which contain over 80 million applications, including 1.5 million related to sustainability. Green technologies are often dispersed across various technological fields, making them difficult to locate. The Y02 superclass was developed to address this issue by categorizing inventions based on their purpose, such as climate change mitigation or adaptation, rather than solely on their technical characteristics, like engine design [89].

The IPC Green Inventory, developed by WIPO, helps users find patent information related to environmentally sound technologies (ESTs) by categorizing specific IPC codes associated with environmental protection technologies like renewable energy and waste management. WIPO GREEN is an online marketplace that connects providers and seekers of sustainable innovations, supporting global climate action by promoting the dissemination and commercialization of green technologies defined in Chapter 34 of Agenda 21 [98]. Together, these tools enhance the classification, identification, and promotion of green technologies, streamlining patent searches and facilitating the practical implementation of sustainable innovations [84].

2. Methodology

As mentioned before, geoengineering encompasses a wide range of technologies in an emerging complementary strategy to achieve the adaptation to and mitigation of climate change, with a significant potential impact on social, economic, and geopolitical fields. However, the domain is not explicitly classified within international patent databases, making it challenging to grasp the full scope of technological advancements and the key contributors. To address this gap and provide a clearer understanding of the technological landscape in geoengineering, we focus on examining specific areas within the existing patent classifications.

Given the broad and diffuse nature of geoengineering technologies, we have chosen to illustrate our analysis through three concrete examples:

(1)

Patents related to carbon dioxide removal (CDR), since they represent a critical component of geoengineering efforts. Analyzing patents in this area will help us identify the innovations and entities driving progress in CDR;

(2)

Patents related to solar radiation management (SRM) with a focus on stratospheric aerosol injection (SAI) and Cloud Marine Brightening (CBM), which are emerging technologies attracting increasing attention;

(3)

Patents filed by the major oil and gas companies, given that such companies play a critical role addressing the climate change challenge, and they have registered patents in technologies and applications for the mitigation of or adaptation to climate change and geoengineering.

To systematically examine the current state of geoengineering patents, we conducted targeted searches within these three categories. This approach allowed us to bypass the limitations of broad patent classifications and delve into the specific technologies and players that are actively shaping the field. The following Table 4 details our methodological approach to identifying, categorizing, and analyzing the relevant patents in these domains.

Table 4. A step-by-step method to build results for the state of the art of patents and geoengineering: illustrating three concrete examples (source: [99]).

Three Concrete Examples	Key Steps	Search Criteria
(1) Patents related to Carbon Dioxide Removal (CDR)	- Search for patent publications - Perform various statistics on the large volume of patent publications - Perform further targeted research in the sub-domain of ocean-based carbon dioxide removal (OCDR).	- Class CPC: Y02C20/40 class - Search in Espacenet - Adding the keyword “ocean” or “sea” for a first exploratory approach of the more targeted search on OCDR
(2) Patents related to Solar Radiation Management with a focus on SAI and MCB	- Define search criteria, to converge towards SAI solutions in the absence of dedicated international classes; - Search for patent publications	- No direct corresponding international classes. Most of the relevant patent publications are classified in A01G15/00 and/or B64D47/00. In addition, the keywords “stratosphere” and “aerosol” are particularly specific and relevant to SAI technology, and are combined with the previous mentioned classes. - As soon as relevant patent publication are identified, we can use such documents to identify further relevant documents by a search of “citing” and “cited” documents, and a search of similar documents. The repetition of such searches allows the convergence to a quite exhaustive result.
(3) Patents filed by the major oil companies in the field of technologies that aim to reduce or adapt to the impacts of climate change	- Identify the key oil companies to be analyzed - Perform general statistics for each oil company	- Search criteria for each oil company combined with the class CPC Y02 (technologies or applications for mitigation or adaptation against climate change) - Statistical criteria including the volume of patents per year over the past 20 years

In summary, to find the latest patents in the categories related to geoengineering, such as CDR, SRM, SAI, MCB, etc., the processed steps can be summarized as follows:

(a)

Access the patent database platform;

(b)

Use the search feature to look for specific categories or keywords;

(c)

Filter the search results by reference to the most recent patents to obtain the latest information;

(d)

Focus on the technological details provided, such as the methods used, specific innovations, and potential applications;

(e)

The search results include patents with titles, abstracts, and possibly full documents that describe the latest innovations in these fields;

(f)

Fill in results in the appropriate format as presented in part III of this article.

By following these steps, we have identified some of the latest patents illustrating three concrete examples presented in Table 4. This approach allows the gathering of specific information about the recent developments and innovations in the field of geoengineering.

In view of replicability, authors wish to detail further the search method for each of the examples being illustrated:

By applying the above methodology to CDR(1), perform the below process:

-

Launch an Espacenet search at https://worldwide.espacenet.com/patent/search (access date 21 August 2024);

-

Fill in the CPC field with “Y02C20/40” and press “search”, so that you reach more than 18,000 patent publications;

-

Press “filters” and “view chart/graph overview” so as to reach the statistics graphs; you should obtain the following link: https://worldwide.espacenet.com/patent/search?q=cpc%20any%20%22y02C20%2F40%22&widgets=family (access date 21 August 2024)

-

In the “Earliest priority date” graph, limit the period to between 2004 and 2022, or any period of interest; you reach statistical graphs according to the chosen period, similar to Figure 1, Figure 2 and Figure 3.

Figure 1. Number of first filing patents by family of inventions in the CPC class Y02C20/40 from 2004 to 2023.

Figure 2. Relative cumulative number of patents in the CPC class Y02C20/40 filed during the 20-year period (2004–2023) in the indicated patent offices.

Figure 3. Nationality of relative patent applicants in the CPC class Y02C20/40 filed during the 20-year period (2004–2023).

By applying the above methodology to SRM/SAI(2), perform the below process:

-

Launch an Espacenet search at https://worldwide.espacenet.com/patent/search (access date 21 August 2024);

-

Fill in the CPC field with A01G15/00 or B64D47/00, and fill in the text field (all text fields) with the keywords “stratosphere* and aerosol”; press “search”;

-

You find about 20 patent publications; read the abstract to select the most relevant publications;

-

Further searches are performed from the identified most relevant patent publications, using professional tools such as “Total Patent” and the citing, cited fields, as well as the “similar options”, to obtain further results, which are read and selected if relevant: such search requires the manual selection from a patent expert.

By applying the above methodology to the third search (3), perform the below process:

-

Launch an Espacenet search at https://worldwide.espacenet.com/patent/search (access date 21 August 2024);

-

Fill in the Applicants field with the name of the company you are searching for and the publication date since 2004; you find the total number of patent publications since 2004;

-

Then, in addition, fill in the CPC field with “Y02” so that you reach the total number of patents including patent applications in class Y02 filed since 2004 for the chosen applicant; you can perform the percentage from the above two identified numbers;

-

Press “filters” and “view chart/graph overview” so as to reach the statistics graphs.

3. Results

3.1. Patents Related to Carbon Dioxide Removal (CDR)

The results obtained using the present methodology provide a comprehensive overview of the CDR patent landscape, helping to visualize the trends, key players, technological focus areas, and the global distribution of innovation. The trend of CDR patent filings in the 20-year period of 2004 to 2023 is presented in the graph below (see Figure 1), that shows the number of CDR-related patent applications filed in the CPC class Y02C20/40 annually over the last 20-year period.

The red curve on the left represents the number of patents filed annually, while the black curve on the right shows the cumulative number of patents from 1 January 2004 to 31 December 2022. It is not possible to go further as all the patent applications from 2023 have not yet been published. The annual number of newly filed patents increased steadily from fewer than 200 in 2004 to approximately 1500 in 2022.

We list in Figure 2 countries and/or regions with the highest number of filed patents in the CPC class Y02C20/40, showing the number of patent applications published in each national and/or regional patent office. In the figure, “WO” refers to the PCT (Patent Cooperation Treaty) patent publication number standing for “World Intellectual Property Organization” (WIPO). It indicates that the patent application is an international application filed under the PCT system and published by WIPO. The format of the publication number typically includes “WO” followed by the year of publication and a serial number, for example, WO2024/123456.

In Figure 2, the data indicate that applicants seek protection equally in the United States (US) and China (CN), followed by Japan (JP), Europe (EP), South Korea (KR), Canada (CA), and Australia (AU), with international patents filed as well (WO).

China and the USA are the leading countries, together accounting for over 13,000 filed patents.

As shown in Figure 3, the leading country in CDR innovation and where most of the patent activity is concentrated is the United States of America (US) with nearly 14,000 patents. This graph shows the distribution of patent applicants by country: the largest applicants are by far the US, then JP (Japan), KR (South Korea), DE (Germany), FR (France), CH (Switzerland), CA (Canada), and NL (The Netherlands).

The top companies, institutions, or organizations that have filed most of the patents related to CDR are l’Air Liquide (France), Mitsubishi Heavy Industries (Japan), Toshiba (Japan), Alstom Technology (France), China Petroleum & Chemicals (China), Honeywell UOP (USA), Shell International (USA), ExxonMobil Upstream Research Company (USA), University of Tianjin (China), Korea Energy Research Institute (South Korea), Linde AG (Germany), General Electric (USA), University of Zhejiang (China), Korea Electric power corporation (South Korea), and Saudi Arabian Oil company ARAMCO (UAE).

In order to analyze more precisely the technical solutions implemented in these CDR patents, it is possible to look more closely at the CPC classes in which they are classified by the patent offices. Thus, we can obtain the following graphs (Figure 4), showing the distribution of CDR patents across different technological classes.

Figure 4. Relative distribution of CDR patents across different technological CPC classes.

The main class is Y02C20, with the first subclass being Y02C20/40, as this was the initial search criterion. However, since most patents are classified into multiple classes, this allows for more precise information on the patented technologies. For example, these classes include the CPC sub-group B01D53/00, which concerns the separation of gases or vapors, the recovery of vapors of volatile solvents from gases, and the chemical or biological purification of waste gases (e.g., engine exhaust gases, smoke, fumes, flue gases, aerosols, etc.).

It also appears that many patents in class Y02C20/40 are also classified under B01D2257/504, which includes technical solutions for separating CO₂, and Y02P20/151, which includes chemical technologies for reducing CO₂ emissions. This is consistent and logical, in line with CDR technologies.

Other patent research is focused on CDR patents related to the ocean. By adding the words “ocean” or “sea” to our search in the class Y02C20/40, we found 377 patents, with 300 of them filed in the past 20 years. These are likely to be ocean-based carbon dioxide removal (OCDR) technologies.

In other words, an analysis of international classes forms a tool that can help to understand the most-used technologies.

3.2. Patents Related to Solar Radiation Management with a Focus on Stratospheric Aerosol Injection (SAI)

Identifying patents related to SRM geoengineering technologies is a difficult process since it requires searching patent databases using classifications and keywords, as there is no specific international class for SRM geoengineering. For instance, it is difficult to draw the line between SRM geoengineering and weather modification patents. Table 5 below summarizes the patent applications and patents found in the SRM field, particularly targeted at SAI, enabling the following conclusions to be drawn:

Table 5. Non-exhaustive list of patent applications that are likely to be in SRM technologies, with details of patent references, filing dates, inventors, geographical areas covered, the SRM sub-category and a brief description (source: Espacenet, https://worldwide.espacenet.com/patent/search, access date 21 August 2024).

Publication Number Filing Date (Priority) Holder Designated Countries	Filing Date (Priority)	Patent Holder (Company/Individual)	Geographical Scope of the Patent	SRM, SAI, MCB, SSG, CDR, MR, Other	Title of the Patent as in the Filed Document
US5003186A	23 April 1990	HUGHES AIRCRAFT puis RAYTHEON COMPANY	US	SAI	Stratospheric Welsbach seeding for reduction in global warming
US5762298A	7 June 1995	CHEN; FRANKLIN Y. K.	US	SSG	Use of artificial satellites in Earth orbits adaptively to modify the effect that solar radiation would otherwise have on the Earth’s weather
US6045089A	8 October 1999	CHEN; FRANKLIN Y. K.	US	SRM	Solar-powered airplane
EP1412054B1 et US7501103B2	31 July 2001	RIES, ERNST	AU, CN, DE, EP, IN, JP, RU, US	Other	Tropospheric volume elements enriched with vital elements and/or protective substances
GB2438156A	18 May 2006	HARVEY PAUL	GB	SRM	Climate regulating solar reflector
US20100074390A1	26 October 2006	NAKAMURA TOMOAKI	JP, US	SAI	Method for weather modification and vapor generator for weather modification
GB2446250A	4 January 2007	WAKEFIELD STEPHEN R	GB	SAI	A dust- or particle-based solar shield to counteract global warming
US8166710B2 et US8985477B2	18 April 2007	INVENTION SCIENCE FUND, LLC	US, GB	SAI	High-altitude structure for expelling a fluid stream through an annular space
US7726601B2	20 April 2007	HERSHKOVITZ BRUNO	US	SRM	Device and method for affecting local climatic parameters
FR2923983A1	26 November 2007	BEL HAMRI BERNARD	FR	other	Device for producing an air current at low temperatures
DE102009004281A1	21 January 2008	OESTE FRANZ DIETRICH	DE	Other	Climate-cooling solid and gas combustion
US20080203328A1	22 February 2008	PALTI YORAM	US	SSG	Outer space sun screen for reducing global warming
US8152091B2 et US8944363B2	12 May 2008	TVG LLC	US (x2)	SAI	Production or distribution of radiative forcing agents
US20090032214A1	2 June 2008	HUCKO MARK	US	SAI	System and method of control of the terrestrial climate and its protection against warming and climatic catastrophes caused by warming such as hurricanes
US20110005422A1	12 July 2009	Stephen Trimberger	US	SRM	Method and apparatus for cooling a planet
US20100252647A1	9 September 2009	ACE RONALD S	US	MCB	Benign global warming solution offers unprecedented economic prosperity
US20100127224A1	30 September 2009	NEFF RYAN	US	SAI	Atmospheric injection of reflective aerosol for mitigating global warming
US9363954B2	15 December 2009	DAVIDSON TECHNOLOGY LIMITED	CN, GB, EP, JP, KR, US	SAI	Atmospheric delivery system
US9456557B2 et EP2381759B1	17 December 2009	RIES, ERNST	AU, BR, CA, CN, DE, ES, EP, JP, PL, RU, US	SAI	Method for cooling the troposphere
US20120117003A1	9 November 2010	BENARON DAVID A	US	SRM	Geoengineering method of business using carbon counterbalance credits
US20110284690A1	7 April 2011	PUCKETT ALEXANDER M	US	SAI	Utility device system for releasing or capturing disbursements for the atmosphere by means of an aircraft
DE102011108433A1	26 July 2011	Meyer-Oeste, Franz Dietrich	DE	SAI	Climate cooling using vaporous hydrophobic iron compounds
WO2013086542A1	7 November 2011	NEUKERMANS, Armand, P.	WO	MCB	Salt water spray systems for cloud brightening droplets and nano-particle generation
US9775305B2 et EP2784560B1	21 November 2011	KOREA AEROSPACE RESEARCH INSTITUTE	EP, JP, KR, US	SRM	Method for controlling land surface temperature using stratospheric airships and reflectors
RU2548067C2	6 August 2012	PEREPECHENKO BORIS PETROVICH	RU	SAI	Aerosol-generating composition, aerosol generator for the creation of artificial cloudiness aimed at the reduction in the Earth’s surface temperature, method of application thereof in the stratosphere
US8882552B2	18 August 2013	Lambert, Kal Karel	US	CDR	Biophysical geoengineering compositions and methods
DE102014013469A1	16 October 2013	Franz Dietrich Oeste	DE	SAI	Climate-cooling processes through the sulfur-free emission of iron-containing aerosols and/or gases
US9491911B2	19 February 2014	Stelmack, Dennis Jason	US	other	Method for modifying environmental conditions with rings comprised of magnetic material
US9457919B2	5 January 2015	BRADLEY CURTIS	US	SRM	Climate regulating system
US10962291B2	17 January 2017	NANJING RUIQIHUANG ELECTRONIC TECH	AU, CN, IN, US	other	Method, device, and system for regulating the climate
US9924640B1	20 January 2017	KESHNER MARVIN S	US	SAI	Modifying sunlight scatter in the upper atmosphere
US11762126B2	20 March 2017	TYAGI SUNIT	AU, IN, US	MCB	Surface modification control stations and methods in a globally distributed array for dynamically adjusting the atmospheric, terrestrial, and oceanic properties
WO2019029835A1	6 August 2017	OESTE FRANZ DIETRICH	DE	SRM	Device and method for cooling the climate
RU2673186C1	11 October 2017	POKHMELNYKH LEV ALEKSANDROVICH	RU	SAI	Device for introducing charges to the atmosphere
RU2678782C1	29 December 2017	Federal State Budgetary Institution “Fedorov Institute of Applied Geophysics” (FSBI “IAG”) (RU)	RU	other	Method of impact on charged airborne dispersions for the weather conditions’ modification
US10687481B2	9 April 2018	SOLOVIEV, Alexander, V.	IL, US	other	Method and means for storing heat in the sea for local weather modification
FR3088622A1	16 November 2018	HAMON CHRISTIAN JEAN YVES	FR	SRM	Device for combating global warming
CN109479592A	14 December 2018	HUANG CHAOYI	CN	other	A tower-free weather conditioning system
US10941705B2	14 July 2019	Hanson, Matthew Vernon	US	SAI	Hanson-haber aircraft engine for the production of stratospheric compounds and for the creation of atmospheric reflectivity and absorption and to increase the ground reflectivity of solar radiation in the 555 nm range and to increase jet engine thrust and fuel economy through the combustion of ammonia and ammonia by-products
US20210037719A1	9 August 2019	Nagami, Colette	US	SRM	Planetary weather modification system
IT201900021840A1	23 November 2019	POETA ROLANDO	IT	other	Method to modify the climate via explosions at high altitudes of methane and/or hydrogen, transported by inflating large aerostatic tanks, and actuating aerostatic tanks
RU2734834C1	30 December 2019	GORYNIN VLADIMIR IGOREVICH	RU	other	Cooler for climate control
US20230249821A1	30 October 2020	SINAPU	US	SAI	Reflective hollow SRM material and methods
AU2021105881A4	19 August 2021	John Macdonald	AU	MCB	Process for generating marine clouds and ocean microbubbles
WO2023080795A1	7 November 2021	ERIKSSON, Roy	WO	SRM	Apparatus and method for reducing particle current and use of the effect
WO2023108278A1	16 December 2021	BELL, Scott Christopher	WO	MR	Systems and methods for atmospheric dispersion of oxidants for the net conversion of atmospheric methane to carbon dioxide
US20220315197A1	1 April 2022	WICHITA STATE UNIVERSITY	US	SRM	Balloon system for reflecting solar radiation
US11477949B1	14 July 2022	Milton Gottlieb	US	SRM	Climate blanket
US20230050373A1	16 July 2022	Olatunbosun Osinaike	US	other	Electromagnetic system to modify the weather
US20240074362A1	5 September 2022	Borisov, Konstantin A.	US	other	Apparatus and related method for global weather modification and precipitation enhancement
AU2023215586A1 et WO2023148137A1	1 February 2022	HENSCHEN, Stefan	AU, DE, WO	SRM	Method for reducing the global greenhouse effect
WO2023073698A1	26 October 2021	Erez Weinroth	US, CN, KR, WO	SAI	Monitoring the spraying of particles into the stratosphere to address global warming using smartphones

-

The rights owners are often isolated inventors or small entities, with few patents in a limited number of countries. Many applications are abandoned quickly due to financial constraints or lack of interest.

-

This trend has been ongoing since around 2006 and continues today.

-

Apparently major oil and gas companies and research centers have not developed significant patent portfolios in SRM, which may indicate that these technologies do not constitute yet an established market, although there are clear indications of increasing investment in SRM research.

SRM solutions often involve implementation at a high altitude or in the outer atmosphere, thus falling outside the national territories covered by patents. As there is no direct corresponding international classes, it appears that most of the relevant patent publications are classified in A01G15/00 and/or B64D47/00, which are detailed as follows: “a variety of mechanisms for delivering sulfur-containing species to the lower stratosphere have been suggested, including aircraft, rockets, artillery, and pipes elevated to high altitudes carrying aerosol precursors”.

➔

A01: agriculture; forestry; animal husbandry; hunting; trapping; fishing

▪

A01G: horticulture; cultivation of vegetables, flowers, rice, fruit, vines, hops or seaweed; forestry; watering (picking of fruits, vegetables, hops, or the like A01D46/00; propagating unicellular algae C12N1/12);

•

A01G15/00: devices or methods for influencing weather conditions.

➔

B64: aircraft; aviation; cosmonautics

▪

B64D: equipment for fitting in or to aircraft; flight suits; parachutes; arrangement or mounting of power plants or propulsion transmissions in aircraft;

•

B64D47/00: equipment not otherwise provided for.

The logic behind the two main classes is that SAI first impacts weather patterns, which can directly impact agriculture, and one of the primary technical challenges of SAI is transporting the aerosol to the stratospheric layer. Many secondary international classes are used, and other classes could be used for searching further.

3.3. Patents Filed by the Major Oil and Gas Companies in the Field of Technologies That Aim to Reduce or Adapt to the Impacts of Climate Change

We began by tallying the total number of published patent applications, with a particular focus on those released over the past two decades. Our analysis specifically targeted the identification of patent applications related to the adaptation to and mitigation of climate change, within this period. To find the relevant applications, we utilized the CPC class Y02, which encompasses “technologies or applications for mitigation against climate change” [89], and also included technologies for adaptation that aim to increase the resilience to climate change.

Based on the information gathered from various credible sources, including financial institutions and other specialized agencies [100], we compiled a list of some of the world’s leading oil and gas producing companies. These companies supply billions of barrels of petroleum products every day to fuel transportation, industry, and more. Despite the growing public concerns regarding climate change and its present and future impacts, the efforts of the fossil fuel industry to reduce the reliance on carbon-based fuels are limited. Given that some of these companies rank among the most profitable globally, we conducted a study of their patent filings over the past two decades. Our analysis reveals that since 2004, most patent filings have fallen into the following categories (listed in alphabetical order):

-

Battery energy storage;

-

Biofuel production;

-

CO₂ capture;

-

CO₂ capture and/or removal;

-

Control and management of climate disasters;

-

Energy recovery;

-

Oil processing with organic materials;

-

Production of chemicals using catalysts;

-

Production of chemicals using catalysts and recycling of catalysts;

-

Solar energy, photovoltaic;

-

Preparation of compounds containing monosaccharide radicals;

-

Wind turbines.

Table 6 presents the proportion of publications in class Y02 relative to the total number of publications over the last two decades: this serves as an indicator of each actor’s commitment to mitigation and adaptation to climate change. Recalling that the Y02 class does not explicitly correspond to geoengineering, it nevertheless integrates in practice certain geoengineering solutions and other solutions relating to the energy transition towards decarbonization.

Table 6. List of patents and patent applications by oil companies (source: https://worldwide.espacenet.com/patent/search, access date 21 August 2024).

List of Oil and Gas Companies (Name, Country)	Total no. of Patents and Patent Applications in the Database and no. Since 2004	Total no. of Patents Including Patent Applications in Class Y02 and % of These Out of the Total Patents Filed Since 2004	Most Protected Technologies in Class Y02 (CPC)
Saudi Aramco (Saudi Arabia)	36,536 33,178	4801 14.5%	Production of chemicals using catalysts, CO2 capture and/or removal, energy recovery
China National Petroleum Corporation (CNPC) (China)	260,753 254,588	32,030 12.6%	Production of chemicals using catalysts and recycling of catalysts, oil processing with bio-based materials
PetroChina (China)	51,814 51,596	4304 8.3%	Production of chemicals using catalysts, climate disaster control and management
ExxonMobil, Chevron, ConocoPhillips (United States)	60,557 38,951	9388 24.1%	Production of chemicals using catalysts, oil processing with bio-based materials, CO2 capture
Shell (Netherlands/United Kingdom)	176,858 42,064	8995 21.4%	Oil processing using bio-based materials, biofuel production of chemicals using catalysts
TotalEnergies (France)	91,316 37,495	8836 23.6	Battery energy storage, solar energy, photovoltaic production of chemicals using catalysts
BP—British Petroleum (United Kingdom)	100,349 16,680	6218 37.3%	Battery, energy storage, production of products
Eni (Italy)	45,003 13,044	3477 26.7%	Production of biofuels, preparation of compounds containing monosaccharide radicals
Equinor (Norway)	11,880 6834	1042 15.2%	Wind turbines, CO2 capture

For each actor listed above, we provide a pie chart in Table 7 that summarizes the top 10 most cited international classes, allowing for a detailed examination of the technologies that each actor is focusing on (in purple).

Table 7. Quantitative analysis of patents from the world’s leading oil and gas producers in the Y02 classification “technologies or applications for mitigation against climate change” (source: Espacenet https://worldwide.espacenet.com/patent/search, access date 21 August 2024).

Company Name, Financial Information, Operations Description, and Website. The Purple Pie Shows the Number of Patents Filed in Class “Y02: Technologies or Applications for Mitigation Against Climate Change” YO2XNN/NN (Number)
Saudi Arabian Oil Co. (Saudi Aramco)—Revenue (TTM): USD 590.3 billion Net Income (TTM): USD 156.5 billion Exchange: Saudi Arabian Stock Exchange https://www.aramco.com/, accessed on 21 August 2024	Saudi Aramco is the world’s largest integrated oil and gas company and has facilities in targeted innovation hubs in the United States, Europe, and Asia. Note: it is the only company on this list not traded in the U.S.
China Petroleum & Chemical Corp. (SNPMF) Revenue (TTM): USD 486.8 billion—Net Income (TTM): USD 10.5 billion—OTC Markets—http://www.sinopec.com/listco/en/, accessed on 21 August 2024	China Petroleum & Chemical is a producer and distributor of a variety of petrochemical and petroleum products. The company’s products include gasoline, diesel, kerosene, synthetic rubbers and resins, jet fuel, and chemical fertilizers, among others. Also known as Sinopec, China Petroleum & Chemical is one of the world’s largest refiners of oil, gas, and petrochemicals.
PetroChina Co. Ltd. (PCCYF)—Revenue (TTM): USD 486.4 billion—Net Income (TTM): USD 20.9 billion—OTC Markets—http://www.petrochina.com.cn/, accessed on 21 August 2024	PetroChina is the publicly listed unit of the state-owned China National Petroleum Corporation. PetroChina is the largest oil and gas producer and distributor in China, contributing approximately 50% and 60% of China’s domestic oil and gas production volume, respectively.
ExxonMobil Corp. (XOM)—Revenue (TTM): USD 386.8 billion—Net Income (TTM): USD 51.9 billion—Exchange: New York Stock Exchange—https://corporate.exxonmobil.com/, accessed on 21 August 2024	ExxonMobil explores, produces, trades, transports, and sells oil and natural gas. An industry leader in profitability in the energy and chemical manufacturing sector, it operates facilities or markets products globally, exploring for oil and natural gas on six continents. ExxonMobil markets fuels, lubricants, and chemicals under four brands: Esso, Exxon, Mobil, and ExxonMobil.
Shell PLC (SHEL)—Revenue (TTM): USD 365.3 billion—Net Income (TTM): USD 43.4 billion—Exchange: New York Stock Exchange—https://www.shell.com/, accessed on 21 August 2024	Shell is an international energy company with locations in 70 countries involved in the exploration, production, refining, and marketing of oil and natural gas, and the manufacturing and marketing of chemicals.
TotalEnergies SE (TTE)—Revenue (TTM): USD 254.7 billion—Net Income (TTM): USD 23.1 billion—Exchange: New York Stock Exchange—https://totalenergies.com/fr, accessed on 21 August 2024	Headquartered in France, TotalEnergies explores and produces crude oil, natural gas, and low-carbon electricity. Total also refines and produces petrochemical products. The company owns and operates gas stations throughout Europe, the U.S., and Africa.
BP PLC (BP) British Petroleum—Revenue (TTM): USD 222.7 billion—Net Income (TTM): -USD 11 billion—Exchange: New York Stock Exchange—https://www.bp.com/, accessed on 21 August 2024	British oil company BP is involved in oil and petrochemical exploration, production, and supply. The company refines and sells petroleum products, including chemicals such as acetic acid, ethylene, polyethylene, and terephthalic acid. Its strategy is to evolve from a global oil company focused on producing resources to an integrated energy company focused on delivering solutions for customers and investors. BP brands include Castrol, Aral, and Amoco
ENI—Revenue (TTM): USD 107.2 billion—Exchange: ENI is listed on the Borsa Italiana (Italian Stock Exchange)—https://www.eni.com, accessed on 21 August 2024	ENI is an integrated energy company engaged in the exploration, production, refining, and sale of oil and gas. It also has operations in power generation and renewable energy.
EQUINOR—Revenue (TTM): USD 35.8 billion—Net Income (TTM): -USD 17 billion—Exchange: Equinor is listed on the Oslo Stock Exchange (OSE) and the New York Stock Exchange (NYSE). https://www.equinor.com/, accessed on 21 August 2024	Equinor is a broad energy company, the largest oil and gas operator in Norway, and a growing force in renewables and low-carbon solutions.

On the right side of each pie slice, the detailed name of the international class is presented, together with the total number of patent publications classified under this specific class (in brackets).

4. Discussion and Findings

Patent protection laws are relatively uniform throughout the world. A patent allows a monopoly to be obtained over the exploitation of a concept for a predetermined period and in the territory where it is granted. Any “international patent” is transformed into national and/or regional patents, to produce the same effect as a national and/or regional patent.

Like any other technology not explicitly excluded from patentability by the law, geoengineering innovations are patentable as long as they meet the criteria defined by patent laws, including novelty and inventive steps. However, geoengineering is controversial because it refers to technologies intended to interfere with the planet’s global climate. Geoengineering is associated with hopes but also raises fears. It generates many controversies. Geoengineering stakeholders often work without transparency, in secrecy, making it difficult to obtain a clear view of the real situation, which can create public suspicion and opposition [101].

The patent system, however, can answer some of the questions that arise and deserves consideration. Indeed, any patent application filed is published 18 months after its filing, forming a database with a wealth of publicly accessible information. Among this information are technical details, marketing information since an actor filing a patent application hopes for a financial return from the exploitation of their protected invention, and information about the actors in a given field. In practice, an investor in geoengineering solutions is generally tempted to file a patent application to recoup their investments, just like in any other field. Thus, observing the information available in patent databases provides reliable and important information on geoengineering techniques, seriously considered markets, and the actors intending to play a role. Patent databases help fill the transparency gap observed elsewhere, ultimately providing a view of the real situation.

To clarify geoengineering patents, it is essential to identify them among the numerous published applications. Patent classifications, like the IPC and the CPC, developed by specific patent offices, categorize patents by precise technological fields. This allows for the effective search and identification of innovations. Geoengineering patents, including those for CDR and SRM technologies, can be found in various sub-domains.

To illustrate, we examined patents in CDR technologies, SRM technologies, and those held by large oil and gas companies involved in geoengineering. The results show that geoengineering patents, including controversial SRM ones, exist and are growing in number, highlighting the sector’s increasing economic importance. Companies invest in these technologies to develop innovations, protect investments, and secure market positions. Consequently, it is expected that these patented solutions will be exploited or attempts will be made to do so.

After observing the situation through patent databases, it appears that there is a need for regulation and governance; indeed, the filing of patent applications in geoengineering raises urgent questions regarding the regulation and governance of these technologies, including not only research and experimentation but also their potential deployment. It is essential to establish international frameworks to oversee these activities to avoid undesirable consequences at the geopolitical level.

A recent report on the “Implications for governance of Stardust’s activities in relation to SAI” [102] informs that Stardust, a USA-incorporated startup with a subsidiary in Israel and investors such as AWZ Ventures and SolarEdge Technologies, has started applying for relevant geoengineering patents applications. Even if Stardust commits not to deploy SAI technology without governmental and intergovernmental decisions, they still aim for maximum transparency within the constraints of their IP process and lead their investors to expect profits from these IP rights, anticipating increased demand due to deficient climate change mitigation. Of course, there is a risk of losing investments if governments do not pursue SAI technologies, and a few recommended actions are listed in the report, including the need to contribute to developing international governance frameworks for SAI, making IP available for free worldwide once secured, and work with governments and public-service foundations to purchase full rights to the IP, making the technology freely available globally if needed [102]. There is an urgent need to start a global debate on geoengineering governance, in spite of the current unrelenting geopolitical tensions and conflicts. The need to discuss these issues globally is illustrated by proposals, such as the one pioneered by Switzerland at the sixth United Nations Environment Assembly held in Nairobi, Kenya in 2024, which suggested an international discussion on SRM. This contrasts with initiatives like the Non-Use Agreement [103] which proposes not to register patents in controversial technologies like SRM, highlighting the different approaches to address the anthropogenic climate change challenge. However, these disagreements should not prevent the establishment of an open multilateral dialogue about geoengineering international governance. The main justification for this open dialogue is that there is increasing private and public investment in geoengineering SRM research, including field experiments, in various countries amounting to tens of millions of US dollars.

The Non-Use Agreement includes, among other things, a prohibition on granting patents in the SRM field, and the signatories commit to refraining from filing patents themselves. This approach to patents is not new and has long been adopted by proponents of open-source software; it was also mentioned during the COVID-19 crisis concerning vaccines. The underlying idea is that patents could hinder certain activities and/or prevent access to the existing solutions that hold greater public interest compared to the private interests of patent holders. These debates about patents often stem from ideologies influenced by misconceptions about the patent system, which is poorly understood. The patent system is simply a means of financing development. The absence of patents on a given set of technologies would not prevent their development and future deployment. Conversely, filing patents does not authorize their deployment in case they are banned by the law. In other words, the issue of patents is relatively secondary in the context of a Non-Use Agreement [14].

5. Conclusions

The present work was based on the hypothesis that the number of climate geoengineering technologies being patented was relatively small in view of the very limited openly accessible and detailed information about the recent field experiments and future plans, including the possibility of deployment. We found that instead, there is a strong movement to file new patents for mitigation against climate change. The major players in this process and the main trends were identified and discussed. However, the classification and taxonomy of patent applications does not correspond to the classification and taxonomy of the different forms of geoengineering that are currently found and discussed in the scientific and technical literature, which leads to ambiguities and disinformation. Furthermore, it makes more difficult the identification of geoengineering patents in the databases. To improve the search capabilities within these databases, it is recommended to update the current patent classification by introducing a geoengineering class, while ensuring that it is consistent with the existing Y02 class.

An agreed international classification list of current geoengineering methods and processes aligned with the scientific definitions adopted by the IPCC and the UNFCCC is required.

One of the motivations for this article was to provide a succinct taxonomy of mitigation and geoengineering climate interventions that can be used by the patent systems, which is presented in Table 1. This alignment would facilitate the precise identification of the relevant technologies and strengthen the coherence of public policies.

In conclusion, the study of patents in geoengineering reveals increasing technological activity, which helps reduce the lack of transparency and information observed outside the patent systems. It shows that there is a need for appropriate regulation and international governance to frame the development and eventual use of these technologies, ensuring that innovations effectively serve the global interest while avoiding potential risks to the environment and society.

Finally, we note that the question of patents is ultimately secondary for SRM research and eventual deployment. If a political decision is made against the use of some climate geoengineering technologies, there would be no incentive to file patent applications. However, that does not prevent a particular technology from being developed and eventually deployed if it provides attractive economic and financial opportunities. Banning such patents would require complex legal changes in all countries, which would be difficult to implement. The safest course of action is to agree, at the multilateral level, on an effective and extensive governance framework for climate geoengineering research including field experiments and eventual deployment.

This framework should encompass critical questions of democracy, accountability, security, and justice.