CCUS was first mentioned in the ‘Outline of the National Medium and Long Term Science and Technology Development Program’ announced by the State Council in 2006 [15], where it was designated as cutting-edge technology. Following that, the Ministry of Science and Technology, the Ministry of Ecology and Environment, and the National Development and Reform Commission successively issued ‘Technology Roadmap Study on Carbon Capture, Utilization and Storage in China’, ‘Technical Guideline on Environmental Risk Assessment for Carbon Dioxide Capture, Utilization and Storage’, ‘the 12th Five-year National Special Plan for the Development of Carbon Capture, Utilization and Storage Technology’, ‘the 13th Five-year Plan to Control Greenhouse Gas Emissions’ and ‘Promoting Carbon Capture, Utilization and Storage Pilot Demonstrations’ [16,17,18]. These documents have made arrangements for science and technology policy, environmental regulation, and demonstration promotion. Additionally, CCUS has been included as an important emission reduction measure in the plans to cope with climate change issued by relevant departments. Some local governments have also established supporting policies and particular actions to aid in the growth of CCUS. For example, Guangdong Province has offered incentives for CCUS demonstration projects based on the electricity generation hours of power plants. While China’s policy advancement in the field of CCUS has demonstrated some worldwide leadership in the past, it is still insufficient to promote CCUS development on a large scale. Overall, due to the positioning of CCUS as a reserve emission reduction technology, most of China’s CCUS support policies are focused on R&D, rarely involving the field of large-scale diffusion and application. Most importantly, there is still a lack of economic incentive policies for CCUS.

China has increased its focus on CCUS because of its indispensable role in future endeavors to achieve carbon neutrality. The 14th Five-Year Plan for national economic and social development, released in 2021, proposes ‘supporting the demonstration of important projects such as carbon capture, utilization, and storage’, marking the first time CCUS has been mentioned in a national five-year plan. CCUS has also received support from the national ‘1 + N’ policy framework on carbon peaking and carbon neutrality. In particular, the two newly released top-level policy design documents have highlighted the deployment of CCUS. One is a document titled ‘Working Guidance For Carbon Dioxide Peaking And Carbon Neutrality In Full And Faithful Implementation Of The New Development Philosophy’ jointly released by the Communist Party of China Central Committee and the State Council [19]. This guidance recommends encouraging CCUS technology research and development, large-scale demonstrations, and industrial applications. Another one is released by the State Council and titled ‘Action Plan for Carbon Dioxide Peaking Before 2030’, which lays out a comprehensive CCUS strategy that includes basic research, technology development, large-scale demonstration, and international collaboration [20]. More specific policy provisions for CCUS are constantly replenished in the follow-up action plans for carbon peaking and carbon neutrality in various fields. During the 14th Five-Year Plan, the government will continue to improve policy supply and coordination, as well as boost CCUS R&D demonstration and development.

There are many design fields and a long technical chain in the CCUS project. Because of these characteristics, the implementation of a CCUS project necessitates a heavy investment, which has always been a significant issue in the development of CCUS. Since last year, the Ministry of Ecology and Environment and the People’s Bank of China (PBOC) have strengthened the design of the investment and financing systems to support the development of CCUS. The Ministry of Ecology and Environment, in collaboration with other departments, issued ‘Guidance on Promoting Investment and Financing in Response to Climate Change’ in October 2020, instructing social capital to enter the field of climate change, and thus the scale of funds will increase significantly in the future [21]. In November 2021, PBOC launches a new tool to promote low-carbon financing, focusing on clean energy, energy conservation and environmental protection, and emissions reduction technology, the latter of which primarily supports CCUS and other technologies [22]. Only in the clean energy sector is it projected that the yearly size of carbon emission reduction support instruments that can be delivered is more than 300 billion yuan. If these three areas are taken into account, the yearly scale of financing tools that may be used should be greater than 500 billion yuan, providing considerable financial support for the expansion of CCUS projects. Simultaneously, a growing number of investment funds and other forms of social and enterprise capital are paying attention to and investing in CCUS as a sophisticated carbon neutrality technology. In addition, China has launched a national carbon market in 2021. Incorporating CCUS into the carbon market mechanism could help companies that adopt CCUS technology to gain some benefit from the carbon market to compensate for the current high costs. Specifically, qualified emitters could be allowed to offset their emission credits directly with CCUS, or approved emission reductions from CCUS projects could be allowed to enter the market for trading.

The new chapter of the domestic CO₂ capture project can be traced back to 2007. After long-term practice, CNPC Caoshe Oilfield in Jilin Oilfield first realized the industrialization of CCUS-EOR technology and established five types of CO₂ oil displacement and storage demonstration areas, with an annual CO₂ storage capacity of 350,000 tons [26]. In the same year, Caoshe Oilfield of Sinopec East China Branch completed a pilot test project with an annual CO₂ injection capacity of 40,000 tons, and a CO₂ recovery plant was built in the later stage with an annual treatment capacity of 20,000 tons [27].

In 2010, Sinopec Shengli Oilfield built the CCUS demonstration project for the first coal-fired power plant in China. The flue gas from the coal-fired power plant was taken as the source of CO₂, and the captured CO₂ was injected into the oil field for oil displacement by using the post-combustion capture technology, with an annual CO₂ capture capacity of 40,000 tons [28]. In 2011, Shenhua Ordos adopted the methanol absorption method to capture CO₂ from the tail gas of coal gasification hydrogen production project, and then injected CO₂ into the saline layer. This project was the first geological storage experimental project of a saline layer in China, with a construction scale of 100,000 t/a. In 2012, Yanchang Petroleum used CO₂ produced by the coal chemical industry and injected CO₂ into the oilfield after purification, pressurization and liquefaction by taking the low-temperature methanol washing technology, thereby reducing the crude oil viscosity, improving the crude oil recovery, and realizing the permanent storage of CO₂. The construction scale of this project was 50,000 t/a. In 2015, the CCUS project of tail gas from the oil refinery of Sinopec Zhongyuan Oilfield was completed. This project increased the oilfield recovery rate by 15% through CO₂ oil displacement of the almost abandoned oilfield. Currently, millions of tons of CO₂ have already been injected into the ground. In 2021, the 150,000 t/a CCS demonstration project passed the 168-h trial operation in CHN Energy Jinjie Co., Ltd., which is the largest demonstration project of the whole process of post-combustion CO₂ capture, oil displacement, and storage in China’s coal-fired power plant. During the trial operation, industrial-grade qualified liquid carbon dioxide products with a purity of 99.5% were continuously produced. The large-scale capture of CO₂ from the flue gas of coal-fired power plants is successfully realized [29].

In addition to the traditional CO₂ capture technology, new CO₂ recycling technology was also carried out in China and was applied in food, fine chemical engineering, and other industries [30]. In 2010, ENN Group used the microalgae carbon sequestration technology in Dalat Banner, Inner Mongolia to use some tail gas absorbed from the coal-to-methanol/dimethyl ether plant as biodiesel and some tail gas as production feed, with a treatment capacity of 20,000 t/a.

With the acceleration of industrialization, domestic research on CO₂ capture projects has also started. Compared with foreign countries, China’s CCUS project started late, and there is no megaton capture project. At present, the capture capacity of the domestic projects only reaches 100,000 tons [31,32,33]. The general development status of CCUS technology in China is shown in Table 1 and the domestic CCUS projects are shown in Table 2 in Appendix.

Known from Table 2, the largest carbon capture demonstration project built in China is the 150,000 t/a CCS project of Jinjie Power Plant. 36% of the projects have a capture capacity of more than 100,000 tons, 39% of the projects have a capture capacity of more than 10,000 tons and 25% of the projects have a capture capacity of less than 10,000 tons. Compared with many foreign commercial operation projects of 1 million tons, CO₂ capture is still dominated by small-scale projects in China. Figure 3 is the bubble diagram of CCUS technology demonstration scale that has been carried out and is planned to be carried out in China. The bubble area is proportional to the capture scale of the demonstration plant. After the carbon neutrality target is put forward, the scale of projects to be built in the future will generally increase. For example, CHN Energy is preparing to build the 500,000 t/a carbon capture, utilization, and storage demonstration project in Taizhou Power Plant. The captured CO₂ will be used for food-grade sales and oilfield displacement, and it is expected to be put into production in 2023. Sinopec prioritized the CO₂ capture technology with its intellectual property rights to prepare high-concentration CO₂ by means of hydrogen, ethylene glycol, and coal chemical production equipment and recycle the flue gas from the owned power plant in the national carbon market. It is comprised of two parts, namely CO₂ capture by Qilu Petrochemical and CO₂ oil displacement and storage by Shengli Oilfield [34]. Qilu Petrochemical transported the captured CO₂ to Shengli Oilfield for oil displacement and storage, realizing the integrated application of CO₂ capture, oil displacement, and storage. This project is expected to be put into production by the end of 2021. In the next 15 years, it is expected that 10.68 million tons of CO₂ will be injected to realize the increased oil production of 2.965 million tons.

Known from Fig. 4, the majority of CO₂ carbon sources come from low-concentration emission sources, such as coal-fired power plants, accounting for 38%. 26% come from high-concentration emission sources such as the coal chemical industry, followed by the petrochemical industry, cement plant, and building materials industry, accounting for 18%, 15%, and 3% respectively. The demonstration of CCUS technology hasn’t been carried out in the iron and steel industry.

Up to now, China has completed the capture of 2 million tons, with an annual capture capacity of 3 million tons and an accumulated CO₂ storage capacity of 2 million tons. As of 2020, there have been 66 large-scale CCUS integration projects worldwide, and 34 pilot and demonstration projects are running or under development. The CCUS facilities currently in operation worldwide can capture and permanently store approximately 40 million tons of carbon dioxide per year. Among the 17 newly increased CCUS projects in 2020, 12 projects are from the USA [35]. The CCUS facilities put in commercial operation in this region have an annual carbon capture capacity of over 30 million tons, much higher than the carbon capture capacity of our country. The completion of these new projects mainly benefits from the incentives from the 45Q tax credit and the Californian Low Carbon Fuel Standard. The development of CCUS in China, especially the large-scale commercial development, needs further effective incentive policies to solve the problems for the investors such as investment and financing channels, investment cost, and yield risk [36].

In addition to reducing emissions, CCUS has the potential for negative emissions. The derived technologies based on CCUS, such as BECCS and DACCS, can be further combined with renewable energy and are also negative emission options with bright prospects. Agriculture and forestry systems are currently the most important carbon sinks in terms of negative emission potential, but their capacity in China is often limited to around 1 billion tons of CO₂ [40]. As a result, negative emission technologies such as BECCS and DACCS will provide the majority of the additional negative emission potential required in the future. If existing power plants are retrofitted to coal-biomass co-fired power generation units, the negative emission potential of BECCS in China is estimated to be around 360 million tons/a [41]. This fraction of the potential is only tied to retrofitting some existing coal-fired power plants; China’s entire BECCS potential will be substantially greater. Without considering the cost, DACCS has a significant negative emission potential [42]. While DACCS is currently in its early phases of development, its cost will decrease as technology advances.

In 2018, industry accounted for roughly 28% of China’s total carbon emissions [43]. Because of the enormous energy input, industries emit a lot of CO₂, especially in the iron and steel, chemical, and cement sectors. The iron and steel industries release nearly 1.8 billion tons of CO₂ per year, making them the largest industrial emitters, accounting for roughly 15% of total national CO₂ emissions and approximately 24% of industrial CO₂ emissions [44]. The cement sector emits more than 1.2 billion tons of CO₂ annually. Since the production energy structure is complex, the consumption forms are diverse, and the sources of CO₂ emissions are various, the process-based emissions in the industry are complex. Because of the aforementioned characteristics, industries such as steel and cement will find it difficult to meet carbon emission reduction targets solely through capacity adjustments, energy savings, and efficiency improvements, indicating that CCUS is required for the deep decarbonization of industrial sectors in certain sectors.

China’s energy resource endowments are characterized by rich coal, poor oil, and lean gas. Coal and other fossil fuels are not only the primary energy sources for Chinese consumer goods but also essential industrial raw materials. Additionally, widespread adoption of new technologies such as renewable energy substitution will take time due to limitations in technology maturity, stability, and economic cost in the power industry. Affected by the remaining operating life of China’s active coal-fired units (about 15-35 years), the direct withdrawal of coal-fired power will cause huge economic losses to China [45]. To a certain extent, CCUS can provide important technical guarantees for the coal-based energy industry to avoid the “carbon lock” restriction, so as to avoid the “depreciation” of fossil energy assets caused by emissions reduction, and can also support relevant industries to continue to use the high cost of infrastructure built in the early stages while meeting the “hard constraints” of low-carbon transformation [46]. China will build a power system dominated by renewable energy in the future, and coal power will be greatly reduced. However, a certain amount of fossil fuel power is needed to ensure the flexibility and security of the power grid. CCUS can solve the emission of this part of fossil fuel power.

Following many nations’ commitments to a carbon-neutral future, the combination of CCUS and related energy systems has emerged as a hotspot, with the potential to promote a new technical and economic paradigm for CCUS development. Integrating CCUS and hydrogen energy production can not only convert high carbon energy into zero-emission hydrogen energy but also incorporate CCUS with low power consumption and low cost in the conversion process, resulting in energy conservation and emission reduction at the fuel source [47]. Integrating CCUS with renewable energy and energy storage systems, likewise, is a viable option for assuring the long-term stability and sustainability of multi-energy supply systems. In addition, CO₂ utilization technologies attract extensive attention for their potential to recycle CO₂, especially in the field of CO₂ hydrogenation to liquid fuels, which can offer a systematic solution for emission reduction in long-distance and heavy-haul transportation. As climate governance improves, the usage of fossil fuels decreases, limiting the amount of carbon that may be used in the industrial sector. Under the circular carbon economy paradigm, utilization technology innovation is gaining traction, with innovative technologies continuing to develop in the future.

The carbon capture technology is to obtain high-concentration CO₂ through CO₂ enrichment, compression, and purification. At present, there are three common carbon capture technologies, namely pre-combustion capture, in-combustion capture, and post-combustion capture [50]. At present, post-combustion capture technology is the most mature capture technology and can be used for decarburization transformation of most thermal power plants. The pre-combustion capture system is relatively complex, and the integrated coal gasification combined cycle technology is a typical technology. The oxygen-enriched combustion technology is one of the most promising technologies for large-scale carbon capture in coal-fired power plants. The CO₂ produced has a higher concentration (90% ~ 95%) and thus is easier to capture. It can be used in new coal-fired power plants and some transformed thermal power plants.

However, the CO₂ capture technology has the following problems such as high heat consumption of absorbent regeneration, high system complexity, and difficult integration. It is necessary to develop high-performance absorbent, master the technology with the strengthened process, matched energy coupling and power plant integration and control, etc., reduce capture energy consumption and realize organic integration of capture system and power generation system, thereby minimizing the impact of CO₂ capture on power generation efficiency. There is little experience in the construction of efficient and practical CO₂ adsorption and membrane separation systems. It is necessary to master the industrial-scale preparation technology of high-performance and low-energy adsorbent and membrane materials and form the CO₂ capture technology with efficient and low-energy adsorption and membrane separation. The main problem of CO₂ capture in the chemical process is to optimize the capture process, shorten the process flow, reduce the construction investment and reduce the operation energy consumption. At present, China has deployed relevant scientific and technological research and development tasks, mainly focusing on key technologies for high energy consumption of CO₂ capture, and is committed to developing high-performance CO₂ capture materials, breaking through key technologies for large-scale CO₂ capture, and realizing industrial demonstration of low-energy 500,000 to 1000,000 CO₂ capture. When the relevant technology gets mature, the energy consumption and cost will be decreased by more than 30% than the existing technology, and it is expected to be widely applied around 2035 [51].

China has developed and formed a number of key technologies for CO₂ capture, oil displacement, and storage, including the CO₂ drive development and experimental analysis technology for the phase state analysis of gas drive reservoir fluid, CO₂ drive reservoir engineering design technology centered on the prediction of production indicators such as injection and recovery, CO₂ drive injection and recovery technology dominated by alternate injection process of water and gas and multi-phase fluid lifting technology, and CO₂ drive safety prevention and control technology for the integrated safety monitoring and warning of “space-sky - near-surface - oil-gas well - geological mass - receptor” [52]. Through the practical development of CO₂ oil displacement and storage in the past ten years, the CO₂ enhanced oil production technology is in the industrial demonstration stage, the CO₂ saline water storage technology has completed the pilot test study, the CO₂ CBM displacement technology has completed the pilot test stage, and the mineralized utilization is in the industrial test stage. The CO₂ enhanced natural gas and shale gas production technology are still in the basic research stage. There are still some practical conditions such as immature carbon market, imperfect gas supply system, high CO₂ oil change rate (gas consumption per ton), and low recovery factor, which will affect the economical efficiency of CCUS projects to varying degrees and further affect the sustainable development of CCUS technology in China [53].

The continental sedimentary low permeability reservoirs in China are characterized by strong heterogeneity, intertwined natural and artificial fractures, large burial depth, and large crude oil viscosity, which pose challenges to the success and benefits of CO₂ oil displacement and storage projects. In addition, China has not yet formed a CO₂ gas source market with a relatively reasonable price and stable supply for the application of CO₂ oil displacement and storage technology. Therefore, there are still a number of technical problems that need to be solved or improved in China’s CO₂ oil displacement technology, such as how to further reduce the investment per unit capacity of CO₂ flooding, how to improve the management level of CO₂ drive reservoir, especially to delay gas channeling and avoid the phenomenon of “no blending”, and continuously improve the effectiveness of gas injection [54].

In terms of CO₂ utilization, mineralization technology is very suitable for flue gas purification treatment without desulfurization in coal-fired power generation and energy-consuming steel, cement, and other important processes. The fixation of CO₂ through direct mineralization and by using waste materials such as coal cinder, coal ash, steel slag, and tailings will greatly improve the process emission reduction capacity and reduce the CO₂ capture cost. However, major issues, such as common principles of mineralization process, key technologies and equipment, and integrated technology of capture and mineralization process, need to be further studied to improve the carbon sequestration efficiency and economical efficiency of the whole process and to form the key technologies for CO₂ emission reduction and integrated mineral processing or slag treatment. The key problem of CO₂ conversion and utilization technology is to improve the efficiency of directional synthesis of high-value fuels/chemicals and the carbon sequestration capacity. Among more than ten chemical and biological transformation technologies, some of them have shown demonstration ability. However, restricted by material performance factors, such as low catalyst activity, short life, poor directional selectivity, poor carbon sequestration efficiency and patience of algae strains, and low CO₂ conversion and utilization efficiency, it is necessary to research and develop a number of cutting-edge technologies for CO₂ conversion and utilization. The high-efficiency catalyst for CO₂ directional conversion has been developed and produced and applied on a large scale to realize the large-scale carbon sequestration of algae strains.

CO₂ transportation is an important link in the application of CCUS technology. At present, there are mainly four transportation modes: pipeline, ship, road tanker, and railway tanker [55]. Transportation by road tanker and railway tanker is difficult to be adopted on a large scale because of the small transportation volume and high cost. Transportation by ship is suitable for low-volume and long-distance CO₂ transportation at sea, and transportation by pipeline has been adopted on a large scale due to the large transportation volume and low cost. There are few CO₂ gas sources near the main oil-producing areas in China, so it is very necessary to collect gas from other places and transport it to the designated land through pipelines. However, the domestic research on CO₂ pipeline technology started late and is currently in the stage of theoretical research and experiment, but the engineering practice construction has been planned, The million ton CO₂ project of Shengli Power Plant is planned to be the largest CO₂ transmission pipeline in China. There is currently one large-scale CCUS project operating in China-the China National Petroleum Corporation Jilin project, which captures some 600 ktCO₂ per year from a natural gas processing plant for transportation via a 10 km pipeline to an oil reservoir for enhanced oil recovery. In the technological development level of each link of CCUS in China, the pipeline transportation technology is the weakest, which is related to the immature design of the pipe network system and the lack of standard specifications for the transportation process. China has a large land area, and the distance between CO₂ emission sources and storage sites is large, so the large-scale long-distance pipeline transportation of CO₂ becomes an efficient and feasible option. The natural gas pipeline transportation technology is relatively mature and the CO₂ pipeline transportation is similar to the natural gas pipeline, but CO₂ captured by flue gas is often accompanied by N2, O2, H2S, water vapor, alkane, and other impurities. Therefore, the transportation of CO₂ with different purity poses new challenges to the design of the pipeline operation process [56]. Based on experience, the large-scale CO₂ pipeline transportation in a supercritical mode has a low operating cost and high efficiency. However, the application of CO₂ pipeline transportation engineering in China is still in the stage of low-pressure gas transportation, and the high-pressure, low-temperature and supercritical transportation have just started. The large-scale CCUS projects require the construction of a CO₂ transportation pipeline and the research on CO₂ pipeline transportation safety and safety monitoring and control technology.

The CCUS demonstration projects in China are characterized by the small overall scale and high cost, and the cost of CCUS mainly includes economic cost and environmental cost. Economic cost includes fixed cost and operating cost, while environmental cost includes environmental risk and energy consumption emission. The operating cost mainly involves capture, transportation, storage, and utilization. It is estimated that the CO₂ capture cost will be RMB 90-390/ton in 2030 and RMB 20-130 /ton in 2060; and the CO₂ pipeline transportation will be the main transportation mode for large-scale demonstration projects in the future. It is estimated that the pipeline transportation cost will be RMB 0.5 /ton • km in 2030 and RMB 0.3 /ton • km in 2060. It is estimated that the CO₂ sequestration cost will be RMB 40 ~ 50 /ton in 2030 and RMB 20 ~ 25 /ton in 2060 [57]. Under the existing technologies, the introduction of carbon capture will increase the extra operating cost of RMB 200-300/ton. For example, the power generation cost of the Shanghai Shidongkou capture demonstration project of China Huaneng Group has increased from about RMB 0.26 /KWH to RMB 0.5 /KWH [58]. The operating cost of the CCS demonstration project of Jinjie Power Plant of CHN Energy Group is about RMB 280 /tCO₂, while the operating cost of the 500,000 t/a carbon capture demonstration project of Taizhou Power Plant under construction is expected to be about RMB 240 /tCO₂.

Seen from the overall cost of the CCUS project shown in Fig. 5, the capture cost is a major part, approximately accounting for 60-80% of the total cost. The carbon capture cost mainly includes fixed costs and operating costs. Fixed cost refers to the initial investment of carbon capture technology, such as equipment installation and land investment, etc. By taking thermal power as an example, the fixed cost investment of carbon capture devices is about RMB 800 to 1000 / tCO₂. Based on the depreciation period of 15 years, the depreciation cost accounts for about 16% [59,60]. The operating cost includes the consumption of water, electricity, steam, and chemicals in the operation process of the carbon capture device, maintenance cost, and operation personnel’s salary. Its reduced proportion is about 84%, in which the steam cost accounts for 27%, the electricity cost accounts for 32%, the amine liquid consumption cost accounts for 12%, the financial cost accounts for 6%, the repair cost accounts for 4% and the operating personnel’s salary and welfare expenses account for 3%.

Measures for reducing the costs mainly include (1) Novel capture technology, with 30% reduction potential focusing on the development of new absorbent (such as two-phase waterless ionic liquid) to reduce the steam cost, the application of new efficient energy-saving equipment to reduce the power consumption cost, the development of new amine recovery device to reduce the amine liquid consumption cost, (2) Scale effect, with 30% reduction potential focusing on the expansion of scale (2 million tons) to reduce the composite cost by about 30%. (3) New business model to reduce comprehensive costs.

In management science, the business model generally refers to the mode in which a single enterprise produces and sells products and does not involve other enterprises [63]. The business model of CCUS technology is quite different from that of a single enterprise, which is determined by the characteristics and development stage of CCUS technology itself. From a technology perspective, a CCUS project has a long technology chain, which inevitably includes more upstream and downstream enterprises. Therefore, the business model of CCUS referred to broadly in the past mainly discusses how all relevant parties of CCUS cooperate in a whole chain project so that the project can be constructed and implemented with low risk and high efficiency.

However, given the current status of CCUS development and its technological characteristics, the future of CCUS is also determined by various stakeholders which should be included in the business model. For example, CCUS technology is still in the early stage of large-scale application, in the absence of government support, the industrial sector alone can not afford the large-scale construction and operation of CCUS projects. So the government will play a critical role in the commercialization and large-scale promotion and is an indispensable important stakeholder in the business model.

In view of the characteristics and current stage of the CCUS project, this paper defines the business model of CCUS as “the organizational mode, business process, relevant policies and mechanism arrangement of all stakeholders to promote the construction and implementation of the project in order to promote the smooth implementation of CCUS project.”

Currently, the existing CCUS business model is usually aimed at projects with a single business chain between the emission source and the storage site. This decentralized business model is mainly designed at the project level, and its goal is to promote the implementation of the project. Consideration of the economy and other facts are often not included in the project decision. With the increase of the implementation of the CCUS project, some disadvantages and challenges of this business model gradually emerge after the technical effectiveness and other aspects have been verified.

Projects from a single emission source to a single sequestration site may face the challenge of a mismatch between supply and demand for CO₂ in technical operations. Taking the current realistic CCUS full chain project (power plant capture with EOR) as an example, the carbon dioxide emission characteristics of the power plant do not match the carbon dioxide utilization in EOR [64]. Emission sources tend to produce carbon dioxide at a relatively constant rate unless the plant is closed for maintenance or shutdown. By contrast, the amount of carbon dioxide required for CO₂-intensive flooding projects varies throughout the life of the project. Initial reservoir assessment requires only a relatively small amount of carbon dioxide to test its adaptability to CO₂-EOR. After that, large amounts of carbon dioxide are injected into the reservoir. After several years of injection, depending on the specific reservoir characteristics, the oil produced will contain carbon dioxide, which must be separated and injected back into the field. As a result, the amount of carbon dioxide required gradually declines. These fluctuating demands pose a huge challenge to a point-to-point model like a power plant to an oilfield.

Each project needs to overcome these challenges of a mismatch between supply and demand for carbon dioxide. In this decomposed business model, all members of the value chain have significant cross-chain risks. For example, if industrial sources of carbon dioxide stopped operating, both pipeline operators and storage operators would have no customers and no revenue. This risk is a major barrier to investment and ultimately manifests itself in higher capital costs and higher project costs. This, in turn, makes CCUS projects appear less economic, further reducing the attractiveness of CCUS implementation.

CCUS development must address two challenges, namely, stimulating economies of scale and diversifying risk. One is regarding the scale effect. At present, the overall cost of CCUS is still high. Although technological progress will further reduce the cost, we should not only rely on technological progress to reduce the cost. Economies of scale are another important way to reduce costs, which in turn tend to drive technology further and increase the slope of the learning curve. The other challenge is risk diversification. Both theoretical research and engineering practice have shown the importance of risk reduction to the success of the CCUS project. The basic goal of CCUS business model optimization is how to disperse and reduce project risks. For a project with a long industrial chain and involving many stakeholders, it is hard to imagine that a project with risks concentrated on a few stakeholders will achieve success. On the contrary, such projects are often difficult to enter the feasibility stage from the very beginning.

Based on the above understanding, the following considerations should be included in the design of the CCUS business model: (1) we should systematically consider the overall business model of CCUS and give a systematic solution, instead of circling on the business model of a single project, when we solve the problem plaguing the basis for the development of CCUS commercial, (2) the current CCUS project is independent projects, the development of each project did not provide the infrastructure for the next new project basis, that is because there is no considering the project as the inheritance of infrastructure, every new project must start from scratch, it is also a huge waste. Therefore, the design of the business model also needs to consider the extensibility and inheritance that the project should provide as the infrastructure. (3) Since CCUS can be regarded as the provider of basic public goods, the role of the government is natural, and it is also appropriate for the government to support the development of CCUS. However, in the current project, government support is still limited to the support of a single project and does not play the role of extension and publicity. Therefore, in the design of the CCUS business model, we should consider more from a systematic and long-term perspective, not just for the design of a single project.

Full-chain CCUS demonstration projects are necessary stages for the commercialization of CCUS technology. In areas with great potential of CCUS, building a backbone pipeline or CCUS-hub will be attractive for large-scale development of CCUS, and there are already 15 CCUS Hub projects announced [65]. This is especially cost-effective to build a large-scale backbone pipeline to minimize the transportation cost and form a CCUS hub. Early-stage low-cost demonstration projects are suggested to link CO₂ capture from high-concentration emission sources to enhanced oil recovery. The full-chain system integration and demonstration of CCUS require enormous capital investment, strong dependency on on-site conditions, long technological chains with high technological densities, and diverse process combinations. Therefore, it is necessary to accurately evaluate the potential and source-sink conditions of CCUS in key regions in China to promote CCUS-integrated project demonstrations in accordance with local conditions. Based on the regional features and CO₂ source-sink mapping, several regions like the Ordos basin have favorable conditions for CCUS clusters or CCUS-hub.