Early Opportunities for Onshore and Offshore CCUS Deployment in the Chinese Cement Industry

Jing-Li Fan; Yifan Mao; Kai Li; Xian Zhang

doi:10.1016/j.eng.2024.09.011

Engineering ›› 2025, Vol. 46 ›› Issue (3) :367 -383. DOI: 10.1016/j.eng.2024.09.011

Research Carbon Capture, Utilization, and Storage—Article

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Early Opportunities for Onshore and Offshore CCUS Deployment in the Chinese Cement Industry

Jing-Li Fan ^a^,^b
, Yifan Mao ^a^,^b
, Kai Li ^a^,^b
, Xian Zhang ^c^,^*

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Abstract

The promotion of deep decarbonization in the cement industry is crucial for mitigating global climate change, a key component of which is carbon capture, utilization, and storage (CCUS) technology. Despite its importance, there is a lack of empirical assessments of early opportunities for CCUS implementation in the cement sector. In this study, a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS retrofitting in the cement industry, called the SSM-Cement framework, is proposed. The framework comprises four main modules: the cement plant suitability screening module, the storage site assessment module, the source–sink matching optimization model module, and the economic assessment module. By applying this framework to China, 919 candidates are initially screened from 1132 existing cement plants. Further, 603 CCUS-ready cement plants are identified, and are found to achieve a cumulative emission reduction of 18.5 Gt CO₂ from 2030 to 2060 by meeting the CCUS feasibility conditions for constructing both onshore and offshore CO₂ transportation routes. The levelized cost of cement (LCOC) is found to range from 30 to 96 (mean 73) USD·(t cement)⁻¹, while the levelized carbon avoidance cost (LCAC) ranges from −5 to 140 (mean 88) USD·(t CO₂)⁻¹. The northeastern and northwestern regions of China are considered priority areas for CCUS implementation, with the LCAC concentrated in the range of 35 to 70 USD·(t CO₂)⁻¹. In addition to onshore storage of 15.8 Gt CO₂ from 2030 to 2060, offshore storage would contribute 2.7 Gt of decarbonization for coastal cement plants, with comparable LCACs around 90 USD·(t CO₂)⁻¹.

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Keywords

Cement industry / Carbon capture, utilization, and storage / Levelized cost of cement / Source–sink matching / Offshore storage continental shale oil

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Jing-Li Fan, Yifan Mao, Kai Li, Xian Zhang. Early Opportunities for Onshore and Offshore CCUS Deployment in the Chinese Cement Industry. Engineering, 2025, 46(3): 367-383 DOI:10.1016/j.eng.2024.09.011

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1. Introduction

The cement industry has high carbon and energy intensity, and significantly contributes to global greenhouse gas emissions [1], [2]. In 2021, this sector globally emitted nearly 2.5 billion tons of CO₂ [3], accounting for approximately 7% of total energy-related emissions [4], [5]. The European Union’s introduction of the Carbon Border Adjustment Mechanism (CBAM), a carbon tariff targeting carbon emissions from imported cement [6], underscores the urgency of exploring low-carbon and sustainable alternatives. The International Energy Agency (IEA) proposed emissions thresholds ranging from 40 to 125 kg CO₂ equivalence (CO_2-eq)·(t cement)⁻¹ by 2050, compared to today’s 375–925 kg CO_2-eq·(t cement)⁻¹ [7].

The achievement of such significant reductions by 2050 is a tremendous challenge [8], necessitating the exploration of technological solutions [9]. First, global cement demand is projected to rise from 4.2 billion tons in 2020 to 4.7 billion tons in 2030 [10], [11], particularly in emerging economies like India, China, and other Asian and African countries; thus, demand reduction alone is impractical. Second, about 60% of the industry’s emissions stem from mineral decomposition [12]. While enhancements like transitioning from wet kilns to dry kilns, improving material efficiency, and substituting raw materials can mitigate process-related emissions, the overall potential for emission reduction is limited even under optimal conditions [4], [13]. Third, the remaining emissions are mostly caused by fuel combustion [13], [14], [15]. While measures like the adoption of low-emission fuels, the improvement of energy efficiency, and electrification can offer partial solutions, they fall short of achieving net- or near-zero emissions [4], [16], [17].

Carbon capture, utilization, and storage (CCUS) has emerged as a promising technology for deep decarbonization in the cement sector [18], [19], [20]. Unlike traditional methods, CCUS allows for the capture of CO₂ emissions from industrial processes and fuel combustion via the same flue gas duct, thus enhancing the overall abatement efficiency [1]. Several major cement companies have already initiated CCUS demonstration projects for research and development (R&D) purposes. For instance, Heidelberg Cement’s Norcem Breviwk Plant in Norway operates a 0.4 Mt·a⁻¹ capture facility using post-combustion technologies [21]. While current CCUS costs are relatively high, reaching up to about 100–150 USD·(t CO₂)⁻¹ [22], ongoing technological advancements and large-scale project deployments suggest significant cost reductions in the near future [23].

Previous research in the cement sector has primarily focused on developing energy technology models to simulate low-carbon transition pathways and CCUS mitigation strategies. For example, Zhang et al. [24] developed the National Energy Technology (NET)-Cement model, a bottom-up approach that projects a nearly 200 Mt CO₂ abatement by 2050 if 30% of clinker production lines are equipped with CCUS technology. Xu et al. [25] and Zhou et al. [26] explored the impact of CCUS technology on CO₂ reduction strategies in China’s cement industry, providing insights into the macro-level decarbonization potential of CCUS in this sector. However, these studies often lack detailed plant-level designs and full-chain CCUS analyses. To address this gap, several bottom-up source–sink matching models have been used to evaluate the plant-scale techno-economics of CCUS retrofits, focusing on specific regions or industries. For instance, Hasan et al. [27] designed a low-cost CCUS supply chain network including 444 multi-sectoral CO₂ sources, 96 of which were cement plants, and 16 were deemed profitable by enhanced oil recovery (EOR) within the United States National CCUS network. Garg et al. [28] coupled the MARKet ALlocation (MARKAL) model with a source–sink mapping model to assess 1345 carbon-intensive sources in India, and identified 108 and 156 cement sources with carbon avoidance costs respectively 83–109 and 84–95 USD·(t CO₂)⁻¹. Wang et al. [29] developed a source–sink matching model aimed at establishing optimal deployment strategies for China’s cement industry. CCUS-based reductions of China’s industrial emissions by 20%, 40%, and 60% were found to be characterized by respective economic costs of 333.4, 352.5, and 376.9 CNY·(t CO₂)⁻¹. Furthermore, the relatively dispersed locations of cement plants distinguish this sector from other carbon sources in terms of source–sink matching. It is thus crucial to explore specific layouts that are conducive to CCUS retrofitting in this industry.

Considering the widespread distribution of cement plants along coastal areas, offshore storage is becoming a viable option to support CCUS deployment due to its vast storage capacity. Zhang et al. [30] assessed the feasibility of offshore CCUS deployment along China’s southeastern coast; 39 cement plants were matched to China’s offshore sequestration sites with a transport range of 50–350 km with total CO₂ emissions of 90.74 Mt·a⁻¹. However, extensive offshore sequestration databases and land–sea transportation routes have yet to be incorporated into CCUS source–sink matching analysis. Recognizing the deterrent effect of high costs on corporate initiatives [31], scholars have emphasized the importance of incentive policies to promote the CCUS retrofitting of plants, mostly in the power sector [32]. However, the effectiveness of such policies in facilitating CCUS project adoption in the cement industry has received less attention. Therefore, addressing these challenges by developing a dedicated CCUS layout that includes both onshore and offshore storage is crucial for identifying early opportunities and quantifying the potential of CCUS retrofitting in the cement industry.

Herein, a comprehensive onshore and offshore source–sink matching optimization assessment framework (SSM-Cement framework) is developed, and is specifically designed for the cement industry. It integrates plant-level CO₂ sources, onshore and offshore storage sites, pipeline networks, geological utilization, full-chain technology costs, and incentive policies into a unified framework. As the world’s largest producer and consumer of cement, the potential and economics of CCUS technology for retrofitting China’s massive existing cement facilities are evaluated [33], [34], [35]. This model proposes several cost-effective CCUS source–sink matching layouts that incorporate onshore and offshore integrated pipeline networks enhanced by the 45Q tax credit and carbon pricing incentives. A detailed plant-level analysis reveals spatial heterogeneity in carbon abatement costs, as indicated by the levelized cost of cement (LCOC), the levelized additional cost of cement (LACOC), and the levelized carbon avoidance cost (LCAC). Considering the impacts of different CCUS incentive policies, the findings further reveal priority opportunities for low-cost retrofitting at both the plant and provincial levels.

2. Methods and data

2.1. Systematic evaluation framework

The comprehensive SSM-Cement framework consists of four main modules, as depicted in Fig. 1. In the first module, a comprehensive database of CO₂ emissions is constructed; it covers 1132 existing cement plants (equivalent to 1550 clinker production lines) in China, which are combined with different industry-related and fuel-related emissions and plant-level production characteristics (e.g., size, lifetime, and capacity). After evaluating the plant-level clinker production scale and residual lifetime, 919 cement plants are identified as potential candidates for CCUS retrofitting. In the second module, a national database of CO₂ storage sites (with a resolution of 40 km × 40 km) is constructed based on their storage potential and injection capacity (reference was made to Fan et al. [36] for the assessment methods); it contains 1063 onshore deep saline aquifer (DSA) storage sites, 535 onshore EOR storage sites, 257 offshore DSA storage sites, and 114 offshore EOR storage sites. In the third module, a source–sink matching model with an optimization process that minimizes the cost of the full CCUS chain (CO₂ capture, pipeline transport, and storage) is constructed. An integrated onshore and offshore transport pipeline network covering national roads and natural gas pipelines is initially generated. This network enables the identification of CCUS-ready emission sources and storage sites based on the accessibility of the pipeline network (< 20 km). Further, considering various constraints such as the storage potential, injection capacity, pipeline flow conservation, pipeline capacity, EOR benefits, 45Q tax credits, and carbon market benefits (depending on the scenario), the cost-effective onshore and offshore shared CCUS pipeline network is obtained. Finally, the abatement potential and costs of CCUS technology retrofits are assessed by combining economic indicators of individual plants, such as the LCOC, LCAC, and LACOC. The regional heterogeneity in the abatement potential and costs in the cement industry is ultimately identified, and provincial CCUS early deployment planning is carried out.

2.2. Cement plant-level assessment

The cement plant-level assessment includes the calculation of CO₂ emissions and the suitability of plant retrofitting with CCUS technology.

2.2.1. Calculation of CO₂ emissions

This dataset covers 1132 operational cement plants and an annual clinker output of 1.51 billion tons, respectively representing around 97% and 98% of the national totals [37], [38]. The specific target is direct CO₂ emissions arising from the cement production process, including mineral thermal decomposition and fuel combustion [33]. Indirect emissions caused by electricity consumption are not included as they cannot be captured within the same plant. Given the possible geographical differences in the Chinese cement industry, the geographic coordinates, clinker production capacity, launch year, operating days, calorific value, and carbon content of each plant are taken into account. These details are used to emphasize the variation between provinces. The clinker emission factors are also adjusted according to the scale of clinker production at each plant. Furthermore, the technique outlined by the Intergovernmental Panel on Climate Change (IPCC) is employed to calculate the amount of CO₂ captured for each cement unit [39], as expressed in Eq. (1):

(1)

E_{i, t} = {PC}_{i, t} \times {RD}_{i, t} {(EF}^{clin} + {EF}^{fuel})

where E_i_,_t represents the annual CO₂ emissions from cement plant i in year t (t CO₂·a⁻¹); PC_i_,_t represents the clinker output capability of cement plant i in year t (t clinker·d⁻¹); RD_i_,_t represents the annual operating days of cement plant i in year t (d), which differs for each province; EF^clin represents the emission factors of the clinker production process, which are respectively 522.02 and 517.41 kg CO₂·(t clinker)⁻¹ for the production capacities of 2000–4000 and ≥ 4000 t clinker·d⁻¹ [33], [39], [40]; and EF^fuel represents the emission factor of the fuels required (kg CO₂·(t clinker)⁻¹) [33], [41], [42], which is calculated by Eq. (2):

(2)

{EF}^{fuel} = (U^{ce} / T^{c}) \times {NCV}^{c} \times {CC}^{c} \times O^{c} \times (44 / 12)

where U^ce represents the coal-equivalent consumption per unit of clinker produced (t cement·(t clinker)⁻¹); T^c represents the conversion coefficient of raw coal, 0.7143; NCV^c represents the low heat value of raw coal, 17.78–26.67 MJ·kg⁻¹, which differs for each province [33], [43];

{CC}^{c}

represents the carbon content of raw coal, 25.64–28.10 kg·GJ⁻¹, which also differs for each province [33]; and

O^{c}

represents the oxidation rate, 0.98 [33].

The annual CO₂ capture from the CCUS retrofitting of the cement plant can be calculated as Eq. (3):

(3)

{Acap}_{i, t} = E_{i, t} \times CR

where Acap_i_,_t represents the annual CO₂ captured from cement plant i in year t (t CO₂·a⁻¹); and CR represents the CO₂ capture rate, 0.9.

2.2.2. Screening of cement plant suitability

The clinker capacity (> 2500 t clinker·d⁻¹) is adopted as the first screening criterion because cement clinker production lines below 2500 t clinker·d⁻¹ were phased out by the end of 2021 [44] according to the Building Materials Industry Phase Out of Outdated Production Capacity Guidance Catalogue co-developed by the China Building Materials Federation. The remaining lifetime (> 15 years) is used as the second screening criterion to ensure that the candidate plants have at least 15 years of operation time after CCUS retrofitting. By applying these criteria, the initial 1132 cement plants are narrowed down to 919 candidates eligible for the CCUS source–sink matching process.

2.3. Source–sink matching optimization model for cement plants

As shown in Fig. 1, the core of the comprehensive assessment framework is the source–sink matching optimization model for the cement industry. Its crucial processes and basic assumptions are subsequently described, and more detailed information about the modeling process can be found in the publication by Fan et al. [36].

2.3.1. Basic assumptions

(1)The operational state and energy consumption of each facility are assumed to maintain their current levels after CCUS deployment begins in 2030. Committed CO₂ emissions over the residual lifetime are determined under the assumption that existing cement plants have an operating life of 40 years.

(2)Due to the current immaturity of pre-combustion capture and oxygen-enriched combustion capture technologies [45], post-combustion technology is considered to be CO₂ capture technology. Widely used amine-based absorbers are assumed to be the carbon capture method utilized in the cement industry [46].

(3)Captured CO₂ is transported via pipelines to the storage site; this is considered to be the least-cost transportation mode when large-scale CCUS technology is deployed [47]. The CO₂ transport pipeline network is assumed to follow existing national roads and gas pipeline routes in China, thus avoiding geographical constraints, land acquisition, and road rights costs. The emission sources and storage sites are assumed to be integrated into the candidate pipeline network based on spatial proximity (< 20 km).

(4)EOR and saline aquifers are respectively considered to be the main approaches for CO₂ utilization and storage, and these facilities are distributed in onshore and offshore basins in China. CO₂ is utilized to EOR and increase oil production while reducing the full-chain costs of CCUS projects [48]. To effectively accommodate the relatively high-volume CO₂ flow in the trunk pipeline, the CO₂ storage sites are assumed to have a resolution grid of 40 km × 40 km. Considering that CO₂ will diffuse in the geological structure after injection, 50 injection wells are assumed to be allowed within each grid [36], although many more wells can be dug in engineering practice.

(5)The pipeline network matching mode allows multiple emission sources to be connected to a shared network and potentially matched to several storage sites simultaneously, with the storage potential and injection capacity rate as constraints [49].

2.3.2. Objective functions and constraints

The source–sink matching model is designed to optimize the integration of emission sources with onshore and offshore storage sites, with the objective of minimizing the overall cost of the complete CCUS chain. Its objective function is expressed by Eq. (4):

(4)

\begin{matrix} Cost = \sum_{i} (CAP_{ca}_{i} + {OM_ca}_{i}) \times S_{i} + \sum_{(n, m), d} {(CAP_tr}_{d} + {OM_tr}_{d}) \times {Dist}_{(n, m)} \times P_{(n, m), d} \\ + \sum_{(well, j)} {((CAP_st}_{(well, j)} + {OM_st}_{(well, j)}) \times K_{j} - {Asto}_{j} \times D^{oil} \times R^{oil} \times P^{oil} \times L_{j}) \end{matrix}

where Cost is the total cost of CCUS full-chain technology for onshore and offshore storage from 2030 to 2060 (USD); CAP_ca_i is the capital cost of CO₂ capture facilities for cement plant i (USD); OM_ca_i is the cumulative operation and maintenance (O&M) cost of CO₂ capture facilities for cement plant i (USD); and S_i is a binary variable that indicates whether cement plant i is being matched by corresponding storage sites (i.e., if cement plant i is matched with a storage site, then S_i = 1; otherwise, S_i = 0). Moreover, CAP_tr_d is the capital cost of CO₂ transport pipelines (USD); OM_tr_d is the cumulative O&M cost of CO₂ transport pipelines (USD); Dist₍_n_,_m₎ is the geographic path length of an arc from node n to m; and P₍_n_,_m_),_d is a binary variable that indicates whether the pipeline with a pipe diameter of d should be constructed in the final pipeline network. CAP_st_(well,_j₎ is the capital cost of the CO₂ storage chain (USD), and OM_st_(well,_j₎ is the cumulative O&M cost of the CO₂ storage chain (USD), subscript “well” represent the actual number of wells drilled; K_j is a binary variable that indicates whether storage site j is being matched; Asto_j is the cumulative sequestration amount for storage site j (t); D^oil is the replacement ratio of CO₂ to oil, which is taken as 4:1 based on an actual engineering project in China’s Shengli Oilfield; R^oil is the replacement ratio of barrels and tons, which is taken as 7.3 barrels (bbl)·(t oil)⁻¹; P^oil is the price of oil; and L_j is a binary variable that indicates whether storage site j is an oil field site.

The cumulative sequestration amount for storage site j must be below its storage potential, as expressed in Eq. (5), and the annual sequestration amount for storage site j must be below its CO₂ injection rate capacity, as expressed in Eq. (6).

(5)

{Asto}_{j} \leq {Tsto}_{j}, \forall j \in J

(6)

\frac{{Asto}_{j}}{Period} \leq {Inj}_{j} \times 50, \forall j \in J

where Tsto_j is the storage potential of storage site j, J is the database of overall storage sites, Period denotes the total number of years in the period of CCUS operation, and Inj_j is the CO₂ injection rate capacity of storage site j.

The CO₂ flow in the pipeline achieves conservation for any Arc(n, m), as expressed in Eq. (7), and the actual CO₂ flow of Arc(n, m) must be below the maximum flow limit for a pipe with diameter d, as expressed in Eq. (8).

(7)

\begin{matrix} {Asto}_{n} \times K_{n} = {Acap}_{n} \times S_{n} + \sum_{(n, m)} {amount}_{Arc (n, m)} \times Period - \sum_{(m, n)} {amount}_{Arc (m, n)} \times Period, \forall n \in N, m \in N \end{matrix}

(8)

{amount}_{Arc (n, m)} \leq \sum_{d} P_{(n, m), d} \cdot {Limit}_{d}

where amount_Arc(_n_,_m₎ is the annual flow amount of CO₂ transported by the arc from node n to m corresponding to the pipeline; N is the database of overall nodes; and Limit_d is the maximum flow for a pipe with diameter d.

2.4. Economic indicators calculation

A comprehensive economic and technical assessment of the full-chain CCUS retrofits in each cement plant is performed based on the results derived from the source–sink matching optimization model. It should be noted that in the model, the results of the CO₂ transportation cost and CO₂ storage cost (EOR revenue) are respectively determined by each constructed pipeline and activated storage site, and do not directly correspond to a specific CCUS-ready plant. A specific cost allocation mechanism proposed by Fan et al. [36] is applied. All possible CCUS-ready plants passing within a single pipeline or storage site are identified, and the allocation weights for transportation and storage costs are then calculated based on the respective cumulative CO₂ captured by the CCUS-ready plants. Finally, all allocated transportation and storage costs are accumulated to represent the cost for each plant. This method yields the plant-level CO₂ transportation costs, CO₂ storage cost, and EOR revenue, which are used to determine the adopted economic indicators.

Levelized costs are considered vital indicators for examining the economic efficiency and competition of technologies [50]. The levelized cost of electricity (LCOE) is generally defined as the cost per unit of generated electricity [51], [52], [53]. Similarly, the LCOC is defined to quantify the cost per unit of cement production [54], as expressed in Eq. (9). Further, the LACOC and LCAC are calculated to demonstrate the additional economic costs associated with the CCUS retrofit. LACOC primarily reflects the additional cost per unit of cement production after the plant is retrofitted with CCUS technology, as expressed in Eq. (10). LCAC primarily reflects the net cost of abating one ton of CO₂ emissions for a cement plant retrofitted with CCUS technology, as expressed in Eq. (11).

(9)

{LCOC}_{i} = \frac{{CAP_pl}_{i} + {CAP_cc}_{i} + \sum_{t} ({OM_pl}_{i, t} + {OM_cc}_{i, t} - {EOR}_{i, t}) \times {(1 + r)}^{- t}}{\sum_{t} {Acem}_{i, t} \times {(1 + r)}^{- t}}

(10)

{LACOC}_{i} = \frac{{CAP_cc}_{i} + \sum_{t} ({OM_cc}_{i, t} - {EOR}_{i, t}) \times {(1 + r)}^{- t}}{\sum_{t} {Acem}_{i, t} \times {(1 + r)}^{- t}}

(11)

{LCAC}_{i} = \frac{{LACOC}_{i}}{{EF_pl}_{i} - {EF_cc}_{i}} = \frac{{LCOC}_{i} - {LCOC_pl}_{i}}{{EF_pl}_{i} - {EF_cc}_{i}}

where LCOC_i represents the LCOC of cement plant i retrofitted with CCUS technology (USD·(t cement)⁻¹); CAP_pl_i and OM_pl_i_,_t respectively represent the construction capital cost and annual O&M cost of cement plant i (USD), as expressed in Eqs. (12), (13); LACOC_i represents the LACOC of cement plant i retrofitted with CCUS technology (USD·(t cement)⁻¹); CAP_cc_i and OM_cc_i_,_t respectively represent the capital cost and annual O&M cost of cement plant i retrofitted with CCUS technology, as expressed in Eqs. (14), (15); EOR_i_,_t is the annual EOR revenue (there is no such benefit for saline aquifers); Acem_i_,_t is the output of cement plant i in year t; LCAC_i is the LCAC of cement plant i retrofitted with CCUS technology (USD·(t CO₂)⁻¹); EF_pl_i and EF_cc_i are the CO₂ emission factor for the absence and presence of CCUS retrofitting in cement plant i, LCOC_pl_i represents the LCOC of cement plant i before retrofitting with CCUS technology, and

r

is the discount rate.

(12)

{CAP_pl}_{i} = UC_pl \times {Acem}_{i}

(13)

{OM_pl}_{i, t} = UO_pl \times {Acem}_{i, t}

(14)

{CAP_cc}_{i} = UC_ca \times {Acem}_{i} + {CAP_tr}_{i} + {CAP_st}_{i}

(15)

{OM_cc}_{i, t} = UO_ca \times {Acem}_{i, t} + {OM_tr}_{i, t} + {OM_st}_{i, t}

where UC_pl and UO_pl respectively represent the unit construction capital cost and annual O&M cost of cement plant i (USD·(t cement)⁻¹); UC_ca and UO_ca respectively represent the unit capital cost and annual O&M cost of cement plant i retrofitted with CCUS technology (USD·(t cement)⁻¹); CAP_tr_i and OM_tr_i_,_t respectively represent the capital cost and annual O&M cost of CO₂ transport pipelines (USD); and CAP_st_i and OM_st_i_,_t respectively represent the unit capital cost and annual O&M cost of the CO₂ storage chain (USD).

2.5. Scenario setting

Currently, there are no substantial incentives for CCUS retrofitting in cement plants aside from EOR benefits. In this study, two incentive policy schemes are investigated: carbon pricing and the 45Q tax credit (Table 1). Given that the cement industry is recognized as a major emitter and has the potential to participate in China’s future carbon trading market, carbon pricing is considered a relevant policy incentive. Additionally, United States legislation (the Inflation Reduction Act) has expanded the 45Q tax credit to provide significant incentives for CCUS, with rates of up to 85 USD·(t CO₂)⁻¹ for permanent storage and 60 USD·(t CO₂)⁻¹ for EOR or other industrial utilization in 2022. This serves as a valuable reference for CCUS incentives in China. When incorporating carbon pricing or the 45Q tax credit into the CCUS retrofitting of China’s cement industry, the objective function of the source–sink matching optimization model is represented by Eqs. (16), (17).

(16)

\begin{array}{l} Cost_45 Q = \sum_{i} ({CAP_ca}_{i} + {OM_ca}_{i}) \times S_{i} + \sum_{(n, m), d} {(CAP_tr}_{d} + {OM_tr}_{d}) \times {Dist}_{(n, m)} \times P_{(n, m), d} \\ + \sum_{(well, j)} {((CAP_st}_{(well, j)} {+ OM_st}_{(well, j)}) \times K_{j} - {Asto}_{j} \times D^{oil} \times R^{oil} \times P^{oil} \times L_{j}) \\ + \sum_{j} {Asto}_{j} \times P^{seq} \times K_{j} \end{array}

(17)

\begin{array}{l} Cost_car = \sum_{i} {(CAP_ca}_{i} {+ OM_ca}_{i}) \times S_{i} + \sum_{(n, m), d} {(CAP_tr}_{d} {+ OM_tr}_{d}) \times {Dist}_{(n, m)} \times P_{(n, m), d} \\ + \sum_{(well, j)} {(CAP_st}_{(well, j)} {+ OM_st}_{(well, j)}) \times K_{j} - {Asto}_{j} \times D^{oil} \times R^{oil} \times P^{oil} \times L_{j}) \\ + \sum_{i} {Acap}_{i} \times P^{c} \times S_{i} \end{array}

where Cost_45Q and Cost_car are respectively the total cost of CCUS full-chain technology for onshore and offshore storage from 2030 to 2060 in scenarios S2_subsidy policy (SP) and S3_carbon policy (CP), unit are USD; P^seq is the CO₂ sequestration allowance under the latest 45Q tax credit, while DSA and EOR sequestration types differ; and P^c is the national CO₂ price in 2030 as predicted in the Net Zero Emissions (NZE) by 2050 Scenario by the World Energy Outlook 2022, with changes in the future.

2.6. Data sources

In this study, the cement plant data were mainly obtained from the cement-clinker enterprise lists publicly released by the provincial Ministry of Industrialization and Information in 2021. Specific details include each plant’s location, operational year, clinker production capacity, equipment models, and other essential information. The annual operating days were collected from policy documents regarding cement kiln shutdowns and production restrictions for each province. The CO₂ storage sites in onshore DSA, onshore EOR, offshore DSA, and offshore EOR considered in this study were sourced from the previous literature [36], [55], [56], [57]. The United States Department of Energy (US DOE) method was applied for storage potential calculations [58], and the injection rate capacity was determined using Darcy’s law [59]. Gross thickness and saline aquifer porosity data were collected from Geological Surveys in China, and recoverable volume, depth, and American Petroleum Institute (API) values were obtained from the Petroleum Basin Atlas of China and IHS Markit [60], [61]. The USD to CNY conversion rate was defined as 6.8974 based on the average in 2021 [62]. The carbon price of 90 USD in 2030 was derived from the NZE by 2050 Scenario by the World Energy Outlook 2022 [63]. The capital costs and annual O&M costs of offshore pipeline transport were both assumed to be 1.55 times higher than onshore costs [64], [65]. Similarly, the capital costs and O&M costs for both offshore EOR and DSA storage were assumed to be three times higher than onshore costs [47], [66]. The main parameters used in the analysis are listed in Table 2 [26], [49], [52], [63], [67], [68], [69], [70], [71], [72].

3. Results and analysis

3.1. Spatial distribution of candidate cement plants and CO₂ storage sites

In China, there is significant regional variation in both cement plant-scale carbon emissions and geological storage capacity, which impacts the overall pattern of CCUS source–sink matching outcomes. Out of the total 1132 existing cement plants, 213 will fail to meet the CCUS retrofit criteria due to having a clinker production capacity below 2500 t clinker·d⁻¹ and an insufficient remaining operational time (< 15 years) for CCUS deployment. The remaining 919 candidate plants are widely distributed across different regions; they are mostly concentrated in the central, eastern, and southern regions, and are more dispersed in the northeast and western regions (Fig. 2(a)). Between 2030 and 2060, plant-scale cumulative CO₂ emissions in China’s cement sector will vary from 11.9 to 283.4 Mt. The top five high-emission sources are Guangdong (2.35 Gt), Henan (2.09 Gt), Sichuan (2.08 Gt), Anhui (2.03 Gt), and Guangxi (1.78 Gt). The economically developed Yangtze River Delta and Pearl River Delta regions have a high demand for cement, and large-capacity facilities are predominantly located in Anhui, Guangdong, and Jiangsu Provinces, which respectively have average clinker production capacities of 5000, 4798, and 4942 t clinker·d⁻¹. In contrast, cement plants in the western and northeastern regions are considerably smaller, with average clinker production capacities ranging from 2500 to 4200 t clinker·d⁻¹ at the provincial level and cumulative CO₂ emissions ranging from 11.9 to 70.3 Mt between 2030 and 2060.

In China, there are 1063 onshore DSA sites, 535 offshore DSA sites, 257 onshore EOR sites, and 114 offshore EOR sites that are potentially linked to candidate cement plants. These sites have respective average CO₂ sequestration capacities of 940, 1672, 20, and 31 Mt, and respective average injection rate capacities of 5, 14, 13, and 15 Mt·a⁻¹. Onshore and offshore DSA sites have average CO₂ sequestration capacities that are 24.1 and 34.4 times higher than those of onshore and offshore EOR sites, respectively. Among the onshore basins, the Tarim Basin, Songliao Basin, and Subei Basin have the largest storage capacities of 282, 168, and 78 Gt, respectively. Among the offshore basins, the East China Sea Basin has the largest storage capacity of 356 Gt (Fig. 2(b)).

The CCUS screening procedure for China’s candidate cement plants is illustrated in Fig. 2(c). In 2020, the overall CO₂ emissions from China’s cement sector amounted to approximately 1.37 Gt CO₂, and 89% of these emissions are covered by the database. After screening the plants based on their infrastructure scale and lifetime, 919 candidates suitable for CCUS retrofitting were identified; these plants have estimated CO₂ emissions of 1.02 Gt·a⁻¹, accounting for about 74% of the total. Subsequently, 316 plants were excluded due to their inaccessibility to the CO₂ onshore and offshore pipeline network (within a 20 km radius). Considering a 90% capture rate, the final number of CCUS-ready cement plants is 603, with a maximum CO₂ emission of 0.60 Gt·a⁻¹. CCUS implementation in these plants would result in a peak reduction of 43.8% relative to the total CO₂ emissions in 2020. These CCUS-ready plants are widely distributed throughout Shandong (40.0 Mt), Henan (39.8 Mt), Anhui (36.5 Mt), Guangdong (36.0 Mt), and Guangxi (35.8 Mt) in China.

As shown in Fig. 2(d), China’s new and large-scale facilities are projected to emit at high levels exceeding 1.18 Gt·a⁻¹ from 2025 to 2040, accounting for 64% of the cumulative CO₂ emissions of 7.6 Gt over the period 2025–2060. After 2040, however, annual CO₂ emissions are expected to decline significantly from 1.01 Gt·a⁻¹ in 2045 to 0.51 Gt·a⁻¹ in 2050. This decline can be attributed to more cement plants reaching the end of their projected lifetime. The results suggest that early and widespread CCUS deployment could effectively mitigate massive CO₂ emissions from China’s existing cement infrastructure, leading to substantial savings on future carbon budgets.

3.2. Spatial layout of source–sink links between CCUS-ready cement plants and CO₂ storage sites

Considering the feasibility of creating onshore and offshore transportation routes, the source–sink matching patterns reveal cost-effective links between CCUS-ready cement plants and four categories of CO₂ storage sites. A typical source–sink matching layout is proposed to explore the maximum feasible abatement potential while balancing the overall CO₂ abatement cost and EOR revenue. This layout supports a cumulative 15.8 Gt of onshore storage (85%) and 2.7 Gt of offshore storage (15%) from 2030 to 2060. The onshore pipeline network is densely distributed in northern, central, southern, southwestern, and northeastern China, whereas the offshore pipeline network is more densely distributed in northern, eastern, and southern coastal areas.

Fig. 3(a) presents a detailed analysis of interprovincial and land–sea CO₂ flows for the period from 2030 to 2060. The five major CO₂ flows during this period exceed 500 Mt, as follows: Guangxi–Beibu Gulf Basin (683 Mt), Jiangsu–Anhui (637 Mt), Guizhou–Beibu Gulf Basin (622 Mt), Shandong–Jiangsu (529 Mt), and Sichuan–Hubei (527 Mt). Notably, the implementation of this CCUS layout necessitates approximately 61 500 km of pipeline infrastructure, among which onshore pipelines constitute the majority, measuring 59 500 km (96.8%), while offshore pipelines account for 3.2% (1975 km). This distribution underscores the significant reliance on terrestrial infrastructure to facilitate the effective transport of captured CO₂. As presented in Fig. 3(b), the total length of pipelines with diameters 4–30 inches (1 inch = 2.54 cm; annual flows between 1317 tons and 21.4 Mt) is 54 200 km, representing a significant proportion (6%–22%) and accounting for approximately 88% of the total pipeline length. These pipelines serve as feeder lines that connect decentralized cement plants and enhance the potential for emission reduction. In contrast, the share of large-diameter pipelines is relatively small, with both 62 and 70 inch pipelines comprising only 1% of the total. These larger pipelines function as backbone lines, and transport substantial CO₂ streams from various regions to designated storage sites. Fig. 4(a) presents the cumulative CO₂ capture across different provinces, highlighting the top five regions, namely Shandong (1.24 Gt), Henan (1.23 Gt), Anhui (1.13 Gt), Guangdong (1.12 Gt), and Guangxi (1.11 Gt), which account for 32% of the total abatement potential. Thus, the large-scale deployment of CCUS technology in China’s cement industry requires the consideration of the specific circumstances of various locations, as well as a variation in the construction of CO₂ capture, transport, and storage facilities.

To achieve a total CO₂ emission reduction of 18.5 Gt, 603 CCUS-ready cement plants across 27 provinces are successfully linked with 180 storage sites. Among the sequestration types, 189 cement plants are linked with 50 onshore DSA sites (13.5 Gt) mostly in the Bohai Bay Basin (onshore area), Nanxiang Basin, and Subei Basin, whereas 275 cement plants are linked with 111 onshore EOR sites (2.3 Gt) mostly in the Ordos Basin, Songliao Basin, and Bohai Bay Basin. Benefiting from favorable geological storage conditions in saline aquifers or oilfields, Anhui, Henan, and Tianjin have the highest cumulative onshore DSA storage (4.02, 3.45, and 2.28 Gt CO₂, respectively), while Xinjiang, Shandong, and Liaoning have the highest cumulative onshore EOR storage (0.48, 0.43, and 0.28 Gt CO₂, respectively; Fig. 4(b)). Three cement plants are linked with five offshore DSA sites (2.1 Gt) mainly located in the Beibu Gulf Basin and Bohai Bay Basin (corresponding to 2.05 and 0.01 Gt CO₂, respectively), while 97 plants are linked with 14 offshore EOR sites (0.6 Gt) mainly located in the Bohai Bay Basin, Pearl River Mouth Basin, and East China Sea Basin (corresponding to 0.35, 0.28, and 0.02 Gt CO₂, respectively); thus, the cost of offshore storage in Guangxi and Guangdong can be significantly decreased through EOR (Fig. 4(b)). EOR-related onshore and offshore storage (2.9 Gt) accounts for only 16% of the total CO₂ storage due to the relatively limited sequestration capacity of oil fields. The spatial heterogeneity of offshore storage sites clearly influences CCUS source–sink links in the eastern coastal regions. Cement plants are preferentially connected with nearby offshore storage sites to reduce overall CO₂ transportation costs and occasionally benefit from offshore EOR. Onshore storage requires a longer average transportation distance (91 km) than offshore storage (31 km) considering the corresponding routes. The majority of CO₂ abatement shares (68% onshore, 79% offshore) occur within a transportation distance of 0–100 km, followed by 20% onshore and 17% offshore within a transportation distance of 100–200 km. This indicates that sharing pipeline network facilities can contribute to significant economies of scale over short distances.

3.3. Economic cost of the CCUS retrofitting of Chinese cement plants

The economic cost analysis for the LCOC, LACOC, and LCAC demonstrates a generally increasing trend across the three scenarios (Fig. 5), indicating the relationships between CO₂ emissions, abatement costs, and EOR abatement rates for CCUS-ready plants. The EOR abatement rate is defined as the proportion of CO₂ cumulatively sequestered to corresponding EOR storage sites relative to total CO₂ capture for each cement plant from 2030 to 2060. A cement plant can be classified as EOR-dominant if its EOR share exceeds 0.5; otherwise, it is DSA-dominant.

As shown in Fig. 5(a), EOR-dominant plants that benefit from fuel revenues tend to fall within the low-cost range of LCOC (−51 to 71 USD·(t cement)⁻¹), whereas DSA-dominant plants are in the high-cost range of LCOC (−5 to 96 USD·(t cement)⁻¹). When various incentive policies are introduced, more cement plants may seek suitable DSA storage sites with sufficient sequestration capacity even if they are farther away, thus decreasing the LCOC by up to 270% while targeting an equivalent CO₂ emission reduction objective. In the S1_no policy (NP) scenario, the overall LCOC range is 31–96 USD·(t cement)⁻¹, with a high EOR abatement rate of plants observed in the range of 31–71 USD·(t cement)⁻¹ and a low EOR abatement rate of plants in the range of 64–96 USD·(t cement)⁻¹. The absence of EOR benefits causes a sharp increase in the LCOC curve. DSA-dominant plants become more common as the cumulative CO₂ abatement exceeds 2.7 Gt. In the S2_SP scenario, the overall LCOC range is from −51 to 73 USD·(t cement)⁻¹, including −51 to 46 USD·(t cement)⁻¹ for EOR-dominant plants and −13 to 73 USD·(t cement)⁻¹ for DSA-dominant plants. With increased sequestration subsidies to DSA sites, the LCOC gap between EOR- and DSA-dominant plants steadily narrows or even disappears as the CO₂ storage potential increases. The S3_CP scenario exhibits a similar cost distribution as the S1_NP scenario, but the introduction of carbon pricing results in a lower overall LCOC of −44 to 17 USD·(t cement)⁻¹. As shown in Fig. 5(b), various scenarios result in cumulative CO₂ storage ranging from 3.85 to 18.50 Gt (21%–100%), with China’s cement market price around 80 USD·(t cement)⁻¹ in 2021 [73]. The S2_SP and S3_CP scenarios, with an LCOC below 80 USD·(t cement)⁻¹, account for the majority (100%) of CO₂ storage. The S1_NP scenario, with a cumulative CO₂ storage of 12.8 Gt, primarily falls within the range of 60–80 USD·(t cement)⁻¹. The S2_SP scenario is mainly in the range of 20–40 USD·(t cement)⁻¹, while the S3_CP scenario exhibits a major share (83%) in the range of 0–20 USD·(t cement)⁻¹. This indicates that incentive policies generally contribute to CCUS cost reduction, with carbon pricing policies demonstrating greater abatement effects.

As shown in Figs. 5(c) and (e), the LACOC, LCAC, and LCOC curves have similar fluctuation patterns. In the S1_NP scenario, the LACOC estimations indicate additional costs or revenues ranging from −2 to 63 USD·(t cement)⁻¹. Specifically, 486 cement plants display a cumulative CO₂ emission reduction of 15.4 Gt (83%) from 2030 to 2060 with the LACOC primarily in the range of 60–70 USD·(t cement)⁻¹ (Fig. 5(d)). Similarly, based on the LCAC estimations in the S1_NP scenario, CCUS retrofitting results in carbon avoidance costs ranging from −5 to 140 USD·(t CO₂)⁻¹. In this scenario, 497 cement plants achieve a cumulative CO₂ emission reduction of 15.4 Gt (83%) from 2030 to 2060 with the LCAC primarily in the range of 80 to 120 USD·(t CO₂)⁻¹ (Fig. 5(f)). The introduction of the 45Q tax credit and carbon market-related incentives leads to a significant decrease in the LACOC and LCAC. Compared to the S1_NP scenario, the average LACOCs under the S2_SP and S3_CP scenarios decrease by 36 and 71 USD·(t cement)⁻¹, respectively, while the average LCACs under the S2_SP and S3_CP scenarios decrease by 78 and 153 USD·(t CO₂)⁻¹, respectively. As a result, under the three CCUS retrofit scenarios, 2, 165, and 603 cement plants with an LACOC and LCAC of less than 0 should be prioritized, as they have cumulative CO₂ emission reductions of 0.1, 4.6, and 18.5 Gt from 2030 to 2060, respectively. The LACOC and LCAC of CCUS-ready plants predominantly fall within the range of 0–40 USD·(t cement)⁻¹ and −120 to 20 USD·(t CO₂)⁻¹, respectively. This indicates that significant incentive effects are generated when the relevant subsidy policy exceeds the threshold.

3.4. Spatial heterogeneity of the CCUS retrofitting of cement plants in different provinces

Resource endowment and geological conditions may contribute to provincial-level spatial heterogeneity in onshore and offshore storage and the associated abatement costs, which can be explored under various CCUS retrofit scenarios. The LCAC exhibits a distinct spatial pattern, increasing sharply from 0–66 USD·(t CO₂)⁻¹ in northwestern China to 94–112 USD·(t CO₂)⁻¹ in southwestern China, indicating a “north-low and south-high” distribution (Figs. 6(a) and (b)). Specifically, onshore storage provides a cumulative CO₂ emission reduction of 15.8 Gt at an average LCAC of 90 USD·(t CO₂)⁻¹, while offshore storage enables cement plants, mainly in coastal areas, to achieve an emission reduction of up to 2.7 Gt at an average LCAC of 91 USD·(t CO₂)⁻¹. This similarity in costs between onshore and offshore storage is due to the potential EOR benefits and the limited transport distances involved when linking offshore storage sites with onshore cement plants.

The northeastern and northwestern regions demonstrate relative cost-effectiveness, with the average LCACs in Ningxia, Xinjiang, and Qinghai even lower than the national median, despite their average CO₂ storage amounts being only 23 Mt. Cement plants in these regions, where coal and oil reserves are abundant, typically have access to low-cost fuels, thus reducing the cost of CCUS projects via CO₂ utilization technologies such as EOR. Similarly, eastern, northern, and central China have moderate LCACs of 84, 86, and 92 USD·(t CO₂)⁻¹, respectively, with the LCAC ranges mainly covering 70–105 USD·(t CO₂)⁻¹. As DSA sites provide more sequestration capacity in addition to accessible oil fields, the average provincial CO₂ storage for these regions increases to cumulative levels of 5.0, 1.9, and 2.9 Gt, respectively. This is especially pronounced for CO₂ sequestration in the Subei Basin, Nanxiang Basin, and Southern North China Basin in central and eastern China. Shandong, Zhejiang, and Hunan Provinces have significant offshore sequestration potential and can link their coastal cement plants to DSA and EOR sites in the Bohai Bay Basin, East China Sea Basin, Beibu Gulf Basin, and Pearl River Mouth Basin. Shandong has an acceptable LCAC of 42 USD·(t CO₂)⁻¹ (below the national average), while the other regions have relatively higher costs ranging from 62 to 103 USD·(t CO₂)⁻¹. These provinces can leverage diverse auxiliary cementitious materials, such as abundant clay, sandstone, iron ore, and coal gangue in the Loess Plateau (northwestern and central China) and more slag resources in eastern China, to reduce process-related emissions. In contrast, southwestern and southern China have relatively high LCACs of 101 and 112 USD·(t CO₂)⁻¹, respectively. Their average provincial CO₂ storage amounts are respectively limited to 0.58 and 0.69 Gt due to severe injection rate capacity constraints in the Sichuan Basin. However, the incorporation of offshore storage could provide CCUS retrofitting opportunities and increase their storage amounts to 0.75 and 0.99 Gt, respectively. For example, nearly 90% of cement plants in Guangdong, Guangxi, and Guizhou could be linked with offshore storage sites in the Beibu Gulf Basin, Qiongdongnan Basin, and Pearl River Mouth Basin. Although these three regions have relatively high LCACs of 80, 99, and 111 USD·(t CO₂)⁻¹, respectively, due to related offshore CO₂ transportation and sequestration, significant emission reductions respectively amounting to 0.27, 0.57, and 0.51 Gt could be achieved by local large-scale cement plants.

The implementation of related incentives would lead to significant cost reductions for CCUS-retrofitted cement plants. When the 45Q tax credit is introduced, the average provincial LCACs will decrease to −34 to 55 USD·(t CO₂)⁻¹ for onshore sequestration and −20 to 46 USD·(t CO₂)⁻¹ for offshore sequestration (Fig. 6(c)). Cement plants in Shandong, Henan, Anhui, Sichuan, and Hunan Provinces emerge as particularly cost-competitive relative to the S1_NP scenario. These provinces offer favorable opportunities for CO₂ emission reduction due to their proximity to the Bohai Bay Basin, Nanxiang, Sichuan, and southern North China Basins, where the cumulative CO₂ emission reduction from 2030 to 2060 ranges from 1.01 to 1.24 Gt due to significant increases in CO₂ sequestration capacity. However, Guangxi, Guizhou, and Anhui could benefit from offshore CCUS deployment. These regions have the potential to achieve cumulative offshore CO₂ sequestration ranging from 0.69 to 1.11 Gt, corresponding to average LCACs of −20 to 46 USD·(t CO₂)⁻¹.

When the carbon pricing policy is introduced, nearly all of China’s candidate cement plants will be able to retrofit with CCUS projects at relatively low costs. The average provincial LCACs for onshore sequestration will fall to between −104 and −45 USD·(t CO₂)⁻¹ with a range of −115 to −46 USD·(t CO₂)⁻¹ for offshore sequestration (Fig. 6(d)). This indicates that the carbon pricing policy has a significant impact on the abatement costs of CCUS retrofitting. For onshore sequestration, cement plants located in Shandong, Henan, and Anhui Provinces show noteworthy potential for early CCUS demonstration projects with low abatement costs and high emission reductions reaching 1.10, 1.23, and 1.13 Gt, respectively. Regarding offshore sequestration, cement plants in Guangxi (average −61 USD·(t CO₂)⁻¹, cumulative sequestration 1.00 Gt), Guangdong (−58 USD·(t CO₂)⁻¹, 0.72 Gt), and Yunnan (−46 USD·(t CO₂)⁻¹, 0.63 Gt) linked with the nearby Beibu Gulf Basin also have viable CCUS retrofitting opportunities. These regions represent economically feasible plant-specific CCUS solutions for large-scale coastal emissions sources, with an average cost of 60 USD·(t CO₂)⁻¹ and a cumulative emission reduction of 0.60 Gt.

3.5. Sensitivity analysis

The impacts of various discount rates on the economic costs of CCUS-retrofitted cement plants are explored. The S1_NP scenario serves as the baseline for comparison, with 8% and 10% applied to assess the abatement costs across plants within the CCUS chain. The results show that the CCUS system cost would increase as the discount rate increases (Fig. 7(a)). Plants connected to DSA storage sites experience a greater cost impact compared to those linked to EOR storage sites. For example, in the S1_NP scenario, the average LCAC of the CCUS system is 88 USD·(t CO₂)⁻¹, with about 104 Mt·a⁻¹ of CO₂ sequestered to oil fields. When the discount rates are adjusted to 8% and 10%, the LCAC respectively increases to 104 and 110 USD·(t CO₂)⁻¹, while the CO₂ sequestered in oil fields respectively falls to 71 and 56 Mt·a⁻¹. These changes are primarily attributed to the lower proportion of CO₂ utilized for EOR, which cannot sufficiently offset the increasing costs of capture, transportation, and storage.

A sensitivity analysis was conducted on the spatial resolution of storage sites. In the S1_NP scenario, reducing the grid size of each site from 40 km × 40 km to 20 km × 20 km, with only one well drilled per grid, would increase the CCUS system cost with the average LCAC reaching 142 USD·(t CO₂)⁻¹ (Fig. 7(b)). Regarding the storage types, the number of storage sites (20 km × 20 km) matched to cement plants was found to increase to different degrees, yet the annual CO₂ storage decreases (Fig. 7(c)). It is noteworthy that due to additional EOR revenue, cement plants matched to oil fields incur lower costs (137 USD·(t CO₂)⁻¹) compared to those matched to saline aquifers (152 USD·(t CO₂)⁻¹), despite higher CO₂ transportation costs from oil fields (11 USD·(t CO₂)⁻¹).

In addition, the number of matches to EOR storage sites consistently exceeds that of DSA storage sites (38 onshore and 3 offshore), yet the annual CO₂ storage only represents a fraction of CO₂ stored in saline aquifers (13% onshore and 8% offshore).

4. Conclusions and policy recommendations

4.1. Conclusions

This study developed SSM-Cement, a comprehensive onshore and offshore source–sink matching optimization assessment framework for CCUS in the cement industry. The framework consists of a cement plant suitability screening module, a potential storage site assessment module, a source–sink matching optimization module, and an economic assessment module. Given prerequisites for constructing an actual CO₂ onshore and offshore transportation route, 603 CCUS-ready cement plants capable of sequestrating 18.5 Gt CO₂ from 2030 to 2060 were identified. A typical spatial layout was established for China’s cement sector, which exhibits a wide range of source–sink links between CCUS-ready cement plants and four categories of CO₂ storage sites. The links were determined by balancing factors including the CO₂ abatement potential, abatement cost, and EOR revenue.

Plant-level CCUS retrofitting costs were investigated using several economic indicators, namely the LCOC, LACOC, and LCAC. In the S1_NP scenario, EOR-dominant plants that benefit from fuel revenues were found to generally have lower costs regardless of the economic indicator used. DSA-dominant plants, conversely, tend to have higher costs. In the S2_SP scenario, with increased sequestration subsidies to DSA sites, the gap in the LCOC between EOR- and DSA-dominant plants was found to gradually narrow or even disappear with the increase of the storage potential. This suggests that higher subsidies will cause DSA-dominant plants to become more economically viable in terms of CCUS retrofitting costs. It is important to prioritize CCUS deployment in scenarios that offer significant EOR benefits, as this can effectively lower the overall costs of CCUS retrofitting. This is particularly evident in the S3_CP scenario, in which practically all economic parameters were found to be negative, indicating a favorable economic environment for CCUS deployment.

Cement plants with low CCUS retrofitting costs were identified to facilitate a large-scale CCUS deployment strategy tailored to China’s cement sector. The spatial pattern of regional LCAC revealed a “north-low and south-high” trend, with costs ranging from 0–66 USD·(t CO₂)⁻¹ in northwestern China to 94–112 USD·(t CO₂)⁻¹ in southwestern China. In northeastern China, onshore oil fields are the preferred storage option for CCUS projects. In central and eastern China, DSAs offer additional sequestration capacity along with accessible oil fields. The Subei Basin, Nanxiang Basin, and southern North China Basin in these regions were found to exhibit particularly significant potential for CO₂ sequestration. Despite slightly increasing (but still reasonable) costs, southern China, including Yunnan, Guizhou, Guangdong, and Guangxi, shows tremendous opportunities for CO₂ sequestration. These regions can benefit from linking offshore DSA and EOR storage sites in the Beibu Gulf Basin, Qiongdongnan Basin, and Pearl River Mouth Basin to allow for an economically viable CCUS solution.

4.2. Policy recommendations

The findings of this work highlight the importance of adopting an integrated, bottom-up approach at the plant level and developing China’s zero-emissions cement market to promote CCUS deployment in the Chinese cement industry. It is crucial to direct adequate investments toward the CCUS retrofitting of cement plants, and to encourage the development of zero-emission cement products to achieve this. Cooperation between the government and local cement companies should be facilitated and funding should be allocated to support CCUS-ready plants in the early phases of implementation. Additionally, the adoption of mandatory CO₂ emission reduction policies can further drive the deployment of CCUS in the cement industry.

To support the carbon neutrality target, early CCUS project demonstrations should prioritize onshore storage for cement plants in Shandong, Ningxia, Jiangsu, Inner Mongolia, and Hebei, and offshore storage should be prioritized for cement plants in Jiangsu and Shandong Provinces (Fig. 8). These regions benefit from spatial proximity to storage sites, thus minimizing transportation costs. Additionally, for cement plants in Qinghai, Xinjiang, Ningxia, Liaoning, and Gansu, the LCAC ranges from 43–62 USD·(t CO₂)⁻¹. By implementing governmental subsidy mechanisms (Figs. 9(a) and (b)), negative-cost opportunities can be readily identified. Furthermore, leveraging the benefits of the carbon market can facilitate cost-effective CCUS adoption in provinces such as Shandong, Henan, Anhui, Guangdong, Guangxi, and Yunnan (Figs. 9(c) and (d)).

It is important to acknowledge that CCUS technology alone, despite its significant abatement potential of up to 43%, will not be sufficient to achieve net-zero emissions for China’s cement sector. Therefore, it is necessary to implement additional strategies such as the early retirement of non-retrofittable plants or incremental technological advancements (e.g., clinker substitution, material efficiency, and biomass fuel substitution). By combining these approaches, the industry can achieve synergistic CO₂ emission reduction. Additionally, the diverse spatial distribution of source–sink links presents challenges and stringent requirements for effective CCUS hub planning in the Chinese cement industry. The proper planning and coordination of a shared CCUS infrastructure are critical in the initial phases to ensure the optimal utilization of resources and the efficient deployment of CCUS technologies.

Acknowledgments

The authors gratefully acknowledge the financial support of National Natural Science Foundation of China (72174196 and 71874193), the Open Fund of State Key Laboratory of Coal Resources and Safe Mining (SKLCRSM21KFA05), and National Program for Support of Top-Notch Young Professionals.

Compliance with ethics guidelines

Jing-Li Fan, Yifan Mao, Kai Li, and Xian Zhang declare that they have no conflict of interest or financial conflicts to disclose.

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