Carbon Emission Flows Research Articles

China's provincial power decarbonization transition in a carbon neutral vision

The power sector plays a crucial role in achieving the China's carbon neutrality target. However, there remain knowledge gaps regarding provincial emission reduction efforts toward carbon neutrality and the impact of carbon flows embodied in electricity transmissions. This study built a modeling framework, linking a bottom-up multi-regional power system model and Quasi-Input-Output approach, to investigate the provincial-level power system transition. Multiple combined scenarios based on shared socio-economic developments and different carbon mitigation policies were designed for a comprehensive assessment. Results indicates that the transition of the power system by 2060, under various scenarios, necessitates 7–7.8 TW of wind and solar photovoltaic power, 4810–6309 TWh of electricity transmissions, and 140–262 GW of coal power retrofits. Notably, carbon emission flows will accumulatively reach 12.7–18.7 Gt from 2020 to 2060. Inner Mongolia will bear a cumulative of more than 5 Gt of carbon flows from North China. When considering the indirect emissions, load centers such as Shandong will have higher peak emissions, and Shandong will replace Inner Mongolia as the largest emitter province. In addition, provincial emission factors under the influence of complex electricity transmissions and carbon flows are estimated.

Tracking Carbon and Ammonia Emission Flows of China's Nitrogen Fertilizer System: Implications for Domestic and International Trade.

China is the world's largest producer, consumer, and exporter of synthetic nitrogen (N) fertilizer. To assess the impact of domestic demand and international exports, we quantified the life-cycle CO2eq and ammonia (NH3) emissions by tracking carbon (C) and nitrogen (N) flows from coal/gas mining through ammonia production to N fertilizer production, application, and export. In 2020, China's N fertilizer system emitted 496.04 Tg of CO2eq and 3.74 Tg of NH3, with ammonia production and N fertilizer application processes contributing 36 and 85% of the life-cycle CO2eq and NH3 emissions, respectively. As the largest importers of N fertilizer, India, Myanmar, South Korea, Malaysia, and the Philippines collectively shifted 112.41 Tg of CO2eq. For every ton of N fertilizer produced and used in China, 16 t of CO2eq and 0.18 t of NH3 were emitted, compared to 9.7 t of CO2eq and 0.13 t of NH3 in Europe. By adopting currently available technologies, improving N fertilizer utilization efficiency and employing nitrification inhibitors could synergistically reduce CO2eq emissions by 20% and NH3 emissions by 75%, while energy transformation efforts would primarily reduce CO2eq emissions by 59%. The production of ammonia using green electricity or green hydrogen could significantly enhance the decarbonization of China's N fertilizer system.

Enhanced integrated energy system planning through unified model coupling multiple energy and carbon emission flows

Integrated energy system plays a crucial role in achieving low carbon emissions while supplying multiple loads. As the energy Internet continues to evolve, integrated energy system, acting as a cell-level prosumer, exhibits intricate coupling characteristics between multiple energy flows and carbon flows. This paper presents a flexible planning method based on a unified energy-carbon coupled operation model. It can realize blank-paper planning under multiple energy-carbon flow constraints, that is, jointly optimize equipment configuration and capacity size from scratch. The proposed method combines clustering algorithms and Latin hypercube sampling to generate the operational scenarios for renewable resources and energy loads, enhancing the representativeness and reliability of planning solutions. The results demonstrate that the proposed method can effectively meet the requirements of electricity, cooling and heat loads under different seasonal scenarios. Furthermore, it elucidates the corresponding carbon emission distribution across distinct energy flows of the planned system. Compared with the conventional fixed equipment connected planning method, the more flexible blank-paper planning method can achieve annual economic cost savings of about 7.5 % and reduce annual carbon emissions by 6.7 %.

A novel exergy-based cost and carbon footprint allocation method in the multi-energy complementary system

Energy efficiency, economic cost and carbon emission of multi-energy complementary systems are three key indicators to sustainable development in the low-carbon background. This paper analyzes the coupling relationships between energy, cost, and carbon emission flows in a combined cooling, heating, and power (CCHP) system. The CCHP system consists of biomass gasification, co-firing internal combustion engine by product gas and natural gas, concentrated photovoltaic thermal solar collector, and absorption heat pump. A novel exergo-carbon method with exergo-economic analyses is proposed to determine the exergy cost and carbon footprint rate of each stream in the CCHP system, and the unit cost and carbon footprint of multiple products of electricity, cold energy and heat energy are obtained by the proposed method. The impacts of co-firing ratio and photovoltaic coverage ratio on energy and exergy efficiencies and cost and carbon footprint of products are analyzed. The sensitivity of biomass carbon footprint is performed to show its influences. The total cost of products including economic and carbon costs, is discussed to guide the carbon market's pricing strategies. Under the design conditions, the unit exergy cost of electricity, chilled water and hot water are 0.1094, 0.7659 and 0.466 $ (kWh exergy)−1, and their unit exergy carbon footprints are 0.3651, 3.9050, and 2.3780 kg CO2-eq (kWh exergy)−1, respectively.

Bi-level distributionally robust optimization model for low-carbon planning of integrated electricity and heat systems

Interdependence among diverse energy forms within integrated electricity and heat systems (IEHSs) holds the potential to harness cooperation effects. This paper proposes a bi-level optimization model for the low-carbon planning of IEHSs, which realizes the coordination between IEHSs and their upstream networks. The precise carbon emissions of IEHSs are traced through carbon emission flows of components, power distribution networks, and district heating networks. Moreover, the distributionally robust optimization approach is employed to account for the inherent uncertainty in renewable power outputs faced by IEHS planning, by incorporating the moment information into an ambiguity set. The bi-level distributionally robust planning model of IEHSs is initially reconfigured into a second-order cone structure, employing the strong duality theory, second-order cone duality theory, and linear decision rules. Subsequently, an iterative approach is introduced to attain convergence of the reformulated bi-level model. Numerical results demonstrate the effectiveness and superiority of the proposed approach for reducing carbon emissions and economic costs of IEHSs.

Multi-agent low-carbon optimal dispatch of regional integrated energy system based on mixed game theory

In the context of global warming and energy scarcity, regional integrated energy system (RIES) can effectively improve energy utilization efficiency and reduce carbon emissions. However, this leads to the increased complexity of the market transactions. To this end, based on the mixed game strategy, a multi-agent low-carbon optimal dispatch model of RIES is proposed in this paper. Firstly, to fully consider the low-carbon objective of the system, a reward and punishment ladder carbon trading mechanism and a ladder integrated demand response (IDR) model are developed. Then, the decision models of the energy management operator (EMO), multiple energy hub agents (EHAs) and the user load aggregator (ULA) are constructed respectively with the goal of economy, and carbon emission flows are introduced as constraints. The interactive trading process of various stakeholders is simulated by a mixed game with master-slave game nested bidding strategy. Finally, the economics and carbon emissions of the system in different scenarios are analyzed by examples, and the effectiveness of the proposed model is verified. Numerical simulation results show that the proposed method not only has good economic and low-carbon environmental protection benefits, but also ensures the interests of various stakeholders.

Research on bi‐layer low carbon scheduling strategy for source‐load collaborative optimization based on node carbon emission intensity

AbstractTo accurately calculate the carbon emission of integrated energy system (IES), and fully explore the potential for load side on carbon emission reduction, this paper proposes a method of guiding load to participate in demand response based on node carbon emission intensity, and constructs a bi‐layer low‐carbon scheduling model for source‐load collaborative optimization. First, the carbon flow calculation model of IES in the total process is established, such as source, network, load, and storage. It can depict the carbon emission characteristics of energy conversion equipment and energy storage devices. The principle of proportional sharing is used to track carbon emission flows, the changes in carbon emission intensity at each node is perceived from a spatiotemporal perspective. Second, carbon flow analysis is incorporated into the load demand response mechanism, and a carbon emission model for load aggregator (LA) after demand response is established based on the node carbon emission intensity. Third, a bi‐layer low‐carbon scheduling model is constructed, which considers the source‐load collaborative optimization. The upper layer is the optimal economic dispatch of IES operators, while the lower layer is the optimal economic dispatch of LAs. Finally, the effectiveness of the proposed method is verified using the system as an example, such as improved 14‐node power grid, 6‐node heating network, and 6‐node nature gas network.

Low-Carbon Economic Dispatch of Integrated Energy System Considering Expanding Carbon Emission Flows

Low-Carbon Economic Dispatch of Integrated Energy System Considering Expanding Carbon Emission Flows

Interprovincial inequality between economic benefit and carbon footprint: Perspective from China's Construction industry

Trade between regions not only brings about the exchange of goods and services but also leads to the transfer of emissions. As one of the larger emitting industries, the unequal exchange between environmental costs and economic benefits embodied in trade of the Construction industry has rarely been quantified. This paper applied a multi-regional input-output model to quantify the Construction-related carbon footprint (CF) and carbon emission flows among Chinese provinces. Subsequently, a regional environmental index was built to investigate the unbalanced exchange between Construction-related environmental costs and economic benefits embodied in the interprovincial trade. We found that the provincial per capita CF of Construction was unevenly distributed, with wealthier coastal regions generally having larger CF than poor inland regions. Compared with inland provinces, coastal ones have gained more economic benefits and lower environmental pressure. For example, over 75% of Construction-related carbon emissions in wealthier provinces (Beijing and Shanghai) were outsourced, while 60% of the value-added triggered by these provinces' Construction was retained within the region. However, with the progress of technology and the optimization of trade structure, the REI index decreased by about 30% during 2012–2017. This inequality problem gradually alleviated. Addressing these inequality issues could provide a basis for developing mitigation strategies across different provinces in the Construction industry.

A network analysis of carbon emission flows among marine industries in China

In recent years, environmental problems have become an important bottleneck restricting the sustainable development of Marine economy in China. CO2 is one of the main greenhouse gases which contributes to marine environmental problems. As CO2 emissions can transfer among industries, identifying the industries that release CO2 most and clarifying the carbon emission flows among marine industries are helpful for decision-makers to curb CO2 emissions of marine industries. This paper applies the network method to measure carbon emission flows. First, carbon transfer coefficient is calculated. Second, carbon transfer network of marine industry is constructed based on carbon transfer coefficient. Then the structure of marine industry carbon transfer network is analyzed. Finally, the method proposed in this paper is applied to the case of China and some suggestions for carbon reduction is put forward.

Virtual Carbon Flow in China’s Capital Economic Circle: A Multi-Regional Input–Output Approach

The Capital Economic Circle (CEC) is the area with the largest economic aggregate in northern China and has a strong status in driving the economic development of China. However, the industrial structure dominated by high energy consuming industries leads to a large number of carbon dioxide emissions, and the imbalance between economic development and carbon emissions in CEC is serious; therefore, it is necessary to explore how to solve the carbon imbalance problem of the CEC by relying on interregional cooperation. Based on China’s multi-regional input–output tables of 2012, 2015 and 2017, this paper proposes the CEC carbon-extended, multi-regional input–output model to measure virtual carbon flow and analyze how the industrial structure leads to the imbalance of carbon flow distribution in CEC. Indicators such as direct carbon emission coefficients, complete carbon emission coefficients and carbon emissions pull coefficients of the industrial sectors in CEC are calculated and the physical carbon emission and virtual carbon flows among the industrial sectors and the regions are evaluated. The results show that there are potential constraints from the uncoordinated configuration of industrial innovation chains among the CEC, and the “carbon imbalance” of CEC is mainly reflected in the backward production technology of Hebei and its inefficient connection with the industrial innovation chain of Beijing and Tianjin. It is suggested that policymakers should promote the low-carbon production system and strengthen green energy development and utilization to enhance green development in CEC. In future research, we should pay attention to the updating method of the input–output table and the development of carbon circular networks. This study has implications for some areas of China and developing countries in Asia, which also have an imbalance between industrial economy development and carbon emissions, and a similarity in space structure and industry layout with CEC.

Patterns and determinants of carbon emission flows along the Belt and Road from 2005 to 2030

The Belt and Road Initiative (BRI) has promoted economic growth of participating countries while giving rise to profound environmental consequences. To steer the BRI towards a low-carbon and green development, it is necessary to analyze past trajectories and future trends of BRI's CO2 emissions. To this end, we assess the patterns and determinants of emission flows along the BRI during 2005–2030 using the multi-region structural decomposition analysis technique. For the period 2005–2015, we show that intermediates export of the BRI embodied more CO2 emissions than final goods export. The significant technological improvement only partly offset the emission growth stemming from the deteriorated cross-border production structure and the surging final demand of the BRI in the past. For the period 2015–2030, our prospective analysis indicates that emissions embodied in exports of participating countries increase by over 20% in the reference scenario where historical development patterns of the BRI continue. The rise might be even higher if the initiative ends. On the contrary, enhancing diffusion and adoption of low-carbon technologies and promoting green trade within the BRI show substantial emission mitigation potential. Our empirical results reveal directions and priorities for policymaking in the pursuit of a green BRI.

Identifying the key sectors in the carbon emission flows along the production chain paths: A network perspective

Effectively reducing carbon emissions is a serious issue faced by many countries. Identifying key sectors in terms of carbon emissions in production activities is vital for policy-making regarding energy related carbon emission reductions. This paper built a carbon-flow-based production chain network and proposed five indicators, including direct outflows, direct inflows, self-flows, indirect outflows and indirect inflows of carbon emissions, to quantify the importance of sectors to carbon emissions. The results showed that there were no strong correlations among the different roles of sectors. This independence of sectoral roles indicated that it was necessary to measure the importance of sectors from different perspectives. The results also showed that a few sectors played important roles in carbon emission flows. It indicated that the growth of carbon emissions in China was direct and indirectly driven by a few key sectors. Finally, the results of clustering analysis showed the clusters exhibited significantly different features. Commonly, industries processing primary products played core roles in production chains. Most industries processing deep-processing products had strong inflows of carbon emissions. Such information provides a valuable reference to make carbon reduction policies according to the roles of sectors in the production chains.

Policy assessments for the carbon emission flows and sustainability of Bitcoin blockchain operation in China

The growing energy consumption and associated carbon emission of Bitcoin mining could potentially undermine global sustainable efforts. By investigating carbon emission flows of Bitcoin blockchain operation in China with a simulation-based Bitcoin blockchain carbon emission model, we find that without any policy interventions, the annual energy consumption of the Bitcoin blockchain in China is expected to peak in 2024 at 296.59 Twh and generate 130.50 million metric tons of carbon emission correspondingly. Internationally, this emission output would exceed the total annualized greenhouse gas emission output of the Czech Republic and Qatar. Domestically, it ranks in the top 10 among 182 cities and 42 industrial sectors in China. In this work, we show that moving away from the current punitive carbon tax policy to a site regulation policy which induces changes in the energy consumption structure of the mining activities is more effective in limiting carbon emission of Bitcoin blockchain operation.

Structural evolution of China's intersectoral embodied carbon emission flow network.

Mount of embodied carbon emissions flow along industrial chains and form a complex network. In order to reveal the structure and evolution characteristics of embodied carbon emission flow network among China's industrial sectors, this study applies a complex network theory to construct six embodied carbon emission flow networks with 30 sectors on the basis of China's input-output tables from 2002 to 2015. Through the analysis of complex network technology indicators, the overall structural characteristics of the network, the key sectors, and the key flow paths are analyzed. Main results show that six embodied carbon emission flow networks all have the small-world characteristics; there is an industrial cluster phenomenon in the network. During the study period, construction, manufacturing, and service-related industry community are the absorption sites for embodied carbon emissions. Coal- and petroleum-related industry communities are the divergent sites for embodied carbon emissions; moreover, electric and heat power and fuel processing are the important "suppliers" of embodied carbon emissions; construction and other service are the important "consumers" of embodied carbon emissions. Non-metallic products are the important "transmitters" of embodied carbon emissions. Metal smelting and chemical industry are at the core of the network because of their high weighted degree and betweenness centrality. The central effect of key sectors continues to increase over time; furthermore, the distribution of embodied carbon emission flows in the six networks all have long-tail characteristics, and this characteristic became more prominent over time. There are key edge-weights in the networks. About 11 to 15% of the edges carry 80% of the embodied carbon emissions. Further based on edge-weight analysis, this study identifies the key paths of embodied carbon emission flow in the six networks, and most key paths pass through construction. Thus, such key sectors and key flow paths should receive more attention when making carbon emission reduction policies.

Ecological network analysis of carbon emissions from four Chinese metropoles in multiscale economies

As megacities, metropoles play an important role in carbon emission reduction in China. In this study, four Chinese metropoles (Beijing, Tianjin, Shanghai, and Chongqing) were selected to investigate integral carbon emissions at three scales (city, national, and global) by combining ecological network analysis with input-output analysis. The complex structures and relationships of carbon emission flows in 2010 due to interregional and international trade could be further evaluated. The results showed that, within the metropoles themselves, because of adjustments to the industrial structure and the promotion of tertiary industry, more than 11% of integral carbon emissions input in Beijing and Shanghai derived from the services and construction sectors. At the national scale, Beijing, Tianjin, and Shanghai were the net recipients of carbon emissions, mainly from the northwestern, central, and northern regions, owing to geographic proximity. The integral flow from the northwest region to Shanghai was the highest (22.37 Mt CO2e). At the global scale, carbon emission flows exported from Beijing, Tianjin, and Shanghai were higher than in Chongqing, as the three metropoles are located near harbors. Shanghai’s integral export value was the highest at over 31 Mt CO2e. This analysis aims to provide a scientific foundation for appropriate decarbonization actions, which can help policy makers allocate emission-reduction targets for metropoles and regions. On the one hand, policy makers can mitigate carbon emissions from an integral perspective; on the other, at the city and regional scales, they can guide metropoles or regions to reduce emissions based on their own development status.

China’s intra- and inter-national carbon emission transfers by province: A nested network perspective

Since China carries an increasingly significant responsibility in carbon emission reduction, a systematic assessment from the multi-scale and multi-regional perspective is essential to examine the region-specific carbon emissions and different kinds of carbon transfer patterns. By identifying carbon emission flows among 31 domestic provincial administrative regions and 184 foreign countries/economies, this work examines the domestic and foreign carbon emission flows of Chinese provinces/municipalities based on the intra- and inter-national relations. Overall, the provinces and municipalities in China are divided into 4 patterns according to carbon emission flows, among which inland provinces mainly engage in domestic carbon emission transfers, western regions generally receive carbon emissions with main carbon outflows in northeastern and central provinces, and coastal regions play an essential role in balancing carbon emission surpluses and deficits between domestic and foreign regions. For different sub-regions in China, recognizing carbon emission transfer relations contributes to the synergetic and sustainable regional development from a tele-connected perspective. With the nested network analysis, the multi-scale and multi-regional assessments focusing upon China’s provinces and municipalities extend the existing research to both national and global scales, providing a solid foundation for sustainable regional development in China.

The mutual benefits from Sino-Africa trade: Evidence on emission transfer along the global supply chain

The carbon-emission transfer between two representative developing economies - China and Africa - behind the international trade has aroused quite a few controversies, which have not been fully estimated and understood yet. In this paper, the Multiregional Input-Output (MRIO) method is applied to the participants of Forum on China-Africa Cooperation (FOCAC) from the global perspective to reveal the roles both China and Africa have played in the global supply chain as either the original emitter or the final consumer, and to depict the evolution pattern of carbon transfer via Sino-Africa trade from the year 2000–2015. The findings are as follows: 1) China has played the role of net exporter of embodied carbon-emission in Sino-Africa trade, for the amount of emitted carbon China had born yet resulted by consumption in Africa well surpassed that vice versa. 2) Compared to the carbon-emission flows embodied in EU-Africa and US-Africa trades, China has shouldered more carbon-emission derived from Africa's consumption. 3) The sectoral contribution and intensities of embodied carbon-emission correspond to the trading pattern between China and Africa, which stems from the two parties' comparative advantages and economic complementarity. 4) The intensities of embodied carbon-emission on both sides are declining towards a rosy prospect, which indicates an improving carbon-emission efficiency of both economies. From a global perspective, both China and Africa play a positive part in carbon-emission reduction. The results in this study can facilitate low-carbon and high-efficiency trading link between the two economies.

Carbon network embodied in international trade: Global structural evolution and its policy implications

There are overwhelming proofs that world-wide carbon emission profiles have been substantially shaped by carbon leakage through international trade. However, it has been unclear how structure and functions of the global carbon transfers evolve in terms of a complex network. Therefore, this study applies a series of network tools to depict the evolution features of the global carbon flow network from 1995 to 2011 as supported by a systems multi-regional input-output analysis. At global level, the network density increases essentially, indicating the widely expanding carbon leakages among economies. The increasingly distinct scale-free distribution for cumulative degree/weighted degree implies the network's intensified heterogeneity structure. At regional level, a new tripartite cluster structure has been identified by the three gradually stabilized communities centered on USA, China and Europe. At national level, the evolution for all economies' roles, especially two prominent groups (i.e. G8 and BRICS), is enunciated by coreness in context of the core-periphery structure, highlighting the significance of monitoring core economies' carbon emission flows. The results urge the need to shift from local carbon mitigation in silos to global collective and inclusive governance. Regional cluster structure's identification highlights the urgency for multinational cooperation on emission mitigation within the three newly formulated communities.

Residential carbon emission embedded in China's inter-provincial population migration

Population migration embodies virtual residential energy consumption and carbon transfer from the origin to the destination. Based on the differences of the per capita levels between the sending-out origins and arriving-in destinations, we develop a model to estimate the inter-spatial transfer flows of residential carbon emissions, broken down by rural-to-urban, rural-to-rural, urban-to-rural and urban-to-urban flows. The net value of transfer-in and transfer-out residential carbon emission contributes to the change of the whole carbon emission. Using the latest census data and energy balance sheet in 2010, China's inter-provincial residential carbon emission flows embedded in the population migration were calculated and visualized. We found that China's non-Hukou migration increased the national total residential carbon emission. The largest transfer flows were mainly from central to eastern China. The northern provinces were also distinct destinations due to the high-carbon energy structure. The regional difference of residential energy consumption structures, the unbalanced regional economic development and origin-to-destination interaction were the main influencing factors. To promote low-carbon and environment-friendly urbanization, the energy optimization policy should be enhanced in the identified regions, especially in the Beijing-Tianjin area.