Global Energy-related CO2 Emissions Research Articles

Fundamental Understanding of Marine Applications of Molten Salt Reactors: Progress, Case Studies, and Safety

Marine sources contribute approximately 2% of global energy-related CO₂ emissions, with the shipping industry accounting for 87% of this total, making it the fifth-largest emitter globally. Environmental regulations by the International Maritime Organization (IMO), such as the MARPOL (International Convention for the Prevention of Pollution from Ships) treaty, have driven the exploration of alternative green energy solutions, including nuclear-powered ships. These ships offer advantages like long operational periods without refueling and increased cargo space, with around 200 reactors already in use on naval vessels worldwide. Among advanced reactor concepts, the molten salt reactor (MSR) is particularly suited for marine applications due to its inherent safety features, compact design, high energy density, and potential to mitigate nuclear waste and proliferation concerns. However, MSR systems face significant challenges, including tritium production, corrosion issues, and complex behavior of volatile fission products. Understanding the impact of marine-induced motion on the thermal–hydraulic behavior of MSRs is crucial, as it can lead to transient design basis accident scenarios. Furthermore, the adoption of MSR technology in the shipping industry requires overcoming regulatory hurdles and achieving global consensus on safety and environmental standards. This review assesses the current progress, challenges, and technological readiness of MSRs for marine applications, highlighting future research directions. The overall technology readiness level (TRL) of MSRs is currently at 3. Achieving TRL 6 is essential for progress, with individual components needing TRLs of 4–8 for a demonstration reactor. Community Readiness Levels (CRLs) must also be addressed, focusing on public acceptance, safety, sustainability, and alignment with decarbonization goals.

Modeling building energy self-sufficiency of using rooftop photovoltaics on an urban scale

The significant contribution of buildings to global energy-related CO2 emissions and climate change has led to projections of a carbon–neutral building stock by 2050. This study evaluates the potential contribution of rooftop photovoltaics to urban energy self-sufficiency by developing an enhanced CityBEM framework, our in-house urban building energy model (UBEM). This methodology enables city-scale, simultaneous simulations of building energy use and rooftop photovoltaic retrofitting with low computational time. CityBEM’s robustness and high spatiotemporal resolution facilitate transient simulations of individual buildings with diverse usage types across large urban areas, addressing common computational constraints and input data limitations in UBEM applications. The rooftop photovoltaic model in CityBEM utilizes a comprehensive approach with physics-based modeling of crystalline PVs, model validation, and a proper design of array networks to manage self-shading effects. More than 57,000 buildings with a combined footprint of 32.37 million square meters are located in the simulation test case covering downtown Montreal (Quebec, Canada) and the surrounding areas. Results indicate that rooftop PV adoption in these buildings could potentially generate 5.9 TWh of electricity annually, reduce energy demand by 27.3%, and achieve an average annual energy saving of 40%. This local generation could also reduce operational CO2 equivalent emissions by over 0.2 megatons. Overall, this study highlights the significant potential of rooftop photovoltaics for a cleaner, more energy self-sufficient urban future.

Carbonate Electrolysis for Energy Efficient Direct Air Capture of CO2

Yearly global energy related CO2 emissions continue to increase, reaching a record breaking 37 billion metric tons in 2022. As a major greenhouse gas, CO2 levels need to be reduced by 10s of gigatons to prevent the worst of climate change, something that is no longer feasible with net-zero emissions alone. Removing atmospheric CO2 is therefore of critical importance for the future of our planet. While major improvements have been made in CO2 capture from large point sources, a significant portion of CO2 emitted each year from the United States comes from distributed sources such as cars and smaller factories. Due to the dilute concentrations of CO2 in ambient air, Direct Air Capture (DAC) needs to be highly selective to preferentially absorb CO2 to collect useable amounts. These challenges have made current DAC systems quite costly, both energetically and economically, and require vastly different strategies than carbon capture from concentrated sources.At Giner, we are developing a novel process for the capture and regeneration of CO2 from air into a purified, concentrated CO2 stream that can be redirected as a feedstock for a wide range of applications, including chemical manufacturing and syngas formation. This process involves the capture of CO2 in a concentrated KOH solution using a high-surface area air contactor to form potassium carbonate. The potassium carbonate is then efficiently electrolyzed in a hydrogen-assisted process to regenerate the CO2 at a low operating potential, increasing the electrical efficiency of the process while producing concentrated and purified CO2. In addition, water, hydrogen, and KOH are also regenerated as byproducts that can be recycled back into the CO2 capture and electrolysis processes, reducing both overall energy and chemical consumption.Giner has developed a unique 3-compartment carbonate electrolysis flow cell. Using our electrolyzer, we have seen operating voltage as low as 1.2 V at 100 mA/cm2 in a 5 cm2 cell for potassium carbonate conversion to CO2 with H2 assisted electrolysis. Significant improvements in operating voltage have come from optimization of gas-diffusion layers (GDLs), cell geometry, and membrane selection. Furthermore, we have achieved >97% pure CO2 formation in the internal flow-through compartment. Currently, scale-up is in progress to apply these developments to approach comparable conditions in a 50 cm2 multi-cell stack. Further developments will enable pairing with an in-house, carbonate based, air contactor allowing for capture and regeneration of over 1 ton CO2 per year. Acknowledgement: The project is financially supported by the Department of Energy's ARPA-E Office under the Grant DE-AR0001495

Sustainability and Resilience Assessment Methods: A Literature Review to Support the Decarbonization Target for the Construction Sector

It is a well-known issue that the 2050 target of carbon emissions neutrality will be reached only with the co-operation of all the interested sectors, and the construction sector could be one of the main contributors to this change. With the built environment globally responsible for about 40% of annual global energy-related CO2 emissions, the construction sector offers an important opportunity to drive transformative change and presents the most challenging mitigation potential among all industrial sectors, which also brings opportunities for adopting sustainability practices and increasing resilience. This paper presents a systematic literature review of those two pivotal concepts to reach the decarbonization goal: sustainability and resilience. Starting from an extensive literature review (2536 scientific documents) based on the PRISMA statement, the definitions and assessment methodologies of those concepts for the construction sector have been studied. The methodological approach followed for their analysis has been conducted on a first selection of 42 documents, further reduced to 12 by using clear inclusion criteria to identify the integrated assessment procedures. The main goal of this study is to clarify the correlation between sustainability and resilience concepts for constructions and their integrated assessment, in line with the latest regulations and market needs. The results show that, currently, sustainability and resilience are mainly evaluated in a distinct way to obtain building energy performance certificates, as well as to quantify the building market value and its complementary contribution to the ‘energy efficiency first’ principle and energy-saving targets towards the emergent issue of climate change. Few works focus on the integrated assessment of both concepts considering the construction industries’ point of view about materials and/or systems for buildings. The novelty of this study is the critical review of the current sustainability and resilience integrated assessment methods used for the construction value chain, declined for four main target groups. Researchers, policymakers, industries, and professionals could gain dedicated insights and practical suggestions to put in practice the elements of circular economy, ecological innovation, and cleaner production, which are essential in order to drive the decarbonization of the built environment.

Porous metal oxides in the role of electrochemical CO2 reduction reaction

The global energy-related CO2 emissions have rapidly increased as the world economy heavily relied on fossil fuels. This paper explores the pressing challenge of CO2 emissions and highlights the role of porous metal oxide materials in the electrocatalytic reduction of CO2 (CO2RR). The focus is on the development of robust and selective catalysts, particularly metal and metal-oxide-based materials. Porous metal oxides offer high surface area, enhancing the accessibility to active sites and improving reaction kinetics. The tunability of these materials allows for tailored catalytic behavior, targeting optimized reaction mechanisms for CO2RR. The work also discusses the various synthesis strategies and identifies key structural and compositional features, addressing challenges like high overpotential, poor selectivity, and low stability. Based on these insights, we suggest avenues for future research on porous metal oxide materials for electrochemical CO2 reduction.

Modeling High-Power Density Ceria-Based Direct Ammonia Fueled SOFC Stacks for Mobile Applications

The transport sector currently accounts for 23% of the global energy-related CO2 emissions, with an average annual growth of +1.8% since 2010, which is faster than for any other end-use sector [1]. Decarbonization of the mobility sector is particularly challenging due to the highly strenuous space, weight and efficiency demands for a power generation system applied for vehicle propulsion. Batteries have established themselves as a solution for the electric propulsion of passenger cars. However, their low energy densities and high recharging durations hinders their deployment in vehicles with large gross weight including trucks, ships, trains and airplanes [2, 3]. High-temperature solid oxide fuel cells (SOFCs) possess many advantageous characteristics compared to polymer electrolyte membrane (PEM) fuel cells that can be effectively exploited in a vehicle, such as high efficiency, fuel flexibility and impurity tolerance. SOFCs can be directly run with a great variety of fuels, such as NH3, which is currently regarded to be a very promising energy and hydrogen carrier, mostly due to its carbon neutrality, favorable volumetric energy density (12.7 MJ/L) and transportability [4].In this contribution, we assess the performance of intermediate temperature direct NH3-fueled SOFC stacks as a highly efficient power generation source for mobile applications by means of a detailed multi-physics modeling approach, comprising investigations on electrode, button cell, and stack scales. The modeled SOFC stack is intended to be integrated in a hybrid system concept by coupling with a gas turbine.Firstly, a 1D model of cell containing a gadolinium-doped ceria (GDC) electrolyte is developed based on an established multi-scale computational framework [2]. The electrochemical sub-model is subsequently parametrized and validated through reproducing measurements collected on a high-power density Ni-GDC/GDC/SSC-GDC cell. In order to physically account for the electronic leakage current due to mixed ionic-electronic conduction (MIEC) properties of the ceria-based electrolyte, the model contains the implementation of a distributed charge-transfer model that solves individual electronic and ionic conduction pathways across all constituents of the membrane-electrode assembly (MEA) [5]. The decomposition of NH3 on the surface of the Ni particles in the fuel electrode is modeled based on a thermodynamically consistent 12-step elementary kinetic mechanism [6]. The thermo-catalytic and electrochemical sub-frameworks are then integrated into a 3D stack model, which is built upon a lightweight design.The numerical simulations indicate that the performance of the SOFC stack based on the anode-supported GDC-electrolyte cell design is not only highly sensitive to the temperature, but also to the selection of the absolute pressure level. Results suggest the stack to reach a very promising performance in the intermediate temperature range with a predicted ASR of ~0.7 Ω cm2 at 550 °C, pure NH3 feed and 50% anode off-gas recirculation. By predicting species, temperature and current density distributions across the stack, the developed model proves itself to be highly instrumental for the identification of design points that provide a feasible trade-off between performance and safety metrics.

Global green hydrogen-based steel opportunities surrounding high quality renewable energy and iron ore deposits

The steel sector currently accounts for 7% of global energy-related CO2 emissions and requires deep reform to disconnect from fossil fuels. Here, we investigate the market competitiveness of one of the widely considered decarbonisation routes for primary steel production: green hydrogen-based direct reduction of iron ore followed by electric arc furnace steelmaking. Through analysing over 300 locations by combined use of optimisation and machine learning, we show that competitive renewables-based steel production is located nearby the tropic of Capricorn and Cancer, characterised by superior solar with supplementary onshore wind, in addition to high-quality iron ore and low steelworker wages. If coking coal prices remain high, fossil-free steel could attain competitiveness in favourable locations from 2030, further improving towards 2050. Large-scale implementation requires attention to the abundance of suitable iron ore and other resources such as land and water, technical challenges associated with direct reduction, and future supply chain configuration.

Urbanization associated changes in biogeochemical cycles.

Urbanization associated changes in biogeochemical cycles.

Macroscopic analysis of chemical looping combustion with ilmenite versus conventional oxides as oxygen carriers

AbstractOver 40% of global energy-related CO2emissions are due to the combustion of fossil fuels for electric energy generation. Albeit CO2capture and storage have been identified as promissory actions to mitigate its emissions, the problem separating N2and CO2remains. A very effective solution for the former problem is to obtain the combustion CO2as a pure molecule, which is possible using the Chemical Looping Combustion (CLC) technology, which uses a solid oxygen carrier to transport the oxygen from an oxidating media (regeneration reactor) to a reducing media (combustion reactor). One of the key issues to apply CLC is to find or develop some material, suitable from the kinetic and thermodynamic points of view, for the reduction-oxidation cycles taking place inside combustion and regenerator reactors. The evaluation of “oxygen carrier” candidates for CLC is based on reactivity (rates and conversions), resistance to carbon accumulation, and “regenerability”, which means the ability of the material for cyclic reduction and oxidation. Another challenging issue to use CLC processes is the loss of oxygen carrier; this problem involves the use of supported metals on materials, such as zirconia, Al2O3, etc. Preparation of this kind of supported carriers requires time, money, and equipment. Meanwhile, the natural mineral ore named ilmenite, which consists of a mixture of iron and titanium oxides, and do not need to be supported, has been seen as promising to increase CLC efficiency as oxygen carrier. In this work, the performance of ilmenite is compared with some other oxygen carriers used in CLC.

Assessment of the role of hydrogen to produce high-temperature heat in the steel industry

The iron and steel industry is a major source of industrial greenhouse gas emissions, accounting for 7–9% of global energy-related CO2 emissions. Current steel production routes are therefore expected to undergo a profound decarbonisation process in the coming decades.This work aims to shed light on the role of hydrogen in decarbonising the supply of high-temperature heat in the steel sector by means of an optimisation framework. The model includes on-site hydrogen production using a low-temperature electrolyser integrated with a compression and storage system and gas burners, which can be fed with hydrogen and/or natural gas to cover the process heat demand. The assessment also takes advantage of real thermal load profiles of a scrap-based electric arc furnace steel plant.A sensitivity analysis is conducted on the electricity, natural gas and carbon prices. Cost-optimal maps are then derived to unveil the combination of energy and carbon prices at which hydrogen becomes convenient for heat production in the steel industry. A general relationship to define the cost-effectiveness of hydrogen is also given.The results show that, at current carbon prices (about 100 €/tCO2), the use of hydrogen becomes economically convenient when the electricity price is less than 0.4–0.6 times the natural gas price. In scenarios with electricity prices lower than about 0.10 €/kWh, as could occur with on-site renewable electricity generation, hydrogen cost falls below 6.5 €/kgH2, leading to cost savings of up to 60–70% compared to a natural gas-based configuration. Finally, when total CO2 emissions (direct + indirect) are considered, hydrogen becomes environmentally beneficial if the electricity carbon intensity is below 123 gCO2/kWh.

Scenarios for mitigating CO2 emissions from energy supply in the absence of CO2 removal

ABSTRACT This paper investigates the effectiveness of different energy scenarios for achieving early reductions in global energy-related CO2 emissions on trajectories to zero or near-zero emissions by 2050. To keep global heating below 1.5°C without overshoot by 2050, global CO2 emissions must decline by about half by 2030. To achieve rapid, early emission reductions entails substantially changing recent pre-COVID (2000–2019) observed trends, which comprise increasing total primary energy supply (TPES) and approximately constant fraction of TPES derived from fossil fuels (FF fraction). Scenarios are developed to explore the effects of varying future trends in these variables in the absence of substantial CO2 removal, because relying on the latter is speculative and risky. The principal result is that, to reduce energy-related emissions to at least half the 2019 level by 2030 en route to zero or near-zero CO2 emissions by 2050, either TPES must be reduced to at least half its 2019 value by 2050 or impossibly rapid reductions must be made in the FF fraction of supply, given current technological options. Reduction in energy consumption likely entails economic degrowth in high-income countries, driven by policies that are socioeconomic, cultural and political, in addition to technological. This needs serious consideration and international cooperation. Key policy insights If global energy consumption grows at the pre-COVID rate, technological change alone cannot halve global CO2 emissions by 2030 and hence cannot keep global heating below 1.5°C by 2050. In the absence of substantial CO2 removal, policies are needed to reduce global energy consumption and hence foster degrowth in high-income economies. Policies to drive technological and socioeconomic changes could together cut global energy consumption and thus total primary energy supply and associated emissions by at least 75% by 2050.

A U.S.‒China coal power transition and the global 1.5 °C pathway

As the world seeks to increase ambition rapidly to limit global warming to 1.5 °C, joint leadership from the world's largest greenhouse gas (GHG) emitters—the United States (U.S.) and China—will be critical to deliver significant emissions reductions from their own countries as well as to catalyze increased international action. After a period of uncertainty in international climate policy, these countries now both have current leadership that supports ambitious climate action. In this context, a feasible, high-impact, and potentially globally catalytic agreement by the U.S. and China to transition away from coal to clean energy would be a major contribution toward this global effort. We undertake a plant-by-plant assessment in the power sector to identify practical coal retirement pathways for each country that are in line with national priorities and the global 1.5 °C target. Our plant-by-plant analysis shows that the 1.5 °C-compatible pathways may result in an average retirement age of 47 years for the U.S. coal plants and 22 years for Chinese coal plants, raising important questions of how to compare broader economic, employment, and social impacts. We also demonstrate that such pathways would also lead to significant emissions reductions, lowering overall global energy-related CO2 emissions by about 9% in 2030 relative to 2020. A catalytic effect from the possibility of other countries taking compatible actions is estimated to reduce global emissions by 5.1 Gt CO2 in 2030 and by 10.1 Gt CO2 in 2045.

Modelling low carbon transition and economic impacts under SSPs and RCPs based on GTIMES

The simulation of global and regional energy system transition and its potential mitigation cost could intuitively reflect the need for earlier climate mitigation actions. To explore the possible transitions of global and regional energy system, this study applied a 14-region energy system model (GTIMES) with scenarios designed using Shared Socio-economic Pathways (SSPs) with Representative Concentration Pathways (RCPs), and detailed depicts the quantification of SSPs trajectories into GTIMES model. Modeling results show that: 1) Global energy-related CO2 emissions will reach 37–74 Gt by 2050 under reference scenarios, while they will decrease to 12–14 Gt under higher possibility pathways to reach 2 °C target, with ratios of non-fossil fuel round to 42%–46%. 2) Electrification level has to increase noticeably in regional transition with a global average level of about 44% to achieve significant emission reduction. 3) Higher level of mitigation cost would happen with the constraint mitigation target, as well as social and economic trajectories chosen. Therefore, following trajectories of sustainable development is necessary.

Cradle-to-Grave Life-Cycle Assessment of Cellulosic Fiberboard

According to the United Nations Environment Programme (UNEP), the construction and operation of buildings accounted for nearly 38% of total global energy-related CO₂ emissions in 2019. The construction sector has been striving to use more low-carbon footprint building products to mitigate climate change and enhance environmentally preferable purchasing. Over the last several decades, there has been substantial growth in engineered wood products for the construction industry. To assess these products used in construction for their environmental profile, lifecycle assessments (LCAs) are performed. This study performed an LCA to estimate environmental impacts (cradle-to-gate and gate-to-grave) of cellulosic fiberboard (CFB) per m³ functional unit basis. The lifecycle inventory data developed were representative of CFB production in North America. Overall, the cradle-to-grave LCA results per m3 of CFB were estimated at 305 kg CO₂ e global warming (GW), 19.3 kg O₃ e photochemical smog formation, 1.03 kg SO₂ e acidification, 0.33 kg N e eutrophication, and 415 MJ fossil-fuel depletion. Except for smog formation, most environmental impacts of CFB were from cradle-to-gate. For example, 71% and 29% of total GW impacts were from cradle-to-gate and gate-to-grave lifecycle stages, respectively. The sensitivity analysis showed that reducing transport distance, on-site electricity use, natural gas for drying, and starch additives in the manufacturing phase had the most influence. Around 353 kg CO₂ e/m³ of CFB is stored as long-term carbon during CFB’s life which is higher than the total cradle-to-grave greenhouse gases (CO₂ e) emissions. Thus, the net negative GW impact of CFB (-47 kg CO₂ e/m³ of CFB) asserted its environmental advantages as an engineered wood panel construction material. Overall, the findings of the presented study would prove useful for improving the decision-making in the construction sector.

Predictive control co-design for enhancing flexibility in residential housing with battery degradation

Buildings are responsible for about a quarter of global energy-related CO2 emissions. Consequently, the decarbonisation of the housing stock is essential in achieving net-zero carbon emissions. Global decarbonisation targets can be achieved through increased efficiency in using energy generated by intermittent resources. The paper presents a co-design framework for simultaneous optimal design and operation of residential buildings using Model Predictive Control (MPC). The framework is capable of explicitly taking into account operational constraints and pushing the system to its efficiency and performance limits in an integrated fashion. The optimality criterion minimises system cost considering time-varying electricity prices and battery degradation. A case study illustrates the potential of co-design in enhancing flexibility and self-sufficiency of a system operating under different conditions. Specifically, numerical results from a low-fidelity model show substantial carbon emission reduction and bill savings compared to an a-priori sizing approach.

Comment on “Energy‐Related Environmental Policy and Its Impacts on Energy Use in Asia”

Comment on “<scp>Energy‐Related</scp> Environmental Policy and Its Impacts on Energy Use in Asia”

Spatial-Temporal Distribution Analysis of Industrial Heat Sources in the US with Geocoded, Tree-Based, Large-Scale Clustering

Heavy industrial burning contributes significantly to the greenhouse gas (GHG) emissions. It is responsible for almost one-quarter of the global energy-related CO2 emissions and its share continues to grow. Mostly, those industrial emissions are accompanied by a great deal of high-temperature heat emissions from the combustion of carbon-based fuels by steel, petrochemical, or cement plants. Fortunately, these industrial heat emission sources treated as thermal anomalies can be detected by satellite-borne sensors in a quantitive way. However, most of the dominant remote sensing-based fire detection methods barely work well for heavy industrial heat source discernment. Although the object-oriented approach, especially the data clustering-based approach, has guided a novel method of detection, it is still limited by the costly computation and storage resources. Furthermore, when scaling to a national, or even global, long time-series detection, it is greatly challenged by the tremendous computation introduced by the incredible large-scale data clustering of tens of millions of high-dimensional fire data points. Therefore, we proposed an improved parallel identification method with geocoded, task-tree-based, large-scale clustering for the spatial-temporal distribution analysis of industrial heat emitters across the United States from long time-series active Visible Infrared Imaging Radiometer Suite (VIIRS) data. A recursive k-means clustering method is introduced to gradually segment and cluster industrial heat objects. Furthermore, in order to avoid the blindness caused by random cluster center initialization, the time series VIIRS hotspots data are spatially pre-grouped into GeoSOT-encoded grid tasks which are also treated as initial clustering objects. In addition, some grouped parallel clustering strategy together with geocoding-aware task tree scheduling is adopted to sufficiently exploit parallelism and performance optimization. Then, the spatial-temporal distribution pattern and its changing trend of industrial heat emitters across the United States are analyzed with the identified industrial heat sources. Eventually, the performance experiment also demonstrated the efficiency and encouraging scalability of this approach.

Economic and environmental benefits of market-based power-system reform in China: A case study of the Southern grid system

China, whose power system accounts for about 13% of global energy-related CO2 emissions, has begun implementing market-based power-sector reforms. This paper simulates power system dispatch in China’s Southern Grid region and examines the economic and environmental impacts of market-based operations. We find that market-based operation can increase efficiency and reduce costs in all Southern Grid provinces—reducing wholesale electricity costs by up to 35% for the entire region relative to the 2016 baseline. About 60% of the potential cost reduction can be realized by creating independent provincial markets within the region, and the rest by creating a regional market without transmission expansion. The wholesale market revenue is adequate to recover generator fixed costs; however, financial restructuring of current payment mechanisms may be necessary. Electricity markets could also reduce the Southern Grid’s CO2 emissions by up to 10% owing to more efficient thermal dispatch and avoided hydro/renewable curtailment. The benefits of regional electricity markets with expanded transmission likely will increase as China’s renewable generation increases.

Potential of Biomass Utilization in Rotary Kiln of Nickel Processing Plant

Global energy-related CO2 emissions rose by 1.4% in 2017 and reached a historic high of 32.5 Gigatonnes (Gt). One of the biggest contributors to CO2 emission is coal combustion that emits 96.1 kg CO2 for each GJ energy production. Top consumers of coal in the world are the iron-steel industry (28.5%) and the non-metallic minerals (21.4%). Rotary kiln is one of the most energy consuming equipment in nickel pyro-metallurgy processing plant. The specific energy consumption for calcine production is determined to be 2.26 GJ/ton calcine. In the rotary kiln, coal is used as fuel and a reducing agent. Charcoal from palm kernel shell has similar characteristics with coal and very suitable to substitute coal. Charcoal from PKS has many advantages compared to other biomass: high fixed carbon content, high heating value, and low ash content. Charcoal from palm kernel shell can be used as fuel and a reducing agent. Potential 9.9% reduction of CO2 emission can be achieved by using 20% PKS charcoal as fuel and 5% PKS charcoal as a reducing agent with minimum impact on the current operation.

Study on the gravity movement and decoupling state of global energy-related CO2 emissions.

Nowadays, developing countries make more and more contributions to CO2 emissions in the world. Thus, it is interesting to explore the gravity movement and decoupling state of global CO2 emissions. Firstly, the gravity movement of global CO2 emissions is explored based on the gravity theory. Then, the contribution decomposition method (CDM) is adopted to identify leading forces of gravity movement. Finally, the decoupling state of CO2 emissions in most countries from economic development (GDP) are studied. In 2015, the biggest CO2 emitter was China, which accounted for 27.52% of global CO2 emissions. In 2015, the country with the biggest per capita CO2 emissions was Qatar. Per capita CO2 emissions for some developed countries in 2015 were lower than that in 1965. Over 1965-2015, the gravity center for global CO2 emissions moves towards the southeast, which is divided into two stages. The gravity movement of per capita CO2 emissions is towards southeast and is divided into four stages. Over 1990-2015, economic growth in 17 countries presented decoupling with CO2 emissions. Strong decoupling (SD) rarely occurred in developing countries, especially in the period 2010-2015.