Achieve CO2 Emission Reduction Research Articles

Experimental study on the influence of particle size and grain grading on the CO2 hydrate formation and storage process in porous media

CO2 sequestration in sediments as hydrate form is considered to be a promising way to achieve CO2 emission reduction in the atmosphere. The key problem with hydrate-based technology for CO2 geological storage is the evaluation of the formation process and gas storage capability of hydrate. In this study, the fundamental issue of different particle size and grain grading affected CO2 hydrate formation and storage characteristics in porous media was deeply analyzed. The effect of various particle sizes and grain grading on the gas consumption rate and gas storage capacity of CO2 hydrate were quantitatively illustrated. The results indicated that the hydrate formation is more difficult in porous media with tiny particle sizes. The gas storage capacity and gas consumption rate of CO2 hydrate increased as the particle size increased within a range of 10–63 μm. The maximum gas storage capacity attains 25.65 L/L when the particle size is 63 μm. Besides, compared with single particle size, porous media with grain gradation is adverse to hydrate formation. The results also show that, the obstruction effect on the gas consumption rate and gas storage capacity is more obvious with the increase of the differences in grain gradation. The cooperative impact of particle size and gradation on hydrate formation was studied. The closer the size of the mixed particles is, the more favorable to hydrate formation. The relevant results will aid in comprehending the hydrate formation properties in submarine sediments and will serve as an essential theoretical reference and guide for CO2 capture and sequestration hydrate-based method.

Research on the evaluation of the renovation effect of existing energy-inefficient residential buildings in a severe cold region of China

The renovation of existing energy-inefficient residential buildings is an important measure to improve building energy efficiency and achieve CO2 emission reduction strategic tasks. At present, existing energy-inefficient residential buildings suffer from high energy consumption for heating, low efficiency, and poor indoor thermal comfort. It is necessary to implement energy-saving renovation on existing residential buildings and evaluate the renovation effect. This article took existing energy-inefficient residential buildings as the research object and selected a targeted evaluation system. Based on expert research, the hierarchical-grey correlation degree method was used to determine the weight of indices. Actual testing was conducted on the three nodes of the heat exchange station, secondary network, and the building ontology during the heating seasons of 2015–2016 and 2016–2017 (before and after renovation). Based on measured data, a fuzzy membership degree evaluation model was constructed, and the evaluation results were determined using a linear weighted method to form a complete evaluation system. The evaluation system covered 12 evaluation indices, and the evaluation indices with the largest weight in the criterion and index layer were energy consumption (0.308) and economic contribution rate (0.183), respectively. The average linear weighted evaluation scores before and after the renovation of each node were 14.16 and 29.04, respectively.

How does the coal-to-gas policy mitigate carbon emissions? The role of fintech development

As energy transition becomes an important way to achieve carbon dioxide (CO2) emission reduction globally, this paper takes China as an example and uses the difference-in-difference (DID) model suitable for policy research to explore the impact of coal-to-gas (CTG) policy, which aims at promoting energy transition and reducing pollutant emissions, on CO2 emissions, and explores the mechanism of action and the spatial spillover effects of the policy. The results of the study show that, first, the implementation of the CTG policy can reduce CO2 emissions in China, and the results still hold under a series of robustness tests. Second, the CTG policy can achieve CO2 emission reduction through regional industrial restructuring, and the rapid development of financial technology promotes the process of CO2 emission reduction in China. Finally, the implementation of the CTG policy may cause the problem of CO2 leakage due to regional differences in the policy. This study not only provides a reference for setting global energy transition policies, but also provides new ideas for China's CO2 emission reduction and CO2 leakage, and provides data support for policy formulation.

Gas production from hydrates by CH4-CO2 replacement: Effect of N2 and intermittent heating

Extraction of CH4 gas from Natural Gas Hydrates (NGHs) while storing CO2 by CH4-CO2 replacement method is a promising technique for achieving CO2 emission reduction and CH4 production. However, improving the kinetics and enhancing the replacement efficiency is the fundamental issue for efficient CH4 production and CO2 safe sequestration, which have become the bottlenecks in NGH extraction. In this work, the CO2 replacement characteristics and kinetics process were further elucidated. The effects of small molecule gas (N2) and intermittent heating on the CO2 replacement were quantitatively investigated. And the enhancement mechanism of N2 and intermittent heating on CO2 replacement were deeply analyzed. The results show that as the proportion of N2 increases, the CH4 recovery rate gradually increases, but the CO2 sequestration rate exhibits a pattern of initial increase followed by a decrease. In addition, the intermittent application of heat has been shown to effectively enhance the replacement performance of pure CO2 in porous media. A thicker quasi-liquid layer forms when the temperature of hydrate reservoir approaches the freezing point, making it easier for CO2 gas to form hydrates. Additionally, when intermittent heating is combined with CO2 + N2 replacement, it results in a more significant promotion of CH4 recovery.

Digital finance, technological innovation, and carbon dioxide emissions

In the context of China’s carbon peak and carbon neutrality goals (the “dual carbon” goals), balancing economic development, environmental protection, and low carbon is a high priority. Therefore, exploring the impact of digital finance on carbon dioxide (CO2) emissions is crucial. In this paper, we select the panel data of 241 cities in China from 2011 to 2020 and use the double logarithm model after verifying model forms to explore the impact of digital finance on urban CO2 emissions. The results show a significant negative correlation between the level of digital finance and the intensity of CO2 emissions. Heterogeneity analysis results show that the eastern region exhibits the greatest inhibitory effect, while the western region exhibits the lowest. The three sub-dimensions of digital finance can all reduce carbon emissions, but the usage depth dimension has the greatest reduction effect, while the coverage breadth dimension is slightly lower. Through mediating effect tests from two dimensions, we find that digital finance can achieve CO2 emission reduction by promoting scientific and technological innovation. These findings have implications for understanding the carbon reduction effectiveness of digital finance and achieving the dual carbon goals.

Direct solar-driven thermochemical CO2-to-fuel conversion with efficiency over 39 % employing hierarchical triply periodic minimal surfaces biomimetic foam reactors

Solar-driven CO2 reforming of CH4 is considered a promising approach for achieving CO2 emission reduction and clean energy utilization simultaneously. However, reactors suffer from uneven temperature distribution and severe carbon deposition, leading to low solar-to-fuel efficiency. This study introduces a novel strategy for highly efficient solar-driven thermochemical CO2-to-fuel conversion based on hierarchical triply periodic minimal surfaces (TPMS) biomimetic foam reactors. The biomimetic hierarchical foam reactor exhibits a remarkably high light-to-fuel efficiency of 39.14 %, with CH4 and CO2 conversion rates reaching 72.6 % and 83.9 %, respectively, along with no obvious attenuation over 50 h. A 73.7 % reduction in temperature non-uniformity and a 96.9 % decrease in the carbon deposition rate are also demonstrated. The underlying mechanism is attributed to unique highly interconnected and smooth hierarchical pores, for which large pores promote the penetration of sunlight while small pores enhance fluid-solid energy transfer. Effects of solar irradiation conditions and foam thermal conductivity are investigated numerically, providing guides for further reactor optimization under different operating scenarios. This work presents a new approach for designing and manufacturing efficient direct solar-driven thermochemical CO2-to-fuel conversion reactors using hierarchical TPMS biomimetic foams.

Revisiting the relationship between business conditions, climate policy uncertainty, and environmental pollution: evidence from the USA.

This paper aims to revisit the interdependency between business conditions, climate policy change, and the environmental pollution of the USA. Interestingly, our paper represents a completion to the existing literature on three levels at least. First, we propose to analyze this issue during normal periods and periods of turmoil, particularly the COVID-19 outbreak. To do so, contrary to previous studies that used economic growth, we employ the ADS index as a real-time business conditions measurement. Second, we employ a frequency approach, based on the continuous wavelet transform, allowing us to understand the nature of the relationship. Understanding whether the relationship holds in the short- or long-term is useful for policymakers in monitoring public policies to achieve CO2 emission reduction as well as to investors interested in high value-added projects. Our analysis shows that, during the last two decades, the relationship between business conditions as well as climate uncertainty index and CO2 emissions is observed during the long- and short-term, and driven through economic conditions. However, during the crisis periods, the effect is detected across various scales and the relationship is bi-directional. Our results have several practical implications for the US policymakers to consider when setting policies for fighting pollution emissions and environmental protection.

Carbon footprint analysis considering production activities of informal sector: The case of manufacturing industries of India

This study estimates an input-output table for India that distinguishes between the formal and informal sectors in 25 manufacturing industries to investigate the informal sector's contribution to the national carbon footprint (CO2 emissions embodied in supply chains). The proposed table reflects the differences in terms of input structure and carbon emission intensity between each industry's formal and informal sectors. The results showed that the informal sector in several industries contributed significantly to the carbon footprint of the top three supply chains with larger CO2 emissions in India. The study suggests that environmental policymakers target the informal sector and identify the actors involved in achieving CO2 emission reduction in the informal sector.

Development of dual-functional materials for integrated CO2 capture and utilization by dry reforming of CH4

Integrated CO2 capture and utilization by dry reforming of CH4 (ICCU-DRM) is an effective way to achieve CO2 emission reduction and resource utilization. However, the process is still in preliminary development stage, and it lacks of efficient and stable dual-functional materials (DFMs) and full understanding of reaction characteristics of ICCU-DRM. In this work, various inert supported Ni/CaO DFMs were synthesized and evaluated by comprehensive adsorption-desorption, catalytic reaction and ICCU-DRM tests. Results show that 5Ni-5Zr/CaO/SBA possesses a very good carbon deposition resistance. Almost no carbon deposition is produced in a continuous ICCU-DRM test for 20 cycles, while the conversion of CH4 and CO2 keeps at 66% and 75%, respectively. Meanwhile, benefiting from the stable micro-structure, 10Ni-CaO-Ca5Al6O14 maintains a high CO2 conversion capacity of 0.44 g g−1 in the stability test with a CO2 and CH4 conversion of 78% and 63%.

Examining the cost-effectiveness of electric vehicle policy in India

ABSTRACT Deployment of electric vehicles (EVs) is being widely used by governments across the world as a policy tool to mitigate the catastrophic effects of global warming and climate change. However, the demand for EVs has been slow in many large automotive markets, including India. To increase the uptake of EVs in India, the central government has introduced a new consumer incentive program and a special tax rate for EVs. In this paper, we estimate the cost-effectiveness of these EV promotion programs in achieving CO2 emission reduction for each State in India. We use emission data of the chosen vehicle and CO2 emission intensity data of each State’s power grid for computation. The results are then compared to other benchmark investments in climate change mitigation. The findings indicate that subsidizing EVs may not be the most cost-efficient method to achieve CO2 reduction.

A new inverse DEA model with frontier changes for analyzing the achievement path of CO2 emissions target of China in 2030

China has promised to reduce its CO2 emissions per gross domestic product (GDP) by 60–65% relative to 2005 emissions by 2030, which puts higher requirements for the quality of China's future economic development. Meanwhile, using current methods to scientifically analyze the realization path of CO2 emission reduction while ensuring future economic development remains a challenge. This study develops a new inverse data envelopment analysis (DEA) method to analyze the annual realization path of CO2 emission reduction and economic growth targets in China from 2020 to 2030. This method not only considers undesirable output and frontier changes but also analyzes the realization path of CO2 emission reduction on the premise of ensuring economic growth. Moreover, the proposed method can analyze resource optimization allocation to achieve the corresponding goals, and its contributions to sustainable development are discussed. The results indicate that (1) In terms of CO2 emission reduction, the eastern region will face the largest pressure of CO2 emission reduction, accounting for 52.85% of the total CO2 emission reduction, followed by the central region, accounting for 37.2%, and the western region will face the least pressure, accounting for 9.95%; whereas in terms of the change trend of CO2 emission reduction, the eastern and central regions show opposite CO2 emission reduction trends, while the trend in the western region is relatively stable. (2) At provincial level, CO2 emission reduction shows a polarized distribution. Many provinces, such as Jiangsu, Guangdong, Hunan, and Chongqing, undertake great pressure to reduce CO2 emission. However, some provinces, such as Shandong, Shanxi, and Yunnan, almost have no potential to reduce CO2 emission while maintaining economic growth. (3) The increasement of human and energy resources input in the future is key to achieving CO2 emission reduction and economic development goals. Finally, some useful implications are summarized by analyzing the results to provide powerful decision support for achieving CO2 emission reduction and economic growth targets of China in 2030.

Accelerating Efficient Installation and Optimization of Battery Energy Storage System Operations Onboard Vessels

Emerging large battery energy storage systems (BESSs) are key enablers in the electrification of the shipping sector. With huge government investments in BESSs, there are large gaps between the government supported BESS initiatives and actual BESS integration results on vessels. This study aims to close these gaps, allowing BESSs to become the preferred solution for ship owners without needing government support. Firstly, this industry-driven study reviews both the industrial approaches to achieve CO2 emission reductions and the fuel savings and emission reductions from 500 BESS installations on various vessels. Secondly, a 630 kWh BESS retrofitted onto a hybrid-electric vessel is used to quantitively identify the improvement requirements for installations and operations. The installations required many custom designs that were expensive and have high failure risks. The standardization of interfaces’ between BESSs and vessels is thus urgently required. The BESS was intended for spinning reserve capacity and peak shaving but in practice was under-used in terms of energy throughput (shallow cycles and low equivalent full cycles of 80 versus the design specification of 480 yearly). Thirdly, this study develops new, integrated BESS operational models by learning from large operational data, balancing BESS degradation against fuel saving and utilizing onshore/offshore green power supply/charging. The R&D of BESS is required to deal with the increasing safety requirements and further CO2 emission reductions. Finally, four BESS acceleration scenarios were established to facilitate the technical and operational transferability through utilizing digitalization.

Coordinated control between a grid forming inverter and grid following inverters suppling power in a standalone microgrid

Battery energy storage systems, fuel cells, and photovoltaic generators are being adopted in distribution networks to achieve CO2 emission reduction. These power sources require inverters to connect to AC networks. However, sub- networks, such as a microgrids containing inverter power sources, may be disconnected from the utility network and operated in a standalone mode during extended blackouts. This study focuses on a standalone microgrid supplied by inverter power sources without a synchronous generator and proposes a new microgrid inverter control. In this inverter control, a single grid forming inverter is operated as a master power source to determine frequency and voltage, and other inverters, called grid following inverters, are operated as subordinate power sources with active and reactive power control. The necessary functions in the energy management system are examined, and the coordinated operation of all inverters in the microgrid is demonstrated via simulation.

Comprehensive optimization of coal chemical looping gasification process for low CO2 emission based on multi-scale simulation coupled experiment

Carbon dioxide (CO2) emission reduction has become an urgent topic to be studied and solved with the in-depth understanding of global warming and frequent occurrence of extreme climate. At present, the application of chemical looping technology in coal gasification to produce high purity synthesis gas is an important way to achieve CO2 emission reduction, ensure energy security, and promote ecological civilization. In this paper, a new fusion research method combining multi-scale modeling and experimental testing is adopted to comprehensively optimize the coal chemical looping gasification (CCLG) process, aiming at ruducing CO2 emissions in the synthesis gas production of CCLG. In order to investigate the effect of main reaction conditions on CCLG process, the pyrolysis and gasification experiments of Meihuajing coal are carried out in a tubular furnace reactor with Fe2O3 and CuO as oxygen carriers respectively. Subsequently, the multi-scale simulation of CCLG process including molecular dynamics (MD) and computational fluid dynamics (CFD) simulations is performed to validate the experimental results and supplement important reaction kinetics data. Both of multi-scale modeling and experimental testing suggest that the optimum pyrolysis temperature range, gasification temperature range, char/oxygen carrier mass ratio (C/O), and steam flow are below 900 ℃, 900–950 ℃, 1:1.5, and 0.15 g/min respectively, providing an effective guidance for the optimal design of practical CCLG pilot plant.

Screening, Monitoring, and Remediation of Legacy Wells to Improve Reservoir Integrity for Large-Scale CO2 Storage—An Example From the Smeaheia Structure in the Northern North Sea

Carbon capture and storage (CCS) is an inevitable action to achieve CO2 emission reduction targets including becoming net-zero by 2050. Increased efforts are therefore required to identify suitable locations for large-scale CO2 storage. In addition to large aquifers, shut down oil and gas fields in the North Sea are logical candidates for offshore large-scale CO2 storage because of their proven storage capacity, reliable caprock integrity, established infrastructure, and public acceptance. However, in some cases, old and legacy wells are subject to high uncertainties in their integrity, and they can compromise CO2 containment in such reservoirs. On the Norwegian Continental Shelf (NCS), such wells are numerous even outside of oil and gas production areas, i.e., legacy wells affecting aquifers. Therefore, there is a clear need for reliable and cost-effective technologies for well integrity evaluation and remediation. This paper discusses a workflow for screening, monitoring, and remediation of legacy wells. In a first stage, the screening of the Horda Platform areas suggested the need for integrity investigation for the exploration well 32/4-1 T2, drilled into the Alpha structure of the Smeaheia fault block if CO2 is stored in the structure. Our initial well screening of drilling documentation indicates that the well is not suitable to be reused for CO2 injection and geophysical monitoring is recommended. In a second stage, a numerical representation of the well architecture is built including realistic geological setting. We evaluate the sensitivity of non-invasive low-frequency electromagnetic monitoring to corrosion levels in the casing. Numerical end-member simulations of assuming casing corrosion of different degrees by changing material conductivity are performed. Results comparing different corrosion scenarios with a base case (no corrosion) give an above noise signal at receiver locations enabling to separate the different cases. Comparison of the gained electrical fields at seafloor suggests that well casing corrosion monitoring should be possible. Finally, the electrochemical deposition potential of the Sognefjord Formation water is analyzed, revealing depositional potential for portlandite, which might be useful for cement remediation. We recommend such an analysis for all legacy wells penetrating candidate reservoirs for future CO2 or hydrogen storage.

Supercritical CO2 coupled with mechanical force to enhance carbonation of fly ash and heavy metal solidification

Accelerated carbonation of fly ash is a potential way to achieve CO2 emission reduction and heavy metal solidification. Slow conversion in the diffusion control stage is the bottleneck of the carbonation technical route. Based on the strong diffusion and permeability of supercritical CO2, and the modification of mechanical force to produce more fresh surfaces and pores, a method consisting of supercritical CO2 coupled with mechanical force was carried out to strengthen the carbonation of fly ash. Research results show that the carbonation efficiency of fly ash under supercritical CO2 is generally higher than under low-pressure conditions, and carbonation under supercritical CO2 can effectively stabilize heavy metals in fly ash. In this work, the optimal amount of carbon sequestration under low-pressure was found to be 42.3 g-CO2/kg-fly ash (g/kg), with a carbonation efficiency of 18.65%. Under the supercritical condition of 8 MPa, the maximum carbon sequestration by fly ash is 54.9 g/kg, and the carbonation efficiency is 24.20%. In experiments with mechanical ball milling modification, the order of carbonation efficiency is: wet milling modified ashes > dry milling modified ashes > raw ashes. Additionally, carbonation has an obvious inhibitory effect on the leaching of Pb, Cr and Cd from fly ash.

A computable general equilibrium (CGE) assessment of technological progress and carbon pricing in India's green energy transition via furthering its renewable capacity

In this paper a Computable General Equilibrium (CGE) model was used to assess the coal cess and technological progress in emerging energy technologies to achieve about 40% electric power generation from non-fossil fuel based energy resources by 2030 in India. To our knowledge there is no other study that has analysed the interactions between regulatory policies, such as the coal cess, and technological progress in low carbon technologies, including carbon capture and storage (CCS), for achieving a target. The main conclusions emerging from the analysis are – first, endogenous technological change in renewables under current level of carbon pricing (coal cess) can help to achieve the low carbon target along with economic gains; second, the coal cess can facilitate the shift towards a low carbon economy by decreasing the relative prices of non-fossil fuel energy and being a source of finance for supporting R&D in renewables; and finally, advances in carbon capture and storage (CCS) technology can help to achieve CO2 emission reduction at a lower economic cost. Thus, besides technology and fund transfers from advanced economies, policy focus on R&D in energy technologies and carbon pricing are required to take Indian economy on a low carbon growth path.

Assessing the CO2 reduction target gap and sustainability for bridges in China by 2040

In China, rapid and continuing infrastructure growth will significantly affect the feasibility of achieving CO2 emission reduction targets. It is uncertain whether the current infrastructure designs are consistent with the national emission targets of China, consequently posing a threat to the national commitment to reaching carbon neutrality. To illustrate the gap in achieving the emission targets with respect to bridges, we present carbon intensity reduction targets relevant to bridges by 2040. By exploring three policy–economic scenarios that combine with CO2 emission reduction policy scenarios of the International Energy Agency and shared socioeconomic pathways, we assess the adaptability of the bridge designs to short-, medium- and long-term carbon intensity targets. We propose a new sustainability design approach based on a bridge big data set that integrates reliability, environmental impacts, and cost. We show that, under the current policy–economic scenario, more than 50% of code-based bridges would meet the five-year CO2 emission target, whereas only one in ten thousand could meet the ten-year target under the new policy–economic scenario. Under the sustainable development policy–economic scenario, none of the bridge designs would meet the carbon reduction targets over the next 20 years. Our findings highlight that the bridges in China need to be duly considered in setting CO2 reduction targets, and in the national move toward zero carbon, careful consideration should be given to implementing our proposed bridge sustainability design.

Techno-economic-environmental assessment of biomass oxy-gasification staged oxy-combustion for negative emission combined heat and power

Climate change mitigation requires developing low-carbon technologies capable of achieving CO2 emission reductions at the gigatonne scale and affordable cost. Biomass gasification, coupled with carbon capture and storage, offers a direction to atmospheric CO2 removal. To compensate for the issues associate with the high-investment requirement of CO2 removal unit and lower efficiency compared to fossil-based power cycles, this study proposed a conceptual system for combined heat and power, based on biomass oxy-gasification integrated with staged oxy-combustion combined cycle (BOXS-CC). Aspen Plus® is used to develop the process model of the proposed cycle. The results obtained in the techno-economic analysis showed that the net power efficiency of the proposed concept with 50.2 kg/s biomass flowrate was 41.6%, and the heat efficiency was 27.4%, leading to a total efficiency of 69.0%, including CO2 compression. Moreover, the economic assessment of BOXS-CC revealed that it can achieve a levelised cost of electricity of €21.4/MWh, considering the heat and carbon prices of €46.5/MWh and €40/tCO2, respectively. Such economic performance is superior compared to fossil fuel power plants without CO2 capture. The environmental assessment shows that BOX-CC system results in net negative emissions of 766 kg CO2 eq./MWhe.

The Relationship between Thermal Characteristics and Microstructure/Composition of Carbon Dioxide Hydrate in the Presence of Cyclopentane

Hydrate-based carbon dioxide (CO2) separation and capture is a new technology for achieving CO2 emission reduction. However, it is still not commercially applied for the ambiguity of microscopic hydrate formation mechanism. In a constant volume experiment of hydrate formation, there are two or more pressure platforms, indicating that there might be two or more different hydrates formation in succession. In order to reveal the relationship between the microscopic process and the gas consumption in the process of hydrate formation, hydrate composition and formation mechanism of cyclopentane-CO2 (CP-CO2) system was investigated using a differential scanning calorimeter (DSC) and Raman spectroscopy. The results indicated CO2-CP binary hydrate and CO2 hydrate are formed successively, and they coexist in the final hydrate. CP-CO2 binary hydrates forms preferentially, and as crystal seeds, inducing the formation of CO2 hydrates. The two hydrates formation processes cause the two pressure-drops. The results provide a scientific basis for increasing the gas consumption in different stages of gas hydrate formation in the presence of hydrate formation promoter.