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With increasingly prominent of climate concerns, promoting carbon neutrality has become a pressing issue. In contrast to most recent studies, which utilized a linear perspective and focused on accelerating carbon neutrality solutions from carbon sources, this study innovatively measures the carbon neutrality index of 30 provinces in China from 2004 to 2020 based on multichannel sources of carbon sinks and sources. It explores threshold effects of its drivers using a spatial autoregressive threshold panel model. The empirical results indicate a non-optimistic overall carbon neutrality situation in China; however, its polarization between provinces has weakened. Furthermore, China's provincial carbon neutrality index has a positive spatial spillover effect, and there is a complex spatial nonlinear relationship between carbon neutrality and its major driving factors, such as human activities and climate change, within the two regimes divided by economic development. These findings offer crucial guidance for China and other developing countries in formulating and implementing effective carbon-neutral planning. For example, developed areas should develop new low-carbon technologies, increase environmental protection expenditures, introduce green and clean enterprises, and expand vegetation areas. Less developed areas must eliminate their reliance on fossil fuel energy, optimize their industrial structure and layout, and strengthen environmental regulations and resource protection awareness. • This paper scientifically quantifies provincial carbon neutrality in China. • We incorporate carbon sinks and sources into the unified accounting system. • Carbon neutrality in adjacent provinces increases 1 unit can lead to that in observing province increases 0.4661 units. • The driving factors of carbon neutrality have clear nonlinear characteristics. • A single threshold effect regarding economic development is found, with a threshold value of 51,761.4012 Yuan. [ABSTRACT FROM AUTHOR]

To achieve the targets in the Paris Climate Change Agreement, carbon capture, utilization and storage (CCUS) will be one of the critical carbon mitigation technologies. For China, the biggest carbon emitter with coal-dominated energy structure, CCUS is expected to play more and more important roles for carbon emissions reduction. This paper looks at a method for designing a pipeline network system for large-scale CO2 capture, utilization, and storage (CCUS) in China. On the basis of performing a moderately significant literature review of past papers and models dating back to the early 2000’s, a updated multi-stage mixed integer programming (MIP) model for carbon source and sink matching (SSM) in ChinaCCUS DSS (Decision Support System) is developed. The Jing-Jin-Ji (Beijing–Tianjin–Hebei) region suffering from increasingly serious air pollution is chose as a case study to address the SSM issue with application of the updated model. The modeling results show that around 2200 km pipeline with investment of around $1.6 billion needed to be built to transport the cumulative sequestrated emissions of 1620 Mt CO 2 in the planning period of 2020–2050. Compared to the single-stage programming, the multi-stage programming could result to better pipeline connectivity. [ABSTRACT FROM AUTHOR]

• We provide the most up-to-date CO 2 emission inventory for China's cement industry. • We construct the G-LEAP model to project the CO 2 emissions of China's cement industry. • The CO 2 emissions could be reduced maximum by 70 percent in 2060, while the remainder will need to come from technological innovation and new growth horizons. This paper aims to assess the emission reduction potential of combined mitigation technologies in China's cement industry, thus transitioning towards carbon neutrality through a suitable technology portfolio and exploring a low-carbon pathway. The G-LEAP model is constructed for future carbon emission projection, incorporating the cement demand projection and technology application. The pathways based on different technology portfolios are developed to estimate the CO 2 emission trajectory of China's cement industry. We maximize the utilization of currently available technologies and assume a high level of innovative technology diffusion rate in the integrated mitigation pathway to explore the maximum abatement potential of the cement industry. The result shows that short-term mitigation mainly relies on improving energy efficiency and alternative low-carbon fuels, which would contribute 9–12% and 17–22% of the cumulative emissions reduction in the integrated mitigation pathway compared to a frozen scenario. Alternative clinkers can significantly reduce process-related emissions, but the potential is determined by the availability of raw materials, which would contribute 30–39% of the cumulative emission reduction. Post- and oxygen-combustion capture is expected to be deployed by 2030 and contribute about 28–44% to cumulative emission reduction. The technology portfolio in the integrated mitigation pathway would reduce China's cement CO 2 emissions by 63–73% compared to the frozen scenario, and the remainder of CO 2 emission would be 300–400 Mt in 2060, which will need the technological innovation and new growth horizons, such as carbon sink approaches or carbon trading. [ABSTRACT FROM AUTHOR]

To cope with global warming, China has promulgated Enhanced actions on climate change : China ’ s intended nationally determined contributions and will start the national carbon emissions trading market in 2017. Carbon emissions are distributed by the form of free quota and paid quota. However, few literatures have focused on how the economy and the environment would be changed by the change of free quota ratio. This paper establishes the 10 scenarios of different free quota ratio of carbon emissions rights and uses a dynamic, recursive computable general equilibrium (CGE) model to simulate the carbon emissions trading market, to explore the relationship between free quota ratio and carbon trading price, and the impact of carbon trading scheme (ETS) on China’s economy and environment. The results show that free quota ratio will not have a direct impact on gross domestic product (GDP) and other economic and environment indicators but carbon trading prices. The prices and the rate of free payment in the current pilot cities in China are still relatively conservative. It is possible to reach emission peak, 8.21 billion ton, in 2025 and accumulative CO 2 reduction from 2017 to 2030 is 20.02 billion tons, or 59.60% of 2010 world’s total CO 2 emission. Cement, minerals, electricity and nonferrous metals under ETS will suffer great losses, so subsidy should be considered. Finally, we suggested that China should reduce the total carbon rights to increase the carbon price in 2017, and gradually reducing the proportion of free quota, from 90% in 2017 to 50% or less in 2030, by which the peak year of CO 2 emission can meet in 2025. We also suggest that ETS is an effective strategy for CO 2 reduction and the ratio should be gradually reduced in ETS to prevent violent fluctuation of carbon price in China. [ABSTRACT FROM AUTHOR]

In the United States, buildings account for 35% of total energy-related carbon dioxide emissions, making them important contributors to decarbonization. Carbon intensities in the power grid are time-varying and can fluctuate significantly within hours, so shifting building loads in response to the carbon intensities can reduce a building's operational carbon emissions. This paper presents a rule-based carbon responsive control framework that controls the setpoints of thermostatically controlled loads responding to the grid's carbon emission signals in real time. Based on this framework, four controllers are proposed with different combinations of carbon accounting methods and control rules. To evaluate their performance, we performed simulation studies using models of a 27-home, all-electric, net zero energy residential community located in Basalt, Colorado, United States. The carbon intensity data of four future years from the Cambium data set are adopted to account for the evolving resource mix in the power grid. Various performance metrics, including energy consumption, carbon emission, energy cost, and thermal discomfort, were used to evaluate the performance of the controllers. Sensitivity analysis was also conducted to determine how the control thresholds and intervals affect the controllers' performance. Simulation results indicate that the carbon responsive controllers can reduce the homes' annual carbon emissions by 6.0% to 20.5%. However, the energy consumption increased by 0.9% to 6.7%, except in one scenario where it decreased by 2.2%. Compared to the baseline, the change in energy cost was between −2.9% and 3.4%, and thermal discomfort was also maintained within an acceptable range. The little impact on energy cost and thermal discomfort indicates there are no potential roadblocks for customer acceptance when rolling out the controllers in utility programs. [ABSTRACT FROM AUTHOR]

• Dispatching strategy of VPP-P2H based on stochastic-bargaining game is proposed. • The model considers the multiple uncertainties on both side of the source and load. • A mechanism based on NH bargaining is used to realize fair profit allocation. • An improved ADMM is used to achieve the decentralized solution of the proposed model. In order to achieve low-carbon development, the joint operation of virtual power plants (VPP) and clean power to hydrogen (P2H) is a hot issue. However, the conventional centralized optimization strategy ignores the information asymmetry between VPP and P2H, resulting in disorderly competition and low market efficiency. Based on this, this paper proposes a decentralized coordinated operation method of the VPP-P2H combined system considering the profits of each player. First, the stochastic optimization operation model of VPP and P2H is built involving the multiple uncertainties on both sides of the source and load. Secondly, based on the Nash-Harsanyi bargaining game theory, a multi-agent decentralized coordinated operation model of VPP-P2H is established. The model is further equivalent to the minimization of coordinated operation cost sub-problem and payment bargaining sub-problem. For the privacy of each player, the improved alternating direction multiplier method (ADMM) is used to solve the above two sub-problems. Finally, the effectiveness of the proposed decentralized coordinated operation model and distributed algorithm are verified. The simulation results show that compared with the individual operation mode, through coordinated operation, the operating costs of P2H 1 , P2H 2 , and VPP are reduced by 19.59%, 18.18%, and 16.61%, respectively. In addition, the improved-ADMM algorithm also improves the solution efficiency of the system. [ABSTRACT FROM AUTHOR]

• This paper estimates carbon emissions released by household travel demand from 47 Japanese cities. • Carbon footprint generated by private transport is found as 1.4 to 13.9 times higher than public transport. • Gasoline's direct combustion is found as the most significant reason to generate the regional difference. • The highest total carbon footprint is found in cities with fewer population. Considering its substantial and increasing contribution to global climate change, the household sector shows potential for larger carbon reductions. Among different household activities, household individual travel demands due to private or public transportation affect the environment via both direct or indirect emissions. To develop insights from a city-level perspective, carbon emissions released due to household travel demands in 47 Japanese cities were estimated in this study using the most recent available data. Given the differences in traveling preferences, spatial distribution and cluster analyses by city were also conducted. The results indicate that cities with a larger carbon footprint usually had a smaller population, whereas in megacities, less carbon per capita was released. The direct combustion of gasoline and train use were the most important factors influencing regional differences in direct and indirect emissions, respectively. The findings also indicate that customized carbon mitigation strategies that consider individual preferences and city size have a better chance of achieving decarbonization of citizen transportation in Japan. [ABSTRACT FROM AUTHOR]

The low efficiency of renewable electricity storage has been considered as a bottleneck of the scalable and low-carbon Power-to-Gas energy transformation concept. This paper investigates the combination of CO 2 biofixation using Spirulina platensis microalgae and catalytic hydrothermal gasification of wet organic feedstock for the storage of fluctuating electricity and direct utilisation of waste CO 2. The presented method enables wet microalgae biomass conversion into H 2 and C 1 -C 2 rich fuel gas stream using hydrothermal conversion that is valorised further to methane. For bridging the gap between theoretical investigations and the application of this approach, experiments were carried out at elevated temperatures (632.9-717.0 °C) based on a central composite design of the experiment. Biogas upgrading was evaluated by ASPEN Plus flowsheeting software. The results show that the proposed storage cycle outperforms the state-of-the-art biological and chemical-based Sabatier methanations with an overall round-trip efficiency of 42.3%. The optimised thermo-chemical process enables to achieve simultaneously high H 2 (9.05 mol kg−1) and CH 4 (7.91 mol kg−1) yields with an enhanced 71.23% carbon conversion ratio. Moreover, the environmental and cost evaluations of the currently proposed bio-synthetic process indicate low associated CO 2 equivalent emission (99.4 ± 12.6 g CO 2 , e q kWh−1) with 144.9 €MWh-1 normalised total annual natural gas production cost. Ideally the proposed storage cycle requires less H 2 from external sources, effective CO 2 utilisation becomes available through the biofixation and hydrothermal conversion of the wet organic feedstock and closed carbon emission cycle can be accomplished. • A closed cycle for energy storage, CO 2 reuse and CH 4 production (144.9 € MWh-1). • Microalgae CO 2 absorption, Catalytic Hydrothermal gasification, gas storage. • Fuel Gas upgrading via water hydrolysis using variable renewable electricity. • Round-trip efficiency of 42.3%, outperforming other storage cycles. • Life cycle assessment shows 99.4 g CO 2,eq kWh-1 greenhouse gas footprint. [ABSTRACT FROM AUTHOR]

• A one-dimensional design method for supercritical carbon dioxide cycles is proposed. • Detailed preliminary design method for turbomachinery and heat exchangers are given. • Demonstration design and comparative analysis of recompression cycles are performed. • Some design considerations for the recompression cycle are presented. The state-of-the-art supercritical carbon dioxide Brayton cycles are complex integrated systems featured with strong coupling effects between the cycle and components. To reveal cycle characteristics precisely and conduct cycle design efficiently, integration of the cycle design and components design are required at the very beginning. In this paper, a one-dimensional design methodology for supercritical carbon dioxide Brayton cycles was proposed, based on the integration between cycle conceptual design and components preliminary design. Details of the preliminary design methodology for turbomachinery and heat exchangers were presented. A 500kWe and 5MWe recompression cycle were designed as demonstration examples, and comparative analysis of cycle performance and components performances were performed. Meanwhile, parametric analysis of some crucial parameters was carried out and some design considerations for recompression cycle were presented. Design results suggest that the 5MWe cycle could reach a higher thermal efficiency of 38.0% compared with 37.0% for the 500kWe cycle, which fundamentally results from the larger mass flow rate. The enhanced mass flow rate would lead to higher turbomachinery efficiency in the 5MWe cycle, and the stator loss reductions contribute to the turbomachinery efficiency improvements. As for the design of recompression cycle, selecting a flow split ratio smaller than its optimum value and a reasonably high effectiveness for each recuperator is recommended. Keeping the rotation speed of the re-compressor within its optimum region is also suggested, especially for low-power cycles. Besides, the main-compressor inlet temperature is a crucial parameter, and a compromise between cycle efficiency and system maintenance should be made. [ABSTRACT FROM AUTHOR]