Monitoring global carbon emissions in 2021

Use of A-Site Metal Exsolution from a Hydrated Perovskite Titanate for Combined Steam and CO2 Reforming of Methane

Metal segregation from a perovskite oxide (ABO₃) usually referring to "redox metal exsolution" has recently been used for in situ preparation of a well-designed catalyst where metal nanoparticles are homogeneously and strongly embedded on perovskite scaffolds upon reduction. The exsolution concept of B-site transition metal ions has grown, but several issues such as segregation of A-site alkaline-earth metal ions (altering electronic structures of the perovskite surface, causing deformation of perovskite structures, or creating undesirable products via side reactions) and carbon formations on metal nanoparticles should be addressed for stable catalysts in greenhouse gas (CO₂ or CH₄) conversion. Here, we suggest a new approach to designing metal-perovskite composite catalysts via A-site metal segregation from a hydrated perovskite titanate. In situ formation of A-site-deficient hydrated CaTiO₃ accompanied with Ni exsolution solids leads to ∼78 and 65% of CH₄ and CO₂ conversion, respectively, suppressing carbon formations and alkaline-earth metal segregations in combined steam and carbon dioxide reforming of methane at 700 °C. It would help to design active and stable metal-perovskite catalysts for energy and environmental applications.

Alkalinity responses to climate warming destabilise the Earth's thermostat

Alkalinity generation from rock weathering modulates Earth's climate at geological time scales. Although lithology is thought to dominantly control alkalinity generation globally, the role of other first-order controls appears elusive. Particularly challenging remains the discrimination of climatic and erosional influences. Based on global observations, here we uncover the role of erosion rate in governing riverine alkalinity, accompanied by areal proportion of carbonate, mean annual temperature, catchment area, and soil regolith thickness. We show that the weathering flux to the ocean will be significantly altered by climate warming as early as 2100, by up to 68% depending on the environmental conditions, constituting a sudden feedback of ocean CO₂ sequestration to climate. Interestingly, warming under a low-emissions scenario will reduce terrestrial alkalinity flux from mid-latitudes (-1.6 t(bicarbonate) a^-1 km^-2) until the end of the century, resulting in a reduction in CO₂ sequestration, but an increase (+0.5 t(bicarbonate) a^-1 km^-2) from mid-latitudes is likely under a high-emissions scenario, yielding an additional CO₂ sink.

Long-Term Stability Challenges and Opportunities in Acidic Oxygen Evolution Electrocatalysis

Polymer electrolyte membrane water electrolysis (PEMWE) has been regarded as a promising technology for renewable hydrogen production. However, acidic oxygen evolution reaction (OER) catalysts with long-term stability impose a grand challenge in its large-scale industrialization. In this review, critical factors that may lead to catalyst's instability in couple with potential solutions are comprehensively discussed, including mechanical peeling, substrate corrosion, active-site over-oxidation/dissolution, reconstruction, oxide crystal structure collapse through the lattice oxygen-participated reaction pathway, etc. Last but not least, personal prospects are provided in terms of rigorous stability evaluation criteria, in situ/operando characterizations, economic feasibility and practical electrolyzer consideration, highlighting the ternary relationship of structure evolution, industrial-relevant activity and stability to serve as a roadmap towards the ultimate application of PEMWE.

Halophilic CO2-fixing microbial community as biocatalyst improves the energy efficiency of the microbial electrosynthesis process

Using saline electrolytes in combination with halophilic CO₂-fixing lithotrophic microbial catalysts has been envisioned as a promising strategy to develop an energy-efficient microbial electrosynthesis (MES) process for CO₂ utilization. Here, an enriched marine CO₂-fixing lithotrophic microbial community dominated by Vibrio and Clostridium spp. was tested for MES of organic acids from CO₂. At an applied E_cathode of -1V (vs Ag/AgCl) with 3.5 % salinity (78 mScm^-1), it produced 379 ± 53 mg/L (6.31 ± 0.89 mM) acetic acid and 187 ± 43 mg/L (4.05 ± 0.94 mM) formic acid at 2.1 ± 0.30 and 1.35 ± 0.31 mM day^-1, respectively production rates. Most electrons were recovered in acetate (68.3 ± 3 %), formate (9.6 ± 1.2 %) besides hydrogen (11 ± 1.4 %) and biomass (8.9 ± 1.65 %). Notably, the bioproduction of organic acids occurred at a high energetic efficiency (EE) of ∼ 46 % and low E_cell of 2.3 V in saline conditions compared to the commonly used non-saline electrolytes (0.5-1 mScm^-1) in the reported MES studies with CO₂ (E_cell: >2.5 V and EE: <34 %).

Recent Advances for Electrode Modifications in Flow Batteries: Properties, Mechanisms, and Outlooks

Flow batteries (FBs) have been demonstrated in several large-scale energy storage projects, and are considered to be the preferred technique for large-scale long-term energy storage in terms of their high safety, environmental friendliness, and long life, including all-vanadium flow batteries (VFBs) and Fe-Cr flow batteries (ICFBs). As the electrochemical reaction site, the electrode parameters, such as the specific surface area, active site, and so on, have a significant impact on the flow battery performance and reliability. Extensive research has been carried out on electrode modification to improve the current density and energy efficiency of the FBs. In this review, the reaction mechanisms of VFBs and ICFBs are discussed in detail firstly, and then the electrodes modification methods are overviewed and summarized from four aspects: self-modification, carbon-based electrocatalysts, metal-based electrocatalysts and composite electrocatalysts. Finally, the recent catalytic mechanism, in situ characterization technology, and future research directions are presented.

Dual Single-Atom Moieties Anchored on N-Doped Multilayer Graphene As a Catalytic Host for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are promising for energy storage, especially in the era of carbon neutrality. Nonetheless, the sluggish kinetics of converting soluble lithium polysulfides into solid lithium sulfide impedes its development. In this work, we design Fe and Co dual single-atom moieties anchored on N-doped multilayer graphene (FeCoNGr) as a catalytic sulfur cathode host for Li-S batteries. With an efficient catalytic role in converting soluble lithium polysulfides into solid Li2S, the FeCoNGr-based Li-S cell demonstrates a capacity of 878.7 mA h g-1 at 0.2 C and retains 77.4% of the initial value after 100 cycles. The first and retained capacities are ∼1.7 and ∼1.8 times those of the NGr (without single atoms)-based cell, respectively. Theoretical calculations reveal that the Fe-N4 moiety has a higher binding energy toward low-order lithium polysulfides, while the Co-N4 moiety has a higher binding energy toward high-order lithium polysulfides. The efficient catalytic conversion of soluble lithium polysulfides into solid lithium sulfides of FeCoNGr plays important roles in outperforming NGr. This work enhances our knowledge on the tandem role of dual single-atom moieties and confirmed the high catalytic efficiency of single-atom catalysts in Li-S batteries.

Information Disclosure Impacts Intention to Consume Man-Made Meat: Evidence from Urban Residents' Intention to Man-Made Meat in China

Meat substitutes such as man-made meat are emerging to promote low-carbon healthy consumption, mitigate climate change, and assist healthy economic development; however, most consumers seem reluctant to make the transition. While profound social change may be required to make significant progress in this area, limited efforts have been made to understand the psychological processes that may hinder or facilitate this transition. To clearly identify the factors influencing the public's intention to consume man-made meat and their influencing paths, this study analyzes the mechanism by which man-made meat information disclosure affects the public's intention to consume these products based on the social cognitive theory of "awareness-situation-behavior" and using structural equation modeling, with residents of seven Chinese cities as examples (647 respondents). The results of this study yielded three main findings. First, low-carbon awareness, personal social responsibility awareness, and man-made meat risk perception significantly influence the public's intention to consume man-made meat, with risk perception having the greatest influence (-0.434). Second, low-carbon awareness and man-made meat risk perception have a significant interaction effect on the public's intention to consume man-made meat (-0.694). Third, man-made meat information disclosure has the most significant moderating effect on the relationship between low-carbon awareness and the public's intention to consume man-made meat, as well as a moderating effect on the relationship between man-made meat risk perception and the public's intention to consume man-made meat.

Can Digital Economy Development Contribute to the Low-Carbon Transition? Evidence from the City Level in China

As a new engine to promote high-quality development and a sustainable economy, the digital economy (DE) plays a key role in achieving carbon reduction targets. In this paper, we use the "broadband China (BC)" policy as a proxy variable for the DE and employ the panel data of Chinese prefecture-level cities from 2006 to 2019 to investigate the effect of DE development on carbon emission intensity and its mechanism of action. It is found that (1) DE development significantly reduces the carbon emissions of cities and presents dynamic and sustainable characteristics; (2) the results of mechanism tests indicate that DE development is more inclined to reduce carbon emission intensity by improving regional innovation quality than by improving regional innovation quantity; (3) the impact of DE development on carbon emission intensity differs among cities with different characteristic attributes and different environmental regulation intensity, and the emission reduction effect is more obvious in non-resource-based cities, cities with lower environmental regulation intensity, and cities with weaker environmental target constraints; (4) the impact of DE development and innovation-driven development strategies on reducing carbon emission intensity has a policy linkage effect.

The influence of the brake pad construction on noise formation, people's health and reduction measures

The brake system is one of the most important systems on the vehicle, especially from the aspect of traffic safety. The use of the braking system comes with many undesirable effects, such as brake wear and noise emission. The noise that originates from brakes is related to the wear of brake elements, the applied materials for manufacture, to the elements which are connected to each other, and all of this represents a very challengeable problem in the automotive industry. In this paper are presented the dominant parameters that influence noise formation, where the main focus was placed on brake pads, as well as how the noise influences people's health. After that, further, in the paper, it was analyzed the influence of the brake pads' construction on the noise formation, and at the end are given the measures for noise reduction. The conclusions of the paper show that the construction of brake pads significantly influences noise emission, noise negatively influences on the people health, and because of the negative influence on the people health, some solutions show that it is necessary to include insulators in the construction of brake pads, and if the space in which people reside is observed, it is necessary during construction to use materials which will prevent noise conduction, into the space in which people reside.

CO2 adsorption enhancement and charge transfer characteristics for composite graphene doped with atoms at defect sites

CONTEXT

The massive emission of carbon dioxide in the world causes global warming and a series of increasingly serious ecological problems. It is urgent to find efficient adsorbent for large-scale CO₂ capture. Graphene as a solid adsorbent has exhibited great potential and development prospects in gas adsorption. Doping atoms at defect sites in composite graphene is considered as one of the promising approaches to enhance the gas adsorption ability. Nevertheless, composite graphene doping with different atoms has not been explored to a large extent so far.

METHODS

In this work, vacancy graphenes with single C-vacancy (VI-G) and with double C-vacancies (VII-G) are doped with nitrogen atoms and metal atoms M (M = Co, Mo, Mn, Fe) to form composite configurations. The Perdew-Burke-Ernzerho (PBE) functional is used under the generalized gradient approximation (GGA) basis set. A comprehensive study of the adsorption effect and charge transfer characteristics of CO₂ molecule on different composite graphene configurations is carried out through DFT calculation. By analyzing the adsorption energy, adsorption distance, energy band structure, and atomic Mulliken population, it is found that the composite graphene doped with metal atoms such as Co-3N-VI, Mo-3N-VI, Mn-3N-VI, Fe-3N-VI, and Mo-4N-VII significantly enhanced the CO₂ adsorption. Further analysis of charge density and density of states (DOS) demonstrates that CO₂ adsorption on M-3N-VI and M-4N-VII reached the same conclusion. Thus, it is concluded that appropriate metal atoms can enhance the adsorption characteristics.

Introduction to CO2 capture and conversion

An introduction to the Nanoscale themed collection on CO₂ capture and conversion, featuring exciting research on advanced nanoscale materials and reactions.

Superfunctional Materials by Ultra-Severe Plastic Deformation

Superfunctional materials are defined as materials with specific properties being superior to the functions of engineering materials. Numerous studies introduced severe plastic deformation (SPD) as an effective process to improve the functional and mechanical properties of various metallic and non-metallic materials. Moreover, the concept of ultra-SPD-introducing shear strains over 1000 to reduce the thickness of sheared phases to levels comparable to atomic distances-was recently utilized to synthesize novel superfunctional materials. In this article, the application of ultra-SPD for controlling atomic diffusion and phase transformation and synthesizing new materials with superfunctional properties is discussed. The main properties achieved by ultra-SPD include: (i) high-temperature thermal stability in new immiscible age-hardenable aluminum alloys; (ii) room-temperature superplasticity for the first time in magnesium and aluminum alloys; (iii) high strength and high plasticity in nanograined intermetallics; (iv) low elastic modulus and high hardness in biocompatible binary and high-entropy alloys; (v) superconductivity and high strength in the Nb-Ti alloys; (vi) room-temperature hydrogen storage for the first time in magnesium alloys; and (vii) superior photocatalytic hydrogen production, oxygen production, and carbon dioxide conversion on high-entropy oxides and oxynitrides as a new family of photocatalysts.

How does national development zone policy affect carbon emissions in China? New evidence from a quasi-natural experiment

The expansion of China's development zones has made great contributions to economic development, as well as provided practical guidance for other developing countries to implement development zone policies. However, in the context of global advocacy of low carbon, literature about how the development zone policy affect carbon emissions is poor, especially in China at the urban level. Therefore, this study takes China's development zone policy as a quasi-natural experiment, using the panel data of 285 cities in China from 2003 to 2020, and adopting the DID model to analyze its impact on carbon emissions. After a series of robustness tests including placebo test, dynamic test (all independent variables are lagged by one period), endogeneity test, and parallel trend test, the results are basically robust. The findings show that the development zone policy indeed significantly reduces carbon emissions. In addition, we find that cities with higher resource endowments, cities in the eastern and central regions, and other larger cities across the country have better carbon emissions reduction effects. To a certain extent, the research in this paper fills the gap of theoretical research on carbon emissions in terms of the development zone policy, and provides some practical basis for future research in the field of carbon emissions.

Monitoring global carbon emissions in 2022

Global CO₂ emissions for 2022 increased by 1.5% relative to 2021 (+7.9% and +2.0% relative to 2020 and 2019, respectively), reaching 36.1 GtCO₂. These 2022 emissions consumed 13%-36% of the remaining carbon budget to limit warming to 1.5 °C, suggesting permissible emissions could be depleted within 2-7 years (67% likelihood).

Clay exfoliation method as a route to obtain mesoporous catalysts for CO2 methanation

A unique method for obtaining a mesoporous catalytic support through the exfoliation of a montmorillonite is reported. This method consisted of the intercalation of Na-clay with Al-Keggin species and polyvinyl alcohol followed by microwave irradiation. The mesoporous support was employed to prepare Ni-catalysts which were used in the natural gas synthesis through CO₂ methanation. The synthesis method was validated confirming the clay exfoliation and the main formation of mesopores. Also, the Ni-catalysts have mainly weak basic surface properties lower than 38 µmol.g^-1, and containing Ni⁰ nanoparticles with sizes between 9 and 12 nm which were thermally stable after reduction and methanation reaction. The catalyst with 5% Ni wt. gave conversions between 50 and 80% with temperatures ranging from 200 to 300 °C and selectivities of 100% towards the formation of CH₄ without coke formation. The (3 and 5% Ni) Ni-catalysts are stable up to 8 h at 400 °C in the methanation reaction maintaining 100% of selectivity.•Mesoporous catalytic supports are obtained through a unique clay exfoliation method (Al-keggin, PVA, and microwaves).•(3% and 5% wt.) Ni-mesoporous catalysts are thermally stable and Ni⁰ nanoparticles between 9 and 12 nm are achieved.•5%wt. Ni-catalyst have no deactivation up to 8 h at 400 °C and displays unprecedented performance at low temperatures in CO₂-methanation with 100% of selectivity.

Prospects for carbon-negative biomanufacturing

Biomanufacturing has the potential to reduce demand for petrochemicals and mitigate climate change. Recent studies have also suggested that some of these products can be net carbon negative, effectively removing CO₂ from the atmosphere and locking it up in products. This review explores the magnitude of carbon removal achievable through biomanufacturing and discusses the likely fate of carbon in a range of target molecules. Solvents, cleaning agents, or food and pharmaceutical additives will likely re-release their carbon as CO₂ at the end of their functional lives, while carbon incorporated into non-compostable polymers can result in long-term sequestration. Future research can maximize its impact by focusing on reducing emissions, achieving performance advantages, and enabling a more circular carbon economy.

AnthroShift in a warming world

Thirty years after the UN Conference on Environment and Development created the UN Framework Convention on Climate Change, efforts to respond to the issue continue to be insufficient to meet the challenges of the climate crisis. This perspective builds on the experience of society’s responses to the COVID-19 pandemic to understand what is needed to get to meaningful climate action. It applies the framework of the AnthroShift to assess how transformational social change is likely to emerge. The paper concludes by determining that the most plausible pathway to an effective social response to the climate crisis would be driven by civil society. However, the level of mass mobilization needed is only possible if society is experiencing large-scale and sustained levels of risk that have tangible long-term consequences in terms of social cost to people and property.

Decarbonizing residential buildings in the developing world: Historical cases from China

China's large residential building stocks lead to the serious effect of operational carbon lock-in, which becomes a major challenge in hitting the carbon peak by 2030. This work is the first to develop the Generalized Divisia Index Method with a matrix of 8 × 14 to identify fourteen factors and analyze the provincial carbon change (especially the decarbonization progress) in residential building operations from 2000 to 2018. It shows that: (1) The operational carbon emissions released by residential buildings increased during 2000-2018, with an average rate of 4.53 % per yr in 30 samples. Behind this, the most positive contributor is residential floor areas, while the most negative contributor is the share of household consumption expenditure in the gross domestic product. (2) The annual decarbonization of most provinces in northern China peaked before 2008, accounting for 4.70 mega-tons of carbon dioxide (MtCO₂) per province per yr, and in central and eastern China mainly peaked in approximately 2014, accounting for 7.21 MtCO₂ per province per yr, and the annual decarbonization in southern China generally continued to grow. (3) High levels of decarbonization and decarbonization efficiency have been observed in northern and southwestern China, with 35.06 MtCO₂ per province of decarbonization and 7.05 % per province of efficiency in 2001-2018. Overall, this study improves the analytical method to assess the decarbonization of building operations, and it helps the governments investigate the building decarbonization potential to promote the schemes of carbon peak.

Near-real-time daily estimates of fossil fuel CO2 emissions from major high-emission cities in China

Cities in China are on the frontline of low-carbon transition which requires monitoring city-level emissions with low-latency to support timely climate actions. Most existing CO2 emission inventories lag reality by more than one year and only provide annual totals. To improve the timeliness and temporal resolution of city-level emission inventories, we present Carbon Monitor Cities-China (CMCC), a near-real-time dataset of daily CO2 emissions from fossil fuel and cement production for 48 major high-emission cities in China. This dataset provides territory-based emission estimates from 2020-01-01 to 2021-12-31 for five sectors: power generation, residential (buildings and services), industry, ground transportation, and aviation. CMCC is developed based on an innovative framework that integrates bottom-up inventory construction and daily emission estimates from sectoral activities and models. Annual emissions show reasonable agreement with other datasets, and uncertainty ranges are estimated for each city and sector. CMCC provides valuable daily emission estimates that enable low-latency mitigation monitoring for cities in China.

Valorization of CO2 to β-farnesene in Rhodobacter sphaeroides

The valorization of CO₂ into valuable products is a sustainable strategy to help overcome the climate crisis. In particular, biological conversion is attractive as it can produce long-chain hydrocarbons such as terpenoids. This study reports the high yield of β-farnesene production from CO₂ by expressing heterologous β-farnesene synthase (FS) into Rhodobacter sphaeroides. To increase the expression of FS, a strong active promoter and a ribosome binding site (RBS) were engineered. Moreover, β-farnesene production was improved further through the supply of exogenous antioxidants and additional nutrients. Finally, β-farnesene was produced from CO₂ at a titer of 44.53 mg/L and yield of 234.08 mg/g, values that were correspondingly 23 times and 46 times higher than those from the initial production of β-farnesene. Altogether, the results here suggest that the autotrophic production of β-farnesene can provide a starting point for achieving a circular carbon economy.

Radiology Environmental Impact: What Is Known and How Can We Improve?

The healthcare sector generates approximately 10% of the total carbon emissions in the United States. Radiology is thought to be a top contributor to the healthcare carbon footprint due to high energy-consuming devices and waste from interventional procedures. In this article, we provide a background on Radiology's environmental impact, describe why hospitals should add sustainability as a quality measure, and give a framework for radiologists to reduce the carbon footprint through quality improvement and collaboration.

Salinity impact on the metabolic and taxonomic profiles of acid and alkali treated inoculum for hydrogen production from food waste

This study evaluated the combined impact of salinity (2.5, 13, and 19.3 g NaCl/L) and inoculum pretreatment (acid/alkali) on the genomic and metabolic profiles of mesophilic fermentative bacteria for hydrogen (H₂) production from food waste. Experimental results revealed that acid-treated inoculum showed the highest H₂ yield (201.12 ± 13.84 mL H₂/g of volatile solids added) under medium salinity levels compared to other experimental conditions. A 7-56% increase in H₂ yield was observed for pretreated inoculum than untreated inoculum. Genomic analysis and metabolic pattern revealed that the H₂ production was mainly through Clostridial-type fermentation under medium to high salinity levels, whereas Enterococcus-type fermentation under low salinity levels. Further, the genomic analysis uncovered that phyla Firmicutes (69.71-96.81%) and genus Clostridium sensu stricto 1 (33.28-94.04%) dominated during the exponential gas production phase. Overall, this study showed the significance of inoculum pretreatment for the bioconversion of food waste at different salinity levels.

Low-Carbon Collaboration in the Supply Chain under Digital Transformation: An Evolutionary Game-Theoretic Analysis

In the face of the challenges posed by the need to drastically decrease carbon emissions, all agents in the supply chain need to strengthen low-carbon collaboration with the support of digital transformation. This study sets up a low-carbon collaboration evolutionary game model of the supply chain based on benefit sharing by introducing digital transformation. The equilibrium-point stability of the supply chain is then analyzed under two separate conditions—i.e., less and more government rewards and punishments compared to supply-chain agents’ strategic risk cost. Furthermore, based on the evolutionary game model, this study draws the system dynamics (SD) flow diagram to analyze the research problem quantitatively. The main results show that: (1) low-carbon benefit-driven effects promotes collaboration benefit sharing, thereby increasing the probability of low-carbon collaboration; (2) digital transformation is an essential regulator of low-carbon collaboration in the supply chain and can amplify the low-carbon benefit-driven effect; (3) collaboration benefit sharing can perfectly coordinate the vertical supply chain under low-carbon collaboration; and (4) government support and management are critical links in the low-carbon collaboration formation path of the supply chain. This research provides theoretical support for low-carbon collaboration in the supply chain under digital transformation.

Investigation on Spectral Characteristics of Gliding Arc Plasma Assisted Ammonia Lean Combustion

Ammonia as a non-carbon fuel is expected to play an important role in the future, but it is difficult to be effectively utilized at this stage due to its flame retardancy and other characteristics. Therefore, we propose to use gliding arc plasma combined with a swirl burner to enhance the combustion performance of ammonia. The electrical characteristics, electron density, gas rotational temperature and the distribution of key active species in the burner were studied via optical emission spectroscopy (OES). With the increase of equivalence ratio (EQR), the width of the Hα line decreases significantly, indicating that the electron density shows a downward trend, even as the gas rotational temperature shows an upward trend. When the equivalence ratio was 0.5, the gas rotational temperature increases by about 320 K compared with the pure air condition. During pure air discharge, there will still be obvious NO emission due to the plasma reaction, but with the addition of NH3, the NO content in the emission is significantly reduced. The light intensity of O atoms in the burner gradually decreases with the increase of the equivalence ratio, the light intensity of H atoms increases first and then decreases, and the light intensity of NH shows an upward trend. The reason may be that the plasma discharge effectively strengthens NH3(E)->NH2+H, NH2+H->NH+H2 and other reactions promote the initial reaction step of NH3 which thus effectively strengthens the NH3 combustion.

Carbon Monitor Cities near-real-time daily estimates of CO2 emissions from 1500 cities worldwide

Building on near-real-time and spatially explicit estimates of daily carbon dioxide (CO2) emissions, here we present and analyze a new city-level dataset of fossil fuel and cement emissions, Carbon Monitor Cities, which provides daily estimates of emissions from January 2019 through December 2021 for 1500 cities in 46 countries, and disaggregates five sectors: power generation, residential (buildings), industry, ground transportation, and aviation. The goal of this dataset is to improve the timeliness and temporal resolution of city-level emission inventories and includes estimates for both functional urban areas and city administrative areas that are consistent with global and regional totals. Comparisons with other datasets (i.e. CEADs, MEIC, Vulcan, and CDP-ICLEI Track) were performed, and we estimate the overall annual uncertainty range to be ±21.7%. Carbon Monitor Cities is a near-real-time, city-level emission dataset that includes cities around the world, including the first estimates for many cities in low-income countries.

DFT Study on the Effect of Na on NO Reduction with Nitrogen-Containing Char from Zhundong Coal

The effect mechanism of Na on reduction of NO with nitrogen-containing char, char(N) still lacks an in-depth study. Based on density functional theory, this study systematically discussed the heterogeneous reaction of NO with four char(N) models, that is, zigzag(N), zigzag(N)@Na, armchair(N), and armchair(N)@Na. Results show that the presence of Na promoted the chemisorption of NO on both zigzag(N) and armchair(N), especially zigzag(N). Mayer bond order analysis revealed that during NO reduction, Na catalyzed the breaking of N-O and C-N bonds in both models as well as dissociation of the N-N structure from the zigzag(N). Dynamics in the 300-1000 K range revealed that the rate constant for the decisive step increased in the order of zigzag(N) < zigzag(N)@Na < armchair(N) < armchair(N)@Na, while the activation energy presented a reverse order. The addition of Na promoted the electron transfer between NO and char(N) and exhibited an obvious catalytic effect on the NO-char(N) reaction by reducing activation energy and increasing the reaction rate constant for the decisive step.

The G20 emission projections to 2030 improved since the Paris Agreement, but only slightly

Many years passed since the adoption of the Paris Agreement, which invites countries to determine their own contributions to climate change mitigation efforts. The Agreement does not offer a standard to measure progress but relies on a process of periodic stocktakes to inform ambition-raising cycles. To contribute to this process, we compare 2021 greenhouse gas emission projections up to 2030 against equivalent projections prepared back in 2015. Both sets of projections were prepared using the same bottom-up modelling approach that accounts for adopted policies at the time. We find that 2021 projections for the G20 as a group are almost 15% lower (approximately 6 GtCO₂eq) in 2030 than projected in 2015. Annual emissions grow 1% slower in the coming decade than projected in 2015. This slower growth mostly stems from the adoption of new policies and updated expectations on technology uptake and economic growth. However, around one-quarter of these changes are explained by the effects of the COVID-19 pandemic on short-term emissions and economic forecasts. These factors combined result in substantially lower emission projections for India, the European Union plus the UK (EU27 + UK), the Unites States, Russia, Saudi Arabia, and South Africa. We observe a remarkable change in South African projections that changed from a substantial increase to now a decline, driven in part by the planned phase-out of most of its coal-based power. Emissions in India are projected to grow slower than in 2015 and in Indonesia faster, but emissions per capita in both countries remain below 5 tCO₂eq in 2030, while those in the EU27 + UK decline faster than expected in 2015 and probably cross the 5 tCO₂eq threshold before 2030. Projected emissions per capita in Australia, Canada, Saudi Arabia, and the United States are now lower than projected in 2015 but remain above 15 tCO₂eq in 2030. Although emission projections for the G20 improved since 2015, collectively they still slightly increase until 2030 and remain insufficient to meet the Paris Agreement temperature goals. The G20 must urgently and drastically improve adopted policies and actions to limit the end-of-century warming to 1.5 °C.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11027-022-10018-5.

Analysis of the Impact of the COVID-19 Pandemic on the Value of CO2 Emissions from Electricity Generation

The study analyzed the impact of the COVID-19 pandemic on the carbon dioxide emissions from electricity generation. Additionally, monthly seasonality was taken into account. It was assumed (research hypothesis) that both the COVID-19 pandemic (expressed in individual waves of infection cases) and the month have a significant impact on CO2 emissions. Analysis of variance (ANOVA) and non-parametric Kruskal–Wallis tests were used to evaluate the significance of the influence of individual explanatory variables on the CO2 emission. The identification of the studied series (CO2 emission) was first made by means of a linear regression model with binary variables and then by the ARMAX model. The analysis shows that in the consecutive months and periods of the COVID-19 pandemic, CO2 emissions differ significantly. The highest increase in emissions was recorded for the second wave of the pandemic, as well as in January and February. This is due to the overlapping of both the increase in infections (favoring stays at home) and the winter season. It can be concluded that working plants, schools and factories had the same demand for electricity, but sources of increased consumption were people staying at home and in hospitals as a result of deteriorated health, isolation or quarantine.

A Big Data-Based Commuting Carbon Emissions Accounting Method—A Case of Hangzhou

Commuting carbon emissions are an essential component of urban carbon emissions, and determining how to reduce them is an area of great debate among researchers. The current research lacks a tool and instrument that can extensively account for residents’ commuting. Traditional methods are mainly based on questionnaire surveys, which have low accuracy at spatial and temporal aspects. High accuracy carbon emission accounting methods can effectively assist urban planning and achieve precise urban emissions reductions. This study applies a taxi commuting carbon emissions accounting method divided into two main steps. Firstly, the carbon emissions of taxi trajectories are calculated using taxi trajectory data and a carbon emission calculation method developed based on VSP. Secondly, the taxi trajectory and POI data are used to filter the commuter trajectory with the help of a two-step moving search method. In this way, the taxi commuting carbon emissions were obtained. Then, the spatial distribution characteristics of residential taxi commuting carbon emissions are analysed by spatial autocorrelation tools, which could facilitate low carbon zoning management. A typical working day in Hangzhou was selected as the research object of this study. The results show that (1) morning peak commuting carbon emissions in the main urban area of Hangzhou reached 2065.14 kg per hour, accounting for 13.73% of all taxi travel carbon emissions; and evening peak commuting carbon emissions reached 732.2 kg per hour, accounting for 4% of all taxi travel carbon emissions; (2) At the grid level, the spatial distribution of commuting carbon emissions in Hangzhou shows a single central peak that decays in all directions; and (3) The results at the resident community scale show that urban public transport facilities influence resident community commuting carbon emissions. In areas such as at the urban-rural border, resident community commuting carbon emissions show high levels of aggregation, and in the main urban area, resident community commuting carbon emissions show low levels of aggregation. This study not only provides a new method of commuting investigation but also offers constructive suggestions for future carbon emission reduction under Hangzhou’s urban planning.

Paris Agreement requires substantial, broad, and sustained policy efforts beyond COVID-19 public stimulus packages

It has been claimed that COVID-19 public stimulus packages could be sufficient to meet the short-term energy investment needs to leverage a shift toward a pathway consistent with the 1.5 °C target of the Paris Agreement. Here, we provide complementary perspectives to reiterate that substantial, broad, and sustained policy efforts beyond stimulus packages will be needed for achieving the Paris Agreement long-term targets. Low-carbon investments will need to scale up and persist over the next several decades following short-term stimulus packages. The required total energy investments in the real world can be larger than the currently available estimates from integrated assessment models (IAMs). Existing databases from IAMs are not sufficient for analyzing the effect of public spending on emission reduction. To inform what role COVID-19 stimulus packages and public investments may play for reaching the Paris Agreement targets, explicit modelling of such policies is required.