Significant Emission Reductions Research Articles

Synthesis of nano-calcium carbonate from waste cement and techno-economic and environmental evaluation

Mineral carbonation stands out not only as an effective method for reducing CO2 emissions but also as a strategic approach to upcycling industrial waste. This study introduces a novel procedure for generating high-purity nano-calcium carbonate (nCaCO3) from waste cement powder, deploying hydrochloric acid (HCl), and sodium hydroxide (NaOH), both obtained through the electrolysis of sodium chloride (NaCl). Our approach, aimed at both environmental preservation and techno-economic feasibility, encompasses optimizing calcium extraction conditions through rigorous analysis of variables such as HCl concentration, solid-to-liquid ratio, and reaction temperature, subsequently proposing a rate law for the extraction process. Furthermore, the method emphasizes the production of high-purity CaCO3 by meticulously removing metallic impurities from the extracted solution with 1.0 M NaOH, culminating in pure calcium hydroxide and the generation of nCaCO3 particles with superior purity (>99 %) and a uniform particle size (80–140 nm). An exhaustive environmental and economic assessment indicates that our process, while consuming varying energy levels based on operational potentials, anticipates a significant reduction in CO2 emissions by 46.1 %, alongside a competitive production cost (335 USD/ton of nCaCO3), thereby demonstrating substantial advantages over traditional methods in terms of sustainability, efficiency, and cost-effectiveness.

Switch to pollution control bonds, else carbon risk will switch us: Evidence from the U.S. electric utility firms

This study explores the implications and effectiveness of pollution control bonds (PCBs) in reducing carbon risk, focusing on a sample of 242 U S. electric utility firms from 2012 to 2022. The research investigates the association of PCB issuances with (i) absolute (unscaled) carbon emissions levels and their three scopes; and (ii) carbon emissions intensity and its three scopes. Using quantile regressions covering the 5th, 25th, 50th, 75th, and 90th quantiles, along with the Propensity Score Matching (PSM) methodology (where the treatment group includes firms using PCBs and the control group comprises firms that do not opt for PCBs), the findings show a significant reduction in carbon emissions due to PCB issuance. Substantial differences were observed between the treatment group and the control group across various quantiles of carbon emissions, particularly for companies with medium to high carbon footprints, both in terms of overall CO2 emissions and scope 2 CO2 emissions. Moreover, disparities between the two groups were notable across all quantiles of scope 1 CO2 emissions. Additionally, among the companies using PCBs, those with lower risk profiles exhibited a smaller carbon footprint, measured by scope 3 CO2 emissions, in comparison to their counterparts. Furthermore, the study highlights a more pronounced impact of PCBs issuance during the second phase of the Kyoto Protocol and the commitment period of the Paris Agreement. The results remain robust when alternative measures of carbon risk are applied. These findings carry significant implications for municipal and financing authorities, as well as investors within the U.S. electric utility industry. This research contributes novel insights to the field of electric utility management.

Towards Sustainable Mobility: Assessing the Benefits and Implications of Internal Combustion Engine Vehicle Bans and Battery Electric Vehicle Uptake in Qatar

The global shift towards sustainable transportation, primarily through vehicle electrification, is critical in addressing climate change. Qatar presents a knowledge gap with specific challenges and opportunities in this transition. This study calculates the potential reduction in CO2-eq, NOx, and PM2.5 emissions resulting from substituting Internal Combustion Engine Vehicles (ICEVs) with Battery Electric Vehicles (BEVs) in Qatar, considering ICEV ban scenarios in 2030, 2035, and 2040, alongside five policy pathways. A Vehicle Stock Model (VSM) simulates Qatar’s fleet evolution from 2022 to 2050, focusing on the vehicle’s operational phase. An ICEV ban in 2030 would result in a 34% cumulative emission reduction in road transport between 2022 and 2050 compared with the Business-as-Usual (BAU) scenario. For NOx and PM2.5, cumulative emissions for the 2030 ICEV ban pathways are approximately 20% and 9% lower, respectively, compared with BAU. This study underscores the necessity of localising environmental strategies to meet Qatar’s specific needs and climate commitments, where results indicate significant emission reductions are possible through BEVs.

Biofuels in Aviation: Exploring the Impact of Sustainable Aviation Fuels in Aircraft Engines

This comprehensive review examines the role of sustainable aviation fuels (SAFs) in promoting a more environmentally responsible aviation industry. This study explores various types of biofuels, including hydroprocessed esters and fatty acids (HEFAs), Fischer–Tropsch (FT) fuels, alcohol-to-jet (ATJ) fuels, and oil derived from algae. Technological advancements in production and processing have enabled SAF to offer significant reductions in greenhouse gas emissions and other pollutants, contributing to a cleaner environment and better air quality. The review addresses the environmental, economic, and technical benefits of SAF, as well as the challenges associated with their adoption. Lifecycle analyses are used to assess the net environmental benefits of SAF, with a focus on feedstock sustainability, energy efficiency, and potential impacts on biodiversity and land use. Challenges such as economic viability, scalability, and regulatory compliance are discussed, with emphasis on the need for supportive policies and international collaboration to ensure the long-term sustainability of SAF. This study also explores current applications of SAF in commercial airlines and military settings, highlighting successful case studies and regional differences driven by policy frameworks and government incentives. By promoting technological innovation and addressing regulatory and economic barriers, SAF has the potential to play a crucial role in the aviation industry’s transition toward sustainability.

Sustainable practices in hospital and operating theaters.

This review aims to provide an update on the results of studies published in the last two years involving the development of sustainable practices in hospital and operating theaters (OT). Recently, many studies evaluated various initiatives to better understand the environmental impact of the OT but also to minimize its environmental impact. Many trials evidenced the positive impact of the instrument's reuse using an appropriate reprocessing procedure. Better waste segregation is associated with a reduction of produced waste and contributes to a significant reduction in CO 2 equivalent emissions. Regarding anaesthetic gas, Desflurane is known to have the worst environmental impact and the majority of the study evidenced that its reduction permits to drastically reduce greenhouse gas emission of the OT. Greening the OT necessitates climate-smart actions such as waste reduction, the improvement of reusable instruments, recycling of our waste and better anaesthetic gas management. Within the last two years, many efforts have been made to reduce and better segregate waste produced in the OT and also to better understand the environmental impact of disposable and reusable devices.

The Effect of Using Environmentally Friendly Materials and Energy Efficiency in the Production Process on Reducing Carbon Emissions in the West Java Automotive Industry

This research quantitatively analyzes the effect of integrating environmentally friendly materials and energy-efficient production processes on reducing carbon emissions in the West Java automotive industry. Through surveys and statistical analysis, the study examines the adoption of sustainable practices among automotive manufacturers and assesses their impact on carbon emissions reduction. Findings indicate that companies actively embracing sustainable practices demonstrate a significant reduction in carbon emissions compared to those with minimal adoption. The results underscore the importance of prioritizing sustainability initiatives within the automotive industry to mitigate environmental impacts and contribute to global efforts to combat climate change.

Optimization of heat management and utilization in batch processes

Batch plants boast operational flexibility in manufacturing process and resource sharing, making batch processes suitable to fluctuating-demand or small-scale production. However, given time dependence of operational behavior, batch processes are more demanding in energy integration than continuous processes, a task which is especially important amid the global net zero-emission current. It is, therefore, imperative to develop sustainable design strategies for intermittent processes. The study introduced a targeting method and developed an innovative over-time heat integration technique to optimize energy utilization in batch processes, involving use of heat transfer media for heat recovery over various time intervals and a heat makeup strategy to heat the media over different periods, in order to enhance heat-energy utilization efficiency. The technique is applicable to both fixed and unspecified batch schedules, the latter of which involves simultaneous design of production schedule and heat recovery systems, increasing flexibility and improving heat energy utilization. Case studies are conducted to demonstrate the proposed method. With the heat makeup technique, energy efficiency can be significantly enhanced, achieving energy savings of 51% and 93.1% in hot and cold utility, respectively. Meanwhile, the simultaneous design of production schedule and heat integration can boost savings up to 53% and 99%. Results have proven the benefits of the technique, including significant reduction of energy consumption and carbon emission, contributing to clean production, environmental protection, and sustainable development.

Widespread 2013-2020 decreases and reduction challenges of organic aerosol in China

High concentrations of organic aerosol (OA) occur in Asian countries, leading to great health burdens. Clean air actions have resulted in significant emission reductions of air pollutants in China. However, long-term nation-wide trends in OA and their causes remain unknown. Here, we present both observational and model evidence demonstrating widespread decreases with a greater reduction in primary OA than in secondary OA (SOA) in China during the period of 2013 to 2020. Most of the decline is attributed to reduced residential fuel burning while the interannual variability in SOA may have been driven by meteorological variations. We find contrasting effects of reducing NOx and SO2 on SOA production which may have led to slight overall increases in SOA. Our findings highlight the importance of clean energy replacements in multiple sectors on achieving air-quality targets because of high OA precursor emissions and fluctuating chemical and meteorological conditions.

Bridging chance-constrained and stochastic optimization for risk estimation of virtual energy hubs dominated by hybrid vehicles under diverse uncertainties: To improve economic sustainability

Virtual energy hubs (VRHBs) combine dispersed energy resources to enhance the efficient use of various energy sources, grid flexibility, and renewable energy adoption. This paper investigates the adoption of VRHBs with power-to-gas (P2G) facilities and hybrid electric-compressed natural gas vehicles (HNGEVs) in the presence of renewable resources to effectively tackle carbon emissions and increase the flexibility of VRHBs. The proposed P2G facility is constructed from carbon capture to collect carbon pollution from fossil fuel resources and HNGEVs to recycle into synthesis gas in a methanation plant. Furthermore, due to severe uncertainties due to renewable resources and energy consumption intensity, the proposed framework utilizes stochastic-driven chance-constrained optimization, which enables decision-makers in VRHBs to account for the probabilistic nature of uncertainties. Chance-constrained optimization explicitly considers uncertainty through probabilistic constraints, providing a more robust and reliable solution compared to deterministic methods. By modeling uncertainties using chance-constrained programming, VRHBs can manage the economic risks under unexpected worst realizations in uncertainties. Based on the results, the P2G facility leads to a significant reduction in the daily emissions by 63.06 % and 42.77 % observed under no-risk and full-risk conditions, respectively. In addition, the suggested chance-constrained method resulted in a major decrease of 69 % in overall operational costs.

The influence of carbon emission trading on the optimization of regional energy structure

The optimization of the energy structure is a crucial element in the development of green and low-carbon economies and societies. Market-based environmental regulations, such as carbon emissions trading, play a significant role in facilitating this transition. This study analyzes panel data from 30 provinces in China from 2007 to 2020. It empirically examines the impact and mechanism of carbon emissions trading pilot schemes on the transformation of energy consumption structure at the macro level, using the difference-in-differences method. The research findings indicate that provinces with carbon emissions trading pilots have experienced significant reductions in carbon emissions and carbon intensity, demonstrating clear emission reduction effects. Additionally, the transformation process of energy consumption structure has been notably accelerated, highlighting the correlation between initial carbon emissions trading and the regional energy utilization framework. Furthermore, in our extended mechanism analysis, we introduce two new variables - green finance and environmental regulation. Our analysis reveals that the level of green finance in carbon emissions trading pilot provinces significantly influences the degree of carbon emissions in these areas. Additionally, environmental regulation has a significant positive impact on the optimization of energy consumption structure.

Electric vehicles as an emission mitigation option: expectations and reality

AbstractGlobally, the reliance on thermal power, constituting 67% of electricity generation, prompts questions for many countries regarding the viability of electric vehicles (EVs) for emission reduction in the transportation sector. This study comprehensively analyzes CO2 emissions in the small family car segment, considering engines powered by different energy sources. The analysis is coupled with Worldwide Harmonized Light Vehicle Test Procedure driving profiles, accounting for specific ambient temperature structures representative of densely populated areas in Türkiye. The constructed model incorporates the hourly temperature of the relevant cities and the hourly electricity production mix by considering the indirect emissions and comparing the ICEVs (Internal Combustion Engine Vehicles) and EVs in different time frames from 2015 to 2020. The resulting emissions from each vehicle type in each city and driving profile, along with the ratio of instances in which EVs exhibit higher emissions than ICEVs, are presented.The findings reveal the intricate interplay between vehicle type, climate conditions, and driving profiles. While the urban driving profile emerges as superior for EVs regarding CO2 reduction, offering a comfortable driving experience without range anxiety and mitigating local pollutants, it exhibits less significant carbon emission reductions at lower and higher speed profiles, particularly in cold climate conditions. EVs are not a silver bullet but a valuable technology for emissions reduction under specific conditions. Policymakers are urged to consider factors favoring EVs over ICEVs regarding CO2 emissions, such as driving profiles, time and climatic conditions when formulating investment policies and subsidies. Graphical abstract

A Big Data-Driven Approach for Early Warning of Enterprise Emissions Alignment with Carbon Neutrality Targets: A Case Study of Guangxi Province

Achieving the target of carbon neutrality has been an important approach for China to mitigate global climate change. Enterprises are major carbon emitters, and a well-designed early warning system is needed to ensure that their emissions align with carbon neutrality goals. Therefore, this study utilized electricity big data to construct an early warning model for enterprise carbon emissions based on carbon quota allocation. Taking key carbon-emitting enterprises in Guangxi as a case study, we aim to provide insights to support China’s dual carbon goals. Firstly, we established the Carbon Quota Allocation System, enabling carbon quota allocation at the enterprise levels. Secondly, we developed the Enterprise Carbon Neutrality Index, facilitating dynamic warnings for carbon emissions among enterprises. The main conclusions are as follows: (1) In 2020, Guangdong received the highest carbon quota of 606 million tons, representing 5.72% of the national total, while Guangxi only received 2.63 billion tons. (2) Only 39.34% of enterprises in Guangxi are able to meet the carbon neutrality target, indicating significant emission reduction pressure faced by enterprises in the region. (3) Over 90% of enterprises in Guangxi receive Commendation and Encouragement warning levels, suggesting that enterprises in Guangxi are demonstrating a promising trend in emission reduction efforts.

The Environmental Benefits of an Automatic Idling Control System of Connected and Autonomous Vehicles (CAVs)

The transportation sector is regarded as the main culprit in greenhouse gas emission in the urban network, particularly idling vehicles waiting at signalized intersections. Although autonomous vehicles can be a promising technology to tackle vehicle idling, their environmental benefits receive little attention compared with their safety and mobility issues. This study investigated the environmental benefits of autonomous vehicles equipped with an automatic idling control function based on the queue discharge time and traffic signal information transmitted from the traffic signal controller via V2I communication using microscopic mobility and emission simulation models, VISSIM and MOVES, in Haeundae-gu in Busan, Korea. This study found that the function contributes to a significant reduction in CO2 emissions by 23.6% for all-inclusive emission and 94.3% for idling emission, respectively. Moreover, total reduced idling time accounts for 47.6% of the total travel time and 94.3% of the total idling time, respectively. Consequently, the autonomous vehicles equipped with automatic vehicle idling control function under C-ITS can play an important role in reducing greenhouse gas emissions and fuel consumption as well in the urban network.

Self-consolidating paste systems using ground granulated blast furnace slag and limestone powder mineral admixtures

This study aims to investigate the blends of supplementary cementitious ground granulated blast furnace slag (GGBFS) with limestone powder (LSP) as mineral admixtures to partially replace cement (up to 30 %) in self-consolidating paste (SCP) systems made at respective water demands. Besides the control formulation (100 % cement), the first set of SCP systems includes GGBFS alone as a partial substitute of cement (5 %, 10 %, 15 %, and 20 %), whereas the second set contains blends of 10 % GGBFS with 10 % and 20 % LSP. For all the seven formulations (1 control, 4 binary and 2 ternary), tests were performed to determine their water demand, setting times and flow behavior, hydration kinetics, mechanical strengths and microstructural properties. Results showed that the fresh and hardened state properties of SCP systems incorporating GGBFS and LSP led to an increase in strength, hydration kinetics were slightly improved and hence enhancement of strength and microstructure of SCP systems. Reduction in initial and final setting times recorded with increased LSP from 10 % to 20 % in ternary SCP formulations. Early compressive strength due to LSP increased in ternary SCP systems as compared to binary formulations, which reflected synergy between GGBFS and LSP in SCP systems. Moreover, environmental assessment results indicate a significant reduction in CO2 emissions by substituting cement with GGBFS and LSP. These findings indicate that both GGBFS and LSP can be successfully used in developing high performance and environment friendly self-compacting concrete (SCC).

Decoupling dynamics: Evaluating the relationship between ship emissions and socioeconomic progress in the Yangtze River Basin from 2007 to 2022

To investigate the decoupling relationship between inland ship emissions and regional socioeconomic development in the Yangtze River Basin, this study constructed an emissions inventory for inland ships from 2007 to 2022, based on inland shipping freight statistics and ship carbon pollution emission intensity. Additionally, the Petri-Tapio decoupling model was employed to analyze the relationship between ship carbon pollution emissions and per capita GDP. The study concluded that CO2 emissions from inland ships in the Yangtze River Basin increased from 2.418 million tons in 2007 to 10.801 million tons in 2022. In 2021, the emissions of NOx and SOx from inland ships in the Yangtze River Basin accounted for 2.27% and 0.0021%, respectively, of China's anthropogenic emissions. Despite a year-on-year increasing trend in ship emissions within the basin, significant reductions in PM and SO2 emissions were observed post-2018 due to the implementation of emission reduction policies. Furthermore, we found that economically developed areas such as Shanghai, Jiangsu, and Zhejiang had higher emissions compared to other regions, with regional ship emissions positively correlating with the level of economic activity. Decoupling analysis results indicated that most provinces in the Yangtze River Basin have not effectively decoupled ship carbon pollution emissions from GDP growth. The findings of this study provide support for the Chinese government to formulate stricter ship emission control policies while promoting the growth of the Yangtze River shipping economy.

Fire behaviour of biochar-based cementitious composites

The study aimed to test the hypothesis that biochar's unique properties, such as its microporous structure, can enhance concrete's resilience to high temperatures. Despite expectations of reduced crack formation and enhanced fire resistance, the experimental results revealed a limited impact on concrete's fire behaviour. The investigation involved the use of two biochar types, fine and coarse biochar as replacements for cement and aggregates, respectively. Fine biochar exhibited higher water absorption and Young's modulus than coarse biochar, but both resisted ignition at 35 kW/m2 radiative heat flux and had peak heat release rates below 40 kW/m2. Incorporating these biochars at varying weight percentages (10, 15, and 20 wt.%) into concrete led to a gradual decline in compressive and tensile strength due to reduced binding ability with increased biochar content. Exposure to 1000 °C compromised mechanical properties across all the samples. However, the biochar concrete maintained compressive strength (compared to the control) with up to 20 wt.% biochar as a fine aggregate substitute after exposure to 600 °C, and as a cement replacement after exposure to 200 °C. This substitution also yielded a significant reduction in CO2 emissions (50 % reduction as the biochar loading amount doubled) from concrete manufacturing, showcasing biochar's potential for sustainable construction practices. Despite not fully supporting the initial hypothesis, the study demonstrated biochar's viability in reducing carbon footprint while maintaining concrete strength under certain fire conditions.

Doing all we can? Destination management organizations’ net-zero pledges and their decarbonization plans

Strong leadership by destination management organizations (DMOs) is urgently needed to foster significant emissions reductions at the macro-level. With an increasing number of DMOs pledging to the Tourism Declares initiative and the Glasgow Declaration, achieving net-zero becomes a responsibility. This study (1) proposes nine macro-level decarbonization factors as a framework for DMOs to strategize their climate actions, and (2) examines whether DMOs’ pledges and plans address critical decarbonization factors. It is found that most DMOs do not fully utilize all effective factors in their climate strategies. More than half of the DMOs focus on improving the energy intensity of tourism businesses and inspiring tourists toward green service, factors that, alone, are insufficient. We identify two key initiatives on which DMOs can have the most influence, yet they are rarely considered: optimizing the marketing mix for low-emission groups and setting a growth threshold. We conclude with recommendations on how they might improve their commitments for real progress toward the net-zero transition.

Systematic review and meta-analysis of ex-post evaluations on the effectiveness of carbon pricing.

Today, more than 70 carbon pricing schemes have been implemented around the globe, but their contributions to emissions reductions remains a subject of heated debate in science and policy. Here we assess the effectiveness of carbon pricing in reducing emissions using a rigorous, machine-learningassisted systematic review and meta-analysis. Based on 483 effect sizes extracted from 80 causal ex-post evaluations across 21 carbon pricing schemes, we find that introducing a carbon price has yielded immediate and substantial emission reductions for at least 17 of these policies, despite the low level of prices in most instances. Statistically significant emissions reductions range between-5% to-21% across the schemes (-4% to-15% after correcting for publication bias). Our study highlights critical evidence gaps with regard to dozens of unevaluated carbon pricing schemes and the price elasticity of emissions reductions. More rigorous synthesis of carbon pricing and other climate policies is required across a range of outcomes to advance our understanding of "what works" and accelerate learning on climate solutions in science and policy.

Socio-environmental Opportunities for Organic Material Management in California's Sustainability Transition.

Contemporary resource management is doubly burdened by high rates of organic material disposal in landfills, generating potent greenhouse gases (GHG), and globally degraded soils, which threaten future food security. Expansion of composting can provide a resilient alternative, by avoiding landfill GHG emissions, returning valuable nutrients to the soil to ensure continued agricultural production, and sequestering carbon while supporting local communities. Recognizing this opportunity, California has set ambitious organics diversion targets in the Short-Lived Climate Pollutant Law (SB1383) which will require significant increases (5 to 8 million tonnes per year) in organic material processing capacity. This paper develops a spatial optimization model to consider how to handle this flow of additional material while achieving myriad social and ecological benefits through compost production. We consider community-based and on-farm facilities alongside centralized, large-scale infrastructure to explore decentralized and diversified alternative futures of composting infrastructure in the state of California. We find using a diversity of facilities would provide opportunity for cost savings while achieving significant emissions reductions of approximately 3.4 ± 1 MMT CO2e and demonstrate that it is possible to incorporate community protection into compost infrastructure planning while meeting economic and environmental objectives.

Digital Economy Development, Common Prosperity, and Carbon Emissions: An Empirical Study in China

Under the new development model, the digital economy has become a new engine to promote the green development of the economy and realize the goal of “double carbon”. Based on the panel data of 30 provinces in China from 2010 to 2020, this paper empirically investigates the impact of the development of the digital economy on energy and carbon emissions using a series of econometric models such as baseline regression, a mechanism test, and the spatial Durbin model, etc. Common prosperity plays an intermediary role between digital economy development and carbon emissions; digital economic development optimizes resource allocation, effectively solves the problem of uneven resource distribution, and reduces energy and carbon emissions while achieving common prosperity. In addition, green innovation, industrial structure, urbanization level, R&D intensity, and the degree of marketization also have different degrees of influence on energy and carbon emissions. Therefore, the government should accelerate the construction of new digital infrastructure and implement the digital economy development strategy according to local conditions, so as to promote the digital economy to produce a more significant carbon emission reduction effect.