Substantial Emission Reductions Research Articles

Performance Evaluation of Diesel Engine Using Novel Variable Compression Ratio Mechanism

Increasingly stringent emission and fuel economy standards brings opportunities and research in automobile engine technology development to make it more efficient and less polluting. There are various performance improvement strategies adopted by different researchers in order to get maximum power from the minimum quantity of fuel alongside substantial reduction in exhaust gas emission. The techniques such as CRDI (Common Rail Direct Injection), VVT (Variable valve timing) and such more are commercially viable and successfully incorporated in vehicles. Along the similar track, this paper highlights the importance of variable compression ratio diesel engine, method of achieving the variable compression ratio (VCR) as per load and speed conditions. Variable compression ratio (VCR) technology is one of the method for improving the automobile engine performance, efficiency, fuel economy with reduced emission for range of fuels. The basis of the VCR engine is to operate at different compression ratio, by altering the combustion chamber volume, as per need of most suitable operating conditions. Apart from this, the fuel injection location needs to be varied as per load and speed conditions. The synchronization of both VCR and variable fuel injector location (VFIL) becomes important. Knowing this fact, the study for the diesel Comet engine (3.7 kW@2100 RPM) is undertaken for variable clearance volume accompanied with VIPL. The work consists of design and development of mechanism consisting of auxiliary cylinder and auxiliary piston which will operate in and out of combustion chamber as per load and speed conditions. The detailed drawings and complete experimentation will be carried out to judge the improvement of performance of diesel engine with modification of variable clearance volume concept. The performance parameters consist of brake power, brake thermal efficiency and brake specific fuel consumption under various load conditions.

Thoughts on the Prospects of Renewable Hydrogen

In the last two years or so, there has been increasing interest in hydrogen as an energy source in Australia and around the world. Notably, this is not the first time that hydrogen has caught our collective interest. Most recently, the 2000s saw a substantial investment in hydrogen research, development, and demonstration around the world. Prior to that, the oil crises of the 1970s also stimulated significant investment in hydrogen, and earlier still, the literature on hydrogen was not lacking. And yet, the hydrogen economy is still an idea only.So what, if anything, might be different this time?This is an important question that we all need to ask, and for which the author can only give two potential answers. First, our need to make dramatic reductions in greenhouse gas (GHG) emissions has become more pressing since these previous waves of interest. Second, renewable energy is considerably more affordable now than it was before, and it has consistently outperformed expectations in terms of cost reductions by even its strongest supporters.While this dramatic and ongoing reduction in the cost of renewables is very promising, our need to achieve substantial GHG emission reductions is the crucial challenge. Moreover, meeting this challenge needs to be achieved with as little adverse social and economic impact as possible.When considering what role hydrogen might play, we should first think carefully about the massive scale and complexity of our global energy system, and the typical prices of the major energy commodities. This provides insights into what opportunities hydrogen may have. Considering a temperate country with a small population like Australia, we see that domestic natural gas and transport fuel markets are comparable to and even larger than the electricity market on an energy basis.

Substantial nitrogen oxides emission reduction from China due to COVID-19 and its impact on surface ozone and aerosol pollution

A top-down approach was employed to estimate the influence of lockdown measures implemented during the COVID-19 pandemic on NOx emissions and subsequent influence on surface PM2.5 and ozone in China. The nation-wide NOx emission reduction of 53.4% due to the lockdown in 2020 quarter one in China may represent the current upper limit of China's NOx emission control. During the Chinese New Year Holiday (P2), NOx emission intensity in China declined by 44.7% compared to the preceding 3 weeks (P1). NOx emission intensity increased by 20.3% during the 4 weeks after P2 (P3), despite the unchanged NO2 column. It recovered to 2019 level at the end of March (P4). The East China (22°N - 42°N, 102°E - 122°E) received greater influence from COVID-19. Overall NOx emission from East China for 2020 first quarter is 40.5% lower than 2019, and in P4 it is still 22.9% below the same period in 2019. The 40.5% decrease of NOx emission in 2020 first quarter in East China lead to 36.5% increase of surface O3 and 12.5% decrease of surface PM2.5. The elevated O3 promotes the secondary aerosol formation through heterogeneous pathways. We recommend that the complicated interaction between PM2.5 and O3 should be considered in the emission control strategy making process in the future.

Evaluation of hybridized performance of amine scrubbing plant based on exergy, energy, environmental, and economic prospects: A gas sweetening plant case study

Gas sweetening is a key process in gas refineries. The equipment involved in gas sweetening generally consume a considerable amount of energy, leading to negative impacts in terms of economic and environmental prospects. This research work includes simulation, analytical, and numerical modeling approaches to evaluate exergy, energy, economic, and environmental analysis of a gas sweetening plant (GSP). Various compositions of methyl-di-ethanolamine (MDEA) and di-ethanolamine (DEA) blend are studied to mitigate exergy destruction, energy loss, and CO2 emissions in the sweetening process. According to the results, the absorber and stripper are responsible for 37% of the total exergy destruction and 29% of the total energy loss, respectively. DEA concentration plays an imperative role in exergy and energy management of the GSP. The optimum amine concentration of 40 wt% decreases the total exergy destruction from 6.6 MW to 4.8 MW and lowers the energy loss by 36.7%. This optimization strategy then results in a substantial reduction in CO2 emissions by 2893.6 tons per year (t/y), compared to the current operation state. The economic assessment confirms the profitability of the plant to be operated at the optimal amine concentration. This research study provides an efficient strategy to optimize a variety of industrial plants that include energy consuming sections.

Recent experiences and divergent pathways to transport decoupling

This study examines the transport decoupling pathways of the 16 selected countries from 1990 to 2015. Transport carbon emissions (i.e. decarbonisation) and road traffic fatalities (i.e. defatalisation) have been chosen as proxies of environmental and social decoupling respectively. Real GNI in purchasing power parity (based to 2011) is used to reflect the decoupling experience. To frame the transport decoupling pathways, we have applied three decision rules and assigned rankings to the eight decoupling categories identified for richer and poorer countries. Each country has five data points for the ranking (five time periods in the 25-year horizon), meaning that a total of 80 data points have been identified and mapped. Four types of decoupling pathways are derived: Improving, Stable 1, Stable 2 and Unstable. Decoupling policies have then been extracted and analysed to identify the different approaches used in each pathway type. The results show that (i) there is no single pathway to transport decoupling, meaning that a wide range of policies have been adopted by individual countries, (ii) most pathways belong to the ‘Stable’ categories with mild fluctuations in the ranks over time and (iii) defatalisation is more successful than decarbonisation in achieving absolute decoupling. The value of this paper is in its novel methodology that has been used to identify the different pathways for decoupling, its application to 16 key countries, and the use of a database that extends over 5 time periods. It makes a clear contribution to our understanding of the complexity of decoupling, the different pathways adopted, and the difficulties of achieving substantial reductions in transport carbon emissions and traffic fatalities.

High time-resolution and time-integrated measurements of particulate metals and elements in an environmental justice community within the Los Angeles Basin: Spatio-temporal trends and source apportionment

Abstract The Los Angeles Basin is home to several environmental justice communities that are disproportionately impacted by localized sources of air pollution. City of Paramount, CA, is one of these communities that encompasses several industrial facilities, including metal-processing and finishing companies, in close proximity to each other as well as to residential neighborhoods and sensitive receptors (e.g., schools and hospitals). Between 2016 and 2019, the South Coast Air Quality Management District conducted an extensive air monitoring campaign in this community to identify and address sources of airborne particulate hexavalent chromium (Cr (VI)) and other toxic metals. Using portable air samplers, 24-hr time-integrated total suspended particulate (TSP) samples were collected every third or sixth day at a total of 49 different locations (including 12 local schools) throughout the city for Cr (VI) analysis. In certain areas, elevated levels of Cr (VI) were initially found; consequently, additional efforts were made to better characterize sources of Cr (VI) and other metals. As part of these efforts, hourly concentrations of 20 metals were also measured continuously over 1.5 years with Xact 625 (Cooper Environmental Services, OR, USA) at two locations within the community. Air monitoring results indicated a substantial reduction in ambient levels of Cr (VI) over time as a result of enforcement actions, rule developments, and voluntary emissions mitigations. Long-term continuous multi-metals measurements provided previously unknown information on the temporal trends of metals and elements, including their diurnal, day-of-the-week, and seasonal variations. The high time-resolution measurements also enabled investigating the impact of exceptional events (e.g., 4th of July fireworks) on the levels of ambient TSP-bound metals. A Positive Matrix Factorization (PMF) source apportionment analysis on the continuous multi-metals data identified five major sources, two of which were associated with the nearby industrial emissions (together accounting for 9.8%–13.8% of total metals concentrations), while the other three were linked with resuspended soil (48.8%–69.8%), brake wear (7.3%–19.1%), and road dust (13.1%–18.3%), all with distinct profiles and temporal variations. Results from this study show how a strategic air monitoring can lead to the discovery of emission sources, and how concurrent inspection and enforcement actions along with voluntary control measures by facilities can result in substantial emission reductions. Highly time-resolved source apportionment results coupled with wind data also provide valuable information on the dynamic variation in source activity and allowed for the identification of the most probable source locations that led to elevated concentrations at the receptor sites.

Drivers of CO2-Emissions in Fossil Fuel Abundant Settings: (Pooled) Mean Group and Nonparametric Panel Analyses

The present inquiry addresses the income-environment relationship in oil-producing countries and scrutinizes the further drivers of atmospheric pollution in the respective settings. The existing literature that tests the environmental Kuznets curve hypothesis within the framework of the black-box approaches provides only a bird’s-eye perspective on the long-run income-environment relationship. The aspiration behind this study is making the first step toward the disentanglement of the sources of carbon dioxide emissions, which could be employed in the pollution mitigation policies of this group of countries. Based on the combination of two strands of literature, the environmental Kuznets curve conjecture and the resource curse, the paper at hand proposes an augmented theoretical framework of this inquiry. To approach the research questions empirically, the study employs advanced panel cointegration techniques. To avoid econometric misspecification, the study also employs for the first time a nonparametric time-varying coefficient panel data estimator with fixed effects (NPFE) for the dataset of 37 oil-producing countries in the time interval spanning between 1989 and 2019. The empirical analysis identifies the level of per capita income, the magnitude of oil rents, the share of fossil fuel-based electricity generation in the energy mix, and the share of the manufacturing sector in GDP as essential drivers of carbon dioxide emissions in the oil-rich countries. Tertiarization, on the contrary, leads to a substantial reduction of emissions. Another striking result of this study is that level of political rights and civil liberties are negatively associated with per capita carbon emissions in this group of countries. Furthermore, the study decisively rejects an inverted U-shaped income-emission relationship and validates the monotonically or exponentially increasing impact of average income on carbon dioxide emissions.

Shifting agricultural practices to produce sustainable, low carbon intensity feedstocks for biofuel production

The carbon intensity (CI) of biofuel’s well-to-pump life cycle is calculated by life cycle analysis (LCA) to account for the energy/material inputs of the feedstock production and fuel conversion stages and the associated greenhouse gas (GHG) emissions during these stages. The LCA is used by the California Air Resources Board’s Low Carbon Fuel Standard (LCFS) program to calculate CI and monetary credits are issued based on the difference between a given fuel’s CI and a reference fuel’s CI. Through the Tier 2 certification program under which individual fuel production facilities can submit their own CIs with their facility input data, the LCFS has driven innovative technologies to biofuel conversion facilities, resulting in substantial reductions in GHG emissions as compared to the baseline gasoline or diesel. A similar approach can be taken to allow feedstock petition in the LCFS so that lower-CI feedstock can be rewarded. Here we examined the potential for various agronomic practices to improve the GHG profiles of corn ethanol by performing feedstock-level CI analysis for the Midwestern United States. Our system boundary covers GHG emissions from the cradle-to-farm-gate activities (i.e. farm input manufacturing and feedstock production), along with the potential impacts of soil organic carbon change during feedstock production. We conducted scenario-based CI analysis of ethanol, coupled with regionalized inventory data, for various farming practices to manage corn fields, and identified key parameters affecting cradle-to-farm-gate GHG emissions. The results demonstrate large spatial variations in CI of ethanol due to farm input use and land management practices. In particular, adopting conservation tillage, reducing nitrogen fertilizer use, and implementing cover crops has the potential to reduce GHG emissions per unit corn produced when compared to a baseline scenario of corn–soybean rotation. This work shows a large potential emission offset opportunity by allowing feedstock producers a path to Tier 2 petitions that reward low-CI feedstocks and further reduce biofuels’ CI. The prevalence of significant acreage that has not been optimized for CI suggests that policy changes that incentivize optimization of this parameter could provide significant additionality over current trends in farm efficiency and adoption of conservation practice.

Sectoral carbon budgets as an evaluation framework for the built environment

The objective of the United Nations Paris Agreement to limit global warming to well below 2°C, with efforts to reach 1.5°C, requires a strict limitation of future global greenhouse gas (GHG) emissions based on a global carbon budget. Applying equity considerations allows for the derivation of national carbon budgets. A key question then arises: How can these national budgets be allocated at the sectoral level? A new method is proposed to allocate carbon budgets at the sectoral level. First, a cost-based approach is used to indicate a necessary carbon budget for each sector. However, the aggregation of these initial sectoral carbon budgets usually exceeds the available national carbon budget. This indicates the relevance of working with sectoral carbon budgets and the required reductions to remain within the overall national carbon budget. This conceptual approach aims at, first, a cost-effective sectoral effort-sharing; second, the design of corresponding strict carbon emission reduction pathways (at both the sector and aggregate levels); and, third, the redesign of investment policies for capital stock improvements to remain within the aggregate carbon budget (involving trade-offs in investment induced emissions for operational emission reduction). Policy relevance Limiting global warming according to the United Nations Paris Agreement requires a strict limitation of future global GHG emissions. A new method is presented to allocate national carbon budgets to the national sectoral level. The carbon budget concept has the potential to provide a transparent and informative tool for the analysis, policy design and monitoring of GHG emission pathways, particularly for the long time horizons involved. The area of activity involving the construction and use of buildings, termed embodied and operational GHGs, requires a particularly large fraction of the national carbon budget. Compared with other sectors, these activities have the highest potential for keeping countries within their national carbon budgets as far as enabling capital stock improvements are concerned that over-proportionally reduce use emissions. The approach can link carbon budgets at the municipal, city and regional levels. It could lend itself to an initially voluntary initiative, later compulsory policy framework for substantial and cost-effective emission reductions.

A chemical cocktail during the COVID-19 outbreak in Beijing, China: Insights from six-year aerosol particle composition measurements during the Chinese New Year holiday

The rapidly spread coronavirus disease (COVID-19) has limited people's outdoor activities and hence caused substantial reductions in anthropogenic emissions around the world. However, the air quality in some megacities has not been improved as expected due to the complex responses of aerosol chemistry to the changes in precursors and meteorology. Here we demonstrate the responses of primary and secondary aerosol species to the changes in anthropogenic emissions during the COVID-19 outbreak in Beijing, China along with the Chinese New Year (CNY) holiday effects on air pollution by using six-year aerosol particle composition measurements. Our results showed large reductions in primary aerosol species associated with traffic, cooking and coal combustion emissions by 30–50% on average during the CNY, while the decreases in secondary aerosol species were much small (5–12%). These results point towards a future challenge in mitigating secondary air pollution because the reduced gaseous precursors may not suppress secondary aerosol formation efficiently under stagnant meteorological conditions. By analyzing the long-term measurements from 2012 to 2020, we found considerable increases in the ratios of nitrate to sulfate, secondary to primary OA, and sulfur and nitrogen oxidation capacity despite the overall decreasing trends in mass concentrations of most aerosol species, suggesting that the decreases in anthropogenic emissions have facilitated secondary formation processes during the last decade. Therefore, a better understanding of the mechanisms driving the chemical responses of secondary aerosol to the changes in anthropogenic emissions under complex meteorological environment is essential for future mitigation of air pollution in China.

Emissions benefits of electric vehicles in Uber and Lyft ride-hailing services

The use of plug-in electric vehicles in ride-hailing services is expected to have substantial emission reduction benefits. However, these benefits depend on the energy fuel mix in the grid and vehicle usage. Here we employ high-resolution data from Uber and Lyft in California to provide insights into the use of electric vehicles in ride-hailing. The growth in electric vehicle use has been rapid in the past two years and a proportionally small number of electric vehicles are already using a large share of electricity provided by the public charging infrastructure. Concerns about the ability of electric vehicles to provide the same level of service as gasoline vehicles has been overstated: we found no statistical difference between the two technologies for services provided to ride-hailing companies. Lastly, the potential environmental and emission reduction benefits are approximately three times higher for electric vehicles being used in ride-hailing compared with those of regular vehicle usage in California. Use of electric vehicles in ride-hailing services such as Uber and Lyft is rising but their impact on environment and emissions remains difficult to assess. Using data from more than 100,000 rides, Alan Jenn shows the substantial emission reduction potential of electric vehicle use in ride-hailing in California.

Emission Regulation of Markets with Sluggish Supply Structures

I examine regulation in the presence of convex investment costs and technology specific capacity stocks. Announcement of future emission taxes reduces current emissions unless fossil fuels are scarce, in which case the effect is ambiguous. Substantial future emission reductions require action today, because it takes time to build up clean production capacity and phase out dirty capacity. The Pigou tax must be coupled with sector specific investment taxes or subsidies to induce the socially optimal trajectory if the private discount rate differs from the social discount rate. If such investment taxes or subsidies are unavailable, a (time-inconsistent) second-best alternative may be to tax emissions above the Pigouvian level during the transition phase. The theory is complemented with a stylized numerical model of the US electricity market.

Automobility and Oil Vulnerability

Climate policies in the European Union require a substantial reduction in carbon emissions from road transport. However, in the last decades the system of automobility has expanded considerably, establishing a process of path dependence that is very difficult to reverse. Changes in current patterns of automobility may increase oil vulnerability of citizens dependent on the use of the car, aggravating forms of social inequity. Based on an analysis of how television news framed a period of oil price rises in a country highly dependent on car use, the article shows that oil vulnerability may resonate with socially shared sociocultural meanings such as lack of trust in political leaders, which may aggravate the social perception of unfairness and compromise public support for energy transitions toward sustainability.

Barriers to the Adoption of Sustainable Construction

Studies have shown that adoption of sustainable construction practice would result in a substantial reduction in the greenhouse emissions from the construction industry. Evolving a sustainable development practice is an emergent concern for the construction industry in both developing and developed countries. Sustainable construction is concerned with site planning and design, community, indoor air quality, energy, materials, water, commissioning and marketability for the benefit of mankind. This requires enormous efforts from all the stakeholders in the industry. Sustainable construction efforts in the Nigerian construction industry have been ineffective as a result of a number of barriers that prevent a smooth transition to sustainable construction practice in the country. The aim of this study is to assess the potential barriers that hinder effective adoption of sustainable construction practice in the Nigerian Construction Industry, with a view to exploring how these barriers can be overcome and thereby achieving sustainable construction in the country. A cross-sectional questionnaire was adopted for the survey. Purposive sampling technique was used to elicit 105 copies of questionnaires from various construction professionals based in Lagos state, Nigeria. Data collected were analysed using frequency, percentage, mean, relative importance index and ranking. The results revealed that key barriers to sustainable construction in the Nigerian Construction Industry are poor government support for sustainable construction, lack of relevant laws and regulations to drive sustainable construction, lack of demand for sustainable construction from clients, low level of awareness of sustainable construction and fear of the cost of adopting sustainable construction. Based on the findings from this study, it was recommended that government should assume a greater role in the popularisation and application of sustainable strategy. The barriers identified and the suggestions made to minimize barriers to the adoption of sustainable construction in Nigeria should offer an enabling environment for stakeholders in construction sector to smoothly adopt sustainable construction for the benefit of humanity. Keywords: adoption, barriers, construction industry, Nigeria, sustainable construction

Sustainability indicators of a naturally ventilated photovoltaic façade system

Building Integrated Photovoltaic (BIPV) systems have been increasingly used as a means to generate electricity on-site, and their diffusion will increase in the near future. The objective of this article is to carry out a sustainability assessment of a BIPV system installed in Turkey regarding the three pillars: environmental, economic and social potential impact, in order to develop different indicators. For the socioeconomic analysis, a Multiregional Input-Output (MRIO) method was used to estimate production of goods and services, value added creation and employment opportunities. For the environmental evaluation, an Environmental Footprint (EF) analysis was performed. The levelized electricity costs and the greenhouse gas emissions abatement costs were also calculated. Results showed that the socioeconomic effects are relevant, although only a 23% of these effects remain in Turkey. The environmental profile is also good in terms of climate change impacts, showing substantial reductions in greenhouse gas emissions compared to fossil fuel alternatives for electricity generation. Regarding the life cycle stages of the technology, the highest environmental impacts are produced in the PV manufacturing processes. The electricity produced is still more costly than fossil-based technologies and in the highest range of PV technologies, but greenhouse gases abatement costs are not so high when compared to other references.

Air quality co-benefits of ratcheting up the NDCs

The current nationally determined contributions, pledged by the countries under the Paris Agreement, are far from limiting climate change to below 2 ∘C temperature increase by the end of the century. The necessary ratcheting up of climate policy is projected to come with a wide array of additional benefits, in particular a reduction of today’s 4.5 million annual premature deaths due to poor air quality. This paper therefore addresses the question how climate policy and air pollution–related health impacts interplay until 2050 by developing a comprehensive global modeling framework along the cause and effect chain of air pollution–induced social costs. We find that ratcheting up climate policy to a 2 ∘ compliant pathway results in welfare benefits through reduced air pollution that are larger than mitigation costs, even with avoided climate change damages neglected. The regional analysis demonstrates that the 2 ∘C pathway is therefore, from a social cost perspective, a “no-regret option” in the global aggregate, but in particular for China and India due to high air quality benefits, and also for developed regions due to net negative mitigation costs. Energy and resource exporting regions, on the other hand, face higher mitigation cost than benefits. Our analysis further shows that the result of higher health benefits than mitigation costs is robust across various air pollution control scenarios. However, although climate mitigation results in substantial air pollution emission reductions overall, we find significant remaining emissions in the transport and industry sectors even in a 2 ∘C world. We therefore call for further research in how to optimally exploit climate policy and air pollution control, deriving climate change mitigation pathways that maximize co-benefits.

The economic and environmental impacts of UK offshore wind development: The importance of local content

We explore, through simulation of a purpose-built Input-Output model of the UK, the economic and emissions impacts of the likely future development of the UK’s offshore wind sector, with a particular emphasis on the importance of local content. We explore six scenarios, including two illustrative simulations of the potential impact of Brexit on local content. We find that future offshore wind development does indeed generate a policy “double dividend” in the form of simultaneous and substantial reductions in cumulative emissions, which in each case exceed a year of the UK’s total emissions, and improvements in economic activity (of nearly £30 billion cumulative increase in value-added when the 60% target for local content is achieved). It is also the case that, as anticipated, the scale of the economic stimulus arising from offshore wind development is directly and strongly related to the extent of local content. Future work could extend the modelling to relax the supply side assumptions of input-output modelling, disaggregate the analysis by regions and households to allow assessment of the impacts on the distribution of both economic activity across regions and income among household quintiles.

Enhanced atmospheric ammonia (NH3) pollution in China from 2008 to 2016: Evidence from a combination of observations and emissions

The increase of gaseous ammonia (NH3) concentration in the atmosphere significantly impacts the regional air quality, human health, and the nitrogen cycle of ecosystems. This study aims to verify the reanalyzed product of IASI NH3 (the ANNI-NH3-v2.1R-I, hereafter referred to as IASI_NH3_R) and to analyze the spatial and temporal characteristics of atmospheric NH3 during 2008–2016 and its underlying influencing factors. Our results show a good agreement between spatial pattern and temporal (annual and monthly) trend of the satellite-derived surface NH3 concentrations and the measured near-ground NH3 measurements over different land covers in Eastern China, suggesting the IASI_NH3_R product can be used to investigate spatial and temporal trends of atmospheric NH3 concentration. The annual mean NH3 column concentrations peaked in the North China Plain (averaged 12 × 1015 mol cm−2 yr−1) and showed a significant increasing trend at a rate of 0.6 × 1015 mol cm−2 yr−1 during the entire period, which can be ascribed to densely populated, intensive agricultural activities and substantial reduction of SO2 and NO2 emissions since 2011. The NH3 column concentrations show a slight increase in winter in most regions of China, probably due to less precipitation amount and increased uncertainty for lower NH3 columns and the thermal contrast (TC). A large seasonal variation of NH3 column concentrations was observed, with the highest values in summer and the lowest in autumn. Such seasonal variation is mainly affected by seasonal differences in NH3 emissions and meteorological conditions. Our results suggest that the current control measures effectively decreased SO2 and NO2 pollution but are not yet apparent in the mitigation of atmospheric NH3 pollution, which also merits more attention considering that no effective measures are being implemented for NH3 emission control at a regional or national scale in China.

Evaluating the effectiveness of multiple emission control measures on reducing volatile organic compounds in ambient air based on observational data: A case study during the 2010 Guangzhou Asian Games

Volatile organic compounds (VOCs) play a crucial role in modulating air pollution by ozone and fine particles, particularly in urban areas. While in recent years short-term intervention actions for better air quality during big events in China did present good opportunities to examine the effectiveness of control measures in reducing anthropogenic VOCs emission, it is highly challenging to interpret the real effect of a specific control measure based on field monitoring data when a cocktail of control measures were adopted. Here we took the air quality intervention actions during the 16th Asian Games (AG) in Guangzhou as a case study to explore the impact of short-term multiple measures on VOCs reduction. The average mass concentrations of VOCs decreased by 52–68% during the AG. These percentages could not reflect emission reduction rates as the concentration might be also heavily impacted by dispersion conditions. Diagnostic ratios, such as methyl tert-butyl ether to carbon monoxide (MTBE/CO) and i-pentane/CO, decreased by over 60% during the AG, suggesting a substantial reduction in gasoline related emissions. A method linking emission reduction rates of two sources with their contribution percentages before and during the AG by using a receptor model was further formulated. With the available reduction rate of 34% for vehicular exhaust obtained during the traffic restriction drill in our previous study, VOCs emissions from gasoline evaporation and solvent use reduced by 45.7% and 13.6% during the AG, respectively. Total VOCs emissions decreased by 25.3% on average during the AG, and the emission control of vehicular exhaust, oil evaporation, and solvent use accounted for 17.0%, 6.3% and 2.0% of total VOCs emission reduction, respectively. This study presented an observed-based method with diagnostic/quantitative approaches to single out the effectiveness of each control measures in reducing VOCs emissions.

Regional carbon imbalance within China: An application of the Kaya-Zenga index

Considering the enlarging inter-provincial disparities in China as regards carbon emissions and carbon intensity (carbon emissions per unit gross domestic product), this paper is the first study to investigate the inter-provincial carbon imbalance by constructing and employing the Kaya-Zenga index. We use China's panel data of provincial-level carbon emissions over 1995–2016 to quantitatively measure the levels of inter-provincial imbalance and polarization in carbon emissions and carbon intensity. Further, we decompose the Kaya-Zenga index into different contributing factors both regionally and structurally and perform a scenario analysis to identify the corresponding regionally differentiated countermeasures regarding carbon emission reduction. The results show that the imbalance in carbon emissions is mainly caused by imbalances in population scale and income level, while the imbalance in carbon intensity predominantly results from imbalances in energy efficiency and energy mix. In addition, for heavy manufacturing provinces, the respective emission-reduction strategy should aim at lowering energy intensity through local technology improvement and inter-regional technology transfer. For light manufacturing and high technology provinces, carbon emission reduction is harder to be achieved; however, a mix of policies of improving energy efficiency, optimizing energy mix, and industrial upgrading should be implemented. The results of the scenario analysis indicate that reducing imbalance in carbon intensity under different scenarios can lead to a substantial reduction in carbon emissions (up to 10%).