Publications

Countries such as China are facing a bottleneck in their paths to carbon neutrality: abating emissions in heavy industries and heavy-duty transport. There are few in-depth studies of the prospective role for clean hydrogen in these ‘hard-to-abate’ (HTA) sectors. Here we carry out an integrated dynamic least-cost modelling analysis. Results show that, first, clean hydrogen can be both a major energy carrier and feedstock that can significantly reduce carbon emissions of heavy industry. It can also fuel up to 50% of China’s heavy-duty truck and bus fleets by 2060 and significant shares of shipping. Second, a realistic clean hydrogen scenario that reaches 65.7 Mt of production in 2060 could avoid US$1.72 trillion of new investment compared with a no-hydrogen scenario. This study provides evidence of the value of clean hydrogen in HTA sectors for China and countries facing similar challenges in reducing emissions to achieve net-zero goals.

China's approach to environmental regulation relies heavily on campaign-style enforcement and blunt-force regulation. While considered effective in the short run, this approach is often inefficient and generates unintended regulatory outcomes in the longer run. At the same time, China continues to experiment with the use of market-based approaches that are theoretically more efficient and have the potential to facilitate sustained reductions in carbon emissions. Arguably the most high-profile example is the Guangdong Emissions Trading Scheme (ETS), which was launched in 2013 as a national pilot scheme. We construct a synthetic control of Guangdong and analyse 51,076 party-led newspaper reports to show that while the ETS reduced emissions in the short run, these reductions were systematically associated with political signalling. Notably, emissions reduced substantially upon the announcement of the ETS in 2011 – a full two years before the scheme was scheduled to begin – before rebounding to near pre-ETS announcement levels by 2017. The presence of an anticipation effect and the systematic association between political signalling and emissions reductions mirrors findings on China's more direct approaches to environmental regulation. Our findings suggest that market-based mechanisms in China may not be qualitatively different from more direct forms of environmental regulation.

Self-perceived health is an important factor for assessing urban residents’ satisfaction and quality of life. However, few have comprehensively investigated the impact of demographics, lifestyle and health awareness, indoor environment characteristics, and neighborhood features on self-perceived health. To fill this gap, we designed a framework using multivariable regressions to derive odd rations and to analyze the determinants of self-rated health, stratified into different sub-groups divided by gender, age, and neighborhood types. The study area is Chengdu, one of the most populous cities in western China. The results show that: (1) female respondents reported worse health, with household income level and marital status significantly affecting self-rated health; (2) elderly people reported the worst health, while unique factors affected only younger people (18–29 years old), such as gender, smoking, and indoor environment characteristics; and (3) different types of neighborhoods influence their residents’ perception of health differently due to historical establishment, current population composition, and housing conditions. Our study provides new observations on neighborhood types, while agreeing with previous studies on the influences of gender and age. We contribute to the field by providing a more complex understanding of the mechanism by which people rate their own health, which is important for understanding the satisfaction of urban residents and the built environment in which they live.

Recent evidence shows that carbon emissions in China are likely to peak ahead of 2030. However, the social and economic impacts of such an early carbon peak have rarely been assessed. Here we focus on the economic costs and health benefits of different carbon mitigation pathways, considering both possible socio-economic futures and varying ambitions of climate policies. We find that an early peak before 2030 in line with the 1.5  C target could avoid ~118,000 and ~614,000 PM2.5 attributable deaths under the Shared Socioeconomic Pathway 1, in 2030 and 2050, respectively. Under the 2  C target, carbon mitigation costs could be more than offset by health co-benefits in 2050, bringing a net benefit of $393–$3,017 billion (in 2017 USD value). This study not only provides insight into potential health benefits of an early peak in China, but also suggests that similar benefits may result from more ambitious climate targets in other countries.

Road traffic crashes have been a leading cause of death in Southeast Asian countries, which greatly harms the development of countries and affects the livelihood of countless families in this region. In this context, a regular review of road safety attainment is needed to understand why road crashes happen and to better guide the ongoing policymaking and implementation of effective countermeasures as well as next-level strategies. This study introduces an easy-to-use, effective, and systematic methodology for multi-criteria decision-making, CRiteria Importance Through Inter-criteria Correlation (CRITIC) - ELimination and Et Choice Translating REality (ELECTRE) - Fuzzy C-Means (FCM) (CRITIC-ELECTRE-FCM). Its purpose is to appraise the road safety attainment of 11 countries in Southeast Asia. Accompanied by the robustness of analyses with other widely used methods, these countries are ranked and grouped into several levels regarding their road safety attainment over the past decade (2009–2018). The findings provide government officials, policymakers, and any stakeholders of these countries with meaningful information (e.g., what has been done well and what has not) and instructive guidance for future action. Overall, the proposed appraisal system serves as an efficacious policymaking support for countries in the region to review road safety attainment, develop future strategies and policies, and implement safety management.

China, with a heavy dependence on coal power, has announced a clear goal of carbon neutrality by 2060. Electrification of final energy use and high penetration of renewable energy are essential to achieve this. The resulting growth of intermittent renewables and changes in demand curve profiles require greater flexibility in the power system for real-time balancing – greater ability of generators and consumers to ramp up and down. However, the plan and market system with regulated prices makes this challenging. We discuss the options to improve flexibility, including 1) increasing supply-side flexibility, through retrofitting existing power plants to boost their responsiveness; 2) promoting flexibility from power grids, through building an efficient power grid with inter-provincial and inter-regional transmission capacity to balance spatial mismatch, given that China has a vast territory; 3) encouraging demand flexibility, through demand-response measures to enable demand shifting over time and space to address fluctuations in renewable energy generation; and 4) providing flexibility from energy storage. We consider policies to achieve this, in particular, power market reforms to unlock the flexibility potential of these sources. Regulated electricity prices and lack of auxiliary services markets are major obstacles and we discuss how markets in other countries provide lessons in providing incentives for a more flexible system.

Swift changes in both industrialization and pollution control in China over the past 15 years have created a complex and evolving relationship between emission sources and the depositional sinks of air pollutants. Here, by combining an emissions inventory, an air quality model and a statistical model to estimate bulk deposition (wet plus a part of dry), we present the changes and driving factors of source–sink relationships of typical pollutants throughout China between 2005 and 2020. We find that the deposition of sulfate and nitrate has declined more slowly than the emissions of their precursors, sulfur dioxide and nitrogen oxides, which we attribute, in part, to increased precipitation. In four developed regions of China, enhanced air pollution transport also plays an important role in the slower decline of deposition compared with that of emissions, as has a changing aerosol chemistry in the case of sulfur compounds. Our analysis shows that reducing deposition is not as simple as merely reducing its precursor emissions and suggests that the design of future policies to reduce associated risks may need to vary by region and species, accounting for their evolving interactions over time.

The paper explores options for a 2050 carbon free energy future for India. Onshore wind and solar sources are projected as the dominant primary contributions to this objective. The analysis envisages an important role for so-called green hydrogen produced by electrolysis fueled by these carbon free energy sources. This hydrogen source can be used to accommodate for the intrinsic variability of wind and solar complementing opportunities for storage of power by batteries and pumped hydro. The green source of hydrogen can be used also to supplant current industrial uses of gray hydrogen produced in the Indian context largely from natural gas with important related emissions of CO2. The paper explores further options for use of green hydrogen to lower emissions from otherwise difficult to abate sectors of both industry and transport. The analysis is applied to identify the least cost options to meet India’s zero carbon future.

Housing reform in socialist China has incurred considerable restructuring and transformation of urban space and society. Yet its specific socio-spatial outcomes have not been fully investigated from the perspective of housing type at the meso- and micro-levels. This study attempts to fill the gap by examining the nature and magnitude of the consequences of housing reform and the corresponding effects on mobility. Specifically, based on census data and a mobility survey, this paper combines statistical breakdowns and structural equation modeling to capture the socio-spatial differentiation of urban structure resulting from housing reform and its influences on individual vehicle kilometers traveled (VKT) and transportation walking. The results reveal that: (1) different types of housing tend to feature internally homogeneous populations in terms of socio-economic composition and socio-psychological condition, with pronounced social stratification; (2) residents in different types of housing display dramatically different travel styles, with substantial mobility inequities; (3) social differentiation appears to have spatial determinants; in particular spatial segregation contributes to increasing social exclusion; (4) the effects of spatial and social characteristics on mobility are led by housing type; and (5) individual mobility patterns are shaped by the joint influences of spatial and social dimensions of housing differentiation. The findings contribute to further understanding of socio-spatial differentiation in countries with a transitional housing market, suggesting that the design of land-use policies should recognize their social effects and that urban mobility planning practices should deliver sustainability that serves a diverse population, including in particular disadvantaged groups in public and replacement housing. This study serves as a mirror to observe the urban transition compared to other political economies and adds additional richness and diversity to the theoretical debates on the issue of socio-spatial differentiation and empirical evidence on residential and mobility inequities across global contexts.

Experimental designs have been recognized as the gold standard for establishing causal mechanisms. However, the application of such designs is complicated by factors such as excessive costs, time consumption, ethical concerns, and political impossibility. Nevertheless, the Chinese government’s replacement housing efforts provide a unique randomized experiment for exploring the causal effects of the built environment on travel behavior. Accordingly, based on a large-scale survey on travel patterns under an experimental design in Shanghai, this study employs a two-step modeling approach, involving logit and Tobit models, to identify the built environment’s effects on auto ownership and vehicle kilometers traveled (VKT). We found that transit service improvements play a stronger role in reducing auto-drive than compact and diverse land-use characteristics. Increasing residential and employment density, as well as land-use mix, discourages car ownership, which in turn reduces VKT, but with lower elasticities than transportation system variables. The findings provide additional evidence and referential estimate for how land-use and transport strategies and policies designed to create a compact, mixed-use, and highly accessible built environment can be used in reducing auto driving. This study expands the VKT reduction elasticities’ database regarding the built environment across global spatial contexts, serving as a model for similar studies elsewhere in the world.

The development of wind power plays an essential role in achieving China's carbon neutrality goals and air quality standards. A large number of studies have addressed the benefits of substituting fossil fuels with wind power on climate and air quality (defined as indirect impact) by macro-scale methodology. In recent years, more and more researchers have discussed its impacts on the general atmospheric circulation and air pollution dispersion (defined as direct impact) by parameterizing wind energy extraction in meso-micro scale models. However, the comprehensive investigation (considering both direct and indirect impacts) of the utilization of wind power on atmosphere environmental impacts remains vacant. Our study first evaluated both the direct and indirect impacts of wind power on air quality through an integrated methodological framework by using WRF-CMAQ system. The present analysis took wind farms located in Zhangjiakou to explore their impacts on air quality in winter, particularly over the downwind Beijing municipal area in the North China Plain. Results indicated that the deployment of wind power leads to spatially mixed direct impacts on PM2.5 concentrations in Beijing with a monthly net increase of 0.067 μg/m3 (0.08%) relative to the regional average. Contrarily, the substitution of coal-burning with wind power in rural household heating would result in notable indirect benefits to monthly PM2.5 concentrations in Beijing, specifically, reducing emissions of CO2 and conventional air pollutants by 64% in rural heating sector. The combined impacts of wind power displayed regional differences: in the wintertime (January), Zhangjiakou PM2.5 concentrations increased (+0.147 μg/m3) whereas, decreases are achieved (−5.642 μg/m3) in Beijing. Therefore, to support the large-scale deployment of wind power, future energy policies should take comprehensive account of the diverse environmental impacts, including both the indirect benefits of fossil energy substitution and the potential direct atmospheric effects on regional air quality.

China forecasts that a 14-fold increase in photovoltaic installations is needed to meet 2060 carbon-neutrality targets. In light of the fact that air pollution impairs photovoltaic performance, pollution control could reduce the installation requirement, but research has not yet taken into account the coeval impact of unfavorable meteorological conditions, which also impair performance. Here, we employ a coupled model to determine the impact of air-pollution control policies on China’s photovoltaic power output in the presence of varying meteorological conditions between 1995 and 2019. We find that the benefits of air-pollution control introduced in 2004 were only partially offset by unfavorable meteorological conditions (primarily in Central and South China) and resulted in solar-power performance improvement of 0.9%/decade from 2008 onward. Further analysis shows that solar-power output in 2020 was 1.7% higher thanks to air-pollution control and that more stringent air-quality targets could reduce the demand for photovoltaic installed capacity needed to meet the 2060 carbon-neutrality target.

The rapidly falling costs of renewable energy has made them the focus of efforts in making a low-carbon transition. However, when cheap large-scale energy storage is not available, the variability of renewables implies that fossil-based technologies have to ramp up-and-down frequently to provide flexibility for matching electricity demand and supply. Here we provide a study on the indirect cost of renewable energy due to thermal efficiency loss of coal plants with such ramping requirements. Using monthly panel data for China, we show that higher renewable share is associated with fewer operating hours of coal-fired units (COHOUR). We use an instrumental variable depending on natural river flows to identify the causal effect of reduced COHOURs in raising the heat rate of coal-fired units. Specifically, a 1 percentage point increase in the share of renewables leads to a 6.4 h reduction per month, and a reduction of one COHOUR results in a 0.09 gce/kWh increase of gross heat rate (+0.03%). We estimate that the thermal efficiency loss indicates 4.77 billion US dollars of indirect cost of renewables in 2019, or 9.44 billion if we include the social cost of carbon emissions. These results indicate that we should consider the indirect impacts of renewables on total coal use and the importance of increasing flexibility of the system.

Measuring road safety achievement through persistent monitoring of subjects, such that they can learn from one another, has been widely encouraged by various countries to support policymaking. In recent decades, the Asia-Pacific Economic Cooperation (APEC) countries have been working together to improve road safety, considering it an important constituent and reflection of their economic development. However, no uniform road safety measurement framework is currently available across the APEC. To this end, the current study develops a practical and efficient methodology, namely, the entropy weight method (EWM) – grey relational analysis (GRA) – singular value decomposition (SVD) (EWM-GRA-SVD), providing government officials and policymakers with a replicable framework for reporting the road safety achievement of countries. The EWM is employed to obtain the weights of the set of indicators, as the weighting inputs of GRA, to form a composite score for ranking, where the SVD is embedded in the GRA for grouping by means of extracting singular values. Using the proposed model, best-performing and underperforming countries are distinguished, whereby each country could learn from others within their assigned group based on an overview of achievements and progress in road safety over the past decade. The results enable decision-makers and policymakers to develop action plans and consider necessary interventions promptly and effectively.

Intra-city Public Charging Stations (PCSs) play a crucial role in promoting the mass deployment of Electric Vehicles (EVs). To motivate the investment on PCSs, this work proposes a novel framework to find the optimal location and size of PCSs, which can maximize the benefit of the investment. The impacts of charging behaviors and urban land uses on the income of PCSs are taken into account. An agent-based trip chain model is used to represent the travel and charging patterns of EV owners. A cell-based geographic partition method based on Geographic Information System is employed to reflect the influence of land use on the dynamic and stochastic nature of EV charging behaviors. Based on the distributed charging demand, the optimal location and size of PCSs are determined by mixed-integer linear programming. Västerås, a Swedish city, is used as a case study to demonstrate the model's effectiveness. It is found that the charging demand served by a PCS is critical to its profitability, which is greatly affected by the charging behavior of drivers, the location and the service range of PCS. Moreover, charging price is another significant factor impacting profitability, and consequently the competitiveness of slow and fast PCSs.

Overseeing road safety progress at regular intervals has and will continue to be advocated as the most promising means to achieve continuous safety improvement. Thus, a scientific approach that can be capable of doing so is disparately required. This study aims to propose a brand-new and efficient methodology for overseeing overall road safety progress at the regional level. To this end, CV-PROMETHEE Ⅱ-JSS, which seamlessly incorporates Coefficient of Variation (CV), Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE), and Joint Singular value decomposition and Semi-discrete decomposition (JSS) in an integrative manner, is developed. Specifically, this is designed to combine the retrospective examination and benchmarking analysis in a comprehensive and systematic framework. Based on the proposed methodology, the road safety development of the European Union (EU) Member States is examined over the past decade (2010–2020), whilst simultaneously benchmarking safety performance looking forward to the next decade (2020–2030). As a result, a detailed picture of changes in road safety for each country is quantitatively depicted, providing policymakers with deeper insights into how progress was achieved. The appropriate benchmarks are also scientifically identified for each laggard member to use as a meaningful reference, which largely avoids the need for reinventing the wheel and trial and error approaches. This study provides the EU27 + 3 countries with a practical paradigm to perform both diagnostics and treatment to improve overall road safety levels in an effective way; supporting the government officials and policymakers in the charting of future strategic directions and intervention priorities, and helping them define ways to accelerate action on proven strategies and policies for better lives. Moreover, this study enriches the existing Multi-Criteria Decision-Making (MCDM) mechanism by introducing the CV-PROMETHEE Ⅱ-JSS, and implies its feasibility and effectiveness in future MCDM cases involving safety-related issues.

Human-induced climate change will increase surface temperatures globally over the next several decades. Climate models project that global mean surface temperature could increase by over 2˚C by 2050 relative to the preindustrial period, with even greater changes at the regional level. These temperature changes have clear and pertinent implications for extremes, and consequentially, heat-induced health issues for people living in particularly hot climates. Here, we study future projections in the demand for AC globally in the 2050s associated with extreme heat events. To do this, we employ an ensemble of CMIP6 models under high and low emissions scenarios. We find that the increasing frequency of extreme temperatures will cause a significant portion of the global population to be exposed to conditions that require cooling. This issue will be especially pervasive in poor countries such as India and Indonesia, which at present lack the AC units required to handle rapidly growing populations and increased frequencies of extreme temperatures. The electricity needed for cooling in these countries could reach as high as 75% of the current total annual electricity demand, which could place serious strain on the electricity grid infrastructure during peak cooling hours. We conclude that demand for cooling in the future will pose a significant challenge for poorer countries whose people will require AC units to handle extreme temperatures. In some countries, the grid infrastructure is insufficient at present to meet projected AC demands, and this need must be considered in future power systems planning.

This study investigates the contribution of formaldehyde from residential building materials to ambient air in mainland China. Based on 265 indoor field tests in 9 provinces, we estimate that indoor residential sources are responsible for 6.66% of the total anthropogenic formaldehyde in China’s ambient air (range for 31 provinces: 1.88–18.79%). Residential building materials rank 6th among 81 anthropogenic sources (range: 2nd–10th for 31 provinces). Emission intensities show large spatial variability between and within regions due to different residential densities, emission characteristics of building materials, and indoor thermal conditions. Our findings indicate that formaldehyde from the indoor environment is a significant source of ambient formaldehyde, especially in urban areas. This study will help to more accurately evaluate exposure to ambient formaldehyde and its related pollutants, and will assist in formulating policies to protect air quality and public health.

The Chinese government is fond of invoking the ‘hurt feelings of 1.4 billion Chinese citizens’ to protest foreign actions and policies. However, this rhetoric might be nothing more than propaganda and attempts to leverage nationalist sentiment. How much do citizens in China actually care about issues completely unrelated to their daily livelihoods? To answer this, the study employs a representative survey to investigate the extent to which rhetoric about ‘hurt feelings’ is consistent with public opinion on four contemporary socio-political disputes involving the NBA, Marriott International, Mercedes-Benz and the city of Prague. Across the scenarios, we found that the Chinese government did not exaggerate the displeasure of audiences—citizens are aware of the cases, were indeed upset by them and advocated for retaliatory measures that were surprisingly more forceful than those adopted in reality. These emotions were largely driven by nationalistic sentiment rather than personal experiences or encounters, suggesting the success of state propaganda in steering the public opinion toward outcomes favourable to the state. These findings support recent studies highlighting the peculiar case of rising nationalism in China, and have important implications for the impact of public opinion on Chinese policymaking.