publications

2024

1. ES&T

   Subsidizing Grid-Based Electrolytic Hydrogen Will Increase Greenhouse Gas Emissions in Coal Dominated Power Systems

   Liqun Peng, Yang Guo, Shangwei Liu, Gang He, and Denise L Mauzerall

   Environmental Science & Technology, 2024

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   Clean hydrogen has the potential to serve as an energy carrier and feedstock in decarbonizing energy systems, especially in “hard-to-abate” sectors. Although many countries have implemented policies to promote electrolytic hydrogen development, the impact of these measures on costs of production and greenhouse gas emissions remains unclear. Our study conducts an integrated analysis of provincial levelized costs and life cycle greenhouse gas emissions for all hydrogen production types in China. We find that subsidies are critical to accelerate low carbon electrolytic hydrogen development. Subsidies on renewable-based hydrogen provide cost-effective carbon dioxide equivalent (CO2e) emission reductions. However, subsidies on grid-based hydrogen increase CO2e emissions even compared with coal-based hydrogen because grid electricity in China still relies heavily on coal power and likely will beyond 2030. In fact, CO2e emissions from grid-based hydrogen may increase further if China continues to approve new coal power plants. The levelized costs of renewable energy-based electrolytic hydrogen vary among provinces. Transporting renewable-based hydrogen through pipelines from low- to high-cost production regions reduces the national average levelized cost of renewables-based hydrogen but may increase the risk of hydrogen leakage and the resulting indirect warming effects. Our findings emphasize that policy and economic support for nonfossil electrolytic hydrogen is critical to avoid an increase in CO2e emissions as hydrogen use rises during a clean energy transition.

2. Nat. Sustain.

   Co-benefits of transport demand reductions from compact urban development in Chinese cities

   Xiangwen Fu, Jing Cheng, Liqun Peng, Mi Zhou, Dan Tong, and Denise L Mauzerall

   Nature Sustainability, 2024

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   Transport is a major contributor to carbon emissions and air pollution in China. Ongoing urbanization provides a unique opportunity for Chinese cities to abate emissions by reducing transport demand via compact urban development (CUD). Here we systematically evaluate the implications of CUD for climate, energy use, air quality and human health in 2050 China under various scenarios of alternative energy vehicle (AEV) deployment and power decarbonization. We find that, with low AEV penetration and carbon intensive power (57% coal + gas), ambitious CUD policy reduces on-road transport CO2 and NOx emissions by 97 Mt (8%) and 95 kt (7%), respectively, and avoids 25,000 premature deaths from ambient air pollution in 2050. CUD delivers less climate and air quality co-benefits as AEV penetration increases and their energy sources decarbonize, but continues to reduce vehicle energy use (up to 10%). With 100% AEV penetration, ambitious CUD policy still avoids 5,800 premature deaths by reducing non-exhaust vehicle emissions and upstream emissions. Our analysis demonstrates that CUD policy would provide considerable environmental and economic benefits in China.

2023

1. Nat. Commun.

   Heterogeneous effects of battery storage deployment strategies on decarbonization of provincial power systems in China

   Liqun Peng, Denise L Mauzerall, Yaofeng D Zhong, and Gang He

   Nature communications, 2023

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   Battery storage is critical for integrating variable renewable generation, yet how the location, scale, and timing of storage deployment affect system costs and carbon dioxide (CO2) emissions is uncertain. We improve a power system model, SWITCH-China, to examine three nationally uniform battery deployment strategies (Renewable-connected, Grid-connected, and Demand-side) and a heterogeneous battery deployment strategy where each province is allowed to utilize any of the three battery strategies. Here, we find that the heterogeneous strategy always provides the lowest system costs among all four strategies, where provinces with abundant renewable resources dominantly adopt Renewable-connected batteries while those with limited renewables dominantly adopt Demand-side batteries. However, which strategy achieves the lowest CO2 emissions depends on carbon prices. The Renewable-connected strategy achieves the lowest CO2 emissions when carbon prices are relatively low, and the heterogeneous strategy results in the lowest CO2 emissions only at extremely high carbon prices.

2. ES&T

   Carbon Mitigation and Environmental Co-Benefits of a Clean Energy Transition in China’s Industrial Parks

   Yang Guo, Mi Zhou, Liqun Peng, Juhua Yang, Mingwei Li, Jinping Tian, Lyujun Chen, and Denise L Mauzerall

   Environmental Science & Technology, 2023

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   Industrial parks are emerging priorities for carbon mitigation. Here we analyze air quality, human health, and freshwater conservation co-benefits of decarbonizing the energy supply of 850 China’s industrial parks. We examine a clean energy transition including early retirement of coal-fired facilities and subsequent replacement with grid electricity and onsite energy alternatives (municipal solid waste-to-energy, rooftop photovoltaic, and distributed wind power). We find that such a transition would reduce greenhouse gas emissions by 41% (equal to 7% of 2014 national CO2 equivalent emissions); emissions of SO2 by 41%, NOx by 32%, and PM2.5 by 43% and freshwater consumption by 20%, relative to a 2030 baseline scenario. Based on modeled air pollutant concentrations, we estimate such a clean energy transition will result in ∼42,000 avoided premature deaths annually due to reduced ambient PM2.5 and ozone exposure. Costs and benefits are monetized including technical costs of changes in equipment and energy use and societal benefits resulting from improvements in human health and reductions of climate impacts. We find that decarbonizing industrial parks brings annual economic benefits of US$30–156 billion in 2030. A clean energy transition in China’s industrial parks thus provides both environmental and economic benefits.

2022

1. Nat. Sustain.

   Environmental benefits and household costs of clean heating options in northern China

   Mi Zhou, Hongxun Liu, Liqun Peng, Yue Qin, Dan Chen, Lin Zhang, and Denise L Mauzerall

   Nature Sustainability, 2022

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   The Chinese government accelerated the clean residential heating transition in northern China as part of a successful effort to improve regional air quality. Meanwhile, China has committed to carbon neutrality by 2060, making strategic choices for long-term decarbonization of the residential sector necessary. However, the synergies and trade-offs for health and carbon of alternative heating options and associated costs have not been systematically considered. Here we investigate air-quality–health–carbon interdependencies as well as household costs of using electricity (heat pumps or resistance heaters), gas or clean coal for residential heating for individual provinces across northern China. We find substantial air-quality and health benefits, varied carbon emissions and increased heating costs across clean heating options. With the 2015 power mix, gas heaters offer the largest health–carbon co-benefits, while resistance heaters lead to health–carbon trade-offs. As the power grid decarbonizes, by 2030 heat pumps achieve the largest health–carbon synergies of the options we analysed. Despite high capital costs, heat pumps generally have the lowest operating costs and thus are competitive for long-term use. With increased subsidies on the purchase of heat pumps, the government can facilitate further air-quality improvements and carbon mitigation in the clean heating transition.

2021

1. One Earth

   Alternative-energy-vehicles deployment delivers climate, air quality, and health co-benefits when coupled with decarbonizing power generation in China

   Liqun Peng, Feiqi Liu, Mi Zhou, Mingwei Li, Qiang Zhang, and Denise L Mauzerall

   One Earth, 2021

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   China is the world’s largest carbon emitter and suffers from severe air pollution, which results in approximately one million premature deaths/year. Alternative energy vehicles (AEVs) (electric, hydrogen fuel cell, and natural gas vehicles) can reduce carbon emissions and improve air quality. However, climate, air quality, and health benefits of AEVs powered with deeply decarbonized power generation are poorly quantified. Here, we quantitatively estimate the air quality, health, carbon emission, and economic benefits of replacing internal combustion engine vehicles with various AEVs. We find co-benefits increase dramatically as the electricity grid decarbonizes and hydrogen is produced from non-fossil fuels. Relative to 2015, a conversion to AEVs using largely non-fossil power can reduce air pollution and associated premature mortalities and years of life lost by ∼329,000 persons/year and ∼1,611,000 life years/year. Thus, maximizing climate, air quality, and health benefits of AEV deployment in China requires rapid decarbonization of the power system.

2019

1. Appl. Energy

   Underreported coal in statistics: A survey-based solid fuel consumption and emission inventory for the rural residential sector in China

   Liqun Peng, Qiang Zhang, Zhiliang Yao, Denise L Mauzerall, Sicong Kang, Zhenyu Du, Yixuan Zheng, Tao Xue, and Kebin He

   Applied Energy, 2019

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   Solid fuel consumption and associated emissions from residential use are highly uncertain due to a lack of reliable statistics. In this study, we estimate solid fuel consumption and emissions from the rural residential sector in China by using data collected from a new nationwide field survey. We conducted a field survey in 2010 which covered ∼17,000 rural residential households in 183 counties in China, to obtain data for solid fuel consumption and use patterns. We then developed a Generalized Additive Model (GAM) to establish the relationship between solid fuel consumption and heating degree days (HDD), income, coal production, coal price, and vegetation coverage, respectively. The GAM was used to estimate solid fuel consumption in rural households in China at the county level. We estimated that, in 2010, 179.8Tg of coal were consumed in Chinese rural households for heating and cooking, which is 62% higher than that reported in official energy statistics. We found that large quantities of rural residential coal consumption in the North China Plain were underreported in energy statistics. For instance, estimated coal consumption in rural households in Hebei (one of most polluted provinces in China) was 20.8Tg in 2010, which is twice as high as government statistics indicate. In contrast, modeled national total consumption of crop residues (used as fuels) we found to be ∼50% lower than reported data. Combining the underlying data from the survey, the GAM and emission factors from literature, we estimate emissions from China’s rural residential sector in 2010 to be: 3.3Tg PM2.5, 0.6Tg BC, 1.2Tg OC, 2.1Tg VOC, 2.3Tg SO2, 0.4Tg NOx, 43.6Tg CO and 727.2Tg CO2, contributing to 29%, 35%, 38% and 26% of national total PM2.5, BC, OC, and CO emissions respectively. This work reveals that current emission inventories in China likely underestimate emissions from coal combustion in rural residential households due to missing coal consumption in official statistics, especially for the heavily polluted North China Plain (NCP) region. Per capita income appears to be the driving factor that results in the difference between surveyed data and official data. Residents with high income prefer commercial energy and have a higher per capita fuel consumption than lower income residents. Therefore, rural residential coal combustion may contribute even more to regional air pollution than the large contributions previously identified.

2. Nat. Commun.

   Inequality of household consumption and air pollution-related deaths in China

   Hongyan Zhao, Guannan Geng, Qiang Zhang, Steven J Davis, Xin Li, Yang Liu, Liqun Peng, Meng Li, Bo Zheng, Hong Huo, and  others

   Nature communications, 2019

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   Substantial quantities of air pollution and related health impacts are ultimately attributable to household consumption. However, how consumption pattern affects air pollution impacts remains unclear. Here we show, of the 1.08 (0.74–1.42) million premature deaths due to anthropogenic PM2.5 exposure in China in 2012, 20% are related to household direct emissions through fuel use and 24% are related to household indirect emissions embodied in consumption of goods and services. Income is strongly associated with air pollution-related deaths for urban residents in which health impacts are dominated by indirect emissions. Despite a larger and wealthier urban population, the number of deaths related to rural consumption is higher than that related to urban consumption, largely due to direct emissions from solid fuel combustion in rural China. Our results provide quantitative insight to consumption-based accounting of air pollution and related deaths and may inform more effective and equitable clean air policies in China.

2018

1. ACP

   Trends in China’s anthropogenic emissions since 2010 as the consequence of clean air actions

   Bo Zheng, Dan Tong, Meng Li, Fei Liu, Chaopeng Hong, Guannan Geng, Haiyan Li, Xin Li, Liqun Peng, Ji Qi, and  others

   Atmospheric Chemistry and Physics, 2018

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   To tackle the problem of severe air pollution, China has implemented active clean air policies in recent years. As a consequence, the emissions of major air pollutants have decreased and the air quality has substantially improved. Here, we quantified China’s anthropogenic emission trends from 2010 to 2017 and identified the major driving forces of these trends by using a combination of bottom-up emission inventory and index decomposition analysis (IDA) approaches. The relative change rates of China’s anthropogenic emissions during 2010–2017 are estimated as follows: −62 % for SO2, −17 % for NOx, +11 % for nonmethane volatile organic compounds (NMVOCs), +1 % for NH3, −27 % for CO, −38 % for PM10, −35 % for PM2.5, −27 % for BC, −35 % for OC, and +16 % for CO2. The IDA results suggest that emission control measures are the main drivers of this reduction, in which the pollution controls on power plants and industries are the most effective mitigation measures. The emission reduction rates markedly accelerated after the year 2013, confirming the effectiveness of China’s Clean Air Action that was implemented since 2013. We estimated that during 2013–2017, China’s anthropogenic emissions decreased by 59 % for SO2, 21 % for NOx, 23 % for CO, 36 % for PM10, 33 % for PM2.5, 28 % for BC, and 32 % for OC. NMVOC emissions increased and NH3 emissions remained stable during 2010–2017, representing the absence of effective mitigation measures for NMVOCs and NH3 in current policies. The relative contributions of different sectors to emissions have significantly changed after several years’ implementation of clean air policies, indicating that it is paramount to introduce new policies to enable further emission reductions in the future.

2016

1. Atmos. Env.

   Assessment of socioeconomic costs to China’s air pollution

   Yang Xia, Dabo Guan, Xujia Jiang, Liqun Peng, Heike Schroeder, and Qiang Zhang

   Atmospheric Environment, 2016

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   Particulate air pollution has had a significant impact on human health in China and it is associated with cardiovascular and respiratory diseases and high mortality and morbidity. These health impacts could be translated to reduced labor availability and time. This paper utilized a supply-driven input-output (I-O) model to estimate the monetary value of total output losses resulting from reduced working time caused by diseases related to air pollution across 30 Chinese provinces in 2007. Fine particulate matter (PM2.5) pollution was used as an indicator to assess impacts to health caused by air pollution. The developed I-O model is able to capture both direct economic costs and indirect cascading effects throughout inter-regional production supply chains and the indirect effects greatly outnumber the direct effects in most Chinese provinces. Our results show the total economic losses of 346.26 billion Yuan (approximately 1.1% of the national GDP) based on the number of affected Chinese employees (72 million out of a total labor population of 712 million) whose work time in years was reduced because of mortality, hospital admissions and outpatient visits due to diseases resulting from PM2.5 air pollution in 2007. The loss is almost the annual GDP of Vietnam in 2010. The proposed modelling approach provides an alternative method for health-cost measurement with additional insights on inter-industrial and inter-regional linkages along production supply chains.

2015

1. ES&T

   Revealing the hidden health costs embodied in Chinese exports

   Xujia Jiang, Qiang Zhang, Hongyan Zhao, Guannan Geng, Liqun Peng, Dabo Guan, Haidong Kan, Hong Huo, Jintai Lin, Michael Brauer, and  others

   Environmental science & technology, 2015

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   China emits a considerable amount of air pollutants when producing goods for export. Previous efforts have emphasized the magnitude of export-related emissions; however, their health consequences on the Chinese population have not been quantified. Here, we present an interdisciplinary study to estimate the health impact of export-related air pollution. The results show that export-related emissions elevated the annual mean population weighted PM2.5 by 8.3 μg/m3 (15% of the total) in 2007, causing 157,000 deaths and accounting for 12% of the total mortality attributable to PM2.5-related air pollution. Compared to the eastern coastal provinces, the inner regions experience much larger export-related health losses relative to their economic production gains, owing to huge inter-regional disparities in export structures and technology levels. A shift away from emission-intensive production structure and export patterns, especially in inner regions, could significantly help improve national exports while alleviating the inter-regional cost-benefit inequality. Our results provide the first quantification of health consequences from air pollution related to Chinese exports. The proposed policy recommendations, based on health burden, economic production gains, and emission analysis, would be helpful to develop more sustainable and effective national and regional export strategies.