In Press
Zhao, Yu, Jie Zhang, and Chris P Nielsen. In Press.

The effects of energy paths and emission controls and standards on future trends in China’s emissions of primary air pollutants

. Atmospheric Chemistry and Physics. Publisher's VersionAbstract
To examine the efficacy of China's actions to control atmospheric pollution, three levels of growth of energy consumption and three levels of implementation of emission controls are estimated, generating a total of nine combined activity-emission control scenarios that are then used to estimate trends of national emissions of primary air pollutants through 2030. The emission control strategies are expected to have more effects than the energy paths on the future emission trends for all the concerned pollutants. As recently promulgated national action plans of air pollution prevention and control (NAPAPPC) are implemented, China's anthropogenic pollutant emissions should decline. For example, the emissions of SO2, NOx, total primary particulate matter (PM), PM10, and PM2.5 are estimated to decline 7%, 20%, 41%, 34%, and 31% from 2010 to 2030, respectively, in the "best guess" scenario that includes national commitment of energy saving policy and partial implementation of NAPAPPC. Should the issued/proposed emission standards be fully achieved, a less likely scenario, annual emissions would be further reduced, ranging from 17% (for primary PM2.5) to 29% (for NOx) declines in 2015, and the analogue numbers would be 12% and 24% in 2030. The uncertainties of emission projections result mainly from the uncertain operational conditions of swiftly proliferating air pollutant control devices and lack of detailed information about emission control plans by region. The predicted emission trends by sector and chemical species raise concerns about current pollution control strategies: the potential for emissions abatement in key sectors may be declining due to the near saturation of emission control devices use; risks of ecosystem acidification could rise because emissions of alkaline base cations may be declining faster than those of SO2; and radiative forcing could rise because emissions of positive-forcing carbonaceous aerosols may decline more slowly than those of SO2 emissions and thereby concentrations of negative-forcing sulfate particles. Expanded control of emissions of fine particles and carbonaceous aerosols from small industrial and residential sources is recommended, and a more comprehensive emission control strategy targeting a wider range of pollutants and taking account of more diverse environmental impacts is also urgently needed.
Zhang, Yanxia, Haikun Wang, Sai Liang, Ming Xu, Weidong Liu, Shalang Li, Rongrong Zhang, Chris P Nielsen, and Jun Bi. In Press.

Temporal and spatial variations in consumption-based carbon dioxide emissions in China

. Renewable & Sustainable Energy Reviews.
Deng, Yu, and Sumeeta Srinivasan. Submitted.

Urban land use change and accessibility: A case study in Beijing, China

. Transportation Geography.Abstract
In the recent past Beijing has experienced a boom in development due to the 2008 Olympic Games and large-scale investment from government stimulus in response to the global financial crisis. Rapid urban growth has been accompanied by many problems including traffic congestion and air pollution. Understanding urban growth and its determinants is important for sustainable development in the coming years. In this paper, we first estimate a binary auto-logistic model of land use change, using physical and socioeconomic characteristics of the location and its accessibility to major centers within the city as predictors. We find that variables determining spatial accessibility, like time distance to the city center, the Central Business District (CBD), industrial centers, employment centers, and the transportation system, affect urban land conversion. Not surprisingly, accessibility of a location is a major predictor urban development.
Lu, Xi, and Michael B McElroy. Submitted.

China's conundrum: More installed wind power than the US but less production

. Science.
Lu, Xi, Michael B McElroy, Xinyu Chen, and Chongqing Kang. Submitted.

Opportunity for offshore wind to reduce future demand for coal-fired power plants in China with consequent savings in emissions of CO2

. Environmental Science & Technology.
Wang, Long, Shuxiao Wang, Lei Zheng, Yuxuan Wang, Yanxu Zheng, Chris P Nielsen, Michael B McElroy, and Jiming Hao. 2014.

Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model

. Environmental Pollution 190, no. July: 166-175. Publisher's VersionAbstract
China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35–50% of THg concentration and 50–70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China.
Wang, SX, B Zhao, SY Cai, CP Nielsen, MB McElroy, T Morikawa, JH Woo, et al. 2014.

Emission trends and mitigation options for air pollutants in East Asia

. Atmospheric Chemistry and Physics 14: 6571-6603. Publisher's VersionAbstract
Emissions of air pollutants in East Asia play an important role in the regional and global atmospheric environment. In this study we evaluated the recent emission trends of sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter (PM), and non-methane volatile organic compounds (NMVOC) in East Asia, and projected their future emissions up until 2030 with six emission scenarios. The results will provide future emission projections for the modeling community of the model inter-comparison program for Asia (MICS-Asia). During 2005–2010, the emissions of SO2 and PM2.5 in East Asia decreased by 15 and 12%, respectively, mainly attributable to the large-scale deployment of flue gas desulfurization (FGD) at China's power plants, and the promotion of highly efficient PM removal technologies in China's power plants and cement industry. During this period, the emissions of NOx and NMVOC increased by 25 and 15%, driven by rapid increase in the emissions from China due to inadequate control strategies. In contrast, the NOx and NMVOC emissions in East Asia except China decreased by 13–17%, mainly due to the implementation of stringent vehicle emission standards in Japan and South Korea. Under current regulations and current levels of implementation, NOx, SO2, and NMVOC emissions in East Asia are projected to increase by about one-quarter over 2010 levels by 2030, while PM2.5 emissions are expected to decrease by 7%. Assuming enforcement of new energy-saving policies, emissions of NOx, SO2, PM2.5 and NMVOC in East Asia are expected to decrease by 28, 36, 28, and 15%, respectively, compared with the baseline case. The implementation of "progressive" end-of-pipe control measures would lead to another one-third reduction of the baseline emissions of NOx, and about one-quarter reduction of SO2, PM2.5, and NMVOC. Assuming the full application of technically feasible energy-saving policies and end-of-pipe control technologies, the emissions of NOx, SO2, and PM2.5 in East Asia would account for only about one-quarter, and NMVOC for one-third, of the levels of the baseline projection. Compared with previous projections, this study projects larger reductions in NOx and SO2 emissions by considering aggressive governmental plans and standards scheduled to be implemented in the next decade, and quantifies the significant effects of detailed progressive control measures on NMVOC emissions up until 2030.
Huang, Junling, and Michael B McElroy. 2014.

Contributions of the Hadley and Ferrel circulations to the energetics of the atmosphere over the past 32 years

. Journal of Climate 27, no. 7: 2656–2666. Publisher's VersionAbstract
The Hadley system provides an example of a thermally direct circulation; the Ferrel system in contrast provides an example of a thermally indirect circulation. In this study, the authors develop an approach to investigate the key thermodynamic properties of the Hadley and Ferrel systems, quantifying them using assimilated meteorological data covering the period January 1979–December 2010. This analysis offers a fresh perspective on the conversion of energy in the atmosphere from diabatic heating to the production of atmospheric kinetic energy. The results indicate that the thermodynamic efficiency of the Hadley system, considered as a heat engine, has been relatively constant over the 32-yr period covered by the analysis, averaging 2.6%. Over the same interval, the power generated by the Hadley regime has risen at an average rate of about 0.54 TW yr−1; this reflects an increase in energy input to the system consistent with the observed trend in the tropical sea surface temperatures. The Ferrel system acts as a heat pump with a coefficient of performance of 12.1, consuming kinetic energy at an approximate rate of 275 TW and exceeding the power production rate of the Hadley system by 77 TW.
Chen, Xinyu, Xi Lu, Michael B McElroy, Chris P Nielsen, and Chongqing Kang. 2014.

Synergies of wind power and electrified space heating: A case study for Beijing

. Environmental Science & Technology 48 , no. 3: 2016–2024. Publisher's VersionAbstract
Demands for electricity and energy to supply heat are expected to expand by 71% and 47%, respectively, for Beijing in 2020 relative to 2009. If the additional electricity and heat are supplied solely by coal as is the current situation, annual emissions of CO2 may be expected to increase by 59.6% or 99 million tons over this interval. Assessed against this business as usual (BAU) background, the present study indicates that significant reductions in emissions could be realized using wind-generated electricity to provide a source of heat, employed either with heat pumps or with electric thermal storage (ETS) devices. Relative to BAU, reductions in CO2 with heat pumps assuming 20% wind penetration could be as large as 48.5% and could be obtained at a cost for abatement of as little as $15.6 per ton of avoided CO2. Even greater reductions, 64.5%, could be realized at a wind penetration level of 40% but at a higher cost, $29.4 per ton. Costs for reduction of CO2 using ETS systems are significantly higher, reflecting the relatively low efficiency for conversion of coal to power to heat.
Huang, Junling, Xi Lu, and Michael B McElroy. 2014.

Meteorologically defined limits to reduction in the variability of outputs from a coupled wind farm system in the Central US

. Renewable Energy 62, no. February: 331–340. Publisher's VersionAbstract
Studies suggest that onshore wind resources in the contiguous US could readily accommodate present and anticipated future US demand for electricity. The problem with the output from a single wind farm located in any particular region is that it is variable on time scales ranging from minutes to days posing difficulties for incorporating relevant outputs into an integrated power system. The high frequency (shorter than once per day) variability of contributions from individual wind farms is determined mainly by locally generated small-scale boundary layer. The low frequency variability (longer than once per day) is associated with the passage of transient waves in the atmosphere with a characteristic time scale of several days. Using 5 years of assimilated wind data, we show that the high frequency variability of wind-generated power can be significantly reduced by coupling outputs from 5 to 10 wind farms distributed uniformly over a ten state region of the Central US in this study. More than 95% of the remaining variability of the coupled system is concentrated at time scales longer than a day, allowing operators to take advantage of multi-day weather forecasts in scheduling projected contributions from wind.
Nielsen, Chris P, and Mun S Ho. 2013.

Op-ed: Clearing the air in China

. New York Times (Sunday Review). Publisher's Version
Nielsen, Chris P, and Mun. S Ho. 2013.

Atmospheric Environment in China: Introduction and Research Review

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 3-58. Cambridge, MA: MIT Press. Click here for the book on the MIT Press website.
Zhao, Yu, Wei Wei, and Yu Lei. 2013.

An Anthropogenic Emission Inventory of Primary Air Pollutants in China for 2005 and 2010

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 225-261. Cambridge, MA: MIT Press. Publisher's Version
Wang, Yuxuan. 2013.

Atmospheric Modeling of Pollutant Concentrations

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 263-289. Cambridge, MA: MIT Press. Publisher's Version
Lei, Yu. 2013.

Benefits to Human Health and Agricultural Productivity of Reduced Air Pollution

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 291-328. Cambridge, MA: MIT Press. Publisher's Version
Nielsen, Chris P, and Mun S Ho, eds. 2013.

Clearer Skies Over China: Reconciling Air Pollution, Climate, and Economic Goals

. Cambridge, MA: MIT Press. Publisher's Version
Zhao, Yu. 2013.

Primary Air Pollutant Emissions of Coal-Fired Power Plants in China

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 161-202. Cambridge, MA: MIT Press. Publisher's Version
Lei, Yu, Qiang Zhang, Chris P Nielsen, and Kebin He. 2013.

Primary Air Pollutants and CO2 Emissions from Cement Production in China

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 203-224. Cambridge, MA: MIT Press. Publisher's Version
Nielsen, Chris P, Mun S Ho, Jing Cao, Yu Lei, Yuxuan Wang, and Yu Zhao. 2013.

Summary: Carbon Taxes for 2013-2020

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 103-157. Cambridge, MA: MIT Press. Publisher's Version
Nielsen, Chris P, Mun S Ho, Yu Zhao, Yuxuan Wang, Yu Lei, and Jing Cao. 2013.

Summary: Sulfur Mandates and Carbon Taxes for 2006-2010

. In Clearer Skies Over China: Reconciling Air Quality, Climate, and Economic Goals, 59-102. Cambridge, MA: MIT Press. Publisher's Version