Wang, Haikun, Xi Lu, and Chris P Nielsen. Submitted.

Understanding China’s carbon dioxide emissions from both production and consumption perspectives

, Atmospheric Chemistry and Physics.Abstract
China is now the largest emitter of CO2 in the world, having contributed nearly half of the global increase in carbon emissions between 1980 and 2010. The existing literature on China’s carbon emissions has focused on two dimensions: the amount of CO2 emitted within China’s geographical boundaries (a production-based perspective), and the drivers of, and responsibility for, these emissions (a consumption-based perspective). The current study begins with a comprehensive review of China’s CO2 emissions, and then analyzes their driving forces from both consumption and production perspectives, at both national and provincial levels. It is concluded that China’s aggregate national CO2 emissions from fossil fuel consumption and cement production maintained high growth rates during 2000-2010. National emissions reached 6.8–7.3 billion tons in 2007, nearly 25% of which were caused by net exports (i.e., exports minus imports) to other countries. However, emission characteristics varied significantly among different regions and provinces, and considerable emission leakage from the developed eastern regions to inland and western areas of the country was found. The objectives of China’s policies should therefore be broadened from continued improvement of energy efficiency to accelerating regional technology transfer and preventing mere relocation of carbon-intensive economic activities from developed coastal regions to less developed, inland provinces. To rapidly and effectively cut down China’s carbon emissions, moreover, its energy supply should be aggressively decarbonized by promoting renewable and low carbon energy sources.
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.

Wind power in China: Current status and challenges for the future

, Nature Climate Change.Abstract
China has more installed wind capacity than the US (91.6 GW vs. 61 GW). Despite this, it produces less electricity (134.9 TWh vs. 167.7 TWh) from this source. A range of factors has been suggested as potential contribution to the Chinese shortfall: wind-generated electricity may be intrinsically less favorable; connections to the grid may have lagged construction of wind farms; the quality of turbines may be inferior; and, for reasons specific to China, wind farms have had to curtail their output in recent years. A logarithmic mean divisia index (LMDI) decomposition approach is used to quantify the relative importance of these factors. We show that curtailment of wind power, differences in turbine quality and delayed connection to the grid are primarily responsible for the US-China difference. The problem of delayed connection to the grid is likely to be less important in the future. Opening the market to international suppliers could alleviate the challenge posed by the current lower quality of domestically produced turbines. The curtailment issue, rooted in the inflexibility of coal-fired systems, especially combined heat and power plants operated to provide district heating in winter, poses a more serious challenge. Options are proposed to address this issue. 
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.Abstract
Although capacity credits for wind power have been embodied in power systems in the U.S. and Europe, the current planning framework for electricity in China continues to treat wind power as a non-dispatchable source with zero contribution to firm capacity. This study adopts a rigorous reliability model for the electric power system evaluating capacity credits that should be recognized for offshore wind resources supplying power demands for Jiangsu, China. Jiangsu is an economic hub located in the Yangtze River delta accounting for 10% of the total electricity consumed in China. Demand for electricity in Jiangsu is projected to increase from 331 TWh in 2009 to 800 TWh by 2030. Given a wind penetration level of 60% for the future additional Jiangsu power supply, wind resources distributed along the offshore region of five coastal provinces in China (Shandong, Jiangsu, Shanghai, Zhejiang and Fujian) should merit a capacity credit of 12.9%, the fraction of installed wind capacity that should be recognized to displace coal-fired systems without violating the reliability standard. In the high-coal-price scenario, with 60% wind penetration, reductions in CO2 emissions relative to a business as usual reference could be as large as 217.2 million tons of CO2 or 46.3% of the potential addition, with a cost for emissions avoided of $37.4 per ton.
Zhao, Y, H Zhong, J Zhang, and CP Nielsen. 2014.

Evaluating the effects of China's pollution control on inter-annual trends and uncertainties of atmospheric mercury emissions

, Atmospheric Chemistry and Physics Discussions 14: 26803-26855. Publisher's VersionAbstract
China's atmospheric mercury (Hg) emissions of anthropogenic origin have been effectively restrained through the national policy of air pollution control. Improved methods based on available field measurements are developed to quantify the benefits of Hg abatement through various emission control measures. Those measures include increased use of flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems for power sector, precalciners with fabric filter (FF) for cement production, machinery coking with electrostatic precipitator (ESP) for iron and steel production, and advanced manufacturing technologies for nonferrous metal smelting. Declining trends in emissions factors for those sources are revealed, leading to a much slower growth of national total Hg emissions than that of energy and economy, from 679 in 2005 to 750 metric tons (t) in 2012. In particular, nearly half of emissions from the above-mentioned four types of sources are expected to be reduced in 2012, attributed to expansion of technologies with high energy efficiencies and air pollutant removal rates after 2005. The speciation of Hg emissions keeps stable for recent years, with the mass fractions of around 55, 39 and 6% for Hg0, Hg2+ and Hgp, respectively. The lower estimate of Hg emissions than previous inventories is supported by limited chemistry simulation work, but middle-to-long term observation on ambient Hg levels is further needed to justify the inter-annual trends of estimated Hg emissions. With improved implementation of emission controls and energy saving, 23% reduction in annual Hg emissions for the most optimistic case in 2030 is expected compared to 2012, with total emissions below 600 t. While Hg emissions are evaluated to be gradually constrained, increased uncertainties are quantified with Monte-Carlo simulation for recent years, particularly for power and certain industrial sources. The uncertainty of Hg emissions from coal-fired power plants, as an example, increased from −48~ +73% in 2005 to −50~ +89% in 2012 (expressed as 95% confidence interval). This is attributed mainly to swiftly increased penetration of advanced manufacturing and pollutant control technologies. The unclear operation status or relatively small sample size of field measurements on those technologies results in lower but highly varied emission factors. To further confirm the benefits of pollution control polices with reduced uncertainty, therefore, systematic investigations are recommended specific for Hg pollution sources, and the variability of temporal trends and spatial distributions of Hg emissions need to be better tracked for the country under dramatic changes in economy, energy and air pollution status.
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.
Zhao, Yu, Jie Zhang, and Chris P Nielsen. 2014.

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 14: 8849-8868. 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 suspended particles (TSP), 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 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 (volatile organic compounds, NH3 and CO, etc.) and taking account of more diverse environmental impacts is also urgently needed.
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.
Zhang, Yanxia, Haikun Wang, Sai Liang, Ming Xu, Weidong Liu, Shalang Li, Rongrong Zhang, Chris P Nielsen, and Jun Bi. 2014.

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

, Renewable & Sustainable Energy Reviews 40: 60-68. Publisher's VersionAbstract
China’s CO2 emissions have sharply increased in recent years with soaring economic development and urbanization. Consumption-based accounting of CO2 emissions could provide new insights for allocating regional mitigation responsibility and curbing the emissions. A multi-regional input–output model is used to study the trends and disparities of consumption-based emissions from Chinese provinces during the period 2002–2007. Results show that China’s consumption-based CO2 emissions grew from 3549 Mt in 2002 to 5403 Mt in 2007 with an annual average growth rate of 8.8%. The annual growth rate in the richer eastern region was over 10% because of a rapid increase in capital investment and the growth of urban consumption. Consumption-based CO2 emissions embodied in interprovincial trades contributed only 10% (351 Mt) to the national total of such emissions in 2002, but 16% (864 Mt) in 2007. Given low per capita emissions currently, China’s consumption-based emissions have much room to grow because of further development of urbanization and stimulation of domestic demand. The government should pay greater attention to controlling CO2 emissions from a consumption-based perspective.
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