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"McElroy, Michael B."
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Fine-particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models
pH is an important property of aerosol particles but is difficult to measure directly. Several studies have estimated the pH values for fine particles in northern China winter haze using thermodynamic models (i.e., E-AIM and ISORROPIA) and ambient measurements. The reported pH values differ widely, ranging from close to 0 (highly acidic) to as high as 7 (neutral). In order to understand the reason for this discrepancy, we calculated pH values using these models with different assumptions with regard to model inputs and particle phase states. We find that the large discrepancy is due primarily to differences in the model assumptions adopted in previous studies. Calculations using only aerosol-phase composition as inputs (i.e., reverse mode) are sensitive to the measurement errors of ionic species, and inferred pH values exhibit a bimodal distribution, with peaks between −2 and 2 and between 7 and 10, depending on whether anions or cations are in excess. Calculations using total (gas plus aerosol phase) measurements as inputs (i.e., forward mode) are affected much less by these measurement errors. In future studies, the reverse mode should be avoided whereas the forward mode should be used. Forward-mode calculations in this and previous studies collectively indicate a moderately acidic condition (pH from about 4 to about 5) for fine particles in northern China winter haze, indicating further that ammonia plays an important role in determining this property. The assumed particle phase state, either stable (solid plus liquid) or metastable (only liquid), does not significantly impact pH predictions. The unrealistic pH values of about 7 in a few previous studies (using the standard ISORROPIA model and stable state assumption) resulted from coding errors in the model, which have been identified and fixed in this study.
Journal Article
Global Potential for Wind-Generated Electricity
The potential of wind power as a global source of electricity is assessed by using winds derived through assimilation of data from a variety of meteorological sources. The analysis indicates that a network of land-based 2.5-megawatt (MW) turbines restricted to nonforested, ice-free, nonurban areas operating at as little as 20% of their rated capacity could supply >40 times current worldwide consumption of electricity, >5 times total global use of energy in all forms. Resources in the contiguous United States, specifically in the central plain states, could accommodate as much as 16 times total current demand for electricity in the United States. Estimates are given also for quantities of electricity that could be obtained by using a network of 3.6-MW turbines deployed in ocean waters with depths < 200 m within 50 nautical miles (92.6 km) of closest coastlines.
Journal Article
Prospective contributions of biomass pyrolysis to China's 2050 carbon reduction and renewable energy goals
Recognizing that bioenergy with carbon capture and storage (BECCS) may still take years to mature, this study focuses on another photosynthesis-based, negative-carbon technology that is readier to implement in China: biomass intermediate pyrolysis poly-generation (BIPP). Here we find that a BIPP system can be profitable without subsidies, while its national deployment could contribute to a 61% reduction of carbon emissions per unit of gross domestic product in 2030 compared to 2005 and result additionally in a reduction in air pollutant emissions. With 73% of national crop residues used between 2020 and 2030, the cumulative greenhouse gas (GHG) reduction could reach up to 8620 Mt CO
-eq by 2050, contributing 13-31% of the global GHG emission reduction goal for BECCS, and nearly 4555 Mt more than that projected for BECCS alone in China. Thus, China's BIPP deployment could have an important influence on achieving both national and global GHG emissions reduction targets.
Journal Article
Trade-driven relocation of air pollution and health impacts in China
Recent studies show that international trade affects global distributions of air pollution and public health. Domestic interprovincial trade has similar effects within countries, but has not been comprehensively investigated previously. Here we link four models to evaluate the effects of both international exports and interprovincial trade on PM
pollution and public health across China. We show that 50-60% of China's air pollutant emissions in 2007 were associated with goods and services consumed outside of the provinces where they were produced. Of an estimated 1.10 million premature deaths caused by PM
pollution throughout China, nearly 19% (208,500 deaths) are attributable to international exports. In contrast, interprovincial trade leads to improved air quality in developed coastal provinces with a net effect of 78,500 avoided deaths nationwide. However, both international export and interprovincial trade exacerbate the health burdens of air pollution in China's less developed interior provinces. Our results reveal trade to be a critical but largely overlooked consideration in effective regional air quality planning for China.International and domestic interprovincial trade of China are entangled, but their health impacts have been treated separately in earlier studies. Here Wang. quantify the complex impacts of trade on public health across China within an integrative framework.
Journal Article
Production of hydrogen from offshore wind in China and cost-competitive supply to Japan
Abstract
The Japanese government has announced a commitment to net-zero greenhouse gas emissions by 2050. It envisages an important role for hydrogen in the nation’s future energy economy. This paper explores the possibility that a significant source for this hydrogen could be produced by electrolysis fueled by power generated from offshore wind in China. Hydrogen could be delivered to Japan either as liquid, or bound to a chemical carrier such as toluene, or as a component of ammonia. The paper presents an analysis of factors determining the ultimate cost for this hydrogen, including expenses for production, storage, conversion, transport, and treatment at the destination. It concludes that the Chinese source could be delivered at a volume and cost consistent with Japan’s idealized future projections.
Journal Article
Ozone pollution over China and India: seasonality and sources
A regional fully coupled meteorology–chemistry model, Weather Research and
Forecasting model with Chemistry (WRF-Chem), was employed to study the
seasonality of ozone (O3) pollution and its sources in both China and
India. Observations and model results suggest that O3 in the North
China Plain (NCP), Yangtze River Delta (YRD), Pearl River Delta (PRD), and
India exhibit distinctive seasonal features, which are linked to the
influence of summer monsoons. Through a factor separation approach, we
examined the sensitivity of O3 to individual anthropogenic, biogenic,
and biomass burning emissions. We found that summer O3 formation in
China is more sensitive to industrial and biogenic sources than to other
source sectors, while the transportation and biogenic sources are more
important in all seasons for India. Tagged simulations suggest that local
sources play an important role in the formation of the summer O3 peak
in the NCP, but sources from Northwest China should not be neglected to
control summer O3 in the NCP. For the YRD region, prevailing winds and
cleaner air from the ocean in summer lead to reduced transport from polluted
regions, and the major source region in addition to local sources is
Southeast China. For the PRD region, the upwind region is replaced by
contributions from polluted PRD as autumn approaches, leading to an autumn
peak. The major upwind regions in autumn for the PRD are YRD (11 %) and
Southeast China (10 %). For India, sources in North India are more
important than sources in the south. These analyses emphasize the relative
importance of source sectors and regions as they change with seasons,
providing important implications for O3 control strategies.
Journal Article
Possible heterogeneous chemistry of hydroxymethanesulfonate (HMS) in northern China winter haze
The chemical mechanisms responsible for rapid sulfate production, an important
driver of winter haze formation in northern China, remain unclear. Here, we
propose a potentially important heterogeneous hydroxymethanesulfonate (HMS)
chemical mechanism. Through analyzing field measurements with aerosol mass
spectrometry, we show evidence for a possible significant existence in haze
aerosols of organosulfur primarily as HMS, misidentified as sulfate in
previous observations. We estimate that HMS can account for up to about
one-third of the sulfate concentrations unexplained by current air quality
models. Heterogeneous production of HMS by SO2 and formaldehyde is
favored under northern China winter haze conditions due to high aerosol water
content, moderately acidic pH values, high gaseous precursor levels, and low
temperature. These analyses identify an unappreciated importance of
formaldehyde in secondary aerosol formation and call for more research on
sources and on the chemistry of formaldehyde in northern China winter.
Journal Article
Transition towards higher penetration of renewables: an overview of interlinked technical, environmental and socio-economic challenges
Investment for renewables has been growing rapidly since the beginning of the new century, and the momentum is expected to sustain in order to mitigate the impact of anthropogenic climate change. Transition towards higher renewable penetration in the power industry will not only confront technical challenges, but also face socio-economic obstacles. The connected between environment and energy systems are also tightened under elevated penetration of renewables. This paper will provide an overview of some important challenges related to technical, environmental and socio-economic aspects at elevated renewable penetration. An integrated analytical framework for interlinked technical, environmental and socio-economic systems will be presented at the end.
Journal Article
Projected changes in seasonal and extreme summertime temperature and precipitation in India in response to COVID-19 recovery emissions scenarios
Abstract
Fossil fuel and aerosol emissions have played important roles on climate over the Indian subcontinent over the last century. As the world transitions toward decarbonization in the next few decades, emissions pathways could have major impacts on India’s climate and people. Pathways for future emissions are highly uncertain, particularly at present as countries recover from COVID-19. This paper explores a multimodel ensemble of Earth system models leveraging potential global emissions pathways following COVID-19 and the consequences for India’s summertime (June–July–August–September) climate in the near- and long-term. We investigate specifically scenarios which envisage a fossil-based recovery, a strong renewable-based recovery and a moderate scenario in between the two. We find that near-term climate changes are dominated by natural climate variability, and thus likely independent of the emissions pathway. By 2050, pathway-induced spatial patterns in the seasonally-aggregated precipitation become clearer with a slight drying in the fossil-based scenario and wetting in the strong renewable scenario. Additionally, extreme temperature and precipitation events in India are expected to increase in magnitude and frequency regardless of the emissions scenario, though the spatial patterns of these changes as well as the extent of the change are pathway dependent. This study provides an important discussion on the impacts of emissions recover pathways following COVID-19 on India, a nation which is likely to be particularly susceptible to climate change over the coming decades.
Journal Article