Opportunities and Challenges in Reducing Air Pollution and Greenhouse Gas Emissions Simultaneously

A number of emerging markets, most notably China and India, are facing the challenge of reducing air pollution and greenhouse gas emissions simultaneously. Air pollution can be addressed in ways which either reduce or increase emissions of greenhouse gases. We analyze various technological interventions and map their impacts on air quality, public health and the emissions of greenhouse gases so that trade-offs inherent in various options become clear.

For example, we find that coal gasification (synthetic natural gas), while producing gas that burns cleanly and thus reduces the emissions of air pollutants, leads to enormous increases in carbon dioxide emissions. Conversely, when renewable energy displaces coal, it essentially eliminates the emissions of both air pollutants and greenhouse gases, thus providing benefits for air quality, public health and climate.

China is the world's largest producer of both coal and solar PV panels. Our researchers are studying opportunities and benefits of displacement of coal with increased penetration of renewable energy  in China, as well as China's role in promoting both coal and renewable energy technologies abroad.

Benefits of Electrification with Renewable Sources

Generating electricity from renewable energy sources is a key strategy for carbon mitigation efforts. Renewably generated electricity can greatly reduce both air pollutant and greenhouse gas emissions compared to fossil fuel (especially coal) electricity generation. The Chinese government plans to greatly scale up renewable energy capacity between now and 2030. However, different renewable energy deployment pathways will influence the range of air quality, human health, and climate benefits. Benefits depend on how much electricity generated from renewable energy is integrated into power grids and the type of power plants or other home cooking/heating/power sources are displaced. Our researchers also consider opportunities for long-distance transmission of electricity from renewable/hybrid sources.  Our researchers also find that improving air quality has the benefit of increasing the generation of solar PV which can then reduce the use of fossil fuels, leading to a virtuous cycle of improving air quality leading to more electricity generation from clean low-carbon solar PV.

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Natural Gas and Synthetic Natural Gas

Our researchers study China's natural gas industry and characterize the interconnections of various environmental impacts resulting from energy source choices and end-use applications. While natural gas is the cleanest fossil fuel option, it still requires freshwater for cooling and emits greenhouse gases (both methane via leakage and CO2 from methane combustion). Replacing coal with natural gas sources has air quality–carbon–water co-benefits. However, building natural gas infra-structure is a commitment to the use of fossil fuels in the future.  China also produces coal-based synthetic natural gas (SNG), which has air pollution benefits compared to direct combustion of coal, but leads to increased carbon dioxide emissions.  The use of conventional natural gas has air quality and greenhouse gas mitigation benefits but has higher emissions of both compared to the use of decarbonized electricity.

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Managing China's Coal Power Plants

China needs to manage its coal-dominated power system to curb carbon emissions, as well as to address local environmental priorities such as air pollution and water stress. Our researchers examine three province-level scenarios for 2030 that represent various potential electricity demand and low-carbon infrastructure development pathways. For each scenario, they optimize coal power generation strategies to minimize the sum of national total coal power generation cost, inter-regional transmission cost and air pollution and water costs. They consider existing environmental regulations on coal power plants and monetize the environmental costs.

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Residential Heating: Solid Fuel Consumption and Emissions

China suffers from severe outdoor air pollution and associated public health impacts. In response, the government has imposed restrictions on major pollution sources such as vehicles and power plants. We show that due to uncontrolled and inefficient combustion of solid fuels in household devices, emission reductions from the residential sector may have greater air quality benefits in the North China Plain, including Beijing than reductions from other sectors. These benefits would be largest in the winter heating season when severe air pollution occurs. Household emissions, mostly from space heating and cooking with solid fuels, are an important and generally unrecognized source of ambient air pollution in China and other developing countries. Alternative fuels and other ways of reducing emissions would have large benefits.

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