Clearing the Skies

Conventional air pollutants are reduced by coal-to-gas switching.

Natural gas is a versatile fuel and raw material that has become increasingly popular across the globe in recent years. When burned for electricity generation, natural gas produces less than half the carbon dioxide (CO2) emissions of coal. While this is one of the most often cited advantages of natural gas, it is by no means the only one.

Compared to coal, natural gas produces much lower levels of conventional air pollutants such as sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter (PM), and mercury (Hg) (1). These pollutants can cause respiratory illness, heart disease, and stroke, and contribute to environmental problems like acid rain and smog. Thus, nations and even whole regions with high coal use and serious pollution can “clear the skies” by switching from coal to USLNG.

Sulfur dioxide is a common air pollutant that is released when coal is burned. It can cause respiratory problems, such as asthma and bronchitis, and can also contribute to acid rain, which can harm crops, forests, and aquatic ecosystems. According to the U.S. Environmental Protection Agency (EPA), natural gas combustion produces only trace amounts of sulfur dioxide, which means that natural gas-fired power plants emit far less of this pollutant than coal-fired power plants (2).

Coal combustion also produces significant amounts of nitrogen oxides. Nitrogen oxides create smog and can also cause respiratory problems and other health issues. Natural gas-fired power plants emit an order of magnitude less NOx than coal-fired power plants (3).

Mercury is a potent neurotoxin that is released when coal is burned. It can accumulate in the food chain, leading to health problems for people and wildlife. The EPA estimates that coal-fired power plants are responsible for roughly half of all mercury emissions in the United States (4). In contrast, natural gas-fired power plants emit negligible quantities of mercury, making gas a much cleaner alternative to coal.

Coal combustion is a major source of particulate matter, which is a complex mixture of tiny particles that can cause respiratory and cardiovascular problems when inhaled. It is estimated that particulate matter from coal-fired power plants is responsible for millions of premature deaths per year (5). In contrast, natural gas-fired power plants emit far lower levels of particulate matter (about two-thirds less) than coal, making gas a much safer option for the environment and human health.

There are, of course, some environmental concerns associated with the extraction and production of natural gas. Methane leaks, for instance, are a significant concern as they can contribute to greenhouse gas emissions and negatively impact air quality. However, these issues are being addressed proactively through new regulations and industry best practices.

References:

National Renewable Energy Laboratory. (2012). Life Cycle Greenhouse Gas Perspective on Exporting Liquefied Natural Gas from the United States. https://www.nrel.gov/docs/fy12osti/53510.pdf

U.S. Environmental Protection Agency. (2021). Sulfur Dioxide (SO2) Pollution. https://www.epa.gov/so2-pollution

U.S. Environmental Protection Agency. (2021). Nitrogen Oxides (NOx) Pollution. https://www.epa.gov/nox-pollution

U.S. Environmental Protection Agency. (2021). Mercury and Air Toxics Standards (MATS). https://www.epa.gov/mats

Global Burden of Disease Study. (2020). Air Pollution. Institute for Health Metrics and Evaluation. http://www.healthdata.org/air-pollution