You may have heard that natural gas is “clean.” Compared to coal, natural gas produces less global warming emissions and air pollution. But coal is just about the dirtiest way to produce electricity, so almost anything will seem cleaner in comparison. The fact of the matter is that natural gas power plants still produce a significant amount of air pollution, and that’s a problem.
NOx is not your friend
The main pollutants resulting from natural gas electricity generation are nitrogen oxides, or NOx. Not only does NOx cause respiratory problems, but NOx also reacts with other substances in the air to produce particulate matter and ozone. Particulate matter and ozone cause the extensive list of adverse health outcomes you hear at the end of a prescription drug commercial – shortness of breath, heart attacks, premature death; the list goes on. In short, NOx is bad news for human health.
Natural gas power plants have an impact on air quality
At this point you might be wondering, “So how bad is it? How much NOx is coming from natural gas power plants?” That is where things get complicated. According to projections from the California Air Resources Board, stationary sources account for roughly 21% of NOx emissions, while mobile sources account for a whopping 74% of NOx emission in the state. However, emissions from natural gas power plants are only a fraction of the emissions from stationary sources, so NOx emissions from natural gas power plants end up being roughly 1% of total NOx emissions in California.
Displays “grown and controlled” oxide of nitrogen projected emissions for 2019, excluding emissions from ocean-going vessels further than three nautical miles from the coast. Data from California Air Resources Board Emissions Projection Analysis.
Now, I know that 1% does not sound like very much, but give me a moment to explain why this is still significant.
First, natural gas power plants do not move – they just sit there and emit NOx when they are operating. Those NOx emissions may linger in nearby communities, leading to serious health problems for the people living near plants. And since half of California’s natural gas power plants are concentrated in some of the most socioeconomically and environmentally disadvantaged communities in the state, these emissions harm communities that are already overburdened with pollution.
Second, just because the electric sector is cleaner than the transportation sector does not mean the electric sector is not dirty. Some of the highest-polluting natural gas power plants emit over 100 tons of NOx per year, which is roughly equivalent to the NOx emissions from traveling 11 million miles (assuming an emissions rate of 8.18 grams of NOx per mile) in a diesel school bus, one of the most-polluting types of vehicles. Furthermore, when studying a proposed natural gas power plant, a California Energy Commission analysis found that local one-hour concentrations of NO2 (one form of NOx) would nearly double from their background levels. These emissions really can affect local air quality, and that is why this is a problem.
The air pollution problem may get worse
The final reason to be concerned about pollution from natural gas power plants is that it may get worse in the coming years. A recent study by the Union of Concerned Scientists found that natural gas power plants in California will start and stop much more frequently in the future, and this increase in natural gas plant start-ups may increase NOx emissions. Natural gas power plants emit more NOx when they are starting up; on average, they emit anywhere between three and seven times as much NOx during start-up than during one hour of full-load operation. As paradoxical as it may sound, California may continue to achieve its global warming emissions reduction goals and increase air pollution from natural gas power plants at the same time.
Let’s make sure that does not happen. Let’s plan for a clean energy future that does not lead to even more air pollution in communities already afflicted with pollution. Let’s make sure we bring everyone along in the transition to clean electricity. UCS recently co-sponsored a bill in the California legislature that was designed to shed light on pollution from natural gas power plants and require better planning for pollution reductions from plants. Though UCS’s legislative effort did not succeed this year, UCS is committed to finding solutions that allow us to transition away from natural gas in a way that is not only economical, but also equitable.