No, Natural Gas Power Plants Are Not Clean

, Energy analyst | November 9, 2018, 2:14 pm EDT
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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 ozoneParticulate 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.

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  • ckahrl

    Time to face facts: you cannot move from natural gas without nuclear. Every solar installation must have a natural gas sister, or it won’t work all day long.

    • HumanBeing

      Ever heard of energy storage?
      Besides battery storage, there’s hydro, compressed air, pin wheel and many more… No need for dirty energy to back clean renewable energy!

      • ckahrl

        Yes, I have heard of energy storage—and only one works. Air compression does not work because of heat loss. (There is a Canadian company claiming that their’s works because they store the heat of compression, but they have yet to build a prototype). Battery storage is pie-in-the-sky expensive. People say that batteries will improve, but in 1970 they said fusion was 20 years away and now it is 30 years away. I am not sure what you mean by the pin-wheel, but there are no large scale prototypes of anything by that name. There are suggestions that we can put big trains on the sides of mountains and haul them up and down, but there are no large demonstrations of that probably because there are large problems with the idea. I knew of some people who put millions into magnetically levitated flywheels and they couldn’t get that to work. (I don’t know why, it seems logical that it would work). So far the only thing that works is pumped hydro. The problem with that is you need mountain passes, two big lakes and lots of water. Some have proposed using Hoover dam for pumped hydro, but the problem is that there is so little water in the Colorado basin that they can’t afford the water loss of pumped hydro and they are also about ready to shut down the Glen Canyon dam because of water loss. One might suggest that all hydropower be reserved for load leveling, but the contracts that allocate the electricity for those dams prohibits it. PS—all other hydro is basically precluded by the fact that we have already dammed up every river in the US, leaving none remaining, while devastating huge ecosystems doing it.