Before natural gas can be routed through the pipelines that fuel power plants, homes, and businesses, it must be processed at a gas processing plant to remove contaminants or to separate ethane and other raw materials used to make chemicals or plastics. According to data available for the first time this year through the Environmental Protection Agency’s Toxics Release Inventory (TRI), 258 gas processing plants reported releasing a combined total of 3.2 million pounds of toxic air pollutants in 2022. These emissions include 633,600 pounds of formaldehyde and 247,300 pounds of benzene, both well-known carcinogens.  

Gas processors are now required to disclose their annual releases of specific toxic chemicals to the TRI, thanks to a rule the EPA adopted in response to a petition the Environmental Integrity Project filed on behalf of a number of environmental groups. To access TRI data, click here.  

Gas processing plants remove hydrocarbons like propane or butane, as well as sulfur and other contaminants from the gas burned to generate heat or electricity for households, businesses, and industrial consumers. Many of these facilities may also separate ethane from gas because ethane provides the raw material used to manufacture plastics and fertilizers. Although the amount and type of pollutant released may vary from one plant to the next, the industry’s TRI reports identify emissions of 21 different chemicals, including benzene, formaldehyde, hydrogen sulfide, n-hexane, toluene, xylene, and methanol.  

Many of the plants that reported the most toxic air emissions  were located in West Texas, including the Targa Resources Midkiff Gas Plant in Reagan County, southeast of Odessa, which released 54,000 pounds of formaldehyde, the most of any gas processing plant; and the Targa Resources Buffalo Gas Plant in nearby Martin, Texas, which reported releasing 27,000 pounds of benzene. (For a listing of the top 10 benzene and formaldehyde polluters, see tables below.) These plants are located in the heart of the Permian Basin, which is the largest oil and gas-producing geologic area in the US.

The new numbers released by EPA underestimate the scale of air pollution from these plants, because less than 42 percent of the 620 gas processing plants currently operating in the U.S. today actually reported their toxic emissions to EPA last year. Some plants may not have reported yet, or may not be required to report because their pollution levels are too low or because they have fewer than 10 employees (see EPA’s criteria at this link).  

Preliminary research also suggests that some gas processors may have under-reported to the TRI. For example, in Colorado, only 19 gas plants reported a total of 113,040 pounds of emissions of eight different pollutants to the TRI. However, state records show that 47 gas plants in Colorado reported 642,242 pounds of emissions of the same pollutants to the state emission inventory. State emissions inventory data for earlier years (2020 or 2021) from other states suggests a similar discrepancy between state and federal data.  

While some states require gas processors to disclose emissions of certain toxic chemicals to an emissions inventory, that data is sometimes difficult for the public to obtain and may not be available for several years after the emissions are reported and may not require reporting of all toxic pollutants.  In contrast, disclosures of toxic chemical releases made to the TRI are easy to access and include the type and amount of chemicals dumped in landfills or discharged to waterways in addition to emissions to the atmosphere.

The majority of gas processing plants are located near natural gas drilling areas in 15 states: Texas, Louisiana, Oklahoma, Colorado, Kansas, Wyoming, New Mexico, North Dakota, California, Pennsylvania, West Virginia, Utah, Alabama, Ohio, and Montana.  

Of these states, Texas houses the most of these plants and accounts for about a quarter of the United States’ natural gas production.

Over the past decade, the U.S. has increasingly relied on natural gas to generate electricity, accounting for about 40 percent of total electricity generated domestically by all sectors in 2022, up from about 30 percent in 2012. The industrial sector accounted for about 32 percent of total U.S. natural gas consumption, up 21 percent since 2012. The residential sector accounted for about 15 percent of total U.S. natural gas consumption, with about 60 percent of U.S. homes using natural gas for heating, cooking, and drying clothes.

The U.S. has become an exporter of more natural gas than it has consumed since 2017, exporting 6.9 trillion cubic feet in 2022, the highest ever recorded, according to the U.S. Energy Information Administration. The U.S. last year became the world’s largest exporter of natural gas. The number of U.S. terminals exporting liquified natural gas (LNG) has increased rapidly, with 31 projects currently proposed or under construction.

This gas export boom is tied to an increase in the number and production of gas processing plants. The overall production output from U.S. gas processing plants grew 40 percent between 2012 and 2021, rising from 17.5 trillion cubic feet in 2012 to 24.7 trillion cubic feet in 2021, according to the U.S. Energy Information Administration.  

The number of gas processing plants could grow over the next few years, according to public records compiled by Oil & Gas Watch. At least four more projects to build or expand gas processing plants are currently under construction, and 24 more are in planning stages across the U.S.  

Benzene and formaldehyde pollution reports submitted to EPA’s Toxics Release Inventory last year indicate that a small number of gas processing plants are responsible for relatively large volumes of emissions. Of the 258 gas processing plants that reported to the TRI, 185 reported emitting benzene. . Both the Buffalo Gas Plant in Martin County, Texas (the No. 1 largest source of this pollutant among gas plants), and the Black River Processing Plant in Eddy County, New Mexico (the No. 2 source), reported emitting at least 19,000 pounds of the chemical, more than double the amount emitted by the third-highest-emitting plant, Tippett Gas Plant in Crockett County, Texas.   

Notably, only 46 plants reported emitting formaldehyde. But both the Midkiff and Ramsey Gas Plants in Texas (the number one and two top emitters of formaldehyde) each reported releasing at least 50,000 pounds of formaldehyde, which was 30 percent more than the third-highest-emitting plant, Block 31 Plant in Crane County, Texas.

On July 25, EPA announced another proposed rulemaking to make changes to its air emissions reporting requirements. If finalized, this rule will require more robust reporting of hazardous air pollutants to EPA’s National Emissions Inventory, including from gas processors, and fill key gaps in current reporting to the TRI and state inventories. EPA is accepting written public comments on this rule until October 18, 2023.

Lead photo: A gas processing plant in Carroll County, Ohio. Photo by Ted Auch, FracTracker Alliance, 2021.