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Shell is moving forward with plans to build an ethane cracker facility near Pittsburgh. But what the heck is an ethane cracker? And what are the potential risks? The Allegheny Front’s energy reporter Reid Frazier did some digging and has everything you ever wanted to know about a kind of petrochemical facility you’ve probably never heard of.

What exactly is an ethane cracker?

An ethane cracker takes ethane, a component of natural gas found in abundance in the Marcellus shale, and processes it—or ‘cracks’ it—into ethylene. It does this by heating the ethane up so hot that it breaks apart the molecular bonds holding it together. Crackers often feed other nearby plants that create more refined products further “downstream.” Crackers are generally very large industrial plants.

Because the price of natural gas is low, companies have announced plans to build new cracker facilities in the U.S. A typical “world-scale” ethane cracker costs in the neighborhood of $5 billion to build and creates about 10,000 jobs during construction. But since plant operations are heavily automated, they only create between 350 and 1,200 permanent jobs.

The vast majority of these facilities are located on the Gulf Coast. If Royal Dutch Shell builds an ethane cracker in Beaver County, it would be the first ethane cracker of this size to be located in the Marcellus shale region. The state has promised more than $1 billion in tax breaks over 25 years to the project, which Shell said could provide up to 10,000 jobs at the height of construction.

What is ethylene and what is it used for?

Ethylene is the most commonly produced petrochemical. It is the root chemical for a kingdom of plastics, resins, adhesives and synthetic products used in virtually every aspect of modern life. It’s used as the basis for plastics like beverage containers, food wrap, polyvinyl chloride (PVC), polyester, and chemicals like those found in antifreeze, solvents, urethanes and pharmaceuticals.

What pollutants are associated with ethane cracker facilities?

These are large industrial operations that handle potentially harmful chemicals. Air pollution from a cracker can include nitrogen oxides, sulfur dioxide and particulate matter—all of which are regulated by the Clean Air Act.

Ethane crackers have the potential to emit large amounts of ethylene, propylene and other so-called ‘highly reactive volatile organic compounds.’ These are chemical compounds that can react quickly in sunlight to form ground-level ozone, or smog.

Fugitive emissions or leaks can occur as a result of incomplete combustion during flaring, as well as from leaks in cooling towers, storage tanks and any of the over 100,000 valves and flanges found in a typical cracker. Large releases can also occur during plant upsets, when a unit must be shut down because of a mechanical problem, power outage or some other unplanned event. In some cases, these flaring events can release hazardous air pollutants like benzene, a known carcinogen.

What are VOCs?

VOCs, or volatile organic compounds, are highly reactive chemical compounds released from industrial processes, consumer solvents and motor vehicles. In the presence of sunlight, VOCs react with oxygen and nitrogen compounds like nitrogen oxides (commonly created by combustion of fossil fuels) to create ground-level ozone, or smog. Exposure to VOCs and ozone has been associated with increased rates of asthma, lung and respiratory infections, and cardiovascular problems.

What is benzene?

Benzene is a building block in the production of petrochemicals. A highly flammable substance made of six hydrogen molecules and six carbon molecules, benzene has been recognized as a human carcinogen. Exposure to benzene may occur through inhalation near industrial facilities—like petrochemicals plants—that use it in their processing. Since it is also a major component of gasoline, inhalation of benzene is possible at gas stations, as well from cigarette smoking. Some immediate signs of high blood levels of benzene include drowsiness, dizziness and confusion. Aside from cancer, long-term exposure to benzene may result in irregular menstruation in women, anemia and immunosuppression.