The ethylene cracker facility that Shell Chemical wants to build in Beaver County to process "wet gases" from the Marcellus and Utica shales has the potential to add significant emissions to the area's industrial air pollutants.
As a result, according to the U.S. Environmental Protection Agency, such an industrial facility would need to utilize "best available control technologies" to meet strict air emissions regulations and offset any emissions increases with equal or greater reductions from other facilities.
The EPA said petrochemical facilities that use heat and pressure to "crack" wet gases -- such as ethane, propane and butane to produce ethylene, propylene and other shorter chain hydrocarbons used to make plastics -- also can emit a wide range of air pollutants.
Those emissions -- nitrogen oxides, sulfur dioxides, carbon monoxide, volatile organic compounds, fine particulates and greenhouse gases -- are produced mainly from burning fuels to heat furnaces where wet gases are cooked under pressure to produce basic building blocks for a variety of petrochemical-based products.
"Such a plant is going to have nitrogen oxide and VOC emissions that play into ozone creation and airborne particulates that add to what is already in the area," said Jeff Robinson, section chief for air permits at EPA's Region 6 office in Dallas, who has extensive experience reviewing cracker facilities (27 of the country's 44 crackers are in Texas). "Regulators will have to assess the air impacts from the facility when Shell sends a construction permit application to the state."
Shell announced on March 15 that it had signed an agreement with Horsehead Corp. to purchase the zinc smelter's 300-acre property along the Ohio River in Potter Township near Monaca, 28 miles from Pittsburgh, for a petrochemical complex that will include a cracker and polyethylene and monoethylene units. The Ohio River there is already lined with multiple smokestack industries and the largest electric power plant in the state, FirstEnergy's Bruce Mansfield coal-burning power plant in Shippingport.
It will take two years for construction of the cracker to begin and another four years and more than $3 billion to build. The facility, which would likely include multiple furnaces, would be the first cracker in the Appalachian region, where production of gas from the Marcellus and Utica shales has boomed in recent years.
Mr. Robinson said state regulators and EPA's Region 3 oversight personnel will likely need to consult with other states where crackers operate for regulatory guidance.
"When Shell builds this, it will trigger a review to determine what the best available control technologies are, and Pennsylvania will have to look to other states to determine what those should be for that facility," Mr. Robinson said. "The cracker in Pennsylvania will be built in line with what is built in Texas and Louisiana."
Almost all of the cracker facilities operating in the U.S. are located in the south, built there beginning in the late 1960s and early 1970s to be close to Texas oil and gas fields and off-shore drilling in the Gulf of Mexico. Most are located near or adjacent to refineries, and are owned by big, familiar corporations such as Chevron, Dow Chemical, DuPont, Eastman Chemical and ExxonMobil.
"The big oil and gas companies had to figure out something to do with refinery byproducts years ago, so they co-located them near their refineries and near the gulf," said James Cooper, vice president for petrochemicals at American Fuel & Petrochemical Manufacturers, an industry trade group.
According to information provided by the trade group, Texas has 27 cracker plants and Louisiana is home to 13. Iowa, Illinois, Kentucky and Delaware each have one facility. The last one was built in 2000 and most can use either petroleum byproducts or natural gas.
Mr. Cooper said each cracker facility is different but all are "tightly engineered and custom designed" not to leak ethane or ethylene.
"You're not getting many emissions from a petrochemical plant's feedstock [raw materials]," Mr. Cooper said. "That would be expensive because when they're leaking they're losing money."
But valve, flange and pipe leaks occur in a process that heats gases under high pressure. Storage tanks can also vent VOCs and other greenhouse gases into the atmosphere, and flaring of gases is a regular occurrence as cracker furnaces are shut down every 50 days or so for cleaning and maintenance.
"Federal Clean Air Act rules require that an assessment of the impact of a major source facility, like a cracker plant, be done," said Mr. Robinson, "and a determination made about whether it will cause or contribute to an area becoming a non-attainment area."
If an area is classified in "non-attainment" of National Ambient Air Quality Standards for any of six primary air pollutants -- nitrogen oxides, sulfur dioxide, fine particulate matter, ozone, lead, carbon monoxide -- a new emissions source, like Shell's cracker plant, would be required to offset its emissions through emissions reductions from other sources in the area, Mr. Robinson said.
According to the state Department of Environmental Protection Bureau of Air Quality website, Beaver County is in non-attainment of the federal standards for ozone and airborne fine particulates and (in the lower Beaver Valley) lead.
The DEP would respond only generally to a series of questions about whether it was consulted about potential air quality impacts from a cracker plant operation in the Monaca area, what the expected air and water environmental discharges might be, and how cracker plant emissions might require offsets or necessitate changes in Pennsylvania's federally mandated emissions plan.
"The plant will be state-of-the-art and built by a world-wide, world-class, environmentally responsible company," Michael Krancer, DEP secretary, said in a statement released by the department. "It will go through the necessary environmental permitting process to ensure compliance with all applicable standards."
Shell didn't answer questions about specific environmental issues or violations at its cracker facilities, but Kayla Macke, a company spokeswoman, issued a statement saying facilities are operated in compliance with permits and environmental and health regulations.
The Beaver County site will be Shell's fifth domestic cracker plant; the others are in Deer Park, Texas, and Norco, La. It has seven others around the world.