Cracker's Emissions Could Rank High in Region

by Reid Frazier

March 24, 2012

What kinds of air pollution could the ethane cracker announced by Shell this month create? What impact would it have on the region's already poor air quality? We took a look at the numbers and found the cracker may have a large footprint in one important aspect of air quality.

The cracker coming to Western Pennsylvania would no doubt add to the local economy. Anywhere from 500 to 1,000 permanent jobs are created at ethylene crackers, plus thousands of other potential jobs that would result from associated businesses that cluster around them.But what of its environmental impact? Would it become a significant source of pollution? And how would it impact Western Pennsylvania's already poor air quality? Shell has kept specifics of the plant close to the vest. And the company declined a request to talk about the plant's potential environmental impact.

But similar plants around the country are significant sources of emissions like Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOCs). Both are precursors to ozone, or smog, a pollutant that already exceeds federal limits in the Pittsburgh region. Ozone can aggravate asthma and increase susceptibility to repiratory illnesses like pneumonia and bronchitis, according to the EPA. The Pittsburgh region is a 'non-attainment' area for ozone, so any new sources of its components will be watched closely by regulators and environmental groups.

Most of the emissions from ethane crackers come from the process of "steam" cracking ethane, a hydrocarbon found in "wet" natural gas like the Marcellus shale, says Goetz Veser, a professor of chemical engineering at Pitt. During this process, ethane is heated to very high temperatures--around 1500 degrees Fahrenheit. The furnaces used to create this type of heat usually run on natural gas, said Veser.

On outlining its plans for the Monaca plant, Shell has referenced a cracker in Norco, La. In addition to ethylene, that plant produces propylene and butadiene, two other important petrochemcials used in the creation of plastics.

If it were located in Pennsyvlania, the Norco facility would be the highest emitter of VOCs in Southwest Pennsyvlania, more than doubling the amount at the next highest source, a coal preparation plant in Greene County run by Consol Energy, according to emissions data from the EPA's 2008 National Emissions Inventory. It would also be among the top 10 plants in southwestern Pennsylvania by NOx emissions, with a 2008 total of 3,791 tons.

The US Steel Clairton Coke Works, the largest NOx emitter in Allegheny County, produced 4,195 tons of NOx that year. It's unclear whether the Monaca site would emit a similar amount of pollution, Veser says. Though the process would likely be similar at the two plants, the Beaver County facility will be required to use the newest, most efficient technology available, likely resulting in lower emissions.

Another Shell "world-scale" cracker opened in Singapore in 2009 produces 2000 metric tons, or 2200 tons, of NOx, according to an impact statement prepared by Shell. This would also qualify as a "top 10" emitter in southwestern Pennsylvania. If and when Shell does produce a plan for the plant, the company may need to supply regulators with air pollution models that can show how its emissions will be dispersed, says Joe Osborne, of the Group Against Smog and Pollution.

Since the Pittsburgh region is already failing federal ozone standards, Shell may need to buy emissions. It could buy these offsets from other companies either shutting down facilities or implementing pollution control measures, says Bonnie Smith, an EPA spokeswoman.

The cracker itself is likely to be only part of the impact--both environmental and economic--expected to take place in and around the proposed Monaca facility. Other plastics and petrochemical facilities are likely to sprout around any cracking plant. That's because ethylene is a gas, making transport difficult. Plants that can use ethylene to create plastics tend to aggregate around cracker plants, says Martha Moore of the American Chemistry Council, an industry group. These facilities can convert ethylene into products that are more easily shipped, like polyethylene pellets, which go into commonly used plastics like freezer bags, milk jugs, and textiles.

Shell said the cracker would be "world scale," which means it would produce more than a million tons of ethylene per year. The company says it's still determining how much ethane would be available, and once it decides that it would determine the size of the complex.

There are 44 crackers in the United States, most concentrated around the Gulf of Mexico, says Jeff Robinson, chief of air permits for EPA's Region 6, which covers Texas and Louisiana. After a decade without a new ethane cracker built in the US, there are about 20 that have been proposed in recent years to take advantage of abundant ethane sources found in shale gas. The ethane comes out of the ground during hydraulic fracturing, or fracking, for natural gas. The process has opened up new areas for drilling in Pennsylvania's Marcellus shale.

Shell recently bought about 700,000 acres of gas leases in the Marcellus, and earlier in March announced plans to build a $1 billion ethane cracker in Monaca. The bottom line, Veser says, is that Shell's cracker will bring jobs, but it will also put pressure on air quality in the region. "Is an ethane cracker going to create emissions? Absolutely," says Veser, who has consulted with Athier, another company looking to build a cracker in the region. "Does it mean we should resist it? I don't think so, unless you stop using the products from that industry--and you can't."