But any short-term good could have long-term costs.

Shell says much of the plastic from the plant can be used to create fuel-efficient cars and medical devices. But the industry acknowledges that some of the world’s waste management systems are unable to keep up with other forms of plastic like water bottles, grocery bags and food containers being discarded by consumers on the move.

Studies have detected plastic fibers everywhere — in the stomachs of sperm whales, in tap water and in table salt. A researcher in Britain says plastic may help define the most recent layer of the earth’s crust because it takes so long to break down and there is so much of it.

“Plastic really doesn’t go away,” said Roland Geyer, a professor of industrial ecology at the University of California, Santa Barbara. “It just accumulates and ends up in the wrong places. And we just don’t know the long-term implications of having all this plastic everywhere in the natural environment. It is like this giant global experiment and we can’t just pull the plug if it goes wrong.”

‘Part of a journey’

The roots of Shell’s sleek, ultramodern plant date back hundreds of millions of years, when the area was occupied by a wide inland sea.

Over time, the earth shifted and the sea was covered by rock, which compressed all of the dead organisms and sediment that had settled on its watery bottom into rich layers of hydrocarbons, including those that make up natural gas.

Ms. Mercer has spent 32 years traveling the world for Shell — in southern Iraq and in eastern Russia — helping turn those hydrocarbons deep within the earth into energy. These days, Ms. Mercer, an English-born, Oxford-educated engineer, works out of a red brick building in Beaver, Pa.