Petrochemical giant BP is considering some big-ticket but secretive improvements for its Berkeley County manufacturing site, saying only that the proposed upgrades are tied to the plant’s energy system.

The British-owned company is in talks with local economic development officials about tax breaks and other incentives in the event the investments are approved.

The 35-year-old chemical plant is on a mostly undeveloped 6,000-acre tract of forestland between the Cooper River and Cainhoy Road, just below the Nucor Berkeley steelmaking site.

BP spokesman Scott Dean said the company is not ready to release details about the project. He described “the nature of the prospective investment” as “proprietary” and “highly competitive.”

“BP Cooper River Chemicals is assessing the potential for making significant capital investments that would help improve the plant’s energy-efficiency in support of the longer term future of the business,’ Dean said in a written statement.

He added: “If and when a decision is finalized and steps taken to move forward, we would be able to comment in greater detail.”

The Cooper River plant makes a white powdery substance called purified terephthalic acid, or PTA, which is used to manufacture polyester, plastic bottles, tires and other products.

According to a publication posted on BP’s website, the South Carolina site had 200 employees in 2012 and was churning out about 2.8 billion pounds of the commodity chemical each year.

The plant was opened in 1978 by Amoco, which was purchased by British Petroleum in early 1999. The last major expansion was completed in 1997, when a $300 million manufacturing unit came online.

Reach John McDermott at 937-5572.