America has a surplus of cheap natural gas thanks to the nation's shale drilling boom, an environment that has prompted companies to spend billions of dollars to upgrade or expand dozens of facilities. While the build-up may be a good thing for the Louisiana economy, it could have a detrimental effect on efforts to curb air pollution, according to a report released Wednesday (Dec. 10) by the Environmental Integrity Project.

According to the report, a total of 46 new or expanded petrochemical facilities nationwide have received final or draft permits to build this year. Collectively, the report estimates those facilities will produce up to 55 million additional tons of greenhouse gases each year.

That is the pollution equivalent of 12 new, 500-megawatt coal-fired power plants operating at full capacity, the report says.

"The shale gas boom has helped revive U.S. manufacturing, but we need a full and honest accounting of its environmental footprint," said Eric Schaeffer, executive director of the Environmental Integrity Project and the report's author. "That accounting should include greenhouse gases from petrochemical industries that are taking advantage of lower fuel and feedstock costs."

The Environmental Integrity Project reviewed Clean Air Act permitting documents filed with the Environmental Protection Agency and state regulators for its analysis.

The U.S. has seen a wave of industrial projects in recent years, particularly in Louisiana and Texas. Projects include new shale gas compressor plants, chemical and fertilizer manufacturing facility expansions, and oil and gas processing plants.

According to the report, companies have received 105 draft or final air permits for new projects in the past three years. Thirty-three of those projects are planned for Louisiana, which was second only to Texas at 49.

Altogether, the nation's newest industrial facilities will release more than 130 million tons of greenhouse gases annually.

Greenhouse gases are the gases that trap heat in the Earth's atmosphere, including carbon dioxide, methane, nitrous oxide and ozone. Scientists have found rising carbon dioxide levels, fed in part by industrial activity, have accelerated climate change.

The report says economic growth and emissions reduction do not have to be mutually exclusive.

It concludes industry can curb emissions amid the boom by operating more efficiently and by stopping leaks from pipes and values.

Other highlights from the report include:

• Companies have applied for or received permits for 57 new oil and gas and chemical projects nationwide. Permits indicate the projects will collectively emit more than 71 million tons per year in greenhouse gases.

• The chemical industry has seen the sharpest growth in new projects, with 22 major projects approved or proposed in 2014, including plants that produce petroleum or use petroleum ingredients to make plastics and other products. Proposed chemical projects are expected to release 27 million additional tons of greenhouse gases each year.

• Eight new fertilizer projects, including the ongoing $2.7 billion expansion of the CF Industries nitrogen complex in Ascension Parish, will emit almost 3 million tons of greenhouse gases.

• Four new liquefied natural gas, or LNG, plants along the Gulf Coast will produce 11.6 million tons of greenhouse gases. LNG plants super-cool methane to its liquid form for transportation and export.