Expansions of oil and gas activity and infrastructure in the Gulf Coast and Southwest regions of the United States could contribute annual greenhouse gas (GHG) emissions of 541 million tons (mmt) of CO2 equivalent (CO2e) by 2030, according to a new study published by the University of Texas at Austin (UT).

This amount is equal to more than 8% of total U.S. GHG emissions in 2017 and roughly equivalent to the emissions of 131 coal-fired power plants, according to the analysis, which was funded by the Cynthia and George Mitchell Foundation.

The study compiles “projected upstream oil and gas production expansions as well as recently and soon-to-be-built midstream and downstream facilities within the region.”

Petrochemical facilities account for the largest fraction of projected emissions at 38%, followed by liquefied natural gas (LNG) terminals at 19%, the study found. Natural gas and oil production come in third and fourth place, respectively, at 18% and 13%.

“Researchers have largely focused on upstream emissions such as fugitive methane associated with new U.S. production; our findings reveal the potentially greater prominence of midstream and downstream sources in the studied region,” researchers said.

The report found that the vast majority of emissions will come from Texas and Louisiana, in line with similar research published this month by the Environmental Integrity Project (EIP). The EIP study found that the ongoing industrial buildout associated with a surge in Lower 48 oil and gas production could release up to 227 mmt/y of additional GHG emissions by end-2025.

“Although the EIP report’s findings are based on permitted emissions, UT researchers accounted for future permitted and non-permitted emissions through 2030,” the UT report’s authors said.

The 541 mmt figure comprises permitted (399.2 mmt), under-construction (75.5 mmt), recently completed (42.2 mmt) and non-permitted (24.2 mmt) emissions.

The upstream, midstream and downstream segments are expected to account for 31.3%, 22.4% and 46.3% of the total, respectively.

“We wanted to understand if the industrial buildout we were reading about was a greenhouse gas mountain or a molehill,” said UT Austin’s Andrew Waxman, assistant professor of economics and public policy at the LBJ School of Public Affairs, and a co-author of the study.

He added, “Emissions from oil and gas production are well known, but our analysis finds over two-thirds of future emissions will come from midstream and downstream sources, including petrochemicals, liquefied natural gas export facilities and refineries. These sources are a pretty big mountain that policymakers and climate modelers don’t seem to be currently accounting for.”

The UT and EIP reports come as industry groups such as the American Petroleum Institute, the U.S. Chamber of Commerce, and the Interstate Natural Gas Association of America are seeking to extol the environmental and economic virtues of natural gas over dirtier fossil fuels such as coal.

George Mitchell, who died in 2013, founded Mitchell Energy and Development Corp., and is often referred to as the father of hydraulic fracturing.