Natural gas advocates are facing fresh criticism about the fuel's climate footprint, even as gas-fired power plants snag market share from coal units that emit vastly more carbon.
Gas critics have argued in recent years that leaks of methane — a potent greenhouse gas — from production wells risk substantially offsetting the carbon advantage gas holds over coal.
And now a new study is raising a separate set of questions about the climate footprint of the U.S. natural-gas production boom.
The Environmental Integrity Project (EIP) report looks at greenhouse-gas emissions from big infrastructure and industrial projects that are cropping up alongside surging U.S. gas production.
"The shale gas boom has unleashed a tidal wave of proposals to build new compressors and pipelines, and expand chemical, fertilizer, and petroleum plants that depend on natural gas for feedstock or fuel," the report states.
"Since January 1, 2012, these industries have proposed or already obtained Clean Air Act permits that authorize a 91 million ton increase in greenhouse gas emissions — as much as the output from twenty large (500 megawatt) coal-fired power plants," adds the study titled "Gas Rush: Increasing Greenhouse Gas Emissions from New Oil, Gas and Chemical Plants."
To be sure, EIP isn't claiming that these emissions negate the advantage of gas-fired power plants that emit roughly half as much carbon dioxide as coal-fired plants.
Indeed EIP predicts the emissions from the various planned gas-related infrastructure projects they surveyed, such as liquefied-natural-gas terminals and chemical plants that use natural gas, would be the equivalent of 10 gigawatts of coal-fired power generation.
That's a lot fewer coal gigawatts than analysts predict will be retired in coming years — due in part to competition from low-cost gas and in part to Obama administration air-pollution rules.
A late 2012 report by the Brattle Group forecasts that 59 to 77 gigawatts of coal-plant capacity will be mothballed over the next five years, while a recent Reuters analysis is less aggressive, predicting about 46 gigawatts of retirements over 10 years.
And the growth of natural-gas-fired electricity plants at coal's expense has helped cut U.S. energy-related carbon emissions to their lowest level since 1994, according to the federal Energy Information Administration.
But the EIP report notes that the build-out of other gas-related or gas-enabled infrastructure means these power-sector climate advantages will be "partially offset by higher emissions from other industries cashing in on cheap and abundant supplies of oil and gas from shale deposits."
EIP Director Eric Schaeffer said the report shows the need for expanded greenhouse-gas regulations beyond the power-plant standards the Environmental Protection Agency is crafting.
"The Obama administration approaches its sixth year without having even proposed greenhouse-gas standards for the natural gas, chemical, or refining sectors, although a review of permits indicates that emissions are escalating rapidly from all three industries. Time is running out for action," he said in a statement.
An oil-and-gas-industry spokesman defended the U.S. natural-gas boom.
"The facts are the facts. The United States is leading the world in reduced emissions while at the same time it is the No. 1 producer of natural gas in the world. It is creating jobs and billions of dollars revenue for the government at the time that it needs it the most," said American Petroleum Institute spokesman Eric Wohlschlegel.
Gas advocates have also fiercely pushed back against the criticisms over methane, and they have an ally in Energy Secretary Ernest Moniz, who has said repeatedly that methane emissions won't negate the fuel's carbon advantages.
But the new EIP report shows that as the U.S. natural-gas boom continues, the industry's role in climate policy will remain contested terrain.