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Clearing the air on Invenergy power plant emissions

With Chicago firm Invenergy’s proposed 1,500-megawatt natural gas-fired power plant looming over Jessup, both sides have made strong claims about the plant’s air emissions.

Invenergy’s representatives and air-quality permit application say the plant will only nudge the region’s air pollution levels imperceptibly higher. The company’s recent advertisements claim the plant will even result in “healthier, cleaner air” by replacing coal-fired plants elsewhere.

Opponents, including the community group Citizens for a Healthy Jessup, seized on projected emissions numbers for nitrogen oxides, carbon monoxide, sulfur dioxide, coarse and fine particles and volatile organic compounds to suggest the plant could harm residents’ health.

Interviews with atmospheric scientists and the region’s power grid operator indicate neither side is offering the complete set of facts.

Of most immediate concern to Midvalley residents are the effects of the plant’s air emissions on local health.

In advertisements in The Times-Tribune, Invenergy presented four bar graphs showing the proportion of existing nitrogen dioxide, carbon monoxide, and fine and coarse air particles in local air, compared to a tiny sliver of additional impact from the plant’s emissions.

Those air emissions will not push the region over clean air standards set by the U.S. Environmental Protection Agency, Invenergy claims in the ad and in its permit application with the state Department of Environmental Protection.

Those claims are most likely true. Lackawanna County attains the EPA’s National Ambient Air Quality Standards, meant to protect public health on a regional level. To gain DEP approval, Invenergy must prove its operations will not push regional air pollution over the edge.

Because all of Pennsylvania lies within an “Ozone Transport Region” stretching from Maryland to Maine, Invenergy must also pass another EPA test to prove it will not cause a significant decline in air quality beyond existing conditions. Several other EPA standards will also apply.

Highway poses greater risks

The standards the EPA uses to safeguard regional air quality, along with separate standards used to protect an individual’s health, are not perfect. They may not protect someone living downwind from such a plant from unknown effects of decades of exposure, said Reto Gieré, Ph.D., a University of Pennsylvania Earth & Environmental Science department chairman who studies health impacts of atmospheric pollution.

“If you live in the plume for 20 years, nobody knows what these guideline values are. They are just made up,” he said. “You can’t make experiments that long. These guideline values or restrictions are basically best judgements but they’re not based on experiments or anything.”

However, other sources of local air pollution could carry greater risks, he said. A busy highway is a potent example, as diesel fumes contain known carcinogens, he said.

“I would consider that much more serious a problem than emissions from such a gas-fired power plant,” he said.

In general, new natural gas plants represent the cleanest of existing fossil fuel generation, said Carnegie Mellon University professor and air quality modeling expert Peter Adams, Ph.D.

“Those things are pretty damn clean,” he said. “In the grand scheme of things, maybe nobody wants it next to them, but a brand new natural gas plant is sort of top of the line.”

For electricity generation, natural gas produces half as much carbon dioxide as coal, less than a third of coal’s nitrogen oxides and 1 percent its sulfur oxides, according to the EPA.

“The gas is a cleaner fuel, so obviously it … emits pollution, but by no comparison to what a coal-fired power plant would emit,” Dr. Gieré said.

In related news, Invenergy received wetlands violation for contractor work.

Healthier air?

Invenergy frequently has touted the comparison to coal and claimed the plant will improve the region’s air quality.

“A Jessup power plant will result in healthier, cleaner air locally by replacing generation from old, polluting coal plants elsewhere in the region,” its May 20 ad states. “The majority of health risks from coal pollution are experienced more than 60 miles from the source.”

That statement rings hollow to the opposition, which points out the closest coal power plants are at least 65 miles from Jessup.

“It’s kind of ironic they choose an area with no coal plants,” Citizens for a Healthy Jessup core member Jerry Crinella said in a recent Times-Tribune editorial board meeting. “To me, it would be a better idea to convert coal facilities. You need to replace a coal plant with a gas plant next door.”

As an example, the group held up PPL Martins Creek, a former coal plant on the New Jersey border converted to burn natural gas.

If Invenergy’s plant does end up displacing one or more coal plants downstream from Lackawanna County, it could realistically improve local air quality, Dr. Adams said.

About a decade ago, a study was done in Pittsburgh to examine fine particles, or PM 2.5, in the city’s air compared to the air upwind at the Ohio-Pennsylvania border, he said.

They found concentrations at the border were only about 10 to 15 percent lower than in Pittsburgh, he said. In other words, 90 percent of Pittsburgh’s fine particle pollution came from outside the area.

“It’s a sort of regional soup we live in,” he said.

To illustrate how fast the air can move across the country, he suggested imagining a weather radar map.

“Imagine looking at your weather forecast and you see the cold fronts, warm fronts, and the low and high pressure systems moving around,” he said. “You see in a few days, things move over multiple states.”

NEPA at heart

Yet, because of the way the power markets work, Invenergy will never be able to point to a specific upwind coal plant its operation would displace.

“Nobody can really make the claim that they themselves are displacing another power plant because it just doesn’t work that way,” said Paula DuPont-Kidd, spokeswoman for PJM Interconnection. PJM is regional transmission organization that coordinates electricity movement across 13 Mid-Atlantic, Midwest and Upland South states.

The first step for a new generator like Invenergy would be to make their power available in an annual auction when local electric utilities purchase power availability three years into the future, she said. This year, they will bid through 2018 and 2019, she said.

Broadly, PJM is witnessing natural gas generation come online as coal wanes, she said.

“It’s an overall trend we’re seeing,” Ms. DuPont-Kidd said. “There has been such a tremendous growth with natural gas-fired generation with the more abundant supplies of natural gas right now … We are seeing a lot of coal plants retire … for multiple reasons, some of which being they are very, very old.”

Northeast Pennsylvania is at the heart of this paradigm shift. Invenergy’s plant is one of at least four large combined-cycle gas plants planned for the region. The others are in Bradford, Lycoming and Luzerne counties.

Climate affects

One serious caveat to the potential benefits of natural gas is its effect on climate. When burned, natural gas is still a source of carbon dioxide, a greenhouse gas.

Natural gas has often been called a “bridge fuel,” a path away from higher-emitting sources. Borrowing a line from a colleague, Dr. Adams described the fear of being stuck with gas for too long.

“No one who builds a bridge walks across it once, turns around and blows it up,” he said.

To avoid catastrophic global warming, climate modelers predict carbon dioxide needs to be reduced by at least 90 percent in 50 years, Dr. Adams said.

“This is at best 50 percent lower, maybe only 30 percent lower,” he said. “If we converted everything to natural gas, we wouldn’t get there. We need to be thinking about stuff that is essentially zero.”

Another problem is methane leaks. Unburned, natural gas is primarily made up of methane, a potent greenhouse gas.

Unknown levels of methane leaks from pipes and other equipment also threaten to unravel any climate benefit the fuel has over coal. Over 100 years, one molecule of methane has 28 to 36 times the global warming potential as one molecule of carbon dioxide, according to the EPA.

Natural gas leakage rates must stay below 3.2 percent to provide climate benefit for power generation compared to coal, according to an influential 2012 study.

Studying methane leaks

A growing body of work is emerging on the how much methane is leaking from oil and gas operations. Levels observed and modeled have ranged from less than 1 percent to more than 17 percent.

“If someone is really concerned about slowing or stopping global warming right now or in the very near future, the warming effect of the methane from leakage is important,” said Richard Alley, Ph.D., a Penn State University climate scientist contributing author to the United Nations Intergovernmental Panel on Climate Change, in an email.

After a decade or so, methane is converted to carbon dioxide in the air, he said, meaning it can be thought of as carbon dioxide to-be. Over many decades, “the extra carbon dioxide from leaking natural gas is small compared to the avoided (carbon dioxide) because natural gas gives more energy per (carbon dioxide) molecule than coal does,” Dr. Alley said.

If coupled with a move to zero-carbon dioxide sources like wind, solar and other renewables, gas can be a bridge to a sustainable future, he said. If gas is added to coal, it speeds warming, especially if leaks continue.

“Ultimately, a truly sustainable system cannot be based on fossil-fuel natural gas, which will be depleted and which contributes to warming,” Dr. Alley said.

This article was written by Brendan Gibbons from The Times-Tribune, Scranton, Pa. and was legally licensed through the NewsCred publisher network.

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