Two steam turbines at the Ninemile Point power plant emit more carbon dioxide than any gas-fired units in America, according to an E&E News review of federal emissions data.
But neither would need to reduce emissions under EPA’s draft rule to limit pollution from power plants.
The discrepancy illustrates the novel approach EPA took in crafting the standard, tailoring requirements to a plant’s fuel type, size and usage. As the agency seeks to green the country’s electric grid, it is balancing the need to deeply slash emissions — and meet the country’s climate targets — with ensuring it doesn’t shut down gas facilities that some industry groups say are needed to ensure grid reliability.
“It is a balancing act of how much to cover, how fast,” said Julie McNamara, deputy policy director of the climate and energy program at the Union of Concerned Scientists. “This is the challenge to EPA: How do we ensure we don’t get unintended outcomes from setting different cut points for different sources in different places.”
The Biden administration has grappled with that back-and-forth. When EPA initially sent its draft rule to the White House for review, it contained standards for coal plants and future gas plants but omitted rules for existing gas facilities. Those were added later at the behest of White House officials, E&E News reported last week.
Few facilities illustrate those challenges like Ninemile Point. The 2,439-megawatt gas plant occupies a peninsula directly across the Mississippi River from a warren of residential neighborhoods in New Orleans.
The plant has five electric generating units: two steam turbines built in the 1970s, two combustion turbines built in 2014 and a third steam turbine, which was also built in 2014.
The five units emitted 23 million tons of carbon dioxide between 2018 and 2022, according to EPA data, making Ninemile Point the sixth largest CO2 emitter among gas burning power plants in the country. It also ranked as America’s top gas-fired emitter of nitrogen oxide, an ozone-forming pollutant.
Yet not all of Ninemile Point’s units would be regulated the same way under EPA’s proposal. The plant’s two dirtiest units, the pair of 1970s-era steam turbines, would effectively be given a free pass to continue polluting at current rates.
That’s because EPA’s rule carves out a specific provision for gas-fired steam turbines, which generally operate as peaking units, ramping up quickly to meet surges in electricity demand and powering down when demand subsides. In 2022, Ninemile Point’s older steam turbines ran less than a third of the year, according to U.S. Energy Information Administration figures.
Gas-fired steam turbines are a relatively small source of overall gas plant emissions. In its regulatory review, EPA concluded that installing carbon capture or co-firing with hydrogen at such units would be costly and fail to produce significant emission reductions because they operate so infrequently.
Instead, the agency proposed capping emissions for gas-fired steam turbines based on how frequently they run. The cap would be set at a rate that most plants, Ninemile Point included, could achieve — an approach that “would not achieve emission reductions but would prevent increases in emission rates,” according to EPA.
Some environmentalists worry the move could backfire. By requiring pollution controls at facilities that operate more often and applying lax standards to peaking units, EPA could create an incentive for power companies to operate dirtier, less efficient units more frequently, they say.
There’s also this: A small number of gas-fired steam units are major emitters. Ninemile Point’s two steam turbines reported emissions of 8 million tons and 6.9 million tons, respectively, over the last five years, making them the first and second largest CO2 emitters among the country’s individual gas-burning electric units. Another steam turbine at the Northside Generating Station in Jacksonville, Fla., reported emissions of 6.3 million tons — the fifth most of any gas unit.
“We do have concerns that some of these units that are a significant chunk of the fleet are not necessarily going to have to do much under this proposal,” said Andres Restrepo, a senior attorney for the Sierra Club. “I think that it’s important that they really hone in on what are the maximum emission reductions they could get.”
Ninemile Point’s three newer units, by contrast, might need to install pollution controls to reduce emissions. The trio form what is known as a combined cycle unit. The two combustion units heat air and gas to turn a turbine and generate electricity. Exhaust from those turbines is then captured and converted into steam, which is fed through the third turbine to create even more electricity.
Combined cycle units accounted for about 85 percent of total gas-fired power generation in 2022 and a corresponding percentage of the fuel’s power plant emissions, according to federal figures.
Under EPA’s proposal, a combined cycle unit greater than 300 MW that runs more than half the year would need to install carbon capture by 2035, or begin co-firing with 30 percent hydrogen in 2032. That figure would rise to 96 percent by 2038.
An EPA spokesperson declined to answer detailed questions about the agency’s rationale for setting the standard. But in its regulatory analysis, the agency said a 300 MW threshold was appropriate because it “focuses on the units with the highest emissions where CCS is likely to be most cost effective.”
Environmental groups are pushing to lower the threshold for plants that would be subject to the regulation. An analysis by the Natural Resource Defense Council found EPA’s proposed standard would only cover 29 percent of gas plant emissions. If EPA lowered the threshold to 150 MW — and applied it to plants that run at least 40 percent of the time — the rules would cover 80 percent of gas plant emissions, according to the analysis.
“Gas is not a clean fuel. Gas is a huge contributor to the climate crisis,” Restrepo said. “We can’t effectively deal with the climate crisis unless we address all forms of emitting generation.”
A question of reliability
Industry groups worry gas plants may struggle to comply with the rule as written. Pollution controls like carbon capture require an extensive build-out of support infrastructure, including pipelines and storage capacity, that could take years to permit and build.
Hydrogen would also require a build-out of new gas pipelines. And it’s unclear where gas plant owners would find an ample supply of hydrogen to meet their fuel needs or if older gas turbines could be retrofitted to run almost completely on hydrogen, said Todd Snitchler, the president and CEO of the Electric Power Supply Association, a trade group representing merchant power plant owners.
EPA’s new rules, he noted, come at a time when regulators are warning of increased risks of power outages due to the rapid retirement of fossil fuel units.
“If you make rules that jeopardize the viability of the gas fleet, you don’t have sufficient resources to keep the lights on in its absence,” Snitchler said. “There’s not enough renewables, nuclear, hydro and storage to power the system if a significant level of gas retires.”
Environmentalists call that argument a red herring. Gas plants would have nine years at the earliest before the first hydrogen requirements would kick in. Power companies will also be able to call on billions of dollars in clean energy subsidies contained in the Inflation Reduction Act to support development of hydrogen and CCS.
Planning for a grid that relies on those technologies needs to begin now to ensure reliability concerns can be addressed, McNamara said.
“If we were to shut all plants overnight, of course there would be problems. Everyone knows that,” she said. “It’s a real issue, demanding planners to plan. But the way reliability is invoked around this rule is mostly in bad faith.”
At Ninemile Point, it remains an open question whether EPA’s standards will apply to its combined cycle units.
The plant’s two combustion turbines have a listed capacity of nearly 195 MW, while the associated steam turbine is listed at 260 MW. At first glance, that would appear to leave the units below EPA’s threshold requiring pollution controls. But the agency’s proposal calls for dividing up the associated steam turbine’s capacity and apportioning it to the combustion turbines based on the amount of heat each combustion turbine generates.
“Assuming the two combustion turbines are used similarly (i.e., the same annual heat input), then the MW output from the steam turbine would be apportioned 50% to each of the combustion turbines,” EPA spokesperson Melissa Sullivan said in an email. That would take the capacity of each Ninemile combustion turbine to 327 MW. Each turbine ran more than two-thirds of the year in 2022, meaning both could be subject to EPA’s more stringent standards.
Entergy Corp., the New Orleans-based utility that operates Ninemile Point, anticipates CO2 emissions from the power plant will be regulated under EPA’s proposal, according to spokesperson Neal Kirby.
Kirby called all of Ninemile Point’s turbines “important resources that provide affordable and reliable power to Entergy Louisiana’s customers.” He said the utility would remain committed to reducing its greenhouse gas emissions regardless of changes in EPA’s rules.