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July 12, 2026 - Data centers are generating new concerns after the federal government granted emergency authorization for the resource-intensive facilities to fire up their backup power to avoid residential outages and keep air conditioners running across 13 states during recent sweltering weather. "It is essentially installing the cheapest and dirtiest type of power plant," said Sierra Club Pennsylvania Chapter Director Tom Schuster.
As a record-setting heat wave loomed late last month, PJM, the regional transmission organization managing the grid in Pennsylvania and a dozen other states, requested and received an emergency order from the U.S. Department of Energy allowing it to call on data centers and other large-load users to switch to backup generators for electricity rather than use grid power in a bid to avoid blackouts on infrastructure already strained by data center demands.
A coinciding request and order also temporarily allowed power generators to exceed their environmental permitting limits during the heat wave to maintain grid reliability.
The backup generation order was initially in effect from June 30 at 11:59 p.m. through July 3 at 11:59 p.m., but it was subsequently extended through July 7. The heat wave did not ultimately necessitate the emergency use of backup generators, according to PJM, which told the government it would deploy all available reliability tools — with a few exceptions — before tapping data centers for power.
The Department of Energy previously gave PJM the same authorization during hot weather from May 18 through May 20.
For more than a year and a half, Northeast Pennsylvania communities have navigated an onslaught of proposals for data centers and hyperscale campuses as companies increasingly turn to the region because of its accessible infrastructure and available land.
Data center campuses operate 24/7 while requiring large amounts of electricity to power their computer hardware and cooling equipment to sustain uses like artificial intelligence and cloud computing. To remain online during a power outage, data centers maintain large fleets of backup generators.
For large proposals like the Wildcat Ridge Data Center Campus in Archbald, which plans to use 1.6 gigawatts, or 1,600 megawatts, to power 14 data centers, the 588 diesel generators that would keep it online during an outage would need to collectively produce more electricity than Lackawanna County's largest power plant.
The Lackawanna Energy Center natural gas-fired power plant in Jessup produces 1,485 megawatts.
Despite fleets of generators producing large amounts of power, they are governed with more lax pollution rules compared to power plants, said Schuster, who is not related to the Scranton councilman with the same name.
He expects future heat emergencies will remain in effect for longer durations if data center development continues outpacing the construction of new power generation projects. Faced with that additional strain, Schuster contends future heat emergencies will be triggered by lower temperatures because demand is outstripping supply.
Generators have emerged as one of the most contentious issues surrounding developments, especially in Archbald where developers propose 51 data centers across six projects, with 30 of the buildings confined to a roughly 1-mile stretch.
Opponents often raise concerns about pollution, noise and the large volumes of diesel fuel stored on site to sustain generators.
By potentially using backup generators to combat grid strain during heat waves, it opens the door for generators to run for longer periods than municipalities previously considered. Discussions so far have focused on mandatory quarterly testing and maintenance schedules when data center operators run their generators, in addition to generator use during power outages. Local governments also typically exempt data centers from noise limits when they have to rely on their backup generators.
During a hearing in Archbald on Monday, Harvard University environmental health scientist and biostatistician Michael Cork, Ph.D., presented his findings from a "screening-level air quality and public health assessment" that examined potential emissions and health impacts from Wildcat Ridge's nearly 600 generators.
Cork, who is the co-founder of EmPower Analytics Group, used U.S. Environmental Protection Agency modeling to determine the development's generators could cause anywhere from $3.3 million to $124 million in annual health damages across Lackawanna County. He also estimated the generators would emit hundreds of thousands of pounds of air pollutants each year.
PJM's rationale
PJM Interconnection Senior Vice President of Operations Michael E. Bryson requested authorization to allow data centers and other large-load users to use their backup generation as a last resort in a June 27 letter to U.S. Secretary of Energy Chris Wright. Bryson attributed the request to temperatures in the 90s- to-100-degree-plus range throughout PJM's territory.
PJM is a regional transmission organization encompassing all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and Washington, D.C. It serves more than 67 million people.
Bryson's letter warned of a potential all-time peak electricity load forecasted during the heat wave. PJM confirmed Friday in a news release that it had reached its highest all-time load on July 2 between 5 and 6 p.m. with an estimated 168,158 megawatts. It surpassed the previous record set in August 2006 by nearly 3,000 megawatts.
The organization said it released a warning July 2 notifying large-load customers of potential emergency action that would require them to be prepared to switch to backup power within 15 minutes, though the action was not needed and never issued.
In his June 30 order granting PJM's request, Wright referenced the not-for-profit North American Electric Reliability Corporation's 2025 long-term reliability assessment. The assessment observed the PJM region is at high risk for energy shortfalls over the next five years and faces significant reliability challenges because new power generation projects are unable to keep pace with escalating demand and expected equipment retirements, according to Wright's letter.
"Currently, there are tens of gigawatts of readily available backup generation that have remained largely untapped," Wright wrote.
Using those backup generators can prevent avoidable blackouts, "Thereby saving lives and reducing costs to the American people," he wrote.
Comparing pollution to power plants
Allowing data centers to run off backup generators during heat waves is "terrifying," Schuster said.
"If you're talking about tapping these as … an untapped power source, that's scary," he said.
Schuster's organization, the Sierra Club, describes itself as the largest and most influential grassroots environmental organization in the country.
The best-performing diesel generators — known as Tier 4 — still produce twice as much nitrogen oxides, or NOx, per kilowatt-hour as a coal-fired power plant, and about 13 times more than the natural gas-fired Lackawanna Energy Center, Schuster said. A lower-quality generator, Tier 2, produces 20 times more NOx than a coal plant per kilowatt-hour, and about 425 times more than the power plant in Jessup, he said.
"They're even worse than coal," Schuster said.
Short-term exposure to high concentrations of nitrogen dioxide, one of the gases making up NOx, can irritate airways and aggravate respiratory diseases, according to the EPA; long-term exposure may contribute to the development of asthma and potentially increase susceptibility to respiratory infections. People with asthma, children and the elderly are considered at greater risk. Developers propose data centers locally near parks, homes and schools.
Diesel generators also put out significantly more particulate matter than natural gas power plants per kilowatt-hour, comparable to coal-fired plants, Schuster said.
Fine particulate matter is 30 times smaller than the width of a human hair — so tiny it can penetrate deep into lungs and enter the bloodstream, according to the EPA. Exposure to the microscopic particles can affect the heart and lungs.
Numerous studies link exposure to health problems, including premature death in people with heart or lung disease, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function and increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing, according to the EPA.
Fine particles are also the main cause of haze in the United States.
Tier 4 diesel generators are comparable in particulate matter emissions to a fully controlled coal power plant, while less stringent Tier 2 generators are six to seven times worse than coal plants per unit of energy, Schuster said. Compared to the Jessup power plant, Tier 4 generators would release about 300 times more particulate matter, and Tier 2 would generate about 2,000 times more, he said.
Even the height of generator exhausts affects how pollution disperses.
Diesel generators emit pollution via exhaust pipes at ground level, whereas power plants use tall smokestacks to better disperse pollutants, Schuster said.
"Depending on how the wind is blowing, this stuff is going to accumulate in the immediate area," he said. "So the impacts along the fence are probably going to be fairly extreme."
He believes Tier 4 generators should be required at minimum, and municipalities should have EPA-standard air quality monitors in the vicinity of data centers to watch for localized air violations.
Assessing impacts
The science is clear that any increase in this pollution will translate into an increased risk of health impacts, Cork said.
With a doctorate in biostatistics from Harvard University, Cork's current research includes the population-level health impacts of AI-driven electricity demand and hyperscale data center expansion. As part of Stop Archbald Data Centers' case against Wildcat Ridge, the grassroots opposition group hired Cork to conduct a health assessment through his EmPower Analytics Group, giving him insight into the local data center landscape.
"We analyzed one proposed Pennsylvania data center, and what I found is that these annual health damages range from roughly $3 million to $124 million, which depends on engine technology and crucially on runtime," he said. "This is around a 40-fold spread, and it really shows that decisions we are making about how often we are running backup generators and the ensuing emissions translate into tens of millions of dollars in health consequences, and what's concerning to me is those costs are almost never quantified before a community is asked to accept the project."
Air pollution is cumulative exposure that can build on itself, Cork said.
"When you have so many backup generators being proposed and being built, but not really analyzed together to understand how the pollution would build upon other sources of pollution, you get a situation where the full extent of the health impacts or its impacts on the community are not well understood," he said.
Cork contends it is misleading to refer to them as backup generators now that they're viewed as grid reliability resources.
He believes the changing use of generators from rare power outages to heat waves should require more scrutiny of their impacts. Communities will be exposed to emissions on the exact days they're most vulnerable with extreme heat and elevated ozone, he said.
The grid needs reliability, but that's not the question, Cork said.
"That question is whether we're widely shifting this health burden onto host communities by turning these massive diesel fleets into grid resources without being explicit about it, and also without any sort of health analysis, any enforceable limits, or the cleanest available technology," he said.
The environmental health scientist has four suggestions for regulators and local officials:
• Quantify the health impacts before approval.
• Set enforceable runtime limits — be very clear how much they allow diesel backup generators to run, and get it in writing.
• Require the cleanest available engine technology.
• Put public monitoring in place.
"These decisions need to be made before a community is locked into risk, not after," he said. "The potential health impacts can be really consequential, and the decisions that are being made today about how and where we are powering AI infrastructure have the potential to shape the air that Americans breathe for decades, and consequently, a lot of our health outcomes."
Local opposition takes stand
Stop Archbald Data Centers co-founder and industrial hygienist Tamara Misewicz-Healey has challenged data center and power plant developers over their plans at more than a dozen public hearings in Archbald this year, cross-examining every witness presented by a developer, including about generators.
"We're not saying a couple generators turning on backup. In Archbald alone, we could have over a thousand, we could have potentially even more than that," the Archbald resident and mother of three young children said. "Then if you look at countywide … thousands, and we didn't measure that yet. And honestly, I think seeing that number, it would take someone's breath away."
Industrial hygienists measure risk, and then the process comes down to adding in controls until that risk is reduced to an appropriate, controllable level that's considered acceptable, she said. Sometimes, that isn't possible without just eliminating a project, she said.
"When you have this level of scale and risk, it has to be taken seriously," Misewicz-Healey said.
The science related to generators and diesel exhaust is well documented, she said.
"That's why this is a little frustrating, too," Misewicz-Healey said. "We have the answers, we know the risks, like we already know we should be taking caution, and then it feels like it was avoided anyway."
The longer generators run, the more they increase the risk and burden on the population, compounded by PJM simultaneously receiving the OK for energy producers like power plants to run at full capacity with exemptions for their air emissions, further increasing pollution, she said. The local valley topography reduces wind movement, keeping the pollution over the region, she said.
If generators power on during a heat wave, communities will be more likely to experience low-level ozone, which causes significant health impacts, she said. The sun helps convert some pollutants from diesel emissions into ozone, Misewicz-Healey said, adding that it's happening when the human body is already under increased stress from the heat.
Children are especially vulnerable because they breathe more per their body weight than adults, she said, explaining that with faster heart rates and more rapid breathing, children endure more exposure.
With 30 data centers proposed near Archbald's popular Staback Park on Eynon Jermyn Road, which houses multiple baseball and soccer fields, playground equipment and basketball courts, children will be breathing more by playing there, leading to even more exposure, she said.
Residents also have concerns that Archbald's noise regulations for data centers are lacking because they exempt generators during emergencies and fail to include decibels measured in a lower frequency range, she said.
"I believe there's always balances, responsible balances, to ensure industry can accomplish what it needs, but not at necessarily the expense of the community," Misewicz-Healey said.
She stressed the need for more data and risk assessment when municipalities make decisions on developments. Without that information, local governments are making blind decisions, she said, calling it naive and irresponsible.
Commissioner's opposition
Lackawanna County Commissioner Bill Gaughan has emerged as one of the data center industry's largest local critics in the last year, attending hearings and speaking out against projects throughout the county.
"The billionaires that are driving this AI revolution that we hear about all the time in the news, they want communities like Lackawanna County to bear the burden while they reap all the rewards," the Democratic commissioner said. "They want our land, they want our electricity, they want our water."
To study those impacts, Gaughan is working toward implementing a countywide cumulative health and environmental impact assessment. There are more than a dozen proposed campuses in Lackawanna County, amounting to over 90 individual data centers, plus four power plants. If those projects materialize, running their generators simultaneously is a disaster waiting to happen, Gaughan said.
"Before another acre of land is committed, or any permit is issued, or anything is approved, the public deserves an honest accounting of the cumulative consequences of these," he said. "These developers and corporations are asking our county to accept unprecedented demands on our electric grid, unprecedented industrial development throughout the county."
The burden should be on developers to prove their projects are actually safe, not placed on residents to prove they're unsafe, he said.
Gaughan recalled a note he wrote to himself while listening to Cork speak about countywide health impacts from generators during Archbald's recent hearing on Wildcat Ridge.
"They get rich, we get sick," he said.
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