We are concerned that the Virginia Department of Environmental Quality (DEQ) has proposed this major change to allow data centers to run Tier II backup diesel generators during planned outage events. Until now, these generators could only be used in the case of regular maintenance or during “sudden and reasonably unforeseeable events where the primary energy or power source is disrupted or disconnected due to conditions beyond the control of an owner of a source”. DEQ’s website (https://www.deq.virginia.gov/news-info/shortcuts/permits/air) currently states under the “Emergency Generator Definition” that, “‘Sudden and reasonably unforeseeable events’ do not include scheduled or planned power outages associated with electricity service provider activities”. This change is a complete reversal of that long standing interpretation. 

Perhaps more troubling is the complete lack analysis to demonstrate that the substantial change in regulation protects Virginia residents and ensures there are no violations of public health standards for PM2.5, ozone, and other pollutants, despite foreseeable scenarios where thousands of diesel fuel generators are operating simultaneously during weather conditions that are likely to result in increased air quality standard violations.

By our count of the permits for data centers alone, there are about 9,000 Tier II diesel generators approved in the state through minor permits. Of those about 4,700, with a total capacity of 12 gigawatts (12,000MW), are in eastern Loudoun. When these data centers were approved, along with the minor air permits for their generators, the public was told the generators would rarely run and were only there to provide backup power in emergency situations. This proposed change is a significant retraction of that public commitment that deserves more vetting and consideration than just a 30 day opportunity to place comments on an agency portal. 

It is unclear why the Department of Environmental Quality, whose mission is to, “protect and enhance the environment of Virginia in order to promote the health and well-being of the Commonwealth’s citizens, residents, and visitors in accordance with applicable laws and regulations” is proposing this change. Your role in a proposal like this should be to review the public health implications of such a change. For that reason we ask that the agency delay this action and provide modeling of scenarios and analysis about the public health implications of this change for the public to comment on and for the agency to use as a basis for their decision. 

If there is an extended period of hot or cold weather, the electrical grid is generally forecast to experience additional demand, impacting reliability. In fact, the Grid Monitor for PJM has forecast precisely those conditions in the 2025-2029 period. In hot weather this may coincide with high ozone days and additional air pollution from nearby wildfires. The DEQ must analyze scenarios where those conditions are present, including a scenario where all 12,000MW of generators are operating simultaneously to determine that no violations of public health standards will occur.

We believe the agency’s current interpretation of sudden and reasonably unforeseeable is correct and should not be changed simply for convenience and cost savings of data centers and utilities without robust analysis of the public health impacts. Planned outages, such as when transmission lines are being built or worked on, are foreseeable and their timelines adjustable, providing data center operators sufficient time to seek alternative options such as renting mobile Tier IV gas generators with higher pollution controls or retrofitting Tier II generators with SCRs (selective catalytic reduction systems) to better protect the public from pollution.

There has never been any cumulative analysis of the hundreds of minor air permits that have been approved in very close proximity to each other, especially in areas of eastern Loudoun and Prince William County where large clusters are approved, meaning we really have very little understanding of what the impacts of this change will be. Depending on the scope of the “planned outage”, this change could potentially allow hundreds to thousands of diesel generators to run for long periods of time during grid work, putting public health at risk. We believe this change should not be allowed or, at the very least, should be strictly limited and regulated.

Although we understand that the proposed change would still limit the usage to the emission standards approved under their minor air permits, we're concerned about how much additional pollution that means for residents. According to the study done last year by the Joint Legislative Audit and Review Commission (JLARC) for the General Assembly, data centers are currently only utilizing 7% of their permitted emissions allowances, on average, which means they potentially have room to increase their emissions an additional 93% during planned outage events. Knowing this, we believe that DEQ should use the scenarios mentioned above and the max permitted emissions to model potential cumulative impact of generators operating in planned outage scenarios.

DEQ must put protecting public health first as their primary mission above all else which means delaying this decision, conducting more analysis of impacts to public health, and allowing more time for public input on those results. 

If however, the agency decides to move forward with this change without doing the analysis we believe should be done, it should at the very least go through a full regulatory amendment process to 9VAC5-540-20 and 9VAC5-80-1110 and incorporate strict limitations, notice requirements, and monitoring, specifically:

• Not allowing Tier II generators to be run for planned outages near “sensitive receptors” (e.g., schools, hospitals, parks, trails and residential areas)

• The public should be given notice about where and when these generators will be running and for how long.

• Each site where emergency generators are running should be inspected daily to monitor fuel usage and should be equipped with air quality monitoring for the duration of their usage.

Thank you for considering our comments.

Sincerely,

Julie Bolthouse
Director of Land Use
Piedmont Environmental Council
jbolthouse@pecva.org