Plan to Relax Data Center Diesel Regulations Narrowed to Only Loudoun

Plans to relax regulations on how often data centers in the region can run their backup diesel generators have been narrowed to only relax those rules in Loudoun.

Data centers, which seek to have as little downtime as possible, have backup diesel generators onsite which typically are permitted to start monthly for testing. The state estimates there are 4,151 such generators at data centers in Loudoun. Based on the state’s estimates those generators collectively put out almost 93 tons of non-methane hydrocarbons and nitrogen oxides per hour of runtime—potent and poisonous greenhouse gases. Other pollutants include almost 51 tons of carbon monoxide per hour.

Dominion Energy last summer warned data center companies that its electricity grid may not be able to supply power to new data centers—but the proposed order from the Virginia Department of Environmental Quality now suggests it may not even be able to power existing data center projects during the peak electricity usage months of summer.

“DEQ is concerned that Loudoun County is an area in which there may not be a sufficient amount of electricity for data centers due to severe, localized constraints in electricity transmission,” a public notice from the state agency reads. “A transmission constraint issue exists in the area which may affect the ability to provide enough electricity to data centers through 2025. In particular, the period between March and July 2023 has been identified as a time of potentially acute stress on the transmission capacity of the grid.”

However the DEQ's notice also said the proposal is "a purely precautionary measure" and "we do not anticipate that any data center will need to use this variance." It also wrote any such activations would likely only affect smaller areas, and data centers would not be expected to turn on all of their generators, since many are redundant backups.

The proposal would allow data centers to run their generators when PJM Interconnection, the company that coordinates power transmission in Virginia, issues an alert about possible capacity problems in the electrical grid. Data center operators would also be required to provide a calculation of the air pollution they generated during that time “as soon as practicable.” The variance would expire at the end of July.

Previously, that variance applied to data centers in Loudoun, Prince William and Fairfax counties; a second draft removed the other two counties and would apply only to Loudoun.

“DEQ takes the public participation process very seriously and is making appropriate revisions to the proposal based on that input,” DEQ Director Michael Rolband stated.

The new notice for the first time included the state’s estimates of those generators’ output of air pollutants. With the revised proposal, the state has scheduled a new public hearing on April 6, although not in Loudoun County, and at 11 a.m. on a weekday. The hearing is scheduled at the DEQ Northern Regional Office in Woodbridge at 11 a.m. Thursday, April 6.

A public comment period, which had previously been set to expire March 14, was also extended until April 21.

The state proposal stirred concern from the Piedmont Environmental Council, which has scheduled a public meeting about the proposal at the Ashburn Library at 6 p.m. on March 28. The council’s announcement said the proposal “is not only short-sighted in addressing the grid constraints, but it has the potential to do real damage.”

“Many of our schools, sports fields, playgrounds and homes are located near data center complexes, and there is real potential for localized air pollution and regional greenhouse emissions with the increased use of these diesel generators,” the council wrote. “Air pollutants such as ozone and particulate matter increase the amount and seriousness of lung and heart disease and other health problems, particularly for children, the elderly and those with pre-existing conditions (asthma, pregnancy, COPD, etc.).”

The full proposal is online at deq.virginia.gov/get-involved/topics-of-interest/data-centers-public-comment, or deq.virginia.gov/permits-regulations/public-notices/air under “REVISED Order and local variance for data centers – Loudoun County, VA.”

The DEQ accepts written comments by email, fax, and mail. Comments must include the full name, address and telephone number of the person commenting. To comment, request public documents or for other information contact Karen G. Sabasteanski, Office of Air Data Analysis and Planning, Department of Environmental Quality, PO Box 1105, Richmond, VA 23218. Call 804-659-1973 or fax 804-698-4510, or email karen.sabasteanski@deq.virginia.gov.

A DEQ public hearing is scheduled in the conference room of the agency’s regional office at 13901 Crown Court, Woodbridge, at 11 a.m. on Thursday, April 6.

This article was updated March 21 at 5:20 p.m.