Nearly every minute of every day since April 22 the Panda Stonewall power plant south of Leesburg has been quietly cranking out millions of megawatts to feed the growing energy needs throughout the eastern U.S.
After two and a half years of construction by Bechtel—with some 800 employees operating on the 101-acre site at the peak and area motorists dealing with frequent delays and detours as massive pieces of equipment were hauled in—there has been little fanfare or attention given to the plant since operations began.
That’s good news for General Manager Mark A. Kadon who has seen the state-of-the-art operation ramp up with few problems and even fewer complaints.
Last week, two men who had a hand in bringing the power plant concept to reality got their first look at the finished product. John A. Andrews II was the developer who conceived the projected and shepherded it through the rezoning stage. Scott K. York was the county chairman when the project was approved in 2010.
After the Board of Supervisors’ approval, the project sat dormant until Dallas-based Panda Power Partners acquired it in 2014 and quickly moved it to construction.
The plant has a capacity of 778 megawatts. Just how much electricity is generated each day depends a little bit on the weather—hot air can lower output—but more so on the complex calculations of PJM, a transmission organization which oversees the electric transmission system serving Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and DC.
The plant is committed to provide a base capacity of 750 megawatts, but also gets orders to meet daily demand above that. In general, the cheapest power closest to demand typically gets the delivery order. And the state-of-the-art, high-efficiency natural gas-powered plant at the edge of Virginia’s Data Center Alley typically gets the call.
“It’s day-to-day. Every day at 1 o’clock we will get a schedule that will come from our energy manager from PJM that tells us tonight at midnight through midnight that day what our output needs to be,” Kadon said.
The plant operates with two gas turbines and one steam turbine. The natural gas is provided by one of two transmission mains that cross the property. The electricity is distributed through a 230 kilovolt line that runs along the gas line easements.
It’s cooled by reclaimed water piped down from the Town of Leesburg’s wastewater treatment plant—3-4 million gallons a day.
Despite all the liquid going in, none comes out. Through a series of delicate thermal and chemical processes, there are only two byproducts of the operation, aside from the electricity itself—steam and salt.
Most residents haven’t seen plumes of steam rising from the plant, a common site at other power plants and even from the cooling towers atop eastern Loudoun’s data centers.
The power plant employs a plume abating hybrid cooling tower, which reheats the exhaust and reduces its humidity before its release. The result is a smoke-free appearance at the plant.
At other power plants, “on a cold winter day you could see a plum going straight up for miles,” Kadon said.
Andrews said he got the idea for the feature, one of the conditions of the project’s approval, while flying over a nuclear plant in eastern Germany that was not emitting a visible plume. He said people generally view the visible steam emissions as “smoke” and he was working to overcome public concerns about pollution being associated with the plant.
The plume suppressing system is only used during daylight hours.
“I can tell you it works great. I’ve been outside when it is not in service. We’ll put it in service, and five minutes later the plume it gone. It’s pretty remarkable,” Kadon said.
The plant uses a brine recovery system to remove salt and minerals from the reclaimed water piped from Leesburg.
“It’s like boiling your coffee like six times until there is nothing left except salt. That salt is a dry cake that we take to the landfill and it is disposed of,” Kadon said.
During the summer months, the plant produced about 10 tons of salt a day. “That’s a 20-foot roll-off dumpster full,” he said.
Andrews and York both questioned whether there was a viable commercial use for the salt—York suggested VDOT could be a wintertime customer. Kadon said that was a frequent question heard as he gives tours, but the buyers haven’t lined up so far.
In the control room during the tour, operator Brian Wade sat alone in front of a wide bank of video monitors displaying every part of the plant’s operations.
One of 27 people working at that plant, the U.S. Navy vet has worked in combined-cycle power plants for the past 15 years. He sits next to a line of red buttons—kill switches—that can shut down systems in cases of emergency. But the sophisticated software and monitoring system, with vibration detectors and probes throughout, will likely react far more quickly than a human minder.
“The plant is going to protect itself faster than we can,” Kadon said.
The control room receives live signals from PJM, which can control the plant’s generation levels remotely.
Andrews, a homebuilder for most of his development career, said he was amazed by the level of complexity needed to manage the power grid. His research for the power plant included a visit to the PJM control center in Pennsylvania.
“What was mind-blowing to me was there is no storage of electricity. So as everyone turns on their air conditioners in this city or there is a blackout there or a powerline down, everything has to be balanced within a nanosecond,” Andrews said.
Other elements of the package approved by supervisors include limitations on outdoor lighting, noise limits that are affirmed in quarterly testing and a natural resource plan for the property calling for the removal of invasive species and additional tree plantings.
York asked about another element in the approved plan—an associated solar power array.
Andrews said that still could be developed on the site, but would be unlikely until the operation would be economically feasible. He said the component was added to the design during planning in 2008 when a bill under consideration in the General Assembly would have mandated solar components in all new power plants. The bill was opposed by Dominion Energy and died during the session.
Recycled Water Powering Loudoun Industry
Panda Stonewall will pay the Town of Leesburg at least $500,000 this year to purchase reclaimed water from the wastewater treatment plant.
“We use upwards of 3 to 4 million gallons a day. And that is pretty much between 90 and 100 percent of the water the town would release to the Potomac that is diverted to this plant as cooling water,” said Mark A. Kadon, the plant’s general manager.
The town retains at least 250,000 gallons of fully treated effluent each day and discharges it to the Potomac River, a requirement to keep the pipeline certified and operational.
“That represents about 7 percent of our total daily flow. So we’re diverting in excess of 90 percent of our reclaimed water to Panda,” said Betsy Arnett, the town’s public information officer.
The plant has a 5 million gallon water storage tank onsite to ensure there’s an adequate supply should there be a disruption at Leesburg’s treatment facility.
The Stonewall operation—which could use more than a billion gallons of water annually—cements Loudoun’s standing as a national leader in the use of reclaimed water.
Starting in 2010, Loudoun Water developed a separate loop to feed recycled water from its Broad Run Water Reclamation Facility to provide cheaper water for the cooling systems at the data centers in Eastern Loudoun. The 14-miles of pipeline serve more than a dozen facilities, delivering 380 million gallons of reclaimed water last year.