This is the second part in a two-part series profiling Dominion Virginia Power's multibillion-dollar investment in combined-cycle natural gas plants. To read the first part, click here.

Dominion Virginia Power, the winner of back-to-back engineering awards for its two newest gas plants, is focused on building the largest 3-on-1 combined-cycle plant in the company's fleet and the nation.

Both the 1,358-MW Brunswick County Power Station, which began full commercial operation in April 2016, and the 1,472-MW Warren County Power Station, which was brought online at the end of 2014, have been recognized by Power Engineering magazine as the Gas-Fired Project of the Year and Overall Project of the Year for the past two years. The stations were selected based on technological innovation, local impact, logistical challenges, creativity and capacity.

The company's latest project, the 1,588-MW Greensville Power Station, is nearly 20% complete with the $1.3 billion plant expected to achieve commercial operations in late 2018.

"Once it's built, it will be the biggest 3-on-1 combined-cycle plant in North America," Ricky Elder, who will be the station director at Greensville, told S&P Global Market Intelligence in a recent interview.

Elder, who also is the director of the Brunswick County Power Station, said the operational aspects continue to improve from Warren County to Brunswick and "then Greensville really steps up to the next level."

It begins with the strict efficiency targets the company has set for Greensville.

"There's a lot of things we did at Greensville to try and make it the most efficient large combined-cycle [plant]," Karl Humberson, director of generation projects for Dominion and director of construction at Greensville, said during a tour of the plant site. "When we did our assessments [with gas turbine manufacturers and construction contractors], we lined up what they could do, guarantees. The main piece we looked at was heat rate. What's the best overall heat rate? How efficient can we get this thing? We feel that we've done a really good job. We're hoping that we even beat our guarantees."

The plant also must meet strict air permit regulations from the Virginia Department of Environmental Quality.

"The [air permit for] Greensville will be the most stringent in the U.S.," Elder said.

While most power plants must meet a target aimed at an average of the anticipated carbon-dioxide emissions over the life of the plant, Greensville will be "the only station in the country" required to meet a new limit every six years, Dominion Virginia Power spokesman Dan Genest noted.

"We're up for the challenge," Elder said.

On top of a commitment to efficiency and requirement to meet its air permit, Dominion Resources Inc. lives by a mantra to complete its projects "on time and on budget" with safety above all else.

"My main purpose out here is to help our contractors and help even Dominion make sure we do those three tiers: safety, schedule, budget," Humberson said.

"There's no project of this magnitude that goes off flawless," Humberson said. "We have multiple challenges we go through on a daily basis. Part of my job is to make sure that my team can help [Fluor Corp.] get through those challenges or we help Dominion understand those challenges and get through them."

Fluor was awarded the engineering, procurement, construction and commissioning contract for Brunswick and Greensville.

Closer look

While there's no doubt Dominion is excited about its Greensville facility, Elder explained what sets Dominion's existing projects apart from other gas plants.

"The difference is the technology," Elder said during a tour of the Brunswick site.

The former manager of the Chesterfield Power Station, which is the site of the company's first combined-cycle unit, Elder said combined-cycle plants have evolved over the last 20 years.

The initial Chesterfield combined-cycle unit was designed to only generate about 220 MW of total capacity. Brunswick, on the other hand, consists of three 280-MW combustion turbines and a 518-MW steam turbine, according to SNL Energy data.

Brunswick's gas turbines suck in fresh air from an inlet air filtration system. The air then travels into the combustion turbine compressor, where the air is heated up to about 700 degrees as it's compressed. The air is then injected into the turbine, where the natural gas is admitted. "That is the motor force to drive the generator," Elder said. "It produces a lot of horsepower."

The gas that comes out of the turbines goes through GE/Alstom heat recovery steam generators, or HRSGs, instead of exiting a chimney at 1,100 or 1,200 degrees, Elder said.

"It takes all that energy that's coming through the gas turbine ... and it goes through this heat recovery boiler and boils water and makes steam. That steam, out of a 3-on-1, is combined into a common header," he said. "We produce about 3.1 million pounds of steam an hour and it drives a large steam turbine. All that energy is being generated by heat that would typically be lost in a simple-cycle plant. It would actually just go straight up to the atmosphere."

Brunswick has duct-fired HRSGs. The natural gas duct burners are similar to a "large gas grill" that operators can "light off and it actually adds a lot more energy into the HRSG, which produces more power out of the steam turbine," Elder said.

The thermal energy created by the combined-cycle process actually drops the heat rate down on the unit "below what a conventional coal unit typically burns at," he said.

"A typical coal unit in today's world ... is in the 10,000 Btu range. This machine here is running in the upper 6,000 Btu range," Elder added. "They're very, very efficient. From a customer standpoint, you can produce the product at a lower cost. It's a cleaner product. It's about 50% cleaner than coal and it only takes about 50 people to run this place, compared to 250 to run a conventional coal unit."

Typical challenges

Elder noted that there are challenges to running Brunswick, starting with the state-of-the-art Mitsubishi Hitachi Power Systems Americas Inc. gas turbines.

"They're very high-tech machines," Elder said. "When you ride in an airplane, you look out the window and you see this jet engine ... well, these jets here are almost as big as the airplane."

"They take a lot of finesse in getting them right," he added. "It's a process you have to go through."

The typical life cycle for a combined-cycle plant is about 35 years.

"I've got a 1960 Cadillac and it runs. It's all about doing the maintenance on it," Elder said. "This thing will run for a long time."

Dominion Virginia Power is known legally as Virginia Electric and Power Co.

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