By Sharryn Dotson, associate Editor
Duke Energy’s 618-MW Edwardsport Integrated Gasification Combined Cycle (IGCC) Station in Knox County, Ind. is already making history as the largest IGCC plant in operation in the U.S.
The technology works like this: Coal reacts with pure oxygen and steam to produce synthetic gas, or syngas, that burns cleaner than the traditional means of burning coal and stripping the pollutants out of the exhaust gas.
But the Edwardsport project did not come without its setbacks, as the project faced several regulatory obstacles over eight years before entering operations.
In the Beginning
|Two heat recovery steam generators help to power the Edwardsport coal gasification plant in Knox County, Inc. Photo courtesy of Duke Energy|
The utility performed a feasibility study in 2005 to determine if the project was necessary. Duke wanted to replace the 160-MW Edwardsport coal-fired plant, which was built in the 1940s and was shut down in March 2011.
Doug Esamann, president of Duke Energy Indiana, said the company was interested in using the IGCC technology.
“We have a lot of coal in the region, so it has long been an economic source of energy for our customers,” Esamann said. “We produced over 90 percent of our energy from coal historically.”
Duke also had to consider load growth, the retirement of older coal-fired power plants and the capacity that needed to be replaced. The utility filed the feasibility study with the Indiana Public Utilities Commission and requested regulators to fund a Front End Engineering Design (FEED) study. Once completed, Duke Energy filed for a Certificate of Public Convenience and Necessity permit, which also included an approval for project cost estimates of $1.985 billion, Esamann said.
Once the utility received approval around late 2007, construction officially began in March 2008. Duke then selected the equipment and contractors, picking General Electric (GE) to provide the syngas turbines, radiant syngas cooler and gasifiers. In turn, GE formed an alliance with Bechtel, which performed the engineering and design work for Edwardsport.
“We’re out securing contracts pre-recession, so the companies were pretty robust and commodity prices were higher than we thought,” Esamann said. “Some of the contracting didn’t come in as low as we thought, so pretty quickly, we had to revise our cost estimate to $2.35 billion.”
Commissioners approved that request, and work was allowed to continue. However, Duke Energy had to go back to the commission to ask for more money for the project because GE and Bechtel increased the cost of materials and quantities.
“One of the criticisms we received is that the estimate went up, but it went up because the folks with the proprietary technology came back and said it would cost more than they initially thought,” Esamann said. “We were well into construction, so we had to go back and ask for another increase that was another $500 million plus, so the cost estimate was now $2.88 billion. They ultimately approved it in 2010.”
GE created a model of the power plant to test its performance through a range of scenarios to identify any potential problem areas, said Delome Fair, general manager of GE’s Gasification business.
|The integrated gasification combined cycle technology on site. Photo courtesy of Duke Energy|
The plant entered commercial operations on June 10, 2013, more than eight years from the first feasibility study and with a final cost of $3.5 billion, including construction costs and interest-carrying costs, Esamann said. Duke is only allowed to pass on $2.6 billion to customers as part of an agreement with state regulators. Due to the distinct technology used at the plant, Duke Energy said it would take 15 months for the plant to build up to its long-term level of availability, but the plant is providing electricity to the grid.
Reliability and flexibility
Although the plant is in commercial operation, there are still a few things that need to be finished on GE’s part, including plant validation and performance testing, GE’s Fair said. The date for the performance test has not yet been set.
The Edwardsport plant is expected to emit 33 percent fewer nitrogen oxides, 75 percent fewer SOx emissions, 62 percent less carbon monoxide. What’s more, it will use less water than a traditional supercritical coal-fired power plant, according to Jason Crew, general manager of GE’s Gasification business. In addition to fewer emissions, the plant was also designed for improved reliability and operations.
“Availability is money in the operators’ pockets,” Crew said. “We wanted an understanding of how the components operate, how the plant works during trips, how does it manage itself overall.”
Fair said the plant was also designed to produce power from both power islands.
“But to achieve availability, we built in flexibility,” Fair said. “In the plant, the syngas can go to either generator, the steam can go to either power island.”
Having two power trains in the plant also means better coordination during maintenance outages or non-peak times. Traditional power plants that use syngas can only run at 85 percent availability, while Edwardsport runs both power islands at 50 percent.
“We are able to coordinate the outages so it is always going to make some power,” Fair said. “You can shut down one and run the other at 100 percent. You get the same total amount of power produced, but the availability is always there.”
Esamann said the plant was built to eventually capture carbon. Due to the expense of capturing carbon emissions, Duke Energy customers did not want the technology installed until it was deemed necessary.
“There’s space left on the site near equipment purposely left for carbon capture equipment,” said Edwardsport Station Manager Jack Stultz said. “When the regulation comes forward, we can get it designed and hooked in.”
Crew agrees. “The plant is ready for the future of carbon capture,” he said. “We think the performance of the plant shows that (coal) is viable and the technology has been demonstrated.”
Tampa Electric’s Polk Power Station in Florida uses single train IGCC technology. GE said they wanted to improve on that system when they were building Edwardsport.
“Edwardsport is the evolution of the technology,” GE’s Crew said. “Polk is a single train technology. We wanted to take it further with Edwardsport.”
Duke Energy’s Stultz said that the community has been behind the plant since the beginning.
“The community has been an amazing support from the time we began efforts to get regulatory approval and air permits. They have been behind us 100 percent and that’s much appreciated,” Stultz said. “That support comes from local community as well as the state.”
Duke’s Esamann said that even though there were challenges in building the plant, it was well worth it.
“I’m proud to be the first to do this,” Esamann said. “The further we go out in time, the more it will pay off in the long run.”
Power Engineerng Issue Archives
View Power Generation Articles on PennEnergy.com