Villified by environmentalists as a colossal boondoggle that will drive up electricity prices for Duke’s approximately 790,000 customers and is not needed to meet power demands in the Midwestern state, Edwardsport’s backers claimed vindication when the 618-mw baseload plant started to supply power to the grid.

The $3.5 billion plant, located in a rural area of Knox County in southern Indiana, uses advanced technology to gasify coal, strip out pollutants and then burn the cleaner gas to generate electricity. Duke, a subsidiary of Charlotte, N.C.-based Duke Energy, calls Edwardsport one of the world’s cleanest coal-burning power plants and says the technology substantially reduces the environmental impact of burning coal to produce electric power.

“Coal has powered Indiana for more than a century,” said Doug Esamann, Duke Energy Indiana president. “But today’s air quality standards require us to use that fuel in a cleaner, more efficient way. Edwardsport turns coal into a cleaner-burning fuel and enables us to continue using an abundant local resource.”

Peabody Energy’s Bear Run mine in neighboring Sullivan County, Ind., is supplying high-sulfur coal to Edwardsport. Bear Run, the largest surface mine east of the Mississippi River, opened in 2010. It sold 7.7 million tons of coal in 2012 and has a capacity of up to 8 million tons annually. The mine produces coal from the Indiana No. 5, 6, 7 and 5A seams.

As the company told the Indiana Utility Regulatory Commission, Edwardsport represents the first time IGCC technology has been used on such a large scale in the U.S. As a result, the plant is expected to ramp up to its long-term level of availability over the next 15 months.

Esamann noted that Edwardsport replaces about 500 mw of older coal-burning generation that Duke recently retired or plans to retire soon because of new Environmental Protection Agency rules. “The average age of coal-fired plants on our Indiana system is 45 years, and this facility is key to modernizing our system and filling the gap left by plant retirements,” he said.

According to Duke, Edwardsport produces 10 times as much power as a former coal plant at the same location that was closed a year or so ago, albeit with about 70% fewer emissions of sulfur dioxide, nitrogen oxide and particulates combined.

Edwardsport uses excess steam that normally would be wasted to power a second turbine and increase plant efficiency and output. It lowers carbon dioxide emissions per megawatt-hour by nearly half compared to the plant it replaced. And, it uses less water than a conventional coal-burning power plant.

Duke said the plant also is a major boon to Indiana’s economy. During the lengthy construction period that started in 2008, about 3,500 construction workers and other professionals were employed on the project. Edwardsport will employ about 140 full-time workers. It will use 1.7 million to 1.9 million tons of coal annually, supporting an estimated 170 mining jobs.