Super Power

Coal is beginning once again to dominate the U.S. market for new electricity generation. Behind the resurgence is an abundant supply, predictable costs, and lower-emissions technology that meets today’s tough environmental standards. By 2030, new coal capacity could top 154 gigawatts, nearly triple the new capacity of natural gas-fired power plants, according to the U.S. Department of Energy.

So all eyes were on Bechtel in June 2005 when it broke ground on the 1,230-megawatt Elm Road Generating Station south of Milwaukee, Wisconsin. The project is viewed by many as a test case in a shifting marketplace for energy producers.

“As Elm Road goes, so will go Bechtel’s U.S. fossil power business,” says Project Director George Conniff. “The whole industry is watching to see how we perform.”

Wisconsin Energy chose Bechtel to expand its electricity generating capacity by delivering two supercritical coal-fired steam-turbine generating units and related civil works next to its existing Oak Creek power plant on the west shore of Lake Michigan. The plant takes solid coal in chunk form and pulverizes it to the consistency of talcum powder, then combusts it with a controlled flow of air to produce 1,050-degree Fahrenheit (566-degree Celsius) steam at 3,800 pounds per square inch. The high-energy steam rotates a turbine generator. The generator converts mechanical energy to electrical energy—in the case of Elm Road, providing enough energy to power more than 1 million households.

“Supercritical” refers to the high pressure of the steam, which boosts efficiency and cuts emissions compared with a subcritical cycle. The first unit is on track to begin operation in 2009; the second will follow in 2010. And at a value of $2.15 billion, it’s the biggest lump-sum turnkey project in Bechtel’s history.

“Everything about this power project is bigger and broader than anything we’ve done before, from the weight of the steel to the height of the buildings to the size of the equipment and the extensive work outside the power block,” says Conniff.

Big jobs call for big tools, so in December 2006 the team rented the largest crane in North America to position sections of a coal conveyor gallery high above the banks of Lake Michigan and over the top of the existing power plant. (See sidebar.)

To increase efficiency, the plant was placed at the lake’s elevation, which required a massive excavation effort. Nearly 162 million cubic feet (4.6 million cubic meters) of earth were moved, with some placed as an embankment to minimize noise. Crews worked many double shifts to complete the foundation of the first boiler building. By early 2007, the steel for the primary boiler structure was nearly complete.

Like just about every other aspect of the project, the boilers dwarf their older counterparts. Elm Road’s boiler buildings will be 270 feet tall (82 meters), compared with the typical height of 200 feet (61 meters). A common chimney serving both units will rise even higher, to 550 feet (168 meters).

Numbers like that mean there’s a lot of material to manage. During the project, crews will place nearly 3 million cubic feet (84,000 cubic meters) of concrete, erect 31,000 tons (28,000 tonnes) of structural steel, erect 230,000 feet (more than 70,000 meters) of large-bore pipe, and lay nearly 7 million feet (2.1 million meters) of electrical cable. Dozens of shipments arrive daily from around the world via barge and truck, demanding months of planning to time deliveries so they meet erection schedules, manage on-site and off-site storage areas, and keep staging areas running smoothly.

The scale of the power block facilities that include the boilers and turbines is vast enough, but work is also spread out in all directions from the power block. “It’s not a compact project,” says Project Manager Stephen DeMinco. “Just managing the number of people and work areas involved is a challenge.”

A 12-mile (19-kilometer) dedicated Union Pacific rail expansion is under way and will be complete by the end of this year. To minimize the impact on local road traffic, an underpass was finished in 2006. When all rail work is finished, nine 135-car trains will deliver coal to the plant weekly.

They’ll journey to an upgraded $200 million coal-handling system, which will service Oak Creek as well as the new power units. Railcars will be flipped upside down to unload the coal, then a series of conveyors and transfer towers will move the coal to a crusher tower. This work will be finished before completion of the first unit, to provide coal to the existing plant. At the station’s peak burn rate, conveyors will deliver nearly 3,000 tons (2,700 tonnes) of coal per hour. A massive storage building is being constructed to hold up to 63,000 tons (57,100 tonnes), or about three days’ worth of fuel.

Significant offshore work also is well under way. In the summers of 2005 and 2006, four 12-foot (3.7-meter) diameter down shafts were sunk 1.5 miles (2.4 kilometers) offshore. They will connect to an intake tunnel some 200 feet (61 meters) beneath the lake’s surface. The tunnel will draw water from the lake for the plant’s cooling system. As of February, 2007, boring of the 9,200-foot (2,800-meter) tunnel had been completed. Two pump houses and a dike wall are also components of this intake system.

Elm Road is the largest private construction job in Wisconsin history. Later this year, the project will hit its peak craft level of more than 1,500 Bechtel direct-hire employees and more than 250 subcontractor personnel. Dozens of third parties are involved, including utilities, the Wisconsin Department of Natural Resources, and the U.S. Army Corps of Engineers.

One reason coal-fired power has a renewed appeal is dramatic improvements in emissions control, and Elm Road’s air quality control system is state of the art. “Federal environmental regulations have become stricter, and the technology has stepped up in response,” says DeMinco.

The boiler includes low-nitrous oxide burners and other technologies that limit the amount of hazardous emissions produced. A selective catalytic reduction system uses a specialized catalyst material and ammonia injection to further reduce nitrous oxide emissions.

A “baghouse,” or fabric collection system, filters particulate matter out of the flue gas. Then another system sprays slurry into the path of released gas, significantly reducing acid gases. This process produces gypsum, a byproduct that is sold for use as wallboard. Yet another step, involving a series of water-cleaned electrified plates and discharge electrodes, creates an electric field to remove any residual acid mist.

Less than two years into the project, the team is progressing ahead of its guaranteed contract schedule, according to customer Tom Metcalfe. He says he has been impressed by the amount of communication and permitting required to keep the project on schedule.

Adding to the complexity of day-to-day work is the fact that the Oak Creek plant is continuing to operate during construction. “There has to be constant communication between crews [at Elm Road] and the Oak Creek operators,” says Metcalfe, project director with Elm Road Services, LLC, a subsidiary of Wisconsin Energy. “We chose Bechtel because it had the stripes to deliver on a very complex $2 billion project.”

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