One reason Elm Road will be among the most efficient coal-fired power plants in the world is its cooling system. The lower the steam turbine’s exhaust temperature, the more heat has been turned into electricity.
Rather than using cooling towers, in which water recirculates from condensers to the cooling tower and back, sending heat into the air, Elm Road has a more efficient “once-through” cooling technology. A tunnel 9,200 feet (2,800 meters) long and 26 feet (eight meters) in diameter will carry water from Lake Michigan into the plant’s condensers and then back to the lake, carrying the heat from the turbine exhaust with it.
The system has been designed to minimize any impact to aquatic life. The tunnel is in bedrock 200 feet (61 meters) below the surface of the lake. Its 24 custom-designed wedge-wire intake screens, with mesh openings, will limit inlet velocity to less than a half foot (15 centimeters) per second. The slow water speed and tiny openings help prevent even the smallest creatures from being pulled in or entrapped. Also, the intake end is positioned along the lake bottom far from shore, where there is minimal aquatic life. “The design and construction of the bypass channel and wetland represent a tremendous team effort,” says Stephen McCracken, assistant manager for Environmental Management with DOE’s Oak Ridge office.
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