Port Washington Generating Station (PWGS) is two for two. Phase 1, placed into commercial service in July 2005, was a
POWER Top Plant. So, too, is Phase 2, the second 545-MW power block of We Energies’ PWGS, located on the shore of Lake Michigan. Phase 2, which entered commercial service on May 23, 2008, after successfully completing its final testing activities, effectively doubles the plant’s output to 1,090 MW (Figure 1).
1. Siamese twins. Unit 2 of the Port Washington Generating Station rises next to Unit 1, which was completed by URS Washington Division’s Wisconsin Power Constructors in 2005. Phase 2, using a virtually identical design, entered commercial service in May this year. Courtesy: URS Washington Division
“[The completion of Unit 2] is a major part of our investment in upgrading the energy infrastructure of the region,” said Rick Kuester, executive vice president of Wisconsin Energy Corp., the parent of We Energies. “The Port Washington units are a cornerstone of our effort to provide the energy our customers need now and in the decades ahead.”
The PWGS, located 25 miles north of Milwaukee, replaces the original station on that site. The historic station, built in 1935 directly adjacent to Lake Michigan, consisted of five pulverized coal-fired units, each of 80-MW capacity. Those units held the world’s heat rate record from 1935 to 1948.
PWGS is an intermediate-load combined-cycle plant built under provisions of Wisconsin’s unique Leased Generation Law, enacted in 2001. The Wisconsin State Legislature decided that a non-utility generation company (such as We Power LLC, a unit of Wisconsin Energy) may build and own new generating units in the state but may not operate them. PWGS Phase 1 was the first plant built under the law’s provision that utilities can lease power plants from an unregulated affiliate. It also was the first plant completed as part of Wisconsin Energy’s Power the Future (PTF) plan. PTF was announced in September 2000 as a comprehensive approach to address electricity supply and reliability issues for We Eneries’ customers in Wisconsin and Michigan’s Upper Peninsula. When complete in 2010, PTF is expected to add approximately 2,300 MW of power generation in the We Energies service area.
Proven prime mover
Phase 2 of this project is a gas-fired combined-cycle plant powered by two General Electric 207FA gas turbines, each exhausting into a three-pressure heat-recovery steam generator (HRSG) with supplemental duct firing supplied by Alstom Power Inc. The HRSGs’ main steam conditions are 2,000 psig and 1,055F. Each HRSG supplies steam to a single D11 three-pressure, reheat, dual-downward-exhaust-flow steam turbine also supplied by GE (Figure 2). Steam condensing occurs via a single-pass, divided-waterbox condenser using lake water for once-through cooling. Steam jet air ejectors maintain condenser vacuum. The cost of the entire plant was approximately $669 million.
2. Building power blocks. Work under way on the gas turbine enclosure and the heat-recovery steam generator inlet duct. A circulating water pump is pictured in the foreground. Note that the building enclosure was completed prior to winter weather setting in. Courtesy: URS Washington Division
Hot-day performance of the combustion turbines is enhanced by inlet air-cooling using lake water as the cooling medium. The chiller coils kick in whenever the lake temperature is five degrees cooler than ambient air temperature--unless the lake water temperature drops below 40F, in which case the chillers automatically throttle off. Hot-day capacity for each power block is 500 MW unfired and 545 MW in the supplemental firing mode. Fuel is solely natural gas, delivered at the combustion turbine operating pressure of 500 psig.
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