Port Washington Generating Station, Port Washington, Wisconsin

Power, Aug 1, 2005 by Wicker, Ken

We Energies' repowered 545-MW gas-fired power plant on the shore of Lake Michigan replaces a coal-fired plant that was the most efficient in the world when it went on-line in 1935. The new plant isn't just more efficient and much cleaner than the old one. It also takes advantage of a new Wisconsin law that allows a non-utility generation company to build and own, but not operate, power plants.

Owner: We Power LLC

Operator: We Energies

Milwaukee-based We Energies is proud of the newest member of its power plant family--the 545-MW natural gas-fired combined-cycle Port Washington Generating Station (PWGS) on the shore of Lake Michigan (Figure 1). PWGS replaces the old Port Washington Power Plant, a coal-fired unit that in its heyday was a model of efficiency (see box). The new plant also is the twin of another unit that will be coming on-line right next door in 2008.

Why is PWGS one of POWER's Top Plants of 2005? Because its combined-cycle configuration is used to meet intermediate loads--which is unusual--and because it is the first power plant built under an interesting new state law that allows utilities to lease power plants from unregulated owners.

Less risk, same reward

We Energies decided to build PWGS after the Wisconsin State Legislature enacted the Leased Generation Law in 2001. The law allows a non-utility generation company (such as We Power LLC, which is owned by We Energies), to build and own--but not operate--new generating units. The law received broad support from a coalition of customers, environmentalists, labor unions, the business community, and the state's municipal and cooperative utilities. We Energies developed its "Power the Future" (PTF) program in response to the law's passage.

"The PTF program works like this," explains Mark Stone, a We Power VP and the director of the PWGS project. "We Energies will be leasing the plant under a long-term contract, as the new law allows." The Public Service Commission of Wisconsin approved the lease, and PWGS will be operated and maintained by employees of We Energies. When the lease expires, We Energies will have the opportunity to renew it, to buy the generation assets outright, or to secure the generation it needs elsewhere--a win-win-win scenario for the holding company.

"It really is a great opportunity for us to get the local generation we need, without incurring the financial risk involved in investing in a new power plant," Stone adds. "We not only get the reliable generation we need within our service territory, but we also can control its cost and availability without worrying about construction costs and delays," chimes in Steve Quade, We Energies' asset manager.

We Energies' PTF strategy represents a corporate commitment to invest in generation infrastructure while minimizing customers' electricity bills. According to Doug Wetjen, a project manager at We Power, PWGS is the first power plant built in line with the strategy. What makes PTF different is that plants built by the unregulated subsidiaries of other holding companies are usually designed as merchant plants, which will sell their output into the open market. In the case of PWGS, the plant was built to serve We Energies' regulated customers alone. "The benefit to We Energies is that we will operate the plant; therefore, O&M costs will remain regulated," Wetjen says.

Key systems and suppliers

PWGS is a combined-cycle plant that is powered by two gas-fired General Electric 207FA gas turbines, each of which feeds a three-pressure heat-recovery steam generator (HRSG) from ABB Alstom Power Inc. (Windsor, Conn.). The HRSGs' main steam conditions are 2,000 psig and 1,055F. Each unit is rated at 575 MW with duct firing and 500 MW without it. The plant's single D11 steam turbine (Figure 3) also was supplied by GE. Washington Group International provided engineering and procurement services for the project, while Wisconsin Power Constructors oversaw construction. The table lists the suppliers of PWGS' major systems and equipment.

Right off the bat, We Energies faced a big challenge: Fitting the new plant within the old plant's building. To do so, the length of the gas turbine/HRSG power trains had to be minimized. The solution chosen was to shorten the transition piece between each gas turbine and its HRSG. According to We Power Project Chief Engineer Paul Haubert, "The new piece uses a squared-off transition rather than the typical sloping one." To verify the design, engineers built a scale model and aerodynamically tested it. "[The design] seemed to work fine in the aerodynamic model, so we went with it," says Haubert. "So far, we haven't had any problems."

Port Washington's sister unit, which breaks ground next year, will have exactly the same equipment complement and therefore should produce some economies of scale. "Having the same equipment improves the consistency of O&M practices and should lower our spare-parts inventory costs as well," Quade explains.

Different strokes

As mentioned earlier, PWGS is an unusual combined-cycle facility in that it was designed as an intermediate-load plant. By contrast, most combined-cycle plants are designed for baseload service, although many run as intermediate-load units. One reason We Energies took this approach is that annual load growth on its system has been a modest 2%. Not having built any intermediate-load or baseload generation since 1985, the utility went with a combined-cycle configuration to maximize the plant's flexibility.