September 1, 2009

Top Plants: Riverside Repowering Project, Minneapolis, Minnesota

Dr. Robert Peltier, PE

Be a Good Neighbor

Kelly kept his promise to minimize the impact of repowering Riverside to the surrounding neighborhood by ensuring that the plant was designed and will be operated as a good neighbor. This was an important promise because the plant is located in an urban setting with single-family homes only a few yards away. Many families have been neighbors of the plant for several generations. Beyond eliminating the inevitable coal dust problems, additional engineering and sound-quieting components were added to the plant to manage the high-frequency noise from the combustion turbines and other noise sources originating in the plant. The noise impact on neighbors will also be lessened because natural gas arrives by underground pipeline rather than unit coal trains.

Removal of the plant’s 475-foot stack also lessens the plant’s visual impact and eliminates what was perhaps the most visible landmark in northern Minneapolis. Employees of Xcel also have demonstrated their desire to be good neighbors by their actions. For example, across the street from the plant are Brady Park and Marshall Terrace Gardens, public parks that Riverside Plant employees helped build.

How’s It Going?

The plant had performed about 80 starts through mid-July with no start-up failures. Overall unit trips were described as "very low," so the first few months of operation are going quite well. The plant is also described as exceeding its guaranteed performance numbers during the initial performance test with a heat rate better than design. Tests with the combustion turbine evaporative coolers in service are the only performance tests remaining.

The plant is designed to be operated as an intermediate-load asset within the Midwest ISO and is usually dispatched after nuclear and baseload coal-fired plants. However, Riverside does have one big advantage: Performance testing shows the plant can turn down from full-load 470 MW net to 230 MW net while staying in compliance with its permit emissions limits. Optimizing ramp rates and controls tuning continue.

—Dr. Robert Peltier, PE is POWER’s editor-in-chief