The Minnesota Public Utilities Commission on Sept. 26 approved an October 2015 application from the Northern States Power subsidiary of Xcel Energy (NYSE: XEL) for a site permit for the Black Dog Unit 6 project.
This is a 215-MW simple-cycle natural-gas-fired combustion turbine unit and associated facilities to be built at the existing Black Dog Generating Station in Burnsville, Minn. The project is expected to be operational by March 2018, and is estimated to cost approximately $100 million. The existing infrastructure at the generating station, which includes the powerhouse building and the 115-kV substation and transmission system infrastructure, will be used to the extent possible. Unit 6 will be fueled entirely by natural gas.
The existing Black Dog station was initially developed as a coal- and gas-fired generation station, begun as four small coal units, all of which have been shut down. There is operational gas-fired capacity at the site.
The project is designed to provide 115-kV electrical power supply to the Twin Cities metropolitan area using existing transmission infrastructure to serve existing distribution substations. The project will be constructed within an existing powerhouse building for the retired Unit 4.
The service life of the project is expected to exceed 35 years. A new natural gas pipeline is needed to increase natural gas supplies to the station. The gas supplier will be responsible for obtaining necessary permits and approvals to construct the pipeline. The pipeline project will undergo a separate environmental review process.
Minnesota statute generally requires a Certificate of Need (CON) to construct a generation facility with a total capacity of 50 MW or more. A CON is not required if the facility is selected in a competitive resource acquisition bidding process established by the commission, which is the case here.
Unit 6 will operate as a peaking generator with an anticipated annual capacity factor of 4%-10%. The Black Dog Unit 6 combustion turbine-generator will consist of the following equipment: Inlet Air Filter and Evaporative Cooler, Compressor, Combustor, Power Turbine, Generator, Main Step-Up Transformer, and an Auxiliary Transformer. Unit 6 will interconnect to the existing substation located on-site. The substation will require minor modifications that include the addition of a motor-operated 115-kV disconnect and minor buswork between the generator breaker at the substation and the high voltage transmission lines coming from the step-up transformer.