The Public Service Commission of Wisconsin on May 6 approved a May 2015 application from Wisconsin Power and Light (WP&L) for a Certificate of Public Convenience and Necessity (CPCN) to construct a new natural gas-fired, combined-cycle (NGCC) facility with a nominal nameplate capacity rating of 650 MW.
The project, known as the Riverside Energy Center Expansion project (Riverside), includes construction of the NGCC facility and a 2-MW solar energy facility, and would be located near the site of the existing Riverside Energy Center in the town of Beloit in Rock County, Wisconsin. The estimated cost of the proposed project is approximately $700 million.
The proposed project includes construction of a new NGCC in a “two-on-one” (2×1) configuration. Under this 2×1 configuration, two natural gas-fired combustion turbine (CT) generator sets produce electricity using a simple-cycle generation process. Hot gases from the CT exhausts are directed into two heat recovery steam generators (HRSG), with the resulting steam from the HRSGs sent through one steam turbine generator to produce additional electricity
The proposed project also includes the installation of the 2-MW solar facility and will require an expansion of the existing high-capacity collector well, modifications to the on-site natural gas supply system, and the construction of a short 138-kV or 345-kV transmission line to connect the Riverside plant to the transmission grid.
WP&L proposes to construct the Riverside NGCC project to meet the energy and capacity needs of WP&L and its customers in a cost-effective and reliable manner. In 2012, WP&L announced plans to retire several older, less efficient coal-fired units. WP&L plans to or has retired:
- Edgewater Unit 3 and Nelson Dewey Units 1 and 2, by Dec. 31, 2015;
- Edgewater Unit 4 by Dec. 31, 2018;
- Rock River Units 3, 4, 5, and 6 by the mid-2020s; and
- the Sheepskin combustion turbine units by the mid-2020s.
The planned retirements will reduce the total capacity of WP&L’s generation fleet by approximately 640 MW. Annual energy produced by the units to be retired represented approximately 17% of WP&L’s energy production in 2013.
Also, WP&L has several short-term energy contracts that are expiring, which further contributes to the need for a cost-effective, long-term energy resource. In total, the retiring generation facilities and the expiring energy contracts served approximately 30% of WP&L’s energy needs in 2014.
The existing Riverside Energy Center units are currently connected to ANR’s Tiffany East Gate Station by a 20-inch delivery lateral. WP&L owns and operates this delivery lateral, which is large enough to continue to provide natural gas service to the existing Riverside Energy Center units as well as the proposed Riverside project. Minimal upgrades will be required at the ANR Tiffany East gate station, and WP&L will need to construct an extension of approximately 1,500 feet from the existing Riverside Energy Center to the proposed Riverside project.
While the final configuration of the transmission interconnection is unknown at this time, WP&L states that it expects the proposed Riverside project will be interconnected with the existing 138 kV transmission system in the area. In September 2014, WP&L submitted a generator interconnection request for the proposed Riverside project to the Midcontinent Independent System Operator (MISO). MISO is processing WP&L’s interconnection request as a part of its February 2015 Definitive Planning Phase (DPP) cycle. The DPP will include a series of studies designed to evaluate the effect of the interconnection of the proposed Riverside project on the existing transmission system.
After MISO completes its DPP studies, WP&L will execute a generator interconnection agreement (GIA) with MISO and the transmission owner, American Transmission Co. LLC (ATC). The GIA will define the necessary interconnection facilities and any transmission system network upgrades that will be required to construct an unconstrained transmission interconnection for the proposed Riverside project.
Said the May 6 aproval order: “The Commission finds that the proposed Riverside project is in the public interest considering alternative sources of supply. WP&L conducted rigorous analyses demonstrating that when compared to a multitude of resource alternatives, including the conversion of existing generating resources, the proposed Riverside project satisfies WP&L’s energy and capacity needs in the most effective manner. In addition, these analyses further demonstrate that the proposed Riverside project will adequately address the present needs of WP&L’s electric system and are necessary to satisfy the reasonable needs of the public for an adequate supply of electrical energy. Lastly, WP&L’s analyses demonstrate that the proposed Riverside project will not impair the efficiency of the applicant’s service, will not provide facilities unreasonably in excess of probable future requirements, and when placed in operation, will not add to the cost of service without proportionately increasing the value or available quantity thereof.”