The Michigan Department of Environmental Quality (MDEQ) is holding a public comment period until June 18, and a public hearing, if requested, on June 20, on Consumers Energy’s proposed installation and operation of a natural gas-fired combined-cycle generating station.
The facility will be located at 10500 North Genesee Road, Mt. Morris, Mich. This site was chosen because it is the location of the existing Thetford power plant, there is adequate natural gas supply, the transmission interconnect is directly adjacent to it, and it is a rural setting of about 233 acres, the DEQ noted. The agency is taking comment on the project’s air permit-to-install.
Consumers Energy, a unit of CMS Energy (NYSE: CMS), has indicated this plant is needed in part to replace some of its older coal-fired capacity, which is due for shutdown in the face of new air emissions constraints. The utility has indicated plans to develop this first as a 700-MW facility, with later expansion to the full 1,400 MW.
Currently, there are several smaller gas-fired simple-cycle combustion turbines (CTs) located at the facility. All of the existing CTs will be retired after the new station is commissioned. The new station is proposed to be located directly east of the existing CTs and will be designed to produce up to a nominal 1,400 MW (gross power output) of electricity for the transmission grid.
The draft air permit for the proposed generating station addresses the following equipment:
- a total of four natural gas-fired F-class combined-cycle CT each coupled to a heat recovery steam generator (HRSG) equipped with a natural gas-fired duct burner (DB), configured into two CT/HRSG trains per block (for a total of two 2×1 blocks);
- two natural gas-fired simple-cycle black start/peaking combustion turbine generators (CTG);
- two air cooled condensers (one per 2×1 block);
- one small diesel engine-powered emergency fire pump;
- two natural gas-fired auxiliary boilers (one per 2×1 block); and
- two fuel gas heaters (one per 2×1 block).
Each CTG is nominally rated at 211 MW to 230 MW of gross power output at ISO conditions (59°F, 60% relative humidity and 14.696 psia). To provide flexibility in meeting future load demands, each CTG unit will be coupled to a HRSG that is capable of unfired and fired operating modes.
The specific electricity generating equipment has not yet been selected by Consumers Energy. There are two likely potential equipment suppliers for the primary CTG. The preliminary performance specifications for the CTG, from each of the potential equipment suppliers vary slightly.
The new station and equipment must be capable of “black starting” and providing power to Consumers Energy’s Karn Station, located nearby, for system restoration during a widespread loss of power. This will be accommodated by first starting a black start/peaking CTG and then one of the four CT/HRSG trains. It is therefore imperative that the generating equipment purchased for this project have proven reliability with minimal outages for maintenance, the DEQ noted.