Brush Unit 2 added to resource mix

On Oct. 1, Tri-State added a new generating resource to its mix of baseload, contracted federal hydropower, intermediate, peaking and renewable generation sources - Brush Unit 2, a 70-megawatt natural gas, combined-cycle unit located in eastern Colorado.

Brush Unit 2 is part of the 300-megawatt co-generation plant operated by Colorado Energy Management.  Tri-State has a 10-year tolling agreement with the plant operators.

According to Susan Hunter, long-term origination specialist, this power agreement is similar to the one Tri-State has with the Fort Lupton plant, which began providing up to 150 megawatts of capacity to the G&T on July 1. “How often we call upon the Brush unit will depend on a number of factors, including weather, market pricing and availability of our baseload generation,” she said.

As a combined-cycle unit, Brush Unit 2 is generally considered to be an “intermediate” resource, meaning it would be scheduled to run after the less-expensive baseload units such as Laramie River and Craig stations, but before the more-expensive, simple-cycle peaking generators such as Knutson or Limon Generating Station.  The price of market power is also a factor as to whether it is more economical to buy market power or run existing units.

Combined-cycle gas plants consist of one or more gas-fired turbine generators equipped with a heat recovery-steam generator to capture heat from the gas turbine exhaust.  This usually makes them more efficient and less expensive to operate than simple-cycle peaking units.

Updated: October 30, 2009