The Federal Energy Regulatory Commission on July 16 granted Yuma Cogeneration Associates a break because various problems had kept it in the 2010-2012 period from meeting the energy efficiency standard for a qualifying facility (QF).
On May 17, Yuma filed a petition for temporary waiver of the QF efficiency standard for the calendar years 2010, 2011 and 2012 with respect to Yuma’s 52.3-MW natural gas-fired topping-cycle cogeneration QF located in Yuma, Ariz. This QF is interconnected to Arizona Public Service’s transmission system and the entire output is sold to San Diego Gas & Electric (SDG&E) under a long-term power purchase agreement (PPA).
The Yuma QF consists of one General Electric Frame 6, natural gas-fired combustion turbine generator, one heat recovery steam generator with supplemental firing, and one extraction/condensing steam generator. The thermal host is a carpet manufacturing facility owned and operated by Shaw Industries. Shaw uses steam from the Yuma QF in its carpet manufacturing process and as a heat source for absorption chillers.
Yuma stated that its QF operated as a baseload generator, running continously each day, until late 2009 when it decreased operation to five days a week for sixteen hours a day. Yuma explained that several factors led to this change, including increased curtailment rights exercised by SDG&E under the PPA, an economic downturn resulting in reduced annual steam offtake at Shaw, and changes implemented by the California Public Utilities Commission to the implied heat rate factor used in the short-run avoided cost rates under the PPA. Yuma stated that the decreased operation led to an average of two to three, and as many as five restarts per week and reduced the efficiency of the QF.
Yuma asserted that its QF’s start-up period lasts three hours, during which it operates at an average efficiency of about 34% to 38%. Yuma stated that the increased frequency of these start-up periods brought the QF’s overall efficiency below the 45% efficiency standard (44.5%, 43.7%, and 43.4% for 2010, 2011, and 2012 respectively). Yuma stated that it was not aware of and did not discover its failure to meet the efficiency standard until late March, when it reviewed and corrected its operating efficiency calculation to include the start-up fuel consumption and energy production.
Yuma stated that it anticipates that the QF will meet the efficiency standard for 2013 and going forward by minimizing the number of shutdowns and start-ups, i.e., running the plant continuously through curtailments, and selling any excess power produced during the curtailment periods to SDG&E under the terms of the PPA.
Yuma contended that its waiver request is timely, unopposed, limited in duration, due to unforeseen circumstances, and consistent with the goals of the Public Utility Regulatory Policy Act of 1978 by encouraging cogeneration facilities that provide economic and environmental benefits, as well as significant energy savings. FERC in the July 16 decision granted the waiver for the 2010-2012 period.