Partial-Load Heat Rate Improvement Reduces Fuel Costs And Delivers Positive Cash Flows

The 385 MW CCGT unit #5 at Genesis Energy’s Huntly Power Station has been in service since June 2007, mainly in base-load operation. Due to the increase of renewable energy in the New Zealand market, operation of Huntly is shifting toward more partial-load operation. The TOMONI® Turbine Cooling Air (TCA) Optimization solution provided Huntley with more precise control of the TCA fans to optimize rotor cooling air temperature through control logic modifications and power electronic inverters. Another important solution for the plant was the “pay-as-you-go” payment method applied for the initial capital investments for the upgrade of the TCA fans and control system. Fuel cost savings from 0.6% partial-load heat rate improvement vary but can be in the range of 200,000–800,000 USD per year, depending on fuel cost and unit dispatch. In addition, as the operating load range changes during normal operation, the TOMONI Turbine Cooling Air Optimization solution automatically comes in and out of service to maximize the economic benefit.