Frontera Final Product

Not Just More Megawatts, Better Megawatts: The Case for Combined Cycle Output Augmentation in a Low Power Price Environment

Currently, the fragmented U.S. wholesale power markets do not face a scarcity of megawatts, as evidenced by the North American Electric Reliability Corporation’s (NERC) recent Summer Reliability Assessment and reported by Public Power Daily here.

However, this does not suggest turbine inlet air chilling (TIAC) is not a valuable resource for U.S. power generators.  TIAC quickly elevates a combined cycle unit’s productive capacity during challenging ambient conditions. The benefits of the additional megawatts produced from low-heat rate/low-cost generation resources may be evaluated on a relative (better) or absolute (more) basis.

 
 
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Supplementary “Duct” Firing for Combined Cycle Power Plants & How it Compares to TIAC

While both Supplementary or Duct Firing and Turbine Inlet Air Chilling (TIAC) are solutions to offset the megawatt output degradation of gas turbines when ambient temperatures rise, the two technologies take very different approaches.  With TIAC, the combustion gas turbine inlet air is chilled. In the case of duct firing, injection of fuel is utilized to increase the temperature and mass flow rate of the exhaust gases.

Rather than competing, the two technologies – duct firing and turbine inlet cooling – can actually complement each other when used correctly.

For maximum power output, power plant owners can utilizing the reliable power augmentation provided by TIAC, and balance the requirements with duct firing.  This scenario allows them to produce the required power at the lowest possible heat rate.

However, the combination of TIAC with Duct Firing is rare – most owners choose one solution over the other. Let’s look at how Duct Firing works.

 
 

Supporting the Use of Renewable Energy with Consistent Inlet Air Temperature

The changes in U.S. electricity supply and usage levels are rapidly reshaping utility load profiles and thus generation and transmission requirements for both new and existing resources.

The recent discovery of relatively cheap natural gas in the U.S. and growing use of the fuel as a baseload power generation source has also coincided with the rapid adoption of renewable resources in many parts of the U.S.  These new components of the electricity supply stack continue to displace more traditional and older forms of baseload power generation, coal and nuclear units, for both economic and public policy motivations.  Unfortunately, these growing pieces of the U.S. generation supply side all are subject to weather related intermittency.