Humid air injection allows the combined-cycle power plant to generate the same power at high ambient temperatures as at low ambient temperatures with only a small heat rate impact. Cost of humid air injection is reduced because of the availability of steam from the existing HRSG or steam turbine.

The power augmentation of combined-cycle plants with AI technology is practically the same as the power augmentation of gas turbine engines with the following additional advantages:

·        The power augmentation is increased as compared to a gas turbine (for the same HAI or DAI injection rates), because the bottoming cycle (steam turbine) power is also increased due to the increased the exhaust gas flow.

·        The specific costs for the HAI technology are reduced to $150-170/kW due to the fact that steam can be extracted from the existing bottoming cycle. The costs associated with the installation of heat recovery equipment for steam generation are avoided.

·        The low specific costs ($/kW) for the incremental power, reduce averaged plant specific costs. This is particularly beneficial for power augmentation of combined cycle plants where typical specific costs are approximately $600-650/kW for new construction.