One has to decide if a CCGT is a pure energy resource paid off through maximum sales of its electricity, or a flexible resource that holds back on production to support the grid.
Eric Gimon and Robbie Orvis, Energy Innovation: Policy and Technology, LLC.
The Combined Cycle Gas Turbine (CCGT) power plant is the Swiss-Army Knife of today's US power system. The CCGT can provide a flexible amount of power at a reasonable price and CCGTs do the lion's share of adjusting generation to match variable load, for example helping to meet day-time loads alongside generators that run 24/7. With cheap gas on the horizon in the near- and medium-term future, CCGTs are, along with renewables, the primary type of capacity being added to the grid today.1
When planners evaluate which types of resources to add to the grid, they often use a set of metrics to compare technologies. One common metric is levelized cost of electricity (LCOE). LCOE is computed by dividing the entire cost of a generation source, including capital, fuel, and other expenses, and spreading it over the megawatt-hours of electricity it will generate over its useful life. While this metric is valuable for comparing generation sources, it is dependent on several assumptions. In the case of CCGTs, there appears to be confusion on both the amount of generation produced by these plants as well as the types of services these units can offer, which leads to a gross underestimate of CCGTs' LCOE.
The LCOEs often quoted for CCGTs assume capacity factors2 that are far above observed data. This discrepancy skews LCOE numbers down, makes them appear cheaper than they are, and distorts decision making.